Dampness in buildings

The problem Surveyors have is this – to determine the exact cause of damp often the precise history of the problem must be known and an occupier usually didn’t know of the problem when they first moved in and so paints the problem as being new.

The problem home owners and tenants have is that they couldn’t care less about the Surveyors problems and force a one-stop full solution as soon as possible. See my ADVICE ON DAMP post on this subject (elsewhere of this site) and the various types of repair solution available.

Put these two problems together and what you get is commercial pressure on Surveyors and Dampness Contractors to shoe-horn one standard solution into nearly all reported dampness problems – “it will cost you £XXX to chemically inject the walls and, by the way, your wall plaster is contaminated and essential  replastering will cost you £XXXX: Now, what’s the problem?”

The good Contractors and Surveyors saw the light many years ago and get tough with pushy clients but the down side is that investigative costs escalate, albeit those costs may considerably reduce your repair cost spend.

One person on this planet has led a revolution in the diagnosis of Dampness and anybody seriously interested in the subject should always hear him out. Therefore, here is a LINK to his web-site = http://www.buildingpathology.net/homeTruths.asp

His name is Mike Parrett and his Building Pathology and Home Truths advice is very well respected. What he is saying is “look beyond the obvious for the correct diagnosis and design of a solution to dampness”.

I must straight away report that Mike may have the same surname as me, and he might be related, but as far as I am aware we have never met and if we are related it is very distant (but our desire to improve House Survey Reportng standards is identical – perhaps in runs in Parrett blood?).

Back to the subject of dampness…….

Once rising damp has been correctly diagnosed (and I refer you do the Condensation TAB for extended comment and resource data for that form of dampness) what happens next?

Your dampness problem must first be defined: often the causes of damp are several and the sorting out process is difficult because one source of damp is lying over another. In a chimney flue or fireplace condensate from fuel combustion, ordinary condensation, falling penetrating dampness might mingle with rising dampness. In this example, what is more important, quickly rectifying “the damp” so as to prevent ground floor rot developing at even higher repair cost budgets or getting the correct apportionment of the problems within the diagnosis?

As a Consultant do I go for immediate client benefit to the problem or slow down and spend more clients money on chemical analysis of the contaminated plaster, employ contractors to further open up the structure so I can take more dampness readings and observations etc…..

Chicken and Egg is an expression that comes to mind here. To be professional or effective? Given time and money I would like to be both but in many cases I have to attempt to explain “all this” to the non-understanding-client and ask for guidance on which direction to take.

So we have got past the diagnosis stage and are about to repair the damp. What can you expect? Let’s take a common example – partial dampness to a ground floor fireplace and both side walls:-

(I recently dealt with this case – a case where a Specialist got his diagnosis wrong and two years later the home owner has the same dampness back again but in the meantime the Specialist has gone bust and the guarantees they issued are worthless).

The symptoms – wall-base plaster slightly blistered; décor darken and slightly flaked; high dampness moisture meter readings at low height on the wall but none in the timber flooring and skirtingboards (highest readings in the fireplace itself – which has not been used for many years but remains ventilated).

The problems – (1) a Specialist came in and said “failure of the damp proof course (dpc)” and ground water is rising up the wall and (2) bringing with it salts that contaminate the wall plaster. (3) These salts stay in the plaster and extract further moisture from the air we breathe”.

The initial suggested solution – (1) hack off the wall plaster to the affected walls up to 1.2m height (after this gravity prevents water climbing higher) (2) drill wall-base holes to take injected silicone that will solidify and stop water rising in the wall (3) replaster the wall to an exact specification.

Two years later (now) the situation is – exactly the same profile of dampness as stated above.

What has gone wrong?

Put simply, the Specialist got it wrong to start with and home owner made another fatal error.

On cost grounds the home owner decided to have the replastering works completed by a local Builder and not the Specialists, the former were much cheaper. The builder was not experienced and the specification was wrong thus invalidating the guarantee (despite, in this case, the guarantee being redundant because the contractor went bust and the client did not take out a FURTHER COST Insurance Backed Option Guarantee).

The error the Specialist made was simply assuming the dampness was mainly or solely from a failed dpc.

Put the two errors together and the result was inevitable: at some time the pressure of ground water salts and exhaust combustion residue will ultimately soak through the plaster. Unfortunately the style of that penetration looks exactly like rising damp and so a real danger exists that another Specialist Contractor could come in and do the exact same works this repeating the cycle.

In this particular case PROinspect used thermal imaging techniques which together with our experience meant that the client got a solution quickly (£600 plus our own fees and the cost of subsequent restoration of decorations).

For completeness – we removed the wall plaster, allowed the exposed masonry to dry out, removed as much residue as possible, checked for and completed minor re-injection of silicone, provided a salt inhibitor slurry to the walls and then replastered correctly.

Whilst on-site we also surveyed for (1) chimney stack problems that could be causing falling penetrating damp, (2) plumbing leaks, (3) lifted lower floorboards to see of the problem damp had caused flooring decay, (4) checked for adequate sub-floor-ventilation air circulation.

So, when the Mortgage Valuation report says your new home has damp and a Specialist Report is needed, do think hard before you reach for the phone.

For those who still need for data, here are a selection of web-sites that may be of use to you:-

A Company who have high diagnostic skills and who we use often is http://www.insitegroup.co.uk/

Like Mike Parrett, Tim Hutton is also a master – http://www.buildingconservation.com/articles/risingdamp/risingdamp.htm

For basic data but also some cool download materials check out this site http://www.safeguardeurope.com/applications/rising_damp.php

One good solution to Condensation and general dampness is to provide a Positive Pressure Ventilation system or install Humidivent intelligent extractor/blowers: see such sites as these for more details – look at these solutions as an improvement to control the problems rather curing the problems:- http://www.petercox.com/services/condensation.html and this one for a PDF version of technical data for an AIRFLOW system (sorry about the long address) – http://www.google.co.uk/search?hl=en&client=firefox-a&rls=org.mozilla%3Aen-US%3Aofficial&q=humidivents&btnG=Search&meta=&aq=f&oq=

And finally, Period Buildings are a completely new and different challenge and usually must not be treated in the same manner as more modern buildings. The following site breaks you into a differing mindset – http://www.spab.org.uk/advice/technical-qas/technical-qa-20-rising-damp/