Home Glossary of Terms A - Z Glossary of Terms
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glossaryMost industries develop their own terminology and very often this ‘techno babble’ is used when communicating with clients. As a consequence some clients will have difficulty understanding what is being talked about or perhaps even worse, precisely what they will be getting for their money. It has also been noticed that for a strange reason known only unto them, some contractors deliberately use ‘techno babble’ in the belief that it will impress a client – perhaps is does - who knows?

To help decipher some of the commonly used words in the building restoration industry we have attempted to explain their meaning when used with regard to building restoration matters. It is fully appreciated that several of the words have other meanings as well. Should you know a ‘techno babble’ word that you feel should be in our list please submit it to us so that it may be included.
Scroll down the page or if you know the word use the A-Z facility below





An inexpensive method of dispute resolution resulting in an immediately enforceable, non-binding dispute settlement by an Adjudicator.

Agrément Certificate

Certificate issued by the British Board of Agrément which is an independent third party accreditation body that tests and confirms the effectiveness of a material or system.

Aqueous Fluid

A term used to describe a timber treatment or damp proofing fluid that is water based.


The main alternative to the court system where the parties have the power to decide many of the procedures that will govern the conduct of their arbitration. The decision is binding in law.


Timber moulding around openings such as doors and windows. (See Moulding)


A sharp edge formed by the meeting of two flat surfaces. Sometimes used when talking about corners.


A class of masonry that consists of blocks of accurately dressed stone with extremely fine bed and end joints.

Barge Board

Wide board fitted on the end of a gable roof just beneath the edge of the tiles/slates following the slope of the roof from the eves to the ridge.


Long strips of softwood, usually 38x19mm or 25mm to which roof tiles or plasterboards are usually fitted.

Bead (or Beading)

Small timber moulding used to cover a join.

Blown (plaster)

Term used to describe plaster that has lost its adhesion to the underlying wall/surface. (See Live)


1) A term used to describe the pattern in which bricks are laid to ensure stability of brickwork. The type of bond used may be determined by the visual appearance of the external face of an exposed brick wall.

2) A term used to describe the adhesion of one material to another.


Shortened name for Carlite Bonding which is Gypsum based light weight plaster.


A commonly used name for a timber preservative that contains Disodium Octoborate Tetrahydrate. Sometimes also referred to as Borate. Usually dissolved in a range of concentrations in glycol. (See Glycol Borate).


Building Research Establishment

BRE Digest 245

A document titled 'Rising damp in walls: diagnosis and treatment' produced by the Building Research Establishment.


A large dimension beam or several large sections fixed together to form a single beam that spans a large opening and supports the structure above e.g. a shop front opening.


The covering of a Damp Proof Course with a permeable material creating a passage for moisture to by pass the Damp Proof Course thereby causing a rising damp problem.

BS 6576 (2005)

British Standard Code of Practice for the 'Diagnosis of Rising Damp and the Installation of Chemical Damp Proof Courses'. The 2005 document supersedes a 1985 document.


British Wood Preserving and Damp-proofing Association. Now the Property Care Association (PCA).


The ability of material to retain an electric charge. In the damp proofing industry this word is sometimes used to describe a type of moisture meter.


A phenomenon caused by surface tension and resulting in the attraction or repulsion of the surface of a liquid in contact with a solid. (See Surface Tension)


A fine bore tube. (See Rising Damp).

Capillary Moisture

Moisture that is present within a material in excess of the air dry (hygroscopic) moisture content. For example capillary moisture will be present within the capillaries of a wall if rising damp of rain penetration is occurring.

Carbide Meter

Type of moisture meter. Measures the pressure of acetylene gas produced within a sealed vessel resulting from the reaction of a measured amount of Calcium Carbide with any water present in the measured sample being tested. Only total moisture content is recorded - reading may be influenced by contaminants. (See Speedy Test)


The liquid in which active ingredients of a treatment formulation are suspended and the means by which the active ingredients are 'transported' from the container into or onto the material to which it is being applied.

