Tel: 07751 738 843
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Welcome to TW Building:

Damp Proofing Surveys & Treatments: Plastering & Tanking.

Covering: Richmond, Twickenham, Teddington & Hampton Areas.

Twickenham, St Margarets, Strawberry Hill, Whitton, Isleworth, Brentford, Kew, Syon Park, Richmond, Petersham, Richmond Hill, Mortlake, Sheen, Fulwell, Teddington, Hampton Hill, Hampton Wick & Hampton.

Postcode Areas: TW1, TW2, TW3, TW4, TW7, TW8, TW9, TW10, TW11, TW12, TW13, TW14, SW14,

Contact Details:

Phone or Text David on 07751 738 843.

 Call David on 07751 738 843 to arrange a rising damp survey if you live in the 
Richmond, Twickenham, Teddington or Hampton areas

Thank you for visiting:

This web site has been created to inform the world wide web about the of damp in buildings and to introduce my services in the above areas of London.

Your property is left Clean and Tidy:

With all projects craftsmanship and high standards of perfection are of paramount importance, works are carried out with a professional attitude and for your peace of mind your property is left: Clean and tidy.

 Call David on 07751 738 843 to arrange a rising damp survey if you live in the 
Richmond, Twickenham, Teddington or Hampton areas

Rising Damp Surveys:

If you have rising damp issues that may require a damp proofing treatment. You will notice damp patches, blistering paint and or plaster above the skirting boards. You may also have associated black mould and or white salt deposits.

Please email images if your property is in one of the areas of London South West and after reading the table below you feel you have rising damp issues.

Damp Surveys not related to Rising Damp:

There will be a charge for a visit and verbal assesment of the issues. Please call for details.

Damp Surveys and works in Tenanted Properties:

I am very sorry but due to consistent issues, I no longer undertake surveys or works in tenanted properties, while they are occupied.

Evaluating your Damp Issues:

Where is the damp / black mould.

Probable causes.

Course of action.

  • On ceilings adjacent to roofing.
  • On ceilings adjacent to guttering.
  • On walls: Isolated patches.
  • On walls: Isolated patches.
  • Around door or window frames.
  • Around door or window frames.
  • The above are examples of.
  • Leaky roof intersections.
  • Leaky guttering intersections.
  • Leaky guttering intersections.
  • Damaged pointing.
  • Rotting timbers.
  • Gaps around the framework.
  • Vertical penetrating damp.
  • Call a builder or roofer.
  • Call a builder or roofer.
  • Call a builder or roofer.
  • Call a builder.
  • Replace rotting timbers.
  • Apply a sealant / re point.
  • On ceilings with no blistering.
  • On walls with no blistering.
  • On tiles in bathrooms & kitchens.
  • The inside of window frames.
  • Behind furniture and corners.
  • Condensation problem.
  • Condensation problem.
  • Condensation problem.
  • Condensation problem.
  • Condensation problem.
  • On ceilings adjacent to pipe work.
  • On walls adjacent to pipe work.
  • Leaky water tanks / pipe work.
  • Leaky pipe work.
  • Call a plumber.
  • Call a plumber.
  • Above skirting boards and in cellars.
  • Rising & laterally penetrating damp.
  • Call 07751 738 843 to arrange a consultation if you live in one of the areas of London South West.

Works Undertaken:

General Building and Plastering works:

Please call David on 07751 738 843 to arrange an appointment. I am available to visit your proposed works on a day that is convenient to yourself from 8am to 10 pm. Sorry I do not plaster ceilings.

Damp Proofing and Plastering of Georgian, Victorian and Edwardian Properties:

I specialize in the damp proofing, plastering (not ceilings, sorry) and refurbishment of Georgian, Victorian and Edwardian properties.

Refurbishment of sash windows, repair of rotting door and window frames:

I also undertake the repair of rotting timbers in windows, doors, door frames, and floor joists.

Page Contents:







Site Links and Contents:









The section illustrates how moisture from the ground is prevented from entering; and how it enters, a building. For further reading you may also like to read my articles about the cause and symptoms of and penetrating damp.

