Home General Building Preservation Questions and Answers
General Building Preservation

Boards over ash

Q Over a year ago we had to have the kitchen and dining room floors dug out and replaced with concrete and all the walls replastered due to the flooring being black ash, and we had rising damp. This was costly and a huge upheaval, we now have noticed white spores under the floor boards in the front of the house as this is still black ash with wooden boards laid directly on top of it. Is there an easier more cost effective way of resolving the damp on the floor boards rather than digging it all out and concreting all the other floors? There appears to be no damp on the walls in the front room or hallway this time, unlike previously in the kitchen and dining room. The house is early 1930s.


A You say white spores? Do you mean white crystalline deposits? Is your floor construction boards nailed to timber fillets with ash mortar between the timber fillets virtually up to the underside of the boards? How do you know it is damp? Is the wood rotten or wet? If you use a moisture meter on such a material (ash) you will record a high reading due to the conductive properties of the ash - even if it is dry. Is this your situation? Please let us know. You should obtain an opinion from a a suitably qualified person.

 

When it rains the house smells?

Q I have a 1900 terraced house with a cellar. Recently water has started to seep in from the ground into the cellar. I noticed that when it rained recently there was a horrible smell in our house, smelled like sewage, but the smell only lasted for a few hours, this seemed to be connected to when the rain fell heavily. The smell has now gone, but there is still water in the cellar any ideas on how to resolve this problem?


A You should have all of your drains (and possibly your neighbours drains) tested first of all. Also get the water authority to test the water in the cellar to see if it is sewage, mains water or rain water. If it is just natural ground water then an answer would be to install drainage together with a sump and pump.

 

What is the risk of fungal decay?

Q I have had a leak in the ceiling from the upstairs flat which has left a damp patch. It is highly likely that the leak was only of a short duration. What is the potential for damage to wooden ceiling joists and the window frame beneath the leak?


A If the leak only happened for a short while then the risk of wood rotting fungal decay occurring is very small indeed. Any timbers affected would very quickly dry down to below the moisture content required for any of the wood rotting fungi to survive.

 

Bitumen odour from under the floor

Q I have recently moved into a 1920's semi-detached bungalow. The ground in the crawl space beneath the floor of the house (between the foundations) has been covered with some sort of bitumen in the past. This bitumen layer has a very strong tar-like smell which is permeating into the rooms of the house. There does not seem to be any problem with dampness or water collection and there are several air bricks ventilating the crawl space. I would be very grateful for any advice as to what the best way to tackle the smell problem would be. Would I be able to cover the ground with some form of thick plastic sheeting or should I go down the much more disruptive route of getting the bitumen removed?


A Sub floor odour percolating up into accommodation areas is not unusual but it is usually a damp musty smell - not bitumen. The bitumen on the floor of the crawl space is there to keep the sub floor area dry so we would advise against removing it. Because the bitumen is doing a good job it is probably reasonably dry beneath the floor and we would suspect that the sub floor ventilation is poor - probably served by a few 9x3 terra cotta air bricks. We would suggest that you improve the sub floor ventilation by fitting into the external walls 9"x6" square pattern cast aluminium or plastic louvre type air vents every 1.5 metres. Also make certain that there are holes in sub floor walls to allow a draught through. With improved sub floor ventilation the smell will be dispersed before it percolates up into the property.

 

When to do damp and timber treatment?

Q We've had a damp and wood worm survey done on our property. The survey established the need for a damp proof course and wood worm treatment. My question is when is it best to carry these works out?  Three of the four walls that were identified as needing a DPC are being knocked down and replaced as part of a side return kitchen extension and the builder has confirmed that he will put his own DPC in the new section. Therefore, should we wait for the building work to finish and get the DPC and wood worm treatment carried out or can everything be done at once?


A We would suggest that the DPC (and we assume re-plastering) in the one remaining wall is undertaken in conjunction with other building works so the 'dirty' mess is all over and done with in one operation. Be careful about who does the replastering on the wall to be treated - make certain the correct specification is followed. Woodworm treatment requires rooms to be empty and no one else on site so we suggest that you discuss this with the builder and programme it in with his work.

 

There is a smell in my flat

Q I live in a ground floor flat in a Victorian country house. We discovered that a spur off the main water intake in the main entrance hall was leaking and appeared to have done so for a period of a few months. The valve has been replaced and the cupboard housing the water intake has dried out quickly. I have been noticing a smell in my flat and I can't locate the source. It is only noticeable for a few minutes at a time and generally when first entering a room. Obviously the leaking water has gone somewhere and I worry that it is under my flat. Now that the leak has been repaired how can I discover if wet rot is the cause of the smell and what should be done about it?


A Wet rot as a general rule does not smell. Dry rot however has a very distinct 'mushroom' smell similar to that experienced when opening a sealed box of mushrooms. The smell you are experiencing could just be a musty smell percolating up from the damp oversite beneath the floors or it could be a musty smell caused by mould present in your flat as a result of condensation which could be occurring but is unseen. The current cold weather (January) will cause condensation to form more readily in properties. Make certain that the sub floor ventilation is good which would disperse odour and aid the oversite drying process which is likely to take years.

 

White powder on roof timbers- Is it dry rot?

Q A year ago we bought a 1930s semi with a three sided (hipped?) roof.  The loft space has been (unofficially) converted into a living area leaving a 3 sided crawl space behind the vertical board walls.  There were roof vents in situ to two sides when we moved in.  We are now in a position where we have to have a re-roof and when I went to see what was to move out of the crawl space I discovered white powder covering most of one of the main ridge rafters and patches on most of the other rafters.  I am horrified!  If this is, as I suspect, dry rot, can affected timbers be treated or would they have to be replaced.  Obviously having to have a re-roof anyway - can the roofing company treat where necessary or do we have to find specialists?  I am terrified this is going to take the job way over our budget.  Any help is would be very much appreciated.


A Thanks for the reply. We would be interested in any photos that you may have and the outcome of the inspection on Thursday. Please do not agree to anything rash or let yourself be talked into a form of treatment that may not be necessary. Please call me first if you want. It sounds like your roof covering may have been renewed at some time in the past since it already has a sarking felt and the magnesium sulphate could possibly be historic left over from the original roof covering. You should cut holes in the felt adjacent to the vents to let the ventilation work.

Q Hi and thanks very much for taking the time to look at my question.

It is true that these timbers are situated beneath a tiled roof.  My worry is that, although there are vents in situ visible from the outside they do not penetrate the felt beneath the slate! (this was spotted on the survey)

I have contacted a local firm who specialise in wet/dry rot etc and they are coming to assess the situation later in the week. I sincerely hope you are right in your diagnosis. It does strike me as strange that it is affecting two particular rafters  (dramatically) while nothing has spread to adjoining timbers - but is just showing in tiny little patches here and there. Would it be helpful to you (and other people) to have photos and the outcome of the inspection on Thursday?  I don't mind at all - if it would help you to help worried home owners like myself!  Please do let me know. Fingers crossed and many thanks once again.

A We think we understand what you are looking at and believe it to be magnesium sulphate and not dry rot. This surface deposit often occurs on timbers beneath a tiled roof - would this be the case?  It would be very unusual for dry rot to affect rafters in a roof.  Very probably all that you need do is brush it off and forget about it.