Cavity/Cavity Wall

The outside wall of a building, made up of an inner and outer layer of brickwork or block work with a space (cavity) between to prevent the transmission of moisture.



Cavity Drainage Membrane

A sheet material manufactured from high density polyethylene or polypropylene incorporating moulded studs to create an air gap between the membrane and the substrate. Commonly used to line basement/cellar walls and floors to create a dry environment. Special components are required for fixing and joining.

Cavity Wall Tie

Purpose made pieces of metal joining the inner and outer layer of a cavity wall together at regular pre-determined centres to strengthen and aid the stability of a cavity wall.


An abbreviation for Cavity Drainage Membrane.


A type of hygroscopic salt. Usually present in a wall that has either had or is currently affected by long standing rising damp. (See Hygroscopic Salts)

Consumer Unit

Similar to a fuse box; the mechanism by which electrical circuits are protected from overload.

Cold Bridge

Localised area of poor thermal insulation such as that caused by a solid concrete lintel that penetrates the thickness of a wall.


The formation of water droplets when water vapour is cooled below its Dew Point temperature. May form on a surface or interstitially. (See Dew Point & Interstitial)


The ability of a material to conduct electricity. In the damp proofing industry this word is sometimes used to describe a type of moisture meter.


Impermeable capping on the top of a wall exposed to the elements to prevent moisture penetration.


A projecting part of a building, usually providing support, often in the form of projecting courses of brickwork.

Cordon Sanitaire

Term used to describe the containment of dry rot within an area of masonry by the injection of a masonry biocide into the masonry in a concentrated band around the perimeter of the infected area. (See also Toxic Box)


1) Ornamental moulding made of plaster fitted at the join of a wall and ceiling.

2) Horizontal moulded projection, usually decorative, crowning a building or structure


Control of Substances Hazardous to Health Regulations 2002


Process of setting by chemical reaction. Relevant to the 'curing' of a chemical damp proof course.

Damp Proof Course (DPC)

An impervious barrier set within a building structure to prevent the movement of moisture.

Types of Damp Proof Course:

1.      Physical: An impermeable building material usually built into a structure during construction although may be introduced into existing structures.

2.      Chemical: A damp proof course formed in an otherwise permeable wall by the injection/introduction of a water repellent formulation

3.      Cream/Gel: A type of chemical damp proof course material.

4.      Injection Mortar: A cement based damp proofing medium containing active ingredients which diffuse into a wall and combine with minerals within the structure to create a damp course by blocking the pores

Damp Proof Membrane

An impermeable sheet material, commonly heavy gauge polythene, incorporated into a solid floor to prevent moisture rising up through the floor.


Electrical refrigeration equipment used to remove air borne water vapour.

Deliquescent Salts

Term used to describe hygroscopic salts which revert to a liquid state in the moisture absorbed by them.

Dew Point (temperature)

The temperature at which water vapour reverts from a gas state to a liquid.


Process of spreading in all directions over a wide area. Used to describe the spread of water based and cream type damp proof course products in masonry and glycol borates in timber

Distribution Board

Electrical equipment that contains switches or protective devices e.g. fuses, circuit-breakers or residual current operated devices, in order to protect individual electrical circuits in a building.

Dot and Dab

Term used to describe a method fixing of plasterboard sheets to the surface of a wall using a plaster adhesive.


A moulding or groove on the under side of an external sill or projection, near to the external edge, forcing moisture to drip thereby preventing water creeping back and causing moisture penetration beneath. Sometimes referred to as Throating.

Dry Lining

A means of providing a smooth decorative surface internally usually using plasterboard. An alternative to plastering walls directly.

Also used to describe the creation of a dry decorative surface by lining a damp wall with an impervious material so that it is unaffected by the underlying dampness - a form of concealment.


A widely used chemical damp proof course system in the form of a water repellent cream. Manufactured by Safeguard Europe.


Part of the roof that overhangs/projects beyond wall below.


A term used to describe white salts deposits containing carbonate and sulphate ions that form on the surface of brickwork or plaster as residual moisture evaporates. Efflorescence salts are naturally present in building materials and merely indicate that moisture is evaporating. They are not significantly hygroscopic.