If you have black mould which you know has been caused by condensation visit who sell kits for the removal of black mould.

 Rising Damp images of poor Jo's Victorian house in Teddington

1: Rising & Laterally Penetrating Damp:

Rising and laterally penetrating damp issues usually effect pre 1920's Georgian, Victorian and Edwardian properties, which do not have a physical damp proof course. Or where the existing damp proof course has failed, been breeched or altered.

Symptoms of rising & laterally penetrating damp:

If present you will have one or more of the following symptoms on the ground floor above the skirting boards or in a basement or cellar.

  • Blistering paint and plaster.
  • Dark and damp patches on walls.
  • Salt deposits, which attract moisture.
  • Black mould growth.

Arrange a survey:

As you can see from the images opposite of poor Jo's kitchen in Teddington, rising and laterally penetrating damp is very distinctive. If you have any of the above symptoms above the skirting boards or in your cellar or basement please call David on 07751 738 843 to arrange a survey.

Please Note: The following section illustrates how moisture from the ground enters a building. The section illustrates how moisture from the ground is prevented from entering a building.

 Movement of moisture from the ground into a 9 inch solid wall. 
Typically damp course provisions in 2 bedroomed houses in the Richmond, 
Twickenham, Teddington and Hampton areas are subjective.

Movement of moisture into a building:

The diagrams opposite illustrate the movement of moisture from the ground into the mortar beds, of a typical Victorian or Edwardian property with a 9 inch solid wall and sand and lime mortar beds; the mortar between the brickwork.

The mortar beds:

Although moisture does flow into the brickwork of a building via capillary action, the major movement of moisture from the ground; into a building, is via diffusion; into the mortar beds. The mortar between the brickwork. Acting like a sponge, the readily absorbing beds of sand and lime absorb moisture both:

 Movement of moisture through the mortar beds of a wall.
  • Horizontally: Lateral Penetrating Damp and
  • Vertically: Rising Damp.
Into the walls of the building from the ground.

The movement of a substance from a region of high concentration to a region of low concentration. Latin "diffundere"; to spread out.

Capillary Action:
Moisture cannot jump from one brick to the other, there has to be a continuous pathway for the movement of the moisture being absorbed into a building. This continous pathway is provided by; the mortar beds, which in older properties is usually a readily absorbing sand and lime mixture. The amount of moisture that flows into a building via capillary action is very small.

The Sub Floor:

Underneath the floorboards of a solid walled building; unless it has been covered by concrete, is an area called the sub floor. The sub floor is a void of 18 inches to 4 feet in depth. In some properties the sub floor becomes a basement or cellar. As you can see from the cross sectional view far right: The brickwork; of the sub floor, is below ground level and in direct contact with the ground.

Moisture can readily diffuse laterally across the mortar bed, then rise vertically. Providing a major pathway for moisture absorption; from the ground, into the building.

 Air brick ventilation into the sub floor area is generally the only 
provision pre 1920's 2 to 3 bedroomed properties in the Richmond, 
Twickenham, Teddington and Hampton areas, have against rising damp.

Air brick ventilation in the Sub Floor:

If you imagine the sub floor area of your property like a small cellar or basement; a void of nothing, 18 inches to 4 feet deep running underneath your house.

Although the retaining walls of the sub floor are in direct contact with the ground. Outside the property just above ground level are air bricks, which allow air to vent into the sub floor. In some terraces the air bricks are also in the party walls so the air can circulate down the entire street.

Purpose of air bricks and a sub floor:

The sub floor allows vented air to circulate underneath your home assisting with the evaporation of moisture absorbed into the walls, before it reaches ground level. It helps keep timbers dry and free of wee beasties eating your floor boards and there is also the accommodation it provides for pipework and cables.

 Outlets for moisture absorbed from the ground into a building.
Outlets for absorbed moisture:

The diagram opposite shows the outlets for moisture which has been absorbed from the ground, via the mortar beds of the sub floor retaining wall.

  • A: Some of the moisture will evaporate within the sub floor or if present the basement or cellar.
  • B: Some will pass into the timbers that are in contact with the wall.
  • C: Some will pass into the ground floor plaster. Causing dampness, decorative spoiling and the blistering of paint and or plaster as it evaporates.
  • D: Some will evaporate outside.
  • E: Some will jump on the floor and do a lap dance.

