DAMP AND TIMBER REPORT JARGON BUSTER
When instructing a surveyor to carry out a survey on a building, whether it be in the case of a pre-purchase, re-mortgage or for rising damp, woodworm or dry rot, you will inevitably, after the survey has been carried out, receive a report from the surveyor. This will detail the construction, condition, and any defects found. Whether it's a building survey or a damp and timber survey to satisfy the mortgage lenders, the report will state the obvious, but will also use terms which you may find confusing. Phrases such as "timbers in contact with damp masonry may be at risk to timber decay" or even terms such as purlins, rendering & dpc mean nothing to some people. We have come across lots of clients who have been confused by some terms used by the surveyor in his report and others who are wondering "what in the world does that mean?"!! This web page has been designed to help you cut through the jargon. For any further advice please feel free to contact Damp Aid (at no cost to yourself) on 0800 0680 881 or via email on our contacts page.
Air brick
A perforated brick or grate built into a wall, to provide ventilation below a suspended floor to prevent fungal decay i.e. dry rot & wet rot and attack by wood boring insects.
Architect
Architects design new buildings and the spaces in and around them and help restore, conserve and adapt old building structures. They usually get involved at the start of a construction project, developing designs that interpret a client's vision. Their work includes - preparing and presenting building design proposals; producing detailed drawings and specifications; liaising regularly with construction contractors and other built environment professionals; visiting construction sites to assess progress and inspecting the quality of work, ensuring it follows the agreed architectural design.
BBA
The British Board of Agrement certifies the quality of building materials, including damp proofing and timber treatment products.
Bell Drip
Angled section at bottom of a rendered wall which allows rainwater to drip off slightly away from the base of the main walls thus preventing bridging of the damp proof course and penetrating damp.
BRE
Building Research Establishment - The BRE Trust Companies, BRE and BRE Global, are world leading research, consultancy, training, testing and certification organisations delivering sustainability and innovation across the built environment and beyond.
BSI
The British Standards Institute administers 'Kitemark' licences relating to a very wide range of goods, materials and systems used in all areas of the construction industry. For example, BS 6576 sets out a code of practice for installing chemical damp proof courses. The BSI also administers the ISO 9000 series of quality management standards. For more information contact BSI, 389 Chiswick High Road, London W4 4AL
Building Survey
This is a far more detailed survey formerly known as a 'Structural Survey'. The report will give a detailed account of any property defects and the best course of action to rectify the problems. It will also give advice on matters that may become a future issue. This can cost anything from £500 - £4,000 depending on the value of the property.
Whilst surveyors will be able to identify and determine the cause of any problems, further specialist advice is usually recommended to obtain estimate for remedial repairs or to obtain access to areas that could not be seen during the surveyor's inspection e.g. at roof level. In the event of a survey highlighting areas of concern, we would strongly recommend you obtain the opinion of a specialist before deciding on which course of action to take. Some of the more common problems are: Structural issues, problems relating to the roof, potential damp and timber defects.
Building Conservation Officer
Building conservation officers work to promote and preserve historically important buildings by offering advice on how to maintain them in an architecturally accurate and sympathetic way. They may work with many different typs of buildings, including houses, churches, windmills, lighthouses and factories, ensuring that they survive for future generations to enjoy. As well as providing valuable evidence of the way people lived and worked in the past, such buildings also help to preserve the character of our cities, towns and villages for the future.
Building Control Surveyor
Building control surveyors make sure that building regulations and other legislation are followed when houses, offices and other buildings are designed and constructed. Before construction gets underway, building control surveyors check applicants plans, drawings and specifications to make sure they meet the regulations. Surveyors can reject plans that fail to meed building regulations or issue certificates for work to commence. Once work begins, building control surveyors visit sites at various phases of construction, checking that work is carried out properly and to the right standards. A building control surveyor issues completion certificates. They may also authorise entertainment licesces, conduct public venue safety inspection, respond to emergencies to assess building safety and approve building demolition. A building control surveyor will also check that property alterations such as extensions meet regulations.