 

Leaking shower and insurance claim

Q I live on the first floor flat of a converted terrace house. Both flats (upstairs and downstairs) are occupied and are owned on a leasehold basis to a freeholder. I have had a persistent leak in my flat on the first floor which had only recently been identified as water from the bath/shower head going behind the bath tiles and seeping underneath the bath into the downstairs flat. The waste pipe in the bath had been a problem and we believed this had been the consistent culprit as the waste pipe was always wet, even when replaced. The bathroom has always smelt mouldy and the real problem of water getting beneath the tiles looks like it has been on-going since the bathroom was remodelled two years ago. The ceiling downstairs has widespread mould on bonding plaster and on wood that has become like papier-mâché once the bonding was taken off. On investigation the joists between us are thoroughly soaked. Further investigation has revealed damage to door frames and water damage to the floor and walls (in the room next to the bathroom). The building insurance is in the freeholder's name. They accept the problem has been over a long period but believe they only need to immediately retile the bathroom and immediately rebond a small part of the downstairs ceiling without any form of drying. They will only replace a small part of the ceiling downstairs in spite of wider spread water marks. The leak has been consistent as long as I have had shower in two years i.e. everyday. How should this be treated professionally?
A Leaks adjacent to showers due to damaged seals, inadequate tile grout, poor sealing doors etc. are very common. It is very important that such leaks should be addressed as soon as possible to reduce the risk of more serious wood rotting fungi developing, such as dry rot, as a result.

It is appreciated that your leak was more 'secret' and from what you describe it sounds like the cause has been identified and we hope rectified. It is very important that the 'wet' parts should be allowed to dry in well ventilated conditions. As wood dries it may warp (especially wet floor boards) and renewing these should form part of your claim. How much of the ceiling is replaced will depend upon the type of ceiling i.e. is it lath and plaster or plaster board? If it is a lath and plaster ceiling this can loose its bond as it dries and collapse at a later date. If it is plaster board it would be just as quick to replace the entire ceiling rather than patch it up which will always show.

To summarise let everything dry as much as possible before covering it up again. As you have identified and rectified the source of moisture the risk of wood rotting fungi is now significantly reduced but you are never in the clear until it is completely dry.



 

Conservatory build problems

Q We have recently had an oak framed conservatory built to join our main converted barn with a converted smaller barn (annexe).  We have now discovered the builder has not put in an adequate damp proof course in the conservatory and this has resulted in damp coming through the floor along  the 4 sides and rising into the brick walls in the barn and annexe (previously we did not have damp in these walls). We have been advised by an independent building surveyor to have the walls treated and get remedial work done on the damp proof course in the floor. Where can we find a contractor who will be able to carry out all the work we require (we do not wish to use our previous builder for obvious reasons). We live in Suffolk.
A Without actually seeing your problem it is difficult for us to advise. It is not clear if it is the conservatory floor that lacks a correctly positioned membrane (or one at all) or new walls that lack a DPC. If the problem is as obvious as you state then we would advise that you address the problem - not the consequences of the problem. It is appreciated that this may be a bitter pill to swallow and may even mean 'undoing' finished work but unless you address it you have to live with it for many years and it will always bug you.

If the work is as recent as you suggest then you very probably have legal recourse against the builder and/or architect. Your surveyor and/or solicitor should advise in this regard. Suffolk is full of great old buildings and your surveyor would be far better placed than us to recommend contractors who would work sympathetically with an old structure.
 

How do I know if my house has faulty wall ties?

Q I have recently moved into a house which was built in approx 1962. I have been told that some properties in the area may have suffered from problems with wall ties. How will I know if I have faulty wall ties?  What signs am I looking for?


A The usual way to examine wall ties is as follows; Locate the original ties with the aid of a metal detector and mark their position with a wax crayon (doesn't wash off if it rains). Select a few on each elevation then drill a hole adjacent to them into the cavity. Insert a fibre optic endoscope into the drilled hole and examine the part of the wall tie that is visible with in the cavity. If necessary remove some of the mortar to expose the part embedded in the mortar of the external skin. What you are looking for is corrosion (rust) that has affected the structural integrity of the wall tie - not just superficial rust.

Visible damage to the property (if any) will depend upon the type of wall ties that you have (fish tails or butterfly wire) and the amount of corrosion that exists. Galvanised fish tail type have the greatest potential to cause visible damage as they expand considerably when they corrode causing horizontal cracking along the mortar course in which they are embedded - approximately every seven courses of brick. This is usually most evident in the top half of the property. Wire type ties will not cause this type of damage as there is less volume of metal to corrode.

 

Polyurethane foam under slates

Q We are looking at a property that has had its slate roof under sprayed with polyurethane foam. So much so that you cannot see the roof timbers at all. Will this cause damp at some stage?


A Whilst the foam on its own will not cause damp the very fact that it is there means something was probably not right before it was applied. This foam is commonly applied when a slate roof starts to suffer from 'nail rot'. This basically means the nails holding the slates in place corrode and the slates start to slip. By applying the foam to the underside it 'sticks' all of the slates in place thus preventing further slip. In so doing it also provides a degree of insulation but this would be better positioned directly over the ceilings rather than under the slates. It probably means that the original roof is 'tired' and may be near to the end of its useful life but the foam has extended its life.

 

Water under kitchen floor

Q Our house is on a slight slope and we have found on renovating that under the kitchen floorboards the soil is damp (with damp evident in the walls too), during heavy rain water runs from the kitchen into the cellar. Being on a budget, to lower the water table to stop this, would it be better to dig a sump pit (for a pump) under the kitchen, or just outside in the garden adjacent to the kitchen.


A Damp soil or even water beneath a timber floor should not be a problem provided the sub floor ventilation is good. You state the water flows into the cellar - does this cause a problem? Is there a drain in the cellar? Is it possible to divert the water elsewhere? A sump and pump is an option but is it really necessary? One should also be careful with running water as this has the potential over time to wash away ground supporting the property. Get professional advice.

 

I want to lay a wooden floor but....?

Q I live in a mid terraced house built around 1880 and I'm planning on installing a wooden floor laminate or floorboards not sure yet. The existing floor is the original terracotta or quarry tiles which I believe are laid directly onto hardcore or soil with no damp proofing. What would I need to do to protect the wooden floor from any damp that could be present? At the moment there is carpet on top of the tiles and there is no sign of any problems with damp but I don't want to put a new floor in then it be ruined by damp. I know one solution would be to dig out the floor and concrete it with a membrane etc, but is there any simpler ways of doing this as I'm not too keen on digging up my front room floor. I've been advised that one way of getting round this would be to lay the wooden floor boards on 1/2 inch battens and this would give a small air gap that  would allow air to flow and eliminate any damp problems.


A You are quite right to be concerned. Water vapour will pass through carpet with relative ease but laying a laminate floor is a different story. Wood is a hygroscopic material and fitting it to battens would not prevent it from absorbing moisture, expanding and ruining the floor. We would suggest that you lay an Oldroyd membrane on the floor first before laying the actual floor. Visit Safeguard Europe's web site as they distribute Oldroyd in the UK. The membrane we have in mind is a very flat profile - we think it is called Xs but not certain. It has a criss cross pattern that allows water vapour beneath to dissipate. You should always take the advice of the company laying the floor.

 

Are properties of a certain age more prone to wall tie failure?

Q Is there any age of properties which are more at risk of wall tie failure? I was once told properties which were built from the early 1930's to the end of the war are more likely to suffer wall tie failure due to the type of metals used during this period. Is this correct?


A It is not a matter of the type of metal - it is more to do with the thickness of the galvanised coating applied to prevent rust. Over the years The British Standard increased the thickness requirement of the galvanised coating many times - the reason why is obvious. This however did not stop the coating being cracked by bending and abuse on site during fixing with the inevitable consequences.

 

Extractors vent into roof space

Q I am a leaseholder within a property & pay a service charge to a management company who look after the building. I have recently experienced problems with condensation which I am trying to rectify (using advice from this website) but have also noticed that there is no ventilation within the roof space. Other properties within the development have roof ventilation tiles except the section I live in. I am concerned as ventilation pipes from extractor fans within my property & other flats lead into the roof area but the hot air has no where to go. I have spoken to the management company who have been less than helpful & basically told me that unless I can confirm that I require ventilation tiles from a building surveyor then they will not assist. As the roof area is shared & they are supposed to maintain this - can you advise if there are ventilation standards that must be adhered to. This was a converted dairy building & the management company are also the owners so obviously don't want to spend any extra money. How can I ensure that the roof area is sufficiently ventilated?
A Are you certain that the pipes vent directly into the roof space? If so then you should engage the services of a qualified structural surveyor to inspect the situation and submit their report to the management company. You should also have a word with the local authority building regulations department and environmental health department and ask their opinion. They may be able to intervene on your behalf.