 Laterally penetrating damp misdiagnosis.
External ground levels above the existing damp proof course:

Lateral penetrating and accompanying rising damp can also be a problem in properties that have a physical damp course. Problems can occur where there has been a build up of debris, raising of driveways, flower beds, etc above the existing physical damp proof course.

Problems caused will be adjacent to where the damp proof course has been bridged and the construction of the wall will dictate how severe the problem is. A cavity wall has a gap (the cavity) making it more difficult for moisture to pass into the ground floor. Whereas a solid wall has no cavity and moisture will readily pass laterally and vertically into the ground floor of the property.

However you should always check to see if external ground levels are above the damp proof course and also if there is a drain or a leaky down pipe near effected areas.

Rising Damp and Black Mould Growth:

It has been documented that the presence of , which are associated with rising damp, kill black mould, implying that if black mould growth is present your growth is caused by condensation, not rising damp.

However this is not always the case as can clearly be seen in the images above of . Black mould growth can be caused by ground floor moisture absorption. Being found above skirtings in corners and areas of reduced ventilation.

Also the amount of salts contained within the absorbed moisture does vary upon geographical area, water table and building materials.

What is a Damp Proofing Course:

Imagine you are sleeping in a tent without a ground sheet on the ground to stop moisture rising into your sleeping bag. Obviously you will wake up in the morning with a damp sleeping bag. To damp proof your tent against rising damp you simply put a plastic ground sheet on the ground. A modern damp proof course is essentially a piece of plastic which the house is built on top of.

Types of Damp Proofing Course:

A: Physical Damp Proofing Course:

A physical damp proof course is made from plastic or in older properties, they are usually constructed from slate or asphalt. They are inserted into the property when it is being built.

B: Chemical Injection: Damp Proofing Course:

Very popular with big damp proofing companies because the chemicals used are cheep and very little building experience is necessary to undertake the injection.
The main drawback with this type of damp proof course, is that the chemicals used are water based and over time usually 20 years, rising and laterally penetrating damp will dissolve the dpc rendering it ineffective.

C: Gel & Cream Injection: Damp Proofing Course:

The major pathway for moisture absorption from the ground is via the sand or lime and cement mortar between the bricks. Gel injection involves drilling a series of holes in the mortar beds and back filling the hole with a chemical gel.
This type of dpc has become popular with the diy market because of its ease of use, however I have used gels in the past and although they are moderately effective in some properties, I don't advocate their use in properties with a sand and lime mortar bed.

D: Mortar Injection: Damp Proofing Course:

Mortar Injection, is by far the most effective method I have used, one drills holes; as with the gel injection, into the mortar beds, but the holes are back filled with a plasticised mortar, which does not deteriorate over time.

Advocation of unnecessary works:

I do find that customers are often confused about damp issues in their homes and damp proofing companies do tend to dramatize the problem. Causing confusion and fear. I have also found that the advocation of unnecessary works is a problem widely associated with damp proofing companies.

In most cases salesmen; not builders or surveyors, are who recommended; albeit, trusted damp proofing companies will send for your survey. Obviously they are interested in their commission and usually have, limited building knowledge.

The report scored the bigger damp proofing companies as follows:

  • Peter Cox 2/3.
  • Rentokil 2/3.
  • Kenwood 1/3.
  • Lifecote 1/3.
  • ProTen 1/3.
  • Timberwise 0/3

2: Rainwater and Vertical Penetrating Damp:

Rainwater which enters your property via defects within its structure is known as The most common areas of defectiveness being; the roof, guttering and gaps where the frameworks of doors and windows intersect with the brickwork or claddings of a building.

Intersections of a roof where rainwater can penetrate 
 causing damp patches, blistering of paint, wallpaper and plaster.

2a: Roofing Defects:

From the images opposite you can see that there are many intersections within the structure of a roof where rainwater can penetrate, common areas of penetration are:

The images opposite have been chosen to show you the many intersections within a roof, i.e. where one section intersects with another. Movement caused by winds, traffic, excessive heat, cold, rain and snow, especially with the increased severity of weather caused by climate change, coupled with lack of maintenance and time, all weaken the intersections.