Expanded Metal Lathing


An approximation, an educated guess, a rough price of what the final cost will be.

Fascia Board

External horizontal timber board attached to the ends of roof rafter feet to which the gutter is fixed.

First fix

A term used to describe the first phase of work undertaken by a joiner, plumber or electrician prior to plastering or other construction work.

Flank Wall

The side elevation of a building.

Flash Point

Minimum temperature at which a flame applied just above the surface of a liquid will ignite flammable liquid vapour in a standard test. Can be in 'closed' or 'open' conditions.


These are narrow pieces of lead that are required at the intersection between the vertical faces of walls or framing and pitched roofs, flat roofs, gutters etc. to prevent moisture ingress.

They are classified into 1) Horizontal Cover Flashings, 2) Apron Flashings, 3) Stepped Cover Flashings and 4) Raking Cover Flashings.


Cement mortar filler on top of a chimney stack at the base of chimney pots or protruding flues.

Flue (Chimney)

Passage for the escape of smoke and other products of combustion.


Word used in the building restoration industry trade when referring to a timber treatment or damp treatment liquid.

Flush Door

Door with completely flat faces.

Fossil Fuel

Coal, oil or gas.


The indent on bed face of a brick.

Fungal Decay (of timber)

Degradation or breakdown of timber due to the action of certain fungi. (See Infection)


Upper triangular part of an outer wall at the end of a pitched roof.

Gable Wall

Term used to describe the side elevation of a building that has a Gable but certain regions use it to describe a side elevation without a gable.

Gas-liquid Chromatography

Process used in chemical analysis to identify certain classes of materials. Used to detect the presence of certain types of previously applied timber preservatives

Glazing Bar

Thin bar shaped to receive a pane of glass.

Glycol Borates

A range of products for timber treatment based on Disodium Octaborate Tetrahydrate dissolved in a variety of glycols. (See Boron)


Term used to describe the method of establishing the total moisture content of a sample by oven drying and accurate weighing in a laboratory. (See also Oven Drying)


When used in connection with a flight of stairs; The going is the horizontal distance between the face of two consecutive stair risers.


Material used to fill small gaps or fissures.


The end face of a brick.

Header Tank

Small open cistern (tank) that feeds water to central heating system.

High Ground Level

External ground level that is too high in relation to internal floor level or it is above internal floor level.

Hipped Roof

A term used to describe a pitched roof, the ends of which are also sloped.

Hopper Head

A small external receptacle fixed to a wall on top of a waste pipe into which other waste pipes discharge.

Hydrostatic Pressure

Hydrostatic pressure refers to the pressure that any fluid in a confined space exerts. If fluid is in a container there will be some pressure on the wall of that container. In buildings the term is often used in association with moisture penetration into cellars or basements and where high external ground level is present.


Instrument used to measure the relative humidity of an atmosphere at a given moment.


Water attracting. Term often used to describe the action of certain salts introduced into a wall and contaminating wall plaster as a result of rising damp. (See Deliquescent Salts)

Hygroscopic Moisture Content

The amount of moisture present in a material solely due to water absorption from the atmosphere. Sometimes referred to as 'Air Dry' moisture content.

Hygroscopic Salts

Salts that have the ability to absorb moisture from the atmosphere. In buildings they can come from different sources e.g. salts dissolved in ground water, contaminated sand, flue combustion products, leaking sewage, animal waste. (See Hygroscopic, Capillary Moisture, Deliquescent Salts, Nitrates, Chlorides and Total Moisture Content)


Not permeable.


Term used to describe the attack of timber by wood destroying fungi.


Term used to describe the attack of timber by wood boring insects

In situ

Meaning to work on an item in position rather than take it off site.

Integral Waterproofer

A powder or liquid additive incorporated into a sand and cement render or concrete. Basically a soap that reduces the amount of water necessary for workability. (See also Render Additive)

Interstitial (Condensation)

The formation of condensation either within the pore structure of a material or between layers of a material.