 

Stairs with no spindles

Q I am interested in putting an offer in for a house. The stairs have only a banister rail and newel post i.e. no spindles. This leaves a huge open space, is this legal please?  Estate agent tells me that it is up to the occupier and therefore the owner is not willing to accept an offer.


A There are building regulations that cover all aspects of a stair case one of which is the maximum gap between the spindles for obvious health and safety reasons. Since you do not have any spindles at all then obviously the stairs do not comply and should a visitor have an accident and suffer damage as a result of no spindles you could be liable. There is nothing to stop you fitting spindles once you have purchased.

 

Earthy smell?

Q I purchased a bungalow built in the early 1970's just over a year ago. I have had a laminate floor laid throughout and vinyl laid in the kitchen and bathroom.  About 4 weeks ago we noticed a damp/earthy smell. The smell is particularly strong in the cupboard in the hall (which has the original floor boards exposed), the airing cupboard (which has carpeting on the floor) and the kitchen, in and around the sink cupboard area. We do not live in the bungalow all the time but visit most weekends. I know we have had some heavy rains this summer and I am wondering if it has become flooded under the floorboards. Is anyone able to tell me what this might be and what action we need to take to resolve the problem? I would be grateful for any suggestions/ideas.
A From what you describe it sounds very much like the smell is percolating up from the sub floor void - not unusual but it could indicate other things. It is likely (and not unusual) that the oversite (ground beneath the floor boards) is damp. The laying of the laminate floor and the vinyl has severely reduced the passage of water vapour from the sub floor area and more importantly the timbers of the floor. It is ESSENTIAL that the sub floor ventilation is more than sufficient. The property should have 9 inch by 6 inch air vents installed every 1.5 metres. Do not use terra cotta type as they are not efficient enough. Use square pattern metal or a plastic louvre type. This should disperse the smell, reduce the moisture content of the flooring timbers and reduce the risk of decay.



 

Need to reduce timber floor moisture content

Q We have had a meter reading of 20% under one floorboard and similar readings at top of floor boards [using pins in] in other paces in two rooms. We had a wood treatment company recommend new air bricks, extra air bricks and surface vents and a damp proof course. Our builder suggested he put in the new and extra air bricks/vents and monitor the moisture levels over 2/3 weeks with carpets removed - as we are going to have bare floorboards. He said if the meter readings go down, then there will be no need for a damp proof course. We don't want to do this if there's a significant risk in the future. What would you advise?
A A damp proof course will have no effect upon the moisture content of your wooden floors - This is all down to sub floor ventilation and you should be targeting a moisture content of 10 - 12% so your builder could be on the right trail. Make sure that there are plenty of 9x6 air vents serving the entire sub floor void. Do not use terra cotta type as they are only 20% efficient and block easily. Use square pattern metal or plastic louvre type.



 

Air vent removed?

Q We recently had french doors fitted in our lounge giving access to the garden. The doors replaced a large window. A surveyor came to take the measurement and to our surprise the damp course bricks from our 1920's house have been removed to allow the french door to be flush with the floor. To our understanding they shouldn't have been removed?? Are we right in thinking so?
A We are not sure what you mean by 'damp course bricks'? Do you mean air bricks? If so these should not be removed as they ventilate the sub-floor void. If they are removed for good reason then alternatives should be introduced otherwise the chance of fungal decay affecting flooring timbers is significantly increased.



 

It takes time to dry

Q Recently I noticed that some of the doors in my house were becoming difficult to close. There was also a smell of damp in the airing cupboard. I did some investigation and noticed a small leak from the top of the hot water tank. I replaced the tank. The leak must have been happening for a long period as there was a large build up of corrosion running down the tank from the leak point. Now I have noticed a large damp patch in the cloak room and in various places along a solid plastered wall coming off the airing cupboard.  The cloak room is 15 feet from the airing cupboard. The doors which are difficult to close are framed on the wall where the damp patches have formed. The skirting boards have also come away from the walls by a small amount on the same wall. The damp patches have stopped rising since the tank was replaced. The house has concrete floors.  I have been using a dehumidifier to dry the walls.  Is there anything else I need to be doing?


A Unless there is another leak from what you describe it is just a matter of time. The use of dehumidifiers will have minimal impact - they do not suck moisture from the wall.

 

Water under the floor - Do I fit a sump and pump?

Q We've recently bought a 1920's house where the 30ft garden backs onto a stream. The kitchen has always shown signs of damp on all walls. Pulling up the kitchen floorboards the last time it rained heavily revealed a stony soil ground about 2ft down. The soil was damp and in some places had small puddles of water (which in turn trickles into the basement). At all other times the soil has felt damp. There is good ventilation; I can't seem to see any type of damp course in the walls. Also the patio area outside the kitchen has been cemented at some point and the ground level is 1ft above the ground level in the kitchen. I was going to get a Kango and break a 5" channel from the patio and the house wall to allow rain water to drain away and also inject Dryzone around the kitchen walls. I also believe a high water table is the general cause of the water under the kitchen. I was going to put in a sump and pump, are these this the best thing to do?
My wife also doesn't like the idea of it being damp soil under the kitchen. Will putting gravel down help get rid of the damp? (Along with and a sump and pump)


A Water under a floor is not unusual and will not cause a problem provided the sub floor void is well ventilated. A sump and pump would be an extravagant unnecessary expense. If you put gravel down the water would still be there - it would just be out of sight in amongst the gravel. A 1920's house will have a damp proof course. Injecting Dryzone alone will not be the complete answer. Re-plastering to the correct specification would also be essential if indeed you actually have rising damp. Where the external ground is high you will need to structurally waterproof the wall and adjacent returns. Diverting the rain is good but you may be over doing it and it probably will change very little.

 

New plaster and salts?

Q We have an old house and we moved in about 2 1/2 years ago. We had most of the house re-plastered; now we have noticed that in the dining room a lot of salt has started to come through the plaster. Can you let me know if there is anything we can do as we paid for the house to be re-plastered and now salt is coming through? Is this because the wrong plaster was used? Am I able to brush the salts off the walls and apply something to stop this happening again or do I have to hack back the plaster and have it all re-plastered?

A What were the walls re-plastered with? The salts that you are seeing are almost certainly Sulphates which are present in most building materials especially the skim coat of plaster which is virtually Calcium Sulphate. The formation of these salts on the surface means that moisture is evaporating form the surface at that point - salts are brought to the surface in solution and crystallise when the water in which they were disolved evaporates off. There must be a source of moisture for this to occur and you first of all must identify and eliminate this. If you sealed the surface now the underlying surface would probably break down as sulphates are destructive due to their expansive forces when they crystallise. It is possible that a waterproof sand and cement render will rectify your problem and it is likely that a certain amount of plaster will have to come off but you must address the source of moisture first.


 

Chimney damp - Going mad!

Q I currently have a damp patch on the internal wall of my chimney breast both upstairs and down stairs. I have the plaster hacked off and attempting to dry but the bricks are not drying. I have made house watertight but it seems the bricks are not drying. I have already re plastered once and the damp patch came straight through again, thus why I am attempting it again! Should I replace the damp bricks? Waterproof membranes? Please help as I'm going mad!