Building Surveyor
Building surveyors advise property and construction clients on areas ranging from the design and development of new buildings to the conservations and restoration of historic buildings. Specific duties can include - advising on technical, financial, environmental, building regulatons, restoration and property legislation matters. Completing property and land surveys and valuations, writing up technical reports and recommendations, preparinge plans, contracts, budgets and other documentation, submitting planning applications and grant requests, overseeing building work and managing projects, giving advice surrounding legal and potentially contentious issues such as insurance claims and liability costs.
BWPDA
British Wood Preserving & Damp-proofing Association. See PCA below for more details.
Cavity air gap membranes /cavity drainage membranes
This membrane is a high density polyethylene extruded membrane which is fixed mechanically to the walls, ceilings and floors but with an air gap for the movement of water vapour. The membrane has studs varying from 3mm to 20mm which retain an air gap between the wall and the membrane. Any water egress behind the membrane will discharge down the wall and into a secret perimeter drainage system. This drainage system is laid at a slight fall and water is then collected in a sump unit which incorporates a pump to then discharge the water to the nearest drain. The wall membrane is mechanically fixed through the studs using a waterproof fixing, complete with rubber waterproof grommet. An independent stud partition is then erected on the inside of the membrane which then accommodates wiring, pipe work, plasterboard and finishes in the usual manner. Metal studding is particularly suitable for basement applications.
Floor membranes similarly have a small air gap and the polyethylene membrane is extremely crush resistant thereby allowing a floor screed to be applied as a useable finish. Alternatively a floating floor comprising polystyrene insulation and tongue and grooved chipboard or Weyroc can be used.
Cavity air gap waterproofing systems are relatively fast to install and commonly have a 10 to 30 year guarantee. It is normal to have the sump and pump unit maintained annually to ensure no build up of grit or debris. With the current and future increase in flood risks some consideration should be given to an independent power pack that provides a battery back up supply should a power cut occur. Similarly high level water alarms can be fitted to advise if the unit is failing or water is rising unexpectedly fast.
It should be expected that any membrane waterproofing system would carry a BBA (British Board of Agreement) Certificate for the membrane material.
Cavity WallA main, external, wall built of two leaves of brick, stone or a type of block, and a space in between. Normally the inner leaf is load bearing and the function of the outer leaf is to protect the inner leaf from the weather, the two leaves are linked by ties, normally of metal. A cavity wall is usually more resistant to damp penetration than a solid wall, and has greater thermal insulation.
Cavity Wall Insulation Technicians
Cavity wall insulation technicians, also know as insulation installers, fit insulation materials between the inner and outer walls of new and existing buildings, in order to conserve energy. They may also lay loft insulations, fit draught- proofing and install sound proofing materials. Usually working alongside another tradesperson, their duties involve - surveying properties first to determine the best methods and materials to use, producing a written report for customers, marking out ventilation, wiring and pipework ducts, calculating the volume of space to be filled and the amounts of material required, drilling holes in the building walls, pumping insulating material in the wall cavity.
Cemetitious Multi-Coat Render (tanking)
Another popular method of basement waterproofing is a cemetitious render whereby multiple coats of render, with a waterproofing agent in a dense sand/cement mix, is applied to the walls and floor. The technique endeavours to create a fully lapped joint of each wall and floor layer of render, thereby creating a fully integrated waterproof lining.
It is vital that the basement surface is fully prepared to form an excellent key for bonding purposes with no loose material or contamination. Whilst this method of waterproofing has proved successful in the past, there is no mechanism for the release of any hydrostatic build up of water pressure and thus a sealed membrane system is often a preferred method. Additionally the cemetitious render must not be punctured in any way thus fixing of sockets, pipes and light fittings can be an issue and an inner stud partition leaf is often used.
Chemical injection Damp proof course
Chemical damp-proof courses are inserted to control the vertical passage of moisture from the ground, and are almost all installed in properties where no damp proof course exists or it has broken down with age.
Condensation
This is caused by high humidity (moisture in the air) within a property. It differs from rising and penetrating damp in that it is caused by excessive moisture within the property that cannot escape, rather that damp coming in.
The most tell tale sign of condensation is mould growth which can be black, white, yellow or green.
The first sign that condensation is a problem is when black pinpricks of mould appear on walls, ceilings or even furnishings. There is usually a musty smell and clothes and shoes in cupboards can become covered in a white or green furry mould. Factors which contribute to condensation include moisture produced from bathrooms, kitchens, drying clothes indoors, paraffin/flue less heaters and insufficient ventilation. If the cause of condensation is not rectified, the mould will grow and can eventually cover whole walls and ceilings and ruin clothes and decorations.