Process of introducing fluids into a solid porous structure in large amounts until the structure is at or near saturation. Commonly used to describe the application of a masonry biocide in conjunction with dry rot control. Considered to be unnecessary.


The vertical side(s) of openings which are formed in walls to receive doors, windows, fireplaces etc.


1) Floor Joist: A bearing timber forming part of a suspended timber floor to which the floor boards are nailed to the top and a ceiling may be attached beneath or

2) Ceiling Joist: A bearing timber spanning an area to which a ceiling is fixed to the underside only.

Joist Hanger

A galvanised metal 'shoe' that is secured to masonry to support the end of a joist without it being in direct contact with the masonry.


An electrical mechanical hammer used to break up surfaces or remove wall render.


The roughness of a surface to aid the adhesion of render/plaster.


A sealing material applied to knots in wood prior to decoration to prevent staining penetrating the decorative finish.

Lateral Penetration

Horizontal passage of moisture through the fabric of a wall either due to rain penetration or as a result of high external ground level.


Process of removal of a salt, preservative or other material by dissolving in a liquid (usually water) which is allowed to percolate through or across the material for a period of time.

Lean-to Roof

The simplest form of pitched roof consisting of rafters inclined at 30º against a wall.


Formed of wood, brick, concrete or steel fixed horizontally and used to support the structure over an opening.


Term used to describe plaster that has lost its adhesion to the underlying wall/surface. (See Blown)

Loose-Fill Insulation

A type of loose material used for insulating cavity walls and lofts.

Low Pressure Injection

Used for the application of water based chemical damp course systems where the material continues to diffuse within a wall after the injection process has been completed. Pressure used usually 0.15Mpa - 0.30Mpa (20 - 40 psi). (See Pressure Injection)

Making good (Make good):

The final part of a job that brings it to a complete state.

Mansard Roof:

A roof that has two pitches on each slope. A purlin normally supports the rafters where the two pitches on the same elevation meet. These roofs often include living accommodation in the roof void.


A voluntary, non-binding 'without prejudice' process in which trained third party negotiators attempt to bring people together to reach settlement.


See Damp Proof Membrane


An extra floor often between levels.

Micro Emulsion

A water based formulation for either timber treatment or rising damp treatment, usually supplied as a concentrate. When mixed with water it forms a micro-emulsion in which the active ingredients are suspended in minute droplets thus enhancing penetration and distribution.


Angled joint as used in the corners of a picture frame.

Moisture Content

The amount of moisture in a material usually expressed as a percentage weight. (See Total Moisture Content)

Moisture Distribution

Variation in moisture content in different sections of a material, usually a wall. (See Moisture Profile)

Moisture Meter

An electrical instrument or device used to determine the presence of moisture in a material. There are three types of moisture meter commonly used.

  1. Electrical conductance meter
  2. Electrical capacitance meter
  3. Chemical reactions meter

Caution needs to be exercised when interpreting the results of any moisture meter.

Moisture Patterns

Variation in moisture content in different sections of a material, usually a wall. (See Moisture Profile)

Moisture Profile

A term used to describe the plotting and recording of the distribution of water in a wall at regular intervals vertically.


Term used to describe the decorative pattern formed along the edge of a building component such as wood, plaster, stone etc.


Vertical post contained within a window frame.

Multiple Injection

Term used to describe a damp proof course injection process when a wall is to be treated from one side by a process of drilling and injection into the same hole at increasing depths.

Newel Post

Vertical post at top and bottom of staircase.


A type of hygroscopic salt. Usually present in a wall that has either had or is currently affected by long standing rising damp. (See Hygroscopic Salts)


Sometimes referred to as strutting. Inserted between large dimension joists to stiffen a floor and prevent joists twisting or tilting. Two types used; herring bone or solid.


A rounded protruding edge. Found on the edge of a stair tread where it projects beyond the riser or the edge of a window board.

Organic Solvent

A carrier (usually white spirit) for certain types of damp proof course and timber treatment fluids. (See Carrier)

Oven Drying

Laboratory method of determining the total moisture content of a sample. (See Gravimetric)


The ground that is beneath a ground floor level suspended timber floor.