A Obviously you are 100% sure that no moisture penetration is occurring and it has been the case for some time. If this is the case then the problem could well be that the bricks are contaminated with hygroscopic salts (moisture attracting) which are a by product of burning coal, as a result of previous leaks. Read articles 2,3 and in particular 12 on this site which will help you understand what is probably the problem. You need to re-plaster with a waterproof render or slurry to prevent the migration of these salts into the new plaster. Make sure that you allow a generous margin around the contaminated areas.

 

Leaking bath seal and stained ceiling

Q I am currently in the process of buying a house (which is around 10 years old) and the survey highlighted a stain on the kitchen plasterboard ceiling. This was apparently caused by water from the bathroom above. The seal around the bath had completely deteriorated and the owner couldn't say exactly how long it had been like this. There is a shower over the bath that is frequently used so water is likely to have been getting through frequently. The owner has since had the bath resealed and the stain painted over. I have removed the side panel from the bath and underneath it is completely dry. However, on a recent inspection there is evidence of the stain coming back. Is it likely that there is rot in the woodwork or plaster board or is it a case of letting everything dry out fully now that the bath has been resealed? Any advice would be much appreciated.
A If you have recently removed the bath panel and everything is completely dry then whilst there was a risk of fungal decay when the leak was occurring, the environment now, from what you say, would no longer support fungal growth.
We note your comment that the stain has returned, however this is likely to be a problem with decoration rather than the ongoing leak.  Water stains are very difficult to obliterate and it is possible that the original stain is now just showing through. Provided there is definitely no ongoing leaks we suggest that you cover the stain with oil-based undercoat paint, or we believe Polycell produce a "stain-blocking" paint. We hope that this is of assistance to you,



 

Water is still getting in

Q I own an old stone built house in the Yorkshire Dales. The walls have been repointed and had 3 coats of silicone waterproof on the outside of the walls. Whenever there is a severe rainstorm, the water comes through the west wall. I have been told that there is a German product that is a render guaranteed to solve this problem. Is this likely to be successful?


A Any correctly applied waterproof render is likely to solve your problem. You may be thinking of a product sometimes referred to as a 'waterproof slurry' which is a high cement content material that is either brushed or towelled on. This would also be effective at preventing moisture penetration. It is also a grey colour which may suit a property in the Yorkshire Dales. You should check that you do not need special permission to apply this before you start - especially if you are in the National Park. We will send you a few names of products under separate cover.

 

Water is comming through our floor!

Q We live in a terraced house about 100 years old. The down stairs wall, at the back of the house, where it joins next door has always had a damp patch on it, however recently moisture (appears to be clean water) is coming up through slight cracks in the asphalt floor, which seemingly was put down many years ago to cover the original flag floor. There are no water pipes in this area at all. Is it possible for rising damp to actually do this? To cure this would we need a damp proof course on the one wall and a new floor fitted?


A If you have what is termed 'free' water coming up through cracks in an asphalt floor then it is almost certainly not rising damp. Rising damp is 'capillary bound' in other words if you stroke your finger across it your finger should not be noticeably wet. Are you sure
water is coming up through the floor and the problem is not just condensation forming on the surface of the floor - which is not unusual? You need to be certain that whatever the problem is you get it correctly diagnosed to avoid undertaking unnecessary work. Does your neighbour have a leak? The damp patch on the wall may well be rising damp but does a garden wall abut the rear elevation externally? If so could this be a possible cause?

 

Q Hello many thanks for your last reply - have since excavated a little of the floor where the water is worst. You can actually now see water running into our house from the outside wall adjoining next doors yard (house above) - have had the water board come and test the water and it is next doors mains that has been leaking for however long - the water has got under the asphalt and has been trapped between there and the original flag floor, the asphalt is cracking in both the living room and kitchen due to this and I don't know how far into these rooms it has spread.

Is this something I can now claim on my building and contents insurance or will I have to claim against next door? - A builder has told me both floors may have to be renewed and also the plaster on at least 3 walls is very wet under the paper. Can you give me any ideas as to whether I should put in a claim?

 

A You should certainly put in a claim but it is more likely to be your fabric insurance rather than contents.

 

Neighbours patio is over our damp course

Q We have just peeled the paint off in our room to find a damp patch on our wall. We live in a mid terrace house with my next door neighbours being staggered forward from ours. The wall with the damp on it is my neighbours back wall which is where their patio has been laid and appears to have gone over our damp course. Now these neighbours moved in about 6 months after we moved in and the patio was already there. Who is responsible for correcting this problem?

A If the dampness in your wall is being caused by the fact that the adjoining property's patio has been laid above the damp-proof course in your wall then the owners of the property in question should be requested to take the appropriate action to remove the problem.

If any part of your neighbour's property is having an adverse effect upon your property we believe that in "legal talk" it is regarded as a nuisance and legal recourse would be available to you. We are not legally qualified and you would need to take professional legal advice on this point. We would like to stress, however, that you should do whatever is possible to resolve the situation amicably with your neighbour. It may well be that when you point out the problem and the effect it is having on your wall internally they will jump to and either lower or remove the patio or install adequate vertical protection.




 

Damp patches on bedroom chimney breast

Q I have damp patches appearing on the chimney breast in my bedroom. These are towards the ceiling and occur in times of high humidity and rain. However during an excessively heavy downpour in summer (3" in 3 hours) no damp patches. The chimney has had "everything" done do it externally: repointed, all new flashings, capped and many treatments of waterproof sealant. All the tiles and felt around the chimney have been replaced. Internally there is an air brick for ventilation. At a loss to know what to fix next?
A It sounds very much like the problem is being caused by hygroscopic salt contamination as a result of a previous leak. Have a look at Articles 2, 3 and in particular Article 12 titled 'What price a correct diagnosis' on this site. It will probably sound very familiar and should help explain what is happening.

 

Water under floor

Q I have a terrace house with a solid floor kitchen but floor boards in the front room. I lifted the floor boards up to find about 5 inches of water under them. What could be causing this? The neighbours filled their front room with concrete so their whole house has solid floors. Could this be affecting my house?
A No idea what is causing it without seeing it. Chances are it is natural ground water but you should have the water main and drains checked just in case. Almost certainly nothing to do with next door who probably had the same problem and it will still be there in amongst the hard core of their solid floor but as it is out of sight the belief is it is cured. Water under a floor is OK provided there is plenty of ventilation.


 

Trickle of water under floor

Q Having just moved to a detached dormer bungalow we seem to have hit a series of problems. House was built in 1959 and has a cellar under the property which is sectioned off into the various rooms up above. At first everything seemed fine until we had a problem with blocked drains. My husband then discovered a pool of water in the cellar room underneath the bathroom. We have eliminated any leaks from above and the drains have been cleared but we are left with a trickle of water coming into this room at ground level. Nobody seems able to point us in the right direction. Could it be drains, could it be ground water or could we have an underground spring and who can help us sort this problem? We live in the north east of England in Gateshead. PS problem is about 6 feet below ground level and we do have a damp course installed. Any advice gratefully appreciated


A If the trickle is permanent then it is either mains water or natural ground water. If it were drains it would be intermittent, smell and be cloudy. You should have a drains test undertaken and have the water tested by the local water authority to see if it comes from a leaking main (tap water contains chemicals they are able to identify) If it is neither of these than all that is left is natural ground water. Provided it is able to drain away freely and subfloor ventilation is good this should not be a problem. If you are concerned you should get a structural surveyor to check that it will not have a detrimental effect on the footings.

 

What is causing springing floor?

Q I live in a Victorian house. By the bay window on the ground floor we are experiencing springing in the floor boards. What would cause this, is it a form of dry rot?


A It is impossible to say what the cause is without seeing it. It could be wet rot/woodworm/dry rot/ in the wall plate and/or joist ends. Or it could just be a piece of packing beneath the plate/joist end that has fallen out. Take a board up and have a look with a torch and mirror.

 

Pipes leaked beneath floor - What to do now?