Coping Stone
Brick or stonework on top of a wall, to stop damp penetrating the top of the wall.
Cordon Sanitaire
One, two or three "containment barriers" provided to contain dry rot mycelium within an area of wall by introducing a masonry biocide through the full thickness of a wall, combined with a surface application over the area contained by the perimeter. This is used to protect masonry adjacent to a dry rot outbreak. (see also Toxic Box below).
C.T.I.S. - Certificated Timber Infestation Surveyor
This qualification was introduced in 1980 when the examining body was the Institute of Wood Science. In 1995 the BWPDA took over the examining role for a short period and in 1998 the Institute of Wood Preserving and Damp proofing became the examining body on behalf of the BWPDA. In 1995 C.T.I.S. ceased to be a stand alone qualification and the examination became module 2 of the current CSRT qualification. About 600 people passed this examination prior to 1995 and they are entitled to use the initials C.T.I.S. after their name.
C.R.D.S. - Certificated Remedial Damp-proofing Surveyor
This examination was introduced in 1982 and the examining body was initially the British Chemical Damp-course Association (BCDA). In 1990, the BCDA amalgamated with the British Wood Preserving Association (BWPA) to form the BWPDA. The Institute of Wood Science and for a short period the BWPDA became the examining bodies. In 1998 the examining role was taken over by the Institute of Wood Preserving and Damp-proofing on behlaf of the BWPDA. In 1995 C.R.D.S. ceased to be a stand alone qualification and it became Module 3 of the current CSRT qualification. About 600 people had passed this examiation prior to 1995 and they are entitled to use the initials C.R.D.S. after their name.
C.S.R.T. - Certificated Surveyor in Remedial Treatment
In 1995 a Legal, Health and Safety module (Module 1) was introduced to run in conjunction with the C.T.I.S. (Module 2) and C.R.D.S. (Module 3) examinations. Candidates who successfully passed all three modules are entitled to use the initials C.S.R.T after their name. Candidates who had previously passed the C.T.I.S. and C.R.D.S. examinations prior to 1995 who then passed the Legal, Health and Safety module are also entitled to use the initials C.S.R.T. Since 1995 around 850 people are now formally C.S.R.T. qualified.
There are unfortunately some cases where an individual may claim to be qualified but in fact they are not. The Property Care Association (PCA) maintains the industry qualifications register and should you wish to confirm a person's qualification you can contact the PCA on 0844 375 4301
C.S.S.W. - Certificated Surveyor In Structural Waterproofing
This examination was introduced in 2004 to cater for the rapidly growing structural waterproofing market. The examination is intended for those who are involved with the diagnosis of problems associated with water entering buildings in below ground situations and designing appropriate remedial measures in order to create the desired level of dryness in the internal environment. The examining body is the PCA. Candidates who pass the examination are entitled to use the initials C.S.S.W.
Damp and Timber Specialist Survey & Report
A timber and damp specialist survey will identify any areas of rising or penetrating damp or timber defects. The cost of an inspection and report is usually fairly minor. The fees for these surveys are usually refundable if the company is subsequently instructed to carry out the required repairs.
Damp-proof course (DPC)
Often abbreviated as DPC. A layer of impermeable material built into a wall to prevent damp rising within it. Older damp proof courses are often of slates; more recently felt impregnated with bitumen; modern construction uses heavy duty polythene. A chemical damp proof course can be injected into an old wall, forming an impermeable layer within the masonry, although its efficiency varies with the type of construction. A vertical damp proof course is required to keep a room below ground level dry(known as tanking), or where a horizontal damp prood course may be bridged. Damp proof courses are also installed in other parts of a structure.
Damp-proof membrane (DPM)
A sheet DPC underneath a solid floor to keep the surface dry.
Diffusion System
A concentrated silane/siloxane 'cream' which is slowly diffused into the masonry. When it reacts with the silica in the masonry it forms a water repellent barrier.