A low wall that projects beyond the eves at the edge of a roof.

Party Wall

The dividing wall that separates two adjoining properties which is common to both.


Term sometimes used to describe a thick 'mayonnaise like' timber preservative material containing an insecticide and fungicide. Enables a thick layer of material to be applied which on dry timber allows greater penetration of preservative but of limited use on wet or damp timber.


Property Care Association.

PC Sum

(Prime Cost Sum)

An approximate sum of money that should be allowed for to cover materials or labour for what is an unknown quantity - e.g. Allow a PC Sum of £X for the cost a kitchen yet to be chosen, or allow a PC Sum of £X for specialist work to be undertaken by a subcontractor.

Pebble Dash

An external wall finish that comprises of small stones bedded in render.

Perimeter Drainage

A gutter like drainage system installed in a basement/cellar floor at the base of walls to divert any water that penetrates to a drain or sump pump. Usually installed in conjunction with a Cavity Drainage Membrane installation. (See CDM, Cavity Drainage Membrane, Sump Pump)


Ability to be penetrated throughout.



Pitch (1)

The slope of a roof.

Pitch (2)

Solid black tar derived substance, which has a number of applications in damp proofing.

Pitch Epoxy

Mixture of pitch, epoxy resin and other components. Sometimes used as a structural water proofing material.


Material that is spread on walls and ceilings to form a smooth surface and harden when dry.


Prefabricated sheets of plaster contained within thick paper. Used for forming walls and ceilings.


See Wall Plate.


Projecting face or section at the base of a wall or column. Frequently used to describe thin sand and cement render applied at the base of a wall externally.


Term used to describe the external finish between bricks which is applied after the brickwork is complete.


Minute opening in a surface through which fluids may pass.

Pore Structure

The dimensions of a pore.

Pressure Injection

Means of introducing a chemical damp proof course into a wall or a timber preservative into timber. (See also High Pressure and Low Pressure Injection)


A manufacturer of moisture meters.

Provisional Sum

When used in a quotation it is a provisional price for materials where the actual cost of the materials is unknown at the time of quoting e.g. 'allow £100 for wall tiles'.


Part of roof construction. A horizontal timber beam, providing intermediate support to rafters. Supported by walls, hip and valley rafters and roof trusses.


Poly Vinyl Acetate. Used to 'seal' surfaces and make them ready to receive plaster, wall paper etc.


A fixed price for a job of work or supply of goods that is binding.


Part of roof construction.Sometimes referred to as Common Rafters or Spars.Similar to joists but inclinedrising from the eaves to the ridge to support a pitched roof covering.

Random Wall

Wall constructed using a random arrangement of irregular shaped stones.


Residual Current Device, a protective device on an electric circuit.

Relative Humidity

The amount of moisture in the air at a particular temperature expressed as a percentage of the maximum possible at that same temperature.

Remedial Wall Tie

A cavity wall tie (usually stainless steel) that is installed into an existing building where the original wall ties have failed due to corrosion.


Relative Humidity


Most modern renders are a mix of cement/lime and sand,applied in two or three coats depending upon the nature of the background and the exposure expected. Sand and cement mixed together at a ratio of 3:1 with water containing a waterproof/salt retardant additive is a render applied to walls internally following the introduction of a remedial damp proof course.

Render Additive

A powder or liquid additive incorporated into a sand and cement render or concrete in order to make the mix more 'workable' and reduce the water requirement. (See also Integral Waterproofer)

Residual Moisture

Moisture that remains in a wall or timber which gradually decreases by drying following rectification of the moisture source.


Vertical side of door or window opening.


The highest point of a pitched roof that receives the head of the spars (common rafters).

Ridge Tile

A purpose designed tile that covers the ridge of a pitched roof.

Ring Main

Electrical power circuit for sockets.


A term used in connection with a flight of stairs. The rise is the vertical distance between the tops of two consecutive stair treads.