Q I own a basement property in a Victorian block built in1884. My property is a converted laundry. In November 2006 it was established that I had a mains burst under my bedroom floor. The solum (oversite) is about 35cm deep and the water was about 15cm.
I had a newly laid real wood floor on chipboard. Two holes, each approx 50cm square were made. The burst was fixed, dehumidifiers were installed by my insurance company and the room was declared dry after about two to three weeks. However an array of lead piping in weak condition had been revealed. I have spent several months trying to ascertain ownership of the pipe as it is not my mains supply so no further work has been done. However, as part of a renovation scheme this work can now go ahead. The lead pipes were replaced last week but unfortunately there had been another undetected leak and dampness has returned. There is also mushroom growth, the big yellow variety that is apparently destructive only to wood and will go away when the room is dried. A fungal expert has been and the architect for the renovation work. Both have inspected and are of differing opinions. The architect feels if we dry out with dehumidifiers all should be well and I can get on with replacing the floor. He does not think DPC is an option in this old property with 3' thick walls. The fungal expert wants to lift the entire bedroom floor to examine the extent of the damp, perhaps continuing through into the next room lifting that floor too to see the extent of water damage and spraying and treating the affected area. He is of a mind that two dehumidifiers cannot dry out the under floor spaces that are away from the holes in the floor. I want to be sure that the damp is eradicated but I don\'t want to be cajoled into unnecessary work. Should I be wary?
PS. these two rooms constitute the entire flat!


A Obviously without seeing the situation it is difficult for us to comment. You do not state from what surface the 'big yellow mushroom' was growing? Was it from wood or was it from the solum/masonry? Has it been identified as dry rot or is it peziza growth?

From what you describe we tend to go along with the architect. It the leaks were beneath the floor then we assume only the oversite (solum) became wet. Most oversites are damp or wet to a certain extent and some even have standing water present, none of which matters PROVIDED the sub floor ventilation is good and adequate. If extra moisture is introduced, say from a leak, this will change the environment and increase the risk of decay however this risk may be minimised by introducing good permanent ventilation. Running dehumidifiers in the rooms above with two holes in the floor will have minimal impact on the level of dampness present in the oversite. You should do whatever is possible to provide maximum permanent subfloor ventilation by installing 9x6 inch air vents in the outside walls of the property to ventilate the subfloor void. When the holes in the floor are made good convert them into traps so that periodic inspections of the subfloor area are possible.

The risk to your floors is one of decay and spray treating them to prevent this is a waste of time since any decay will start at bearing surfaces or embedded sections of timber which are impossible to treat by spray alone. Be careful using someone who suggests this in your circumstances as they may not know what they are doing.

To conclude - permanently ventilate and monitor could be the right course to follow.

 

Can I knock the chimney breast down?!!

Q I want to redecorate my bedroom and wanted to know if I can just knock down the chimney breast. It continues down into the front living room.


A You certainly should not knock down a chimney breast! Not only does it continue down into the living room but more importantly it also continues up through the roof to the chimney stack and all this weighs very many tons. To remove a chunk out of the middle would be very dangerous! If you really want to do it consult a structural engineer.
 

Should I block up my air vents?

Q I live in a 1930's semi-detached property and it has air vents on the ground floor (about 9 inch by 6 inch) every 1.5 metres. I feel as though the ground floor has a really bad draft problem because of these so would like to block them up. Is this something that I can do or can it cause problems to the property?


A You certainly should not block up or obstruct any air vents serving the sub floor void or anywhere else for that matter. To do so would significantly increase the chances of timber floors being affected by wet rot or dry rot so do not do it! If the draft is that bad line the floors with hardboard before laying the carpets. If you have bare boards then draft is the price you pay for this decorative effect.


 

Dot and Dab troubles - What should I do?

Q We have recently redecorated our lounge room and noticed that some of the (acrylic) paint was not drying. It is a Victorian terrace and the wall in question is load bearing, double leaf and is part external and part internal (due to a kitchen extension to the rear.
On closer inspection the plaster was quite soft and the skirting board was removed which showed evidence of rot in the past (How old? - we are unsure). The damp spots are clearly evident on the part of the wall that is internal and then completely absent on the external section.
To add more confusion, the other side of the wall in the now kitchen is dry with no evidence of marking at all. The damp has only penetrated the Plasterboard where it was affixed with bonding cement. I have removed the two damaged pieces of plasterboard (up to approx 1m) and would appreciate any advice on how to continue.


A We think we understand what you are describing. Are you saying that the lounge side of the internal section of the main rear elevation wall, which separates the lounge from the (back addition) kitchen is showing signs of damp? Are you also saying that this section of wall has been plasterboard lined - using a dot and dab technique and the damp patches are only showing where the plaster dabs are?

Assuming the answers to the above are yes then the length of wall in question is usually between 3 to 4 metres long. Whatever is happening 'dampwise' in one part of such a wall is almost certainly happening along its entire length. The fact that it is not showing beneath the window on the external section or on the kitchen side of the internal section probably means that some other type of damp protection may be present on the surface of these sections of wall - may be they are rendered?

Plasterboard dot and dab is not an advisable wall finish system especially is there is, or has been damp as it will eventually show through where the dabs are. The long term solution is to apply two coats of sand and cement render at a ratio of 3:1 incorporating a waterproof additive in the gauging water mix. This should be applied to a height of 4-500 mm past the height of any dampness present. It may be skim finished. Fix back skirting boards with physical protection between them and the wall such as plastic DPC. Hope this is of use but if you have any further queries please ask again.

 

Wet timbers in my roof

Q Our cottage was built in 1870 and was a hay loft originally. Our loft is unusual in that it is not possible to ventilate the loft as there is no gap between the roof felt and the wall plate for air to get from the ventilated soffit through to the inside of the loft. Also loft insulation has been tightly stuffed into the eaves. After we bought the cottage we found the rafters had a white deposit like dust in the area adjacent to the roof felt and this deposit gets wider as the roof narrowed to the eaves. I measured a wood moisture content of 25% in the rafters very close to the felt. It was more like 17% at the same location away from the felt near the edge of the wood. I ventilated the loft space which had completely still air by inserting soffit vents into the felt at a number of locations and sealing around them with mastic. The gaps in the slates allowed air to blow in. This has helped quite a lot but the relative humidity in the rafters is still high enough for dry rot to take hold although there is no evidence of it. Is it true that dry rot can only start when wood touches masonry, which in my case is where the wall plate touches the wall, an area completely coved in loft insulation? Should I remove the loft insulation in that area and spray a dry rot inhibitor. Should I also spray all the other wood in the loft? Should I lay a plastic sheet in the loft to act as humidity barrier to stop humid air rising into the loft from below? Should I be concerned or do nothing on the basis it's been OK all these years. Please, I need expert advice! Thanks for your time.


A It is not necessarily true that dry rot can only start when it is in contact with masonry but this tends to be the case as masonry that has become wet acts as a reservoir to provide a constant supply of moisture. It is unlikely that the masonry at the top of your wall just beneath the roof felt is sufficiently wet for this to happen. Even from what you describe there is likely to be a reasonable draught in the area of the rafter feet. Roof void condensation would appear to be your main problem and you should do everything possible to increase the ventilation to reduce this. Pull back the insulation 'stuffed' into the eaves - it will let something in. Investigate the possibility of installing ridge ventilators and ventilators that replace slates on each of the slopes to enable a draught to happen.

Do not waste your time spraying anything to prevent fungal decay. A spray treatment is not sufficient for this purpose and the parts that are most likely to decay are those that you would not be able to coat - even if it did work! Do not lay polythene as this will cause other problems. Our advice would be to ventilate as much as possible above the insulation. You cannot have too much ventilation in a loft space and as it is above the insulation it would not affect the warmth of the house. What you describe tends to be a
winter problem as in the summer it is too hot and dry up there for anything to live!