Dry Rot
The true Dry Rot fungus (Latin name Serpula lacrymans) is the more serious of the wood destroying fungi. It causes extensive damage to structural timbers if not treated in time. It will spread undetected behind wall plaster and even through thick walls in search of timber to attack. Timber affected by dry rot is brown, dry and brittle with cube shaped (cuboidal) fractures and can be crumbled by hand. The fruiting body (or fungus/mushroom growth) gives off millions of spores which resembles red dust and is often mistaken for brick dust.
Efflorescence
Salts brought to the surface when moisture evaporates from the surface of brickwork or plaster.
Electro Osmosis
This is an active system which introduces an electrical current into the wall just above the ground level. It involves the insertion of a continuous titanium band into the mortar joint along with electrodes positioned at intervals. The current repels rising moisture back down the wall. As long as the charge is maintained the walls will remain dry and free of damp.
Exchange of Contracts
Once the contract has been signed by both parties and you have transferred the deposit to your solicitor (normally 10% of the purchase price), your solicitor should be getting close to being ready to exchange contracts. You will normally need to have agreed on a completion date with the seller prior to exchange of contracts. This is done either directly or more usually via the solicitors or estate agents. At exchange of contracts the purchase becomes legally binding. If either party were to pull out of the transaction at this time, there are likely to be heavy financial implications for the person that withdraws from the sale.
External ground lowering
Carried out where external ground level is bridging the damp proof course.
Freezteq - Frozen damp-proof course system. (BBA Cert. 92/2849)
This involves drilling holes in the base of walls to within 25mm of the wall thickness then inserting frozen "ice sticks" of damp-proofing fluid into the holes. These then melt and the dpc fluid diffuses into the brickwork. This has to be carried out four times within a 24 hour period.
Fungal Decay
The infection of timber by wood-destroying fungi such as Wet rot and Dry Rot. (see timber decay below)
Flashings
Strips of (usually) lead fixed to waterproof a joint, eg between a roof and a wall, or at the base of a chimney stack.
Flaunching
Cement work at the top of chimney stacks securing the terminal pot.
French Drain
A French drain is a trench that has a land drain installed at the bottom of the trench and has been backfilled with shingle or similar coarse stone. The purpose of such a drain is to change the pattern of drainage in a certain area. The usual reason for installing a French drain is to ease the situation where a damp problem exists within the base of an external wall.
Gel and Cream Injection Damp Proof Courses
In recent years a new generation of damp proofing products has emerged. Water soluble thrixotropic gels can be injected into any damp substrate using a simple cartridge gun or compression pump. This gel then reacts to form a silicone repellent which is completely water resistant.
Silicone emulsion creams are injected into any form of masonry at low pressure through holes pre-drilled. This formulation then creates polysiloxanes once the liquid cream has migrated into all of the pores of the substrate.
GPI (formerly GPT & GPIC)
Guarantee Protection Insurance Ltd. - Provides specialist insurance to cover Rising damp (damp proofing), woodworm treatment, dry rot treatment & wet rot treatment. (37 Carrick Street, Ayr, Ayrshire, Scotland KA7 1NS)
Homebuyer Report
A Homebuyer Report covers the same issues as a Building Survey, but in less detail. The report should include a brief description of any defects and where necessary will indicate what should be done to rectify any problems. A Homebuyer Report includes a valuation of the property for the client's use whereas the Building Survey does not. This report should cost between £300 - £1,000 and is usually based on the value of the property.
Hygroscopic Salts
Hygroscopic means "the ability to absorb moisture from the surrounding environment". The salts (Chlorides and nitrates) which originate in the soil, are transported with damp as it rises through masonry. Hygroscopic salts can cause walls to remain damp even if there is no source of water ingress.
IWSc
Institue of Wood Science - The purpose of the Institute of Wood Science is to advance and encourage the scientific, technical, practical and general knowledge of timber and wood based materials.
Joist
Horizontal timbers supporting floors or roof structure.
Lintel
A beam, normally of timber concrete, steel or stone, spanning a window or door opening.
Masonry
Brickwork, stonework or blockwork.
Mastic
A generic term used for flexible sealant, e.g. around window openings.
Mortgage Offer
Once your lender has made all the relevant checks, they will issue a mortgage offer, which is a document setting out the details of the mortgage. You will receive one copy, whilst another will go to your solicitor. Assuming everything is in order and you sign the offer, the morgage is effectively in place.