Riser (1)

A vertical water pipe from the water mains.

Riser (2)

Part of a flight of stairs being the vertical section connecting each stair tread. (See Tread)

Rising damp

(in buildings)

The vertical flow of moisture up through a permeable masonry structure where the water source originates from ground water. The water rises through pores by a process loosely termed capillarity.

Roof Truss

Quite common until the 1920's the function of a roof truss is to support the purlins. Sometimes found in very large buildings where big rooms resulted in few load bearing walls. More recently a roof truss means a prefabricated structural timber framework delivered to site to form part of a roof.

Roof Void

The space beneath the roof structure and above the ceiling joists of the uppermost room(s) in a building. Also called an attic.


Rolled Steel Joist

Rubble Fill

Term used to describe material that has been deliberately deposited between an inner and outer skin of a stone wall.

Rubble Filled Walls

Solid walls consisting of inner and outer layers of stone, block or brick with rubble fill between.


Rain Water Pipe

Salt Band

The area of a wall that is at the maximum height to which rising damp has occurred where hygroscopic salts are present at their highest concentration.

Salt Profile

The analysis of masonry samples that have been removed at regular intervals vertically from a wall to establish the distribution of salts. Often used in conjunction with moisture profiles to determine the effectiveness of a damp proof course. (See Moisture Profile)

Sarking Felt

Waterproof material, supplied on a roll. Fixed beneath the roof tile battens when laying a new roof or recovering and existing roof.


Maximum stable amount of one material which may be contained in another e.g. active ingredient in a solution, water vapour in the atmosphere etc.


Framework that contains glass. A sash may be fixed or opening.


Layer of fine concrete used to provide a smooth surface to a solid floor so it is ready to receive the floor's decorative covering.

Second Fix

Term used to describe the fixing of electrical, plumbing or joinery items that would not be possible or practical until plastering or other work is complete.

Setting (coat)

Final coat of plaster onto which decoration is applied. Sometimes called 'Skim Coat'.

Shore up

To provide temporary support.


Water soluble organic salt of silicones - sodium or potassium. A component in some water based chemical damp proof course fluids.


Organic polymer of silicone, usually in the form of a solution which is highly water repellent. Soluble in hydrocarbon solvents such as white spirit and also available in concentrated micro emulsion formulations.


The bottom horizontal section of a door or window frame weathered to cast off rain water. The underside of a sill will have a 'drip' or 'throating' to prevent water running back. (See Drip)

Skim (coat)

Final coat of plaster onto which decoration is applied. Sometimes called 'Setting Coat'.

Skirting (board)

Horizontal run of timber, tiles, plaster or render fixed to the wall at the junction of a floor and wall to protect the plaster/wall and cover the joint between plaster and the floor.

Sleeper Wall

Walls beneath a suspended ground floor which provide intermediate support for floor joists.


Semi-fluid mixture of finely ground solids and water. Many structural waterproofing materials are applied as slurry.


The visible covering of the underside of flight of stairs or a projecting surface

Soil pipe

A vertical pipe that takes waste water and sewage away from a building

Solid wall

A wall that does not have a cavity.


That which can be dissolved in a liquid. (To form a solution)


In terms of damp and timber treatment materials solvent means a hydrocarbon carrier, usually white spirit, in which active ingredients are dissolved to form a solution.


Term used to describe the erosion or flaking of bricks or stone surface primarily due to the actions of the elements or sulphate deposits.


The distance between two points that will support a beam or lintel etc.


The triangular shaped panelling that creates the enclosed space beneath a flight of stairs.

Speedy Meter

A type of moisture meter. (See Speedy Test)

Speedy Test

A test procedure to determine the total moisture content of a sample. Measures the pressure of acetylene gas produced within a sealed vessel resulting from the reaction of a measured amount of Calcium Carbide with water present in the measured sample being tested. Only total moisture content is recorded - reading may be influenced by contaminants. (See Carbide Meter)


Waste material dug out during excavation.


Vertical pipe carrying waste away from sinks and toilets.