 

Water under my floor!

Q My property has a 6' void under the floor similar to a cellar but I believe its purpose is for a soak away, as the property is at the bottom of a slight hill. There is permanently about 8 inches of clear water at the bottom of the void. Rainfall seems to have little effect on the level, and if I pump the water out it returns in a few days. There are no visible leaks down the walls so the water appears to rise from the concrete floor. Could this be the water table? If so could the floor level be raised to overcome the problem, rather than tanking the whole space?


A The void depth beneath the ground floor is usually dictated by site conditions during construction and is not usually a functional area i.e. a soak away. Water beneath a floor is not usually a problem provided the sub floor void is well ventilated. From what you describe is sounds very much like the water table but your local water authority is able to test the water to see if it is from the main. Provided it is well ventilated I would not worry. I have surveyed many properties with a similar situation and one Victorian property was actually built over a stream with no adverse consequences. If you backfilled with pea shingle it would take many cubic metres and all that would be achieved would be to put the water out of sight - it would still be there. Tanking? It does
not justify the expense. Just make sure the ventilation is good.

 

Plaster bubbles

Q I have discovered gypsum plastering in my home that is rough and course to the touch and appears to have a lot of air bubbles in it similar to the texture of a pumice stone, but not so marked - what is the cause? There are also areas around the window which have gone very brown with salty patches, and some of the plaster has literally gone rock hard, almost impossible to hack off - what has happened?

A To answer your first question. Without seeing the evidence makes a diagnosis less certain but possibly the bubbles were 'trapped' in the plaster at the time of application - perhaps the mix had too much water.

Your second question sounds very much like rain has penetrated around the frame at some time and brought forward sulphates, which are present in abundance in gypsum plaster (calcium sulphate), to the surface of the plaster where they reform as crystals, sometimes breaking down the surface. If not rain penetration then regular condensation forming on the window frame and trickling onto the adjacent plaster might have a similar effect. Sorry we are not able to be more specific.




 

Rusty corners

Q The corners of my outside wall have rust coming through. Can I cover it up?


A We assume that the external walls of your property's walls are rendered. It sounds like galvanised metal angle beads may have been used to form the corners and they are now corroding. You could expose and treat the affected areas with a rust inhibitor but the situation is likely to be on going. Severely corroded angle beads will cause adjacent render to crack and fall away due to the forces exerted by corroding metal which expands considerably. Eventual reforming of the corners, preferably without angle beads seem likely.

 

Perishing bricks

Q The lowest (ground level) course of bricks to my 1900'ish house seems to be perishing.  Water seems to be being absorbed and some patches of damp are appearing. Moss is growing - especially as we have had such a wet/damp run of months.  I intend to improve the paths and drainage around the bricks...what should I do to/with the bricks? Is replacement possible?


A It is difficult to advise on your concern without seeing it. Yes it is possible to remove and replace perished bricks but this is very labour intensive. Have you considered a waterproof sand and cement plinth at the base of the wall in question? A good time to apply this is when the adjacent path has been excavated.

 

Why put lining paper on a new plastered wall?

Q Why would a builder put lining paper on the walls after plastering it?


A Even a newly plastered wall may have a few blemishes and lining paper would eliminate this. Lining paper also provides a better surface to receive paint and some would argue a better finish. It sounds like a good job but reading between the lines is something more going on that we do not know about? Was the lining paper in the original quote? What is your concern?

 

Laminate floor causing damp?

Q I have recently (in the last 12 months) completed laying a laminate floor in my hall and dining room. I have noticed that the wall separating the hall and dining room is now suffering with a low level (no more than 8" up the wall) damp problem. The paint is peeling off and it is starting to smell a little of damp. The laminate floor butts up to both sides of the wall, which in turn has skirting boards sealed to the wall and floor. Could the new floor/skirtings be causing the damp issue? The wall affected is an internal wall on a 20 year old house with no external contact at all. Any ideas would be greatly appreciated, Thank you.


A It sounds like the damp is a consequence of laying the laminate floor but it is very difficult to speculate what might be the cause without seeing it. If you have suspended timber floors then subfloor condensation due to the reduced vapour permeability of the laminate floor is a possibility. Could laying the floor have caused a leak in a central heating pipe or put strain on a joint causing it to leak? We would not expect rising damp in a 20 year old property. It is possible that the laminate has changed a micro climate somewhere - perhaps behind the skirting to cause the problem. You will probably have to take the skirting off and look behind to see what is happening.

 

Black ash under floors

Q Over a year ago we had to have the kitchen and dining room floors dug out and replaced with concrete and all the walls replastered due to the flooring being black ash, as we had rising damp. This was costly and a huge upheaval. We now have noticed white spores under the floor boards in the front of the house as this is still black ash with wooden boards laid directly on top of it. Is there an easier more cost effective way of resolving the damp on the floor boards rather than digging it all out and concreting all the other floors? There appears to be no damp on the walls in the front room or hallway this time, unlike previously in the kitchen and dining room. The house is early 1930s.


A You say white spores? Do you mean spores or white crystalline deposits? Is your floor construction boards nailed to timber fillets with ash mortar between the timber fillets virtually up to the underside of the boards? How do you know it is damp? Is the wood rotten or wet? If a moisture meter is used on such a material you will record a high reading due to the conductive properties of the ash - even if it is dry so you should be very careful to get the diagnosis correct. Is this your situation? Please let us know.

 

How do I remove bitumen from walls?

Q How do l remove bitumen from the walls of a cob cottage?


A With great difficulty so we suggest that you do not bother. Consider covering the walls with a plaster membrane which will make removal unnecessary and at the same time this will deal with any contamination or damp problems that may be present and the reason why the bitumen was applied in the first place.


 

Water under my floor and a gas leak

Q I live in a ground floor flat and 4 years ago there was a gas leak in the property and they discovered that the leak was caused by about 4 and a half feet of water underneath my flat that had rusted the pipe. I have been told that the water has been there for at least 10 years. I just want to know if that can cause dampness inside the property and any structural damage and if any what would be the course of action. Thank you for your time and help.

A Water beneath a property is not usually a problem provided the area above it is well ventilated. A gas pipe is usually buried in damp/wet ground in any event so the water beneath your property was not the only contributory factor. Provided the water is not 'running/flowing' it should not cause structural problems nor should it cause dampness in the property.


 

Will wall ties fix a bowed wall?

Q Hi. I'm looking at buying an end of terrace Victorian house. Only problem is, the back of the external wall is bowed. I've been told putting wall ties in will fix this problem. Is that right?  Will this prevent the problem in future? Thanks
A We would suggest that you definitely get a structural engineer to look at it before proceeding with the purchase - This is a different person to a surveyor. It may need something more than wall ties.


 

Puddles on floor and fungi

Q I've got a 20mm screed in kitchen and there is water forming on top in small puddles its in one area of the kitchen this being the centre. This area of the floor is beginning to swell. This problem came to light when I had a laminate floor fitted 5 months ago water started to seep through the joints leaving puddles on the surface. When I pulled it up the underlay was saturated but all the edges were dry. I have let it dry out but in the centre there are the small puddles. 3 years ago when I moved in there was cork on the kitchen walls and the radiator had been removed from this room. Is this the reason why? I've had the radiator put back in the kitchen 2 years ago. There have been fungi growing under kitchen units. Help?
A From what you describe it sounds very much like there is a water pipe leak. A 'normal' damp floor is just that - damp. If you have puddles (free water) forming then there is almost certainly a leak somewhere beneath the floor. Are the radiator pipes buried in the solid floor? Is the fungi brown leathery fleshy growths or 'skinny mushrooms'? Either of these is indicative of a leaking water pipe. Let us know how you get on and sorry for the delayed reply

 

Obstructed air vents

Q We had a dwarf wall built for our conservatory last year and recently had slabs put down around the bottom of the conservatory, but we noticed that the slabs have covered the vents in the brickwork and wonder if it is necessary for us to put vents back in to the wall further up from the slab? Your help would be appreciated.
A You should certainly never cover or obstruct any air vents - they are there for a reason. The vents are likely to be there because the conservatory would have blocked the original vents of the property so it is possible they have an effect upon the sub floor environment of the house as well. If your slabs are covering the vents then it is likely that the slabs are also high in relation to the damp course and may be bridging it? You had better check this. If practical and the DPC is not bridged why not cut sections out of the slabs to accommodate the air vents?