Parapet
A wall built up above roof level.
Parquet floor
Small strips of hardwood laid in an interlocking pattern on a solid floor.
Party Wall
A wall separating, and shared by, adjoining properties.
Penetrating damp
Penetrating Damp is caused by moisture penetrating through the roof or walls. Causes include: defective pointing/flashings, faulty rainwater goods, defective roof coverings, plumbing leaks, defects around window joinery and doors, and many more.
Such defects generally cause localized problems and readily become evident in the form of damp patches appearing.
Pointing
the neat finishing or mortar joints in masonry
PCA (formerly BWPDA)Property Care Association - The PCA is the premier trade body representing specialists in structural waterproofing, damp proofing, wood preservation, structural maintenance & flooding
Purlin
a large horizontal timber, part of the roof structure, supporting the rafters, and normally supported by load bearing walls.
Quantity Surveyor
Quantity surveyors are essentially construction accountants, managing the costs and contractual side of building and civil engineering projects. This means they must follow one of the degree level routes that the Royal Institution of Chartered Surveyors (RICS), Chartered Institution of Civil Engineering Surveyors (ICES) or the Chartered Institute of Building (CIOB) approves.
Rafters
A sloping timber, part of the roof structure, supporting the tile or slate battens and probably resting on purlins.
Rainwater Goods
Properties guttering and down pipes.
Rendering
The sand/cement finish to an external wall, or the first coat in plastering.
Ridge
The horizontal top of a pitched roof.
Rising damp
Rising damp is a condition caused by ground moisture rising up a masonry wall by capillary action. It occurs where there is no damp-proof course or where the damp-proof course has been damaged or bridged. Where present, moisture can rise up the wall to an average height of approx 1.2 metres and it can sometimes leave a characteristic horizontal 'tide mark'.
Rural Surveyor
Rural surveyors manage the interest of landowners and tenants of rural properties. The may manage one or several estates and advise on - the law, rural estate management of staff, stock and land; forestry and woodland management' conservation, building maintenance and the extraction of minerals from land; agricultural matters; developing the non-acricultural use of rural land.
Silane diffusion (dpc cream) - (e.g. Peter Cox Drywall Diffusion dpc BBA 02/3976 or Safeguard Dryzone BBA 97/3363)
This involves drilling 10mm holes into the mortar joint and injecting a damp-proofing cream into the holes with a caulking gun or hand pump. The cream slowly diffuses, releasing a vapour which reacts within the masonry to form a water repellent resin, thus forming a barrier against rising damp.
Siliconate transfusion - (e.g. Wykamol Siliconate K dpc - BBA 02/3961)
Holes are drilled into the wall and then a series of units and tubes are inserted into the holes. The transfusion units are then filled with the siliconate fluid (enough to saturate the brickwork) which is then gravity fed from the units into the brickwork to provide a layer of damp-proofing fluid. Although this ensures a better distribution of the damp-proofing fluid it is time consuming.
Silicone treatment
Weathering and frost damage of masonry can be reduced by spraying with silicone-based liquid thus preventing penetrating damp.
Slurry injection - (e.g. Vandex Injection Mortar dpc)
This involves drilling 18-20mm holes along a mortar line, approximately 230mm apart, from both sides of the wall and at an angle of about 30 degrees downward to a depth equivalent to the wall thickness. The holes on either side are staggered to give an overall spacing of 115mm. Water is then flushed into the holes to remove any dust. The damp-proof injeciton mortar is then mixed with water, enough to last 30 minutes otherwise it will solidify, to form a smooth paste which is then injected into the holes with a caulking gun. A reaction between the salts in the structure, moisture and the chemical results in a crystaline growth which will block all pores and fine cracks in the wall. This creates a solid damp-proof barrier through which moisture cannot pass. This method is advantageous for thick walls and stone walls which may be unsuitable for pressure injection, however it is messy and time consuming and results in unsightly plugged holes!
Structural Engineer
Structural engineers are involved in the design and construction of a range of structures such as office blocks, housing developments, hospitals, schools, bridges and tunnels. They often work alongside architects and are responsible for working out how buildings and structures will be made to stand up to the stresses and strains placed upon them. They have to ensure that a project is designed and built to be visually appealing, meeting all the necessary safety requirements. Work may include producing design solutions, meeting with clients and other members of the design team to discuss plans and preparing drawings and building specifications.