The side face of a brick


Part of a flight of stairs. A string is the sloping board that runs from the foot to the head of a flight of stairs and supports the ends of the treads and risers of a staircase. (See also Tread and Riser)

Sub Floor Ventilation

The movement of air beneath a ground floor suspended floor facilitated by air vents at the appropriate level that penetrate the external walls.

Sub Floor Void

The space beneath a floor.


Material or surface onto which a treatment or coating is applied. (See Suction)


Term used to describe the ability of a substrate to absorb water when re-plastering/re-rendering.


A formed chamber within a solid floor of a basement or cellar to contain any water that may penetrate behind a Cavity Drainage Membrane system prior to being pumped out

Sump Pump

A submersible electric pump fitted into a sump to pump away any excess water that collects in a sump.

Surface Tension

The force at the surface of a liquid that causes moisture to rise within a capillary or fine pore causing capillary rise. The force or energy is created by the tendency of a liquid wanting to form a sphere.

Suspended Floor

Consists of bearing timbers called joists covered by floor boards

T & G Boarding:

Softwood floor boards that have a protruding 'tongue' along one edge and a 'groove' along the other hence the term 'Tongue and Groove'. Also used to describe a type of wall panelling.


Term used to describe the application of a waterproof material directly onto a substrate. (See Tanking)


Term used to describe a waterproofing system applied directly to one face of a wall, floor or ceiling to prevent the penetration of water by capillary action and/or hydrostatic pressure. Typically used in cellars and basements where to be true tanking it should be applied to all walls, floors and when relevant ceilings.

Tide Mark

A mark left on a surface where water was or is present.


Method of chemical analysis. Used to determine the concentration of materials.

Total Moisture Content

The combined total of a material's hygroscopic (air dry) moisture content and capillary moisture content. (See Hygroscopic and Capillary Moisture Content)

Toxic Box

Term used to describe the containment of dry rot within an area of masonry by the injection of a masonry biocide into the masonry in a concentrated band around the perimeter of the infected area. (See Cordon Sanitaire)


The process of introducing a damp course fluid into a wall using the influence of gravity and diffusion only from small inverted bottle reservoirs.

Trap (1)

A curved section of drain that holds water thereby creating a seal that prevents odours escaping.

Trap (2)

An opening in a floor that provides access beneath.


Part of a flight of stairs. A tread is the horizontal part of a stair on which one treads when ascending or descending a flight of stairs. (See also Riser and String)


A thicker joist that supports cut (trimmed) joists to create an opening in a floor e.g. for a stair case or fire place. A trimmer is supported by trimming joists.


Thermostatic Radiator Valve. Fitted to radiators to regulate temperature irrespective of boiler controls/room thermostat.

U Value

Measure of thermal conductance of a material.

Vapour Barrier

A layer of material that does not permit the passage of water vapour through it.


The edge of a roof that runs from the eaves to the ridge at a gable.

Vertical DPC

A vertically installed damp proof course to prevent the horizontal movement of moisture in masonry. Commonly used to isolate a treated section of wall from an attached untreated section.

Wall Plate

1) Part of a suspended timber floor construction that provides a level bearing and fixing point for the joists and uniformally distribute loads from the joists to the wall below the plate,

2) Part of a pitched roof construction that receive the feet of the spars (spars) and ceiling joist ends and

3) Part of a flat roof structure that receives the ends of the flat roof joists.

Wall Solution

A term used to describe a masonry biocide that is often used in dry rot control.

Water Based

Term used to describe a type of treatment formulation that uses water as the carrier of the active ingredient.

Water Repellent

A material applied to the surface of a wall to prevent the penetration of water but permits the passage of water vapour.

Wet and Dry Bulb Hygrometer

An instrument that consists of a pair of wet and dry thermometers held in a slotted frame which can be whirled around rapidly to produce a constant rate of air flow. Used for determining the Relative Humidity by measuring cooling due to evaporation of water. Has been superseded by electronic instruments,


Term used to describe the wrapping of timber in an impervious material to prevent direct contact with masonry that is or may become damp.


© Peter Macdonald 2009

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