Although it can be difficult to ascertain where rainwater is penetrating the roof and its associated intersections of your property You will notice damp patches and or mould on wall to ceiling intersections and on ceilings. If left unattended you will get decorative spoiling and over a prolonged period, rotting timbers and loose plaster. A good place to start looking for the cause of penetration, is to view your property using Google maps: Then call a roofer. Climbing on roofs is dangerous.

 Intersections of a guttering system 
where rainwater can penetrate.

2b: Guttering Defects:

There are a vast array of intersections within a guttering system that can incur movement and become loose. Noticeable signs of a problem will be isolated damp / mould patches, on walls and on the wall the ceiling junction, adjacent to guttering. Leaks can also splash onto the ground and you may notice isolated patches at ground level, which are sometimes misdiagnosed as rising damp.

Guttering defects can cause confusion to homeowners when isolated patches of damp appear which may over time cause plaster & decorative damage.

To ascertain if you have leaky guttering, simply go outside or look out of a window, when it is raining, you will also notice dark and wet patches on external walls after rain fall.

You should also note that drainage pipe work, soil stacks can also leak, so if you notice dark areas on external walls near soil stacks when it has not been raining, this is more than likely the cause, taking special note, where drainage from sinks, baths and washing machines intersect with soil stacks.

 Mortar bed and brickwork erosion of a derelict building. 
 Illustrating an extreme case of. If left unnatended pointing 
 defects can cause damp in properties with a solid wall.

2c: Pointing Defects & Cracked Rendering:

Unless there is a considerable amount of mortar erosion, pointing defects rarely cause internal dampness. The amount of dampness is also dependant upon the walls construction; Is it a solid or, a cavity wall.

Solid walls are normally present in properties built before 1920, they lack a cavity and the mortar between the bricks is usually a sand and lime mixture; which is more absorbent than a sand and cement mix, which accompanies a cavity wall. It is generally solid walls that can develop internal dampness caused by pointing defects.

However the purpose of pointing is to provide protection against the penetration of rain as well as provide an attractive finish to the brickwork and if you leave damaged pointing unattended, bricks will start to erode.

Cavity walls gained widespread use in the 1920's. The cavity allows penetrated rainwater to drain away from the cavity of the building through weep holes. If rainwater does pass into the cavity via damaged pointing, it simply drains away.

Cracks in external rendering, are caused by using too much cement in the render mix, making the render too strong and unable to move with the building as it moves. Yes believe it or not your house moves. Especially in built up areas where there is a dramatic increase in the amount of cars and heavy goods lorries on the road. Simply slam your front door very hard and feel the movement.

As with damaged pointing cracks in external rendering do not generally cause internal dampness. However if that is the cause of rainwater penetration the cracks will more than likely be associated with subsidence, wherein water penetration will be the least of your worries, but should be rectified by the company you choose to undertake your subsidence works.

Gaps around window and door frames allow 
 rainwater to penetrate into a building and can cause
 damp patches and decorative spoiling.

2d: Gaps around door and window frames:

Where a door or window frame intersects with the brickwork or cladding of a building rainwater can penetrate, if there are gaps around the intersection.

Gaps are generally caused by the opening and predominately closing of doors and windows, extreme weather conditions and lack of maintenance. Internally you will notice either or all, of the following symptoms around the internal walls of the framework.

If the windows and doors are plastic, simply applying a silicone sealant around the framework will stop rainwater penetration, do not use cement because it will not adhere to the plastic. Wooden door frames and windows are sealed with either silicone or sand and cement, especially old sash windows.

Please Note: When old rotting doors and windows are replaced, problems can occur when bonding plaster is used to make good. This is because the bonding plaster contains cork, which acts like a sponge sucking residual moisture that collected in the mortar beds, before the windows or doors were replaced.

 Black mould caused by condensation not rising damp.
 Therfore a damp proofing treatment not required. 
 Note:The absence of blistering paint.