Structural Survey
Now known as a Building Survey (see above). The surveyor examines the property externally such as chimney pots/stacks, roof coverings, soffits & facias, gutters and downpipes and external walls to see if there is any current evidence of settlement or subsidence. He will examine windows & external timbers, endeavour to identify a damp proof course, will lift inspection chambers to examine drain runs. He will examine the site to identify any visually apparent problem with the boundaries. He will also advise if trees present a threat to the stability of the building. He will examine inside lofts to inspect the roof structure, the insulation, water installations and chimney stacks, checking that there is adequate support. He will check internally for cracks or signs of settlement of subsidence. A damp test will be carried out to ground floor areas. This can give an indication of whether sub-flor timbers are at risk of dry rot or wet rot. He sill also inspect timbers, plumbing, electrics and heating. If there are obvious problems he may recommend specialist reports.
Tanking (See Water proofing & Cemetitious Multi-Coat Render)
Timber decay
Timber decay occurs in timber which becomes wet and is attacked by one of a number of wood-destroying fungi. It always arises because the wood has become wet (above 20% moisture content). Finding the source of dampness and eliminating the ingress of moisture is always necessary. (see fungal decay above).
Toxic Box (Perimeter Box Treatment)
Four sided "containment barrier" provided to contain dry rot mycelium within an area of wall by introducing a masonry biocide through the full thickness of a wall, combined with a surface application over the area contained by the perimeter. This is used to protect masonry adjacent to a dry rot outbreak. (see also Cordon Sanitaire above). "Toxic" is an emotive word as the masonry biocides used for dealing with Dry Rot are not classified as toxic, therefore Perimeter Box Treatment is the preferred term.
Trust Mark
A government backed initiative to help consumers find reliable and trustworthy tradesmen. Every firm's technical skills have been independently checked through on-site inspections. It is widely supported by consumer protection organisations and the building industry.
Valuation Survey
When you formally apply for your mortgage, they will arrange a basic valuation report, to check that the property is worth enough to support the amount you want to borrow. The fees for valuations are generally set by the lender. This report does not go into any real detail on the state of the property, so you may want to instruct a surveyor to carry out a more detailed inspection for your own peace of mind. There are two types to choose from: Homebuyer report & Building Survey. (See details under relevant headings).
Vapour barrier
An impermeable layer, often of polythene, fixed to prevent condensation and possible rot within a timber structure.
Vernacular Buildings & Structures
Vernacular rural buildings, such as byres, mills and kilns, are an integral part of United kingdom's cultural heritage and contribute to landscape and local character in rural areas. These rural buildings were usually built using local materials and traditional techniques, and many pre-date the advent of mass-production techniques and the use of new building materials such as concrete. Examples of vernacular buildings / structures include simple farm or estate buildings, byres, mills, kilns, smiddy cottages, workshops, dovecotes, boundary walls, drystone dykes, ha ha's, walled gardens, bridges, green houses, Dutch barns, gate piers, statues, fountains.
Wall plate
A timber along a wall top, to carry floor joists or rafters.
Water proofing (Tanking)
It is common where walls and floors are located below ground level for ingress of either dampness or even running water. This lateral and rising damp penetration is caused either by capillary action or by hydrostatic pressure. The term for overcoming such waterproofing situations in cellars and basements is 'tanking'. A good tanking system can perform well enough to enable cellars and basements to be transformed into habitable living rooms and bedroom areas.
A trend over the last decade has evolved whereby property owners are actively having basement areas added to houses which were originally built without them. This has become very much the vogue in areas of high property value such as London, where in some areas there is hardly a street without several houses having 'basement creations' constructed. Whilst the techniques for adequate waterproofing of new basements is excellent, the disruption and diversion such operations can have on the local water table, are in some cases inadvertently causing neighbouring properties significant damp and flooding problems.
Tanking traditionally took the form of an asphalt lining applied to both the basement walls and floors. Today the method more often constitutes a cemetitious render coating or a cavity air gap membrane.
Weather board
A board fixed at the bottom of a door, or door opening, to prevent rainwater driving in.
