Sometimes only the best will do. You may choose to reward yourself for all your hard work over the years with that Ferrari you always coveted in your youth, or maybe a Rolex watch. At other times the best you can get is essential, like when buying a car safety seat for your baby.
Like everything else in life, damp surveys vary tremendously. It should therefore come as no surprise to hear that I have been called in countless times for a second opinion, or to resolve damp problems that arose/reappeared following works carried out as recommended in other damp surveys. These damp surveys were produced by a wide range of companies and surveyors – national and local. As I usually get to see the original report, I must by now be one of the leading experts on third party damp surveys!
To be meaningful, complete and useful, any damp survey must be almost the equivalent of what used to be called a full structural survey – I should know, I used to do full structural surveys and depending on the age of the house, 80-90% of every survey was devoted to checking for damp and the problems it causes. I'm not referring just to obvious damp patches on walls, mould in corners, or mushrooms growing from the skirting boards. Things like cracks in walls, failing wall ties, woodworm in floors and roofs, springy floors, or even subsidence, can all be the result of undiagnosed damp.
To ensure you get the very best advice on how to resolve any existing damp properly without doing lots of unnecessary work, and to detect the early stages of future damp problems so they can be averted, only the very best diagnostic and detection equipment is used for my damp surveys:
- As it is vital to know the humidity and temperature conditions in different parts of the building, these are measured with a Vaisala HM42. These instruments are built to order in Finland and are the only meters with a probe fine enough and long enough to measure the conditions in critical spaces, such as underneath most wooden ground floors.
- Hidden inconsistencies within the structure can make certain areas prone to damp or mould. These often create incredibly tiny temperature differences on the surface of walls and ceilings, which can be detected by thermal imaging cameras. These temperature differences are detected by a Testo 875-1i which is the most sensitive camera available – it is twice as sensitive as most other cameras available for building diagnostics.
- The only guaranteed way to determine if a wall is damp is to measure the actual moisture content of its timber components. This is done using a Protimeter Surveymaster, a top of the range premium grade professional meter specifically calibrated for measuring moisture in the structural timber found in UK buildings.
- To locate potential moisture and salt problems in and behind plaster, particularly dense modern plasters, variations in the electrical capacitance within the walls is measured using a Trotec T660 meter. To ensure penetration through modern plaster, this meter is capable of measuring the capacitance up to 4cm within the wall – around 2 times deeper than most other meters.
- To locate and track moisture even when hidden deep inside walls, a Trotec T610 meter is used to send microwave pulses into the walls and measure the distinctive reflections returned by water molecules. This is the only meter able to do this and it allows moisture to be detected when it is hidden up to 30cm inside the wall.
Using these specialist instruments, enables your walls to be mapped in the detail required to work out if you have an existing or developing damp problem. This data, together with any visual evidence recorded, must then be analysed and cross referenced to determine what the real problems are, where any damp is coming from, how advanced it is, what damage is occurring, and how to rectify it – this stage can easily take several days.
The following letter details one client's experiences as a result of sub-standard damp surveys.
A personal story of damp survey experiences
Further to my telephone call, again thank you very much for your letter.
As I said to you at the time of your survey, dampness in the plaster of the lower parts of ground floor walls, especially in the hall, had been present for very many years – but I had put off doing anything about it because overall it didn’t seem to be getting any worse, it was better when the central heating was used more, and I had been told that ‘treatment’ would involve extensive, high, stripping of plaster in association with Damp Proof Course (DPC) injection.
However, in 2012 a surveyor [from a large well known national damp proofing company] assured me that the plaster was all fine and that only DPC injection was needed, and I decided to go ahead, and had this done by them in a lot of the ground floor walls - getting their 30 year guarantee against ‘rising damp’.
Because this work did not resolve the problem, I complained to them in July and December 2013, and on the latter occasion they sampled the brickwork from the worst affected areas in the hall. The samples were chemically tested (in my presence) and found to be dry, so they rejected my complaint against them.
Then, still concerned, I reverted to a local company of experience, who in January 2014 ‘treated’ the ‘rising damp’ (as they said) in the hall walls by extremely intensive DPC injection and stripping of the plaster to a height of 1 metre. When they re-plastered the walls they left only a small gap between the bottom of the plaster and the floor, and they re-mounted the skirting boards at their original level. For these areas I got their 30 year guarantee.
This work certainly improved the hall situation (obviously, in retrospect, by changing the original plaster which had accumulated salts) – as did separate re-plastering of a kitchen and a cloakroom wall prior to re-decorating – but some recurrence of low level dampness in the plaster of the hall walls ultimately led to me asking you last year for your assessment and opinion.
Of course your report revealed the true diagnosis and made sense of the whole situation. As you said at the time you strongly doubted if the brickwork had ever been damp.
