Rentokil damp survey says I need all of my home's ground floor, damp coursed

scankaroo

I live in an 80 year old end terrace. Living in it since March 2006, damp has always been shown around the skirting boards on the wall dividing us and next door, particularly under the stairs in cubby hole.

Got a free survey done today from Rentokil and they diagnosed that the whole ground floor of my home has no damp course. They quoted £3,700 to put it in.

I know I can get this done much cheaper locally so I won't be using Rentokil. When I moved in, in March 2006, my house survey failed to show there was no damp course. If it did I'd have bargained on the price or not bought.

Is there a case against that surveyor for failing to spot this? Could they be liable for the cost of putting damp course in?

What about Rentokil surveys? Does anyone have any prior experience of this and possibly any mis-diagnosis of damp problems (ie., after the bigger priced, unnecessary, jobs). They're a reputable company so I doubt it, but you can never be sure.

Any advice or feedback is appreciated.

20000RPM

To me, this sounds like rubbish. Did they do any drilling or hacking off plaster to have a look underneath, or did they just use a meter with electrodes on it?

There's a lot more about this online. Also see Jeff Howell, who writes for the Telegraph on home maintenance. Here's something that may be relevant http://www.telegraph.co.uk/property/propertyadvice/jeffhowell/6582652/Jeff-Howells-DIY-advice-damp-proof-course.html

David_Aldred

Dear Skangaroo,
Given that you state the house is only 80 years old it will have been built with a damp proof course (dpc) at that time under public health legislation and the Building Regulations. It may not be readily seen now because it may be hidden by re-pointing of mortar beds / raised ground levels etc but that does not mean the property will not have been built with such.

Electrical damp meters cannot prove rising dampness and this is clearly stated as fact within British Standard for chemical damp proof courses BS6576. Such damp meters are a useful tool for highlighting areas of concern that should be further investigated but that is all when applied to wall surfaces. If you place your fingers over th eends of an electrical damp meter probe you get a high reading - does that mean your fingers have rising damp? No of course it doesn't.

The only way to prove rising dampness is to remove several wall samples from each and every wall under investigation and subject them to laboratory analysis which is described within Building Research Establishment (BRE) Digest 245.

So if the house was built with a dpc what you have been subjected to is nothing more than a guess from somebody selling damp proof courses for their own profit (most are paid upon commision) who not surprisingly states that what you need is a new dpc throughout for symptoms of low level dampness.

A slate or bitumen dpc may crack with settlement over time if the house has been subject to structural movement but this would only allow small amounts of rising dampness (if present at all) to rise up through such cracks and would not correlate with full wall lengths of dampness throughout the property as you describe.

Because true rising dampness of any signifiance to properties built with a dpc is so rare an occurence and because it is so difficult to prove the recommendation of BS6576 is to take a practical common sense approach approach and to therefore rule out all other obvious moisture sources first and then monitor for drying down to see if addressing what is obvious resolves the problem.

Remember the poor old dpc within the wall itself can get the blame even when it is not its fault such as debris within the base of a cavity wall will allow moisture to rise up through the debris and give all the affects of rising dampness irrespective of whether the dpc in the wall itself is effective or not. Such debris will also provide a pathway for penetrating dampness to strike across the wall and because the wall is solid at this point it will be cold and prone to condensation.

Similarly if there is a gap between solid floors and walls or if the sub floor void beneath suspended timber ground floors is poorly ventilated low level dampness to surrounding walls will occur whether or not the dpc is effective. These and a host of other reasons are usually found to be the true cause of low level dampness to properties built with a dpc.

The dpc contractor remains on a winner because if after their magical dpc and associated re-plastering the dampness returns over a period of time they simply state it is nothing to do with the dpc and of course they are right because it was nothing to do with the dpc in the first place in the vast majority of cases.

I hope this helps clarify a few of your concerns. Kindest regards, David Aldred Independent damp and timber surveyor

keystone

A DPC contractor is bound to say that TBH because its in their interests so to do.

Cheers