 

Have the punctured the floor membrane?

Q Recently I had the kitchen, utility and hall tiled. In order to match the required height of floorboards going into the sitting room, they decided to raise the height of the floor they were tiling by using 9mm ply screwed into the screed. They turned out be incompetent and actually have raised the floor by 8mm too much and used the wrong type of adhesive for the tiles. Now I'm left wondering about what else is wrong and my biggest
concern being that they used 40mm long screws to hold the 9mm ply down, drilling directly into the screed. Could this have penetrated the damp proof course or would this be much further down? The house is a new build only completed in Dec 06.

A The membrane should be under the concrete that is beneath the screed i.e. about 150mm down. If it was beneath a conventional screed it would be 50mm down so you should still be OK

 

Damp on new plaster in conservatory

Q I had a conservatory built and then what was the 'house' outside wall in the conservatory plastered. This wall now has a damp problem at ground level. The conservatory company (xxxxx) reported their damp proof course was sound. An external surveyor advised our house (which is only ten years old) has porous bricks and there is evidence of external damp above the DPC. He suggested the cause of the problem is that the water within the external brickwork is running down to the bottom and thus causing damp within the conservatory. He advised his company would spray the outside brickwork with a treatment to overcome this. I have since painted the walls a water sealer but the problem still persists. Do you think this is the cause of the problem and the solution would work? If no what do you suggest I do. The damp only appears in the winter.


A From what we understand the dampness is showing at the base of what was an external wall that is now within the new conservatory and that the original external face of this wall was plastered since it is now within the conservatory? Is this correct? If this is the case then the DPC installed by xxxxxx in their structure is of little relevance? Maybe we are misunderstanding?

Was the wall plastered with a lightweight plaster such as Carlite Bonding? Has this been cut short of the original property's DPC or is it bridging it? You may have to take the skirting off to inspect this but first of all establish the line of the original DPC.

Without seeing the problem it is difficult to be specific.  We understand the suggested theory to be that rainwater is penetrating the brickwork above the roofline of the conservatory and then running down the internal face of the external skin of the cavity brickwork and accumulating on top of the original DPC at the base of the wall. Why therefore are there no other damp patches higher up the wall where this water hits wall ties and protruding mortar on its way down when the volume of water would be greater before it is 'absorbed' as it runs down? We do not swing with this theory. Let us know how you get on.

 

Bowed wall

Q I am hoping to buy a house that has had the wall ties replaced in 2000. Now it has been pebble dashed on and the exterior wall is bowed. Will this now cause a new problem? i.e. the weight on the (weaker?) wall. Please advise thanks.
A We would advise that you obtain the opinion of a structural engineer before purchasing.

 

Leaking water main under my floor

Q I own a basement property in a Victorian block built in1884. My property is a converted laundry. In November 2006 it was established that I had a mains burst under my bedroom floor. The solum (oversite) is about 35cm deep and the water was about 15cm.
I had a newly laid real wood floor on chipboard. Two holes, each approx 50cm square were made. The burst was fixed, dehumidifiers were installed by my insurance company and the room was declared dry after about two to three weeks. However an array of lead piping in weak condition had been revealed. I have spent several months trying to ascertain ownership of the pipe as it is not my mains supply so no further work has been done. However, as part of a renovation scheme this work can now go ahead. The lead pipes were replaced last week but unfortunately there had been another undetected leak and dampness has returned. There is also mushroom growth, the big yellow variety that is apparently destructive only to wood and will go away when the room is dried. A fungal expert has been and the architect for the renovation work. Both have inspected and are of differing opinions. The architect feels if we dry out with dehumidifiers all should be well and I can get on with replacing the floor. He does not think DPC is an option in this old property with 3' thick walls. The fungal expert wants to lift the entire bedroom floor to examine the extent of the damp, perhaps continuing through into the next room lifting that floor too to see the extent of water damage and spraying and treating the affected area. He is of a mind that two dehumidifiers cannot dry out the under floor spaces that are away from the holes in the floor. I want to be sure that he damp is eradicated but I don't want to be cajoled into unnecessary work. Should I be wary?
PS. these two rooms constitute the entire flat!

A Obviously without seeing the situation it is difficult for us to comment. You do not state from what surface the 'big yellow mushroom' was growing? Was it from wood or was it from the solum/masonry? Has it been identified as dry rot or is it peziza growth?

From what you describe we tend to go along with the architect. It the leaks were beneath the floor then we assume only the oversite (solum) became wet. Most oversites are damp or wet to a certain extent and some even have standing water present, none of which matters PROVIDED the sub floor ventilation is good and adequate. If extra moisture is introduced, say from a leak, this will change the subfloor environment and increase the risk of decay however this risk is minimised by introducing good permanent ventilation. Running dehumidifiers in the rooms above with two holes in the floor will have minimal impact upon the level of dampness present in the oversite. You should do whatever is possible to provide maximum permanent subfloor ventilation by installing 9x6 inch air vents in the outside walls of the property to ventilate the subfloor void. When the holes in the floor are made good convert them into traps so that periodic inspections of the subfloor area are possible.

The risk to your floors is one of decay and spray treating them to prevent this is a waste of time since any decay will start at bearing surfaces or embedded sections of timber which are impossible to treat by spray alone. Spray treatment is rarely sufficient to prevent fungal decay. Be careful using someone who suggests this in your circumstances as they may not know what they are doing.

To conclude - permanently ventilate the subfloor area and regularly monitor it could be the right course to follow.



 

Wet timbers in my roof

Q Our cottage was built in 1870 and was a hay loft originally. Our loft is unusual in that it is not possible to ventilate the loft as there is no gap between the roof felt and the wall plate for air to get from the ventilated soffit through to the inside of the loft. Also loft insulation has been tightly stuffed into the eaves. After we bought the cottage we found the rafters had a white deposit like dust in the area adjacent to the roof felt and this deposit gets wider as the roof narrowed to the eaves. I measured a wood moisture content of 25% in the rafters very close to the felt. It was more like 17% at the same location away from the felt near the edge of the wood. I ventilated the loft space which had completely still air by inserting soffit vents into the felt at a number of locations and sealing around them with mastic. The gaps in the slates allowed air to blow in. This has helped quite a lot but the relative humidity in the rafters is still high enough for dry rot to take hold although there is no evidence of it. Is it true that dry rot can only start when wood touches masonry, which in my case is where the wall plate touches the wall, an area completely coved in loft insulation? Should I remove the loft insulation in that area and spray a dry rot inhibitor. Should I also spray all the other wood in the loft? Should I lay a plastic sheet in the loft to act as humidity barrier to stop humid air rising into the loft from below? Should I be concerned or do nothing on the basis it's been OK all these years. Please, I need expert advice! Thanks for your time.
A It is not necessarily true that dry rot can only start when it is in contact with masonry but this tends to be the case as masonry that has become wet acts as a reservoir to provide a constant supply of moisture. It is unlikely that the masonry at the top of your wall just beneath the roof felt is sufficiently wet for this to happen. Even from what you describe there is likely to be a reasonable draught in the area of the rafter feet. Roof void condensation would appear to be your main problem and you should do everything possible to increase the ventilation to reduce this. Pull back the insulation 'stuffed' into the eaves - it will let something in. Investigate the possibility of installing ridge ventilators and ventilators that replace slates on each of the slopes to enable a draught to happen.