Just to record that in the period 2012 to 2014 I thoroughly checked all the skirting boards which were removed to allow DPC injection, and found only one small area (about a couple of inches) of (? old) woodworm damage/decay on the back of one board. I treated this area intensively, and painted the backs of the original skirting boards with (real) creosote, and where in the hall I replaced some boards because of surface damage accumulated over 80+ years and /or in the removal of them – painted the backs of the new lengths before they were fitted.
Since your report I have not proceeded to having the plaster removed to a height of 3 inches and the skirting boards raised (I noted that you did not feel this to be a matter of urgency) so there remains some low level dampness in the plaster. Currently I expect this to lessen when the central heating goes on in the winter. I would of course prefer it not to be there, but in the context of all that has gone before, and with the reassurance of your report, for the present I will just accept and monitor it.
I did have the kitchen chimney breast wall re-plastered as you advised, and it and the other walls which were done independently of DPC injection seem fine.
Your other recommendations concerned the outside of the property, and I’ve had:
- A gap created between the front wall of the house and the low garden wall.
- The timber in, actually 2, of the bay window bottom corner joints replaced, and all the front windows repainted (the side and back ones are UPVC).
- The little splits in the rendering above the kitchen window and door repaired and repainted.
- The ground around the side and required part of the front of the house lowered to expose two clear courses of brick work beneath the DPC.
- The mortar in the exposed brick work, notably at the side of the house, all thoroughly raked out where necessary, and replaced with an appropriate, coloured, lime pointing mortar.
This letter is just to let you know the outcome of your survey and report, and to record for anyone interested the whole situation.
Once again my sincere thanks for your expert advice and help.
As a matter of interest, the letter above refers to chemical testing of the wall to prove it was dry. Fortunately in this case, the wall was dry but this method generally only ever seems to be used when a company has a vested interest in 'proving' that a wall is dry! What they don't tell you, is this test is incredibly easy to falsify. If not done correctly it will always give a low or zero moisture reading and even when it doesn't, the result is often meaningless anyway (I won't bore you with the technical reasons why). One thing you can be absolutely certain of though – if anyone does a chemical moisture test on your wall and it gives 0% as proof of a dry wall, the test has not been done correctly.
What are your damp survey options?
You have a choice of 3 survey packages to ensure you get the optimum value from my expertise and the almost £9,000 worth of equipment I need to bring to your home:
|Damp plus||Standard damp||Basic damp or mould|
|Survey includes interior checks of:||Entire house||All parts affected by damp||For general damp/suspected rising damp, only the ground floor areas.
If mould is main problem, all affected areas.
|Survey includes exterior checks of:||Entire house||All parts contributing to interior damp||Ground floor walls only|
|Survey includes accessible roof spaces||Yes||Only when at risk of damp||No|
|Checks for damp||Yes||Yes||Yes|
|Checks for timber decay||Yes||Interior timber only||No|
|Checks for decaying brick and stone||Yes||Main external walls only||No|
|Checks for salt contaminated plaster||Yes||Yes||Yes|
|Checks for missing/inadequate insulation||Yes||Only if mould is present||Only if mould is present|
|Checks for inadequate or excessive ventilation||Yes||Only if mould is present||Only if mould is present|
|Checks for roof problems (subject to visibility/access)||Yes||Only where there is evidence of leaks||No|
|Checks for floor problems||All floors||Only floors in areas surveyed as above||Only for general damp/suspected rising damp – ground floors only|
|Checks for incorrect ground levels||Yes||Yes||Only for general damp/suspected rising damp|
|Checks for minor maintenance issues that could lead to future damp problems||Yes||No||No|
|Checks for previous building work that is incompatible with the house||Yes||No||No|
|Additional checks on the building possible by request||Yes – £50 per item||Yes – £50 per item||No|
|Comprehensive printed report with prioritised advice||Yes||Yes||Optional at £100|
|Electronic pdf copy of report with prioritised advice||Yes||Yes||Yes|
|Back-up verbal advice included||Available for 3 years||Available for 2 years||Available for 6 months|
|Time allowed for survey inspection||Up to 5 days||Up to 1 day||Up to ½ day|
|Package price (excluding any additional options)||£1360 + travel||£800 + travel||£500 + travel|
My travel for all damp surveys is based on the shortest RAC recommended route from my office at Aylsham in North Norfolk to the survey location. To give you an idea of what this is likely to amount to, here are some approximate travel charges for various locations: Norwich £15, Lowestoft and King's Lynn £45, Colchester and Peterborough £90, Lincoln £110, Derby and London £145, Manchester £235, Cardiff £295, Edinburgh £440.
Your next step is to telephone me on 01263 734815 for an impartial discussion about your damp concerns. Often a discussion is all that is needed to provide the pointers needed to resolve your concerns.
If you are unable to telephone, you can email me at firstname.lastname@example.org
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