3: Black Mould caused by Condensation:

Condensation and associated black mould is a problem commonly associated with buildings built after 1920. If your black mould problem is caused by condensation the mould will typically grow:

Although rising damp and condensation both cause dampness, moisture from rising damp comes from behind the plaster, because it is coming from the ground, whereas the moisture that creates condensation, is created within the building itself. The moisture can come from a variety of sources:

Note: In the image opposite showing black mould caused by condensation, the paint and plaster are not blistering, whereas in the image above of poor where the black mould is caused by rising damp you will notice the paint and plaster are blistering.

Please Note: I do not get involved with Black Mould problems when the mould is caused by condensation. Please visit: who sell products which reduce condensation and kits to eliminate black mould.

of mould growth caused by condensation. Note: Some of the images; the ones with blistering paint, are actually rising damp.


It has been a great pleasure to contribute my knowledge about dampness and black mould in buildings to the world wide web and my prospective customers.

I hope the web site will educate you about building construction and the cause, symptoms, treatment and control of damp and black mould in buildings.

Please e mail if you have any suggestions.

Further Reading:

who sell extraction units to prevent condensation.

who sell kits which eliminate black mould.


Bonding Plaster:

A light weight sticky internal plaster for application onto brickwork or plaster board, before the final finish coat. Bonding plaster contains cork and should never be used on solid walls, as found in properties built before 1920, because the cork absorbs and holds moisture.


Generally a wooden section which replaces the brickwork of part or all of a building.

Dead air space:

Air circulates in circles, have you ever seen a square hurricane. Therefore there will always be pockets where air does not circulate, this is known as a dead air space.


A lead or plastic strip, which seals the intersection of a roof with the brickwork or cladding of a building.

Gulleys and valleys:

An area where rainwater generally drains into the guttering or another section of a roof.

Hygroscopic salts:

A hygroscopic substance can attract water molecules from its surroundings. Chloride and Nitrate salts which are sometimes associated with lateral penetrating and rising damp are said to be Hygroscopic.


The section where one part of a buildings structure joins another.

Mortar Beds:

The sand or lime and cement between bricks.

Ridge tiles:

The tiles at the apex of a roof intersection.

Soil stack:

The soil stack is a large plastic pipe; more often than not, found adjacent to toilets and bathrooms, which drains toilet and bathing waste.

 Listings on the following web sites: 
 The Indipendant, 192, My, UK find your,
 The Sun, Touch Local, Scoot, Yelp, Thomson Local.

Covering the following London SW, KT and Twickenham TW Postcode Areas:

London Borough of Richmond upon Thames: The Twickenham TW Postcode Region:

Twickenham   TW1: Twickenham, St. Margarets & Strawberry Hill.

Twickenham   TW2: Twickenham, Whitton, Strawberry Hill & Fulwell.

Twickenham   TW9: Richmond, Kew & Sheen.

Twickenham TW10: Richmond Hill, Sheen & Richmond Park.

Twickenham TW11: Teddington, Fulwell & Bushy Park.

Twickenham TW12: Hampton, Hampton Hill & Fulwell.

London Borough of Richmond upon Thames: The London SW Postcode Region:

London SW13: Barnes & Richmond.

London SW14: Mortlake & East Sheen.

London Borough of Hounslow: The Twickenham TW Postcode Region:

Twickenham   TW3: Whitton.

Twickenham   TW4: Whitton.

Twickenham   TW7: Isleworth.

Twickenham   TW8: Brentford, Kew Bridge & Syon Park.

Twickenham   TW13: Feltham & Hanworth.

Twickenham   TW14: Feltham & Bedfont.

Covering the Postcode Areas:

TW1, TW2, TW3, TW4, TW7, TW8, TW9, TW10, TW11, TW12, TW13, TW14, SW13, SW14.
 Call David on 07751 738 843 to arrange a rising damp survey if you live in the 
Richmond, Twickenham, Teddington or Hampton areas
Copyright TW Building 2013. All rights reserved.
8a Queens Road, Twickenham, Middlesex, TW1 4EX.
Mobile: 07751 738 843. Landline: 020 8892 6637.
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