Do not waste your time spraying anything to prevent fungal decay. A spray treatment is not sufficient for this purpose and the parts that are most likely to decay are those that you would not be able to coat - even if it did work! Do not lay polythene as this will cause other problems. Our advice would be to ventilate as much as possible above the insulation. You cannot have too much ventilation in a loft space and as it is above the insulation it would not affect the warmth of the house. What you describe tends to be a
winter problem as in the summer it is too hot and dry up there for anything to live!




 

How long do new wall ties last?

Q If wall ties are replaced how long do they last? Would a mortgage be granted on the property in future?

A New replacement wall ties are stainless steel and will last a very long time - most companies give a thirty year guarantee. Replacement ties should not affect the granting of future mortgages on the property - in fact it will probably help the situation
 

Water leaking out of wall

Q The back of my 30s terraced house has steps from a 3ft wide concrete area outside the back door, down to ground level (approx 5ft below). There is a retaining wall which has clear water leaking out from between the bricks at several points - up to 4 courses. We have had our drains, which are at the level of the house, checked and lined - didn't solve the problem and had the water board look at it who told us we should get a sample and look in yellow pages for a lab to test it. Shouldn't they be able to do this? We wonder if the water may be due to a raise in the water table, but our neighbours don't appear to have a problem. We don't know who to contact to discover the cause - any advice will be much appreciated.


A One would have thought that the water authority would have been more proactive. They are able to test the water to see if it came from the mains. They know what 'additives' they put into the water and therefore they know what to test for. Have another go at them. Have you taken some floor boards up and looked under the floor? Have you tried turning the water off in the street to see if the 'flow' stops? Has anyone 'listened' to the incoming main to check it is not leaking? (Sounds strange but it is possible to do this)

If it is trickling out of the wall above the height of the garden it is unlikely to be the water table unless your garden is a bog! Sorry not to have been much help

 

Water beneath my floor

Q I recently moved into a 1930's semi with suspended timber floors. I needed to remove some of the floorboards to treat the rooms for woodworm. In so doing I noticed large puddles of water underneath the suspended floor. I checked to see if my drainpipes were leaking or if the air bricks were damaged and letting water in. Pipes seemed to be OK and I had the air bricks replaced. The water only appears after significant rainfall and subsides after a few days. We have a drive which slopes towards the front of the house although it would appear as if the water is coming up through the concrete base rather than finding its way in from higher up. A friend suggested that we live in an area with a high water table and that as long as the ventilation is good and the water is subsiding that it shouldn't be a problem. Any advice to substantiate/refute this claim would be gratefully appreciated!

A There are several questions about water beneath floors on our web site. Water beneath floors is not unusual. Provided you have checked out all of the obvious thing such as in coming water mains, drains tests etc. then it is a natural phenomenon. As your friend says make certain the sub floor ventilation is good and there should be no problem.


 

Are wall ties covered by insurance?

Q I have been told by my insurers that my wall ties are corroded and need replacing and that it is not covered on the insurance. Is that normal?

A We are curious how your insurer would know the condition of the wall ties in your property? Wall tie corrosion is very unlikely to be covered by insurance. It is all part of the general maintenance and wear and tear of an old property.


 

Structural movement

Q The house I want to buy is approx. 110 years old and may be suffering some form of structural movement, evident through uneven floors and some bowing near the front window. The adjoining property has several large metal rods in place on the front and rear walls. What are they? Is this a serious issue for my property?

A We would strongly advise that you seek the opinion of a structural engineer before proceeding with the purchase. The metal rods you describe may be tie bars, inserted through the entire property to stop the walls bulging. They are no longer permitted today.


 

Soil pushed through slate beneath my floor

Q I have just found I have rising damp. It's in a small corner of my house. People that have checked it have explained to me that old houses like my own have like a slate material under the floorboards that try and stop rising damp, however, on removing damaged floorboards I found a fair bit of soil and rubble and was told that some slates might be damaged or missing causing the soil to push through and with all that soil it is causing rising damp. My question is, in this situation how do I go about fixing this problem? It hasn't spread too far but I don't know what to do.  Any information would be great as I have never had a problem like this before and like usual my insurance have told me I'm not covered even though I'm on the highest premium.

A It is possible that we may be misunderstanding what you are describing but the slate that you refer to will, if it is present, only be through the thickness of the walls - not covering the whole area beneath the floors in your house. Most old properties have soil and a certain amount of rubble beneath the floors so this is not unusual - it has not 'pushed through' from anywhere - it has been there since the house was built. You need to be certain that what you are looking at is actually rising damp and it is not caused by something else. We would advise that you get the opinions of an independent expert or at the least several damp proofing companies who are members of the Property Care Association (PCA) and whose surveyors are CSRT qualified. Good luck


 

Has ramp bridged the DPC?

Q I have a back entrance to my extension which I have built a slope up to just underneath the doorstep for wheelchair access. Is this OK?


A Provided you placed a vertical damp proof course against the wall where the ramp abuts the property to prevent it bridging the existing DPC you should not have a problem. If you did not it might be a problem. Do you know what course the original DPC is in to check this?

 

Perrished chimney plaster

Q I have bought a 1930s house and plaster is crumbling on chimney breast. It's west-facing but dry - the chimney has been removed but taken down to 2' below roof height and left open to breathe in the loft. No sign of damp at all. The plaster is greyish roughcast presumably intended to be papered. How can I remedy it? Thanks.
A Because it is on a chimney there is an increased chance that the crumbling plaster was caused by an old historic leak and the plaster is likely to be salt contaminated as a result of by products from burning coal in the past. We would therefore suggest hacking it off and replacing it with waterproof sand and cement render and a skim finish. Make sure you take it to well beyond the edges of the perished plaster - usually the whole face of the chimney breast makes a better job.


 

Leaking new garage roof

Q I have just had a double garage built on the side of my house. The garage consists of a flat roof construction. The roofers have used felt not lead to seal between roof and wall of main house which is rendered. When I get heavy rain I get a couple of runs of water down the main house wall inside the garage. The roofers don't want to know, any suggestion how I can overcome this problem.


It sounds like the flashing has not been chased into the wall. You should certainly get the roofers back as the roof is currently not fit for purpose and not what you paid for. If they resist consult Citizens Advice Bureau and if necessary take them to court.


 

Earthquake and wall tie failure

Q A recent earthquake occurred in my town, i.e. Folkestone in Kent. On inspection of my property following this, it was found that there was a gap between my first floor landing window and the brickwork outside. A loss adjuster appointed by my insurance company, visited my property and he informed me that it was 'wall tie' failure, but was NOT covered on my buildings insurance policy; this being the case across the board on ANY buildings policy. I questioned this fact and said that there was no evidence of this damage PRIOR to the earthquake and therefore I was of the mind that the earthquake had been to blame and I should not be held personally liable for the repair bill, but that it should be covered by my policy. Could you please therefore advise me on this matter?

A Thank you for your question - we have never had an earthquake related question before!

Did the loss adjuster actually inspect the wall ties? Did he locate the original ties with a metal detector, drill a hole adjacent to them, insert an endoscope and look at a few to gain an overall picture of the condition of the original wall ties? If he did not then we do not know how he can make such a sweeping statement.

It would also depend upon what he means by wall tie failure. The wall ties may be perfectly satisfactory but in an earthquake situation they 'failed' to perform adequately or on the other hand they may have failed because they were/are corroded. The former we feel should be covered - the latter may be not. Go back and pin him down. Get a few wall tie contractors in to have a look and may be provide evidence that they are not corroded if this is the case. Let us know how you get on


 
Contact Peter: Email - info@dampdecay.co.uk - Telephone: 015242 71794