99% damp reading on survey

gemmacots

Before I appoint a damp specialist surveyor I was wondering if anyone has any insight into my problem please. 

We have just had a survey on a house. we are looking to purchase and 2 internal and external walls have shown a damp reading of 99.9% on opposite sides of the house. The surveyor in question said that the floors in the house at some point have been replaced from a floating floor and filled with cement so he said we need to check with building regs to see if the membrane beneath the cement for damp was put in place. 

We have obviously requested this but have not yet heard back. I was just wondering what solution would there be if there is no damp membrane as I assume if I asked for a damp specialist company to come they will tell me to dig it all up and start again or may try to get me to purchase a dpc which, upon reading the heritage site is not needed. The house has had no one living in it for the past six months so I assume the heating has been off and along the skirting boards on the walls affected there are some nails which have rust so we’re assuming this is due to the damp. Also, they have filled the air bricks with silicone. The surveyor said this may be due to the fact that there is now cement so they are redundant but the one’s higher up in the wall have have also been filled. 

If we find out there is no membrane beneath the cement. How could we tackle this if this is causing the damp on the walls? Could I add a liquid dmp on top of the cement?

The issue may not even be due to the cement floor but not sure who to appoint before I go ahead with the purchase. Thanks in advance for any insight. 

grumpy_codger

I'm no expert, but if the walls don't have DPC I don't see how lack of membrane under the floor can result in increased dampness of the walls.

That said, personally I'd never have a suspended floor replaced with a concrete slab laying on the ground, even with a membrane.

FreeBear

Think about it for a moment - A 99% reading would mean that the walls are running with water.

Your surveyor has been using one of those pointy damp meters which will only ever give a half accurate reading on untreated wood. On anything else, salt contamination, type of paints, and the actual material will throw the readings so far out as to render them worthless. The best way to get an accurate measure of damp in the wall is to take a small sample and place it in a carbide meter.

If you get a specialist damp surveyor, make sure he/she has no affiliation with a damp treatment company, and preferably no links with the PCA.

daveyjp

"The house has had no one living in it for the past six months"

If there is no heating on this is far more likely the reason why damp has been recorded.

Albermarle

The surveyor said this may be due to the fact that there is now cement so they are redundant but the one’s higher up in the wall have have also been filled. 

Air bricks are there to ventilate under suspended wooden floors. So if they are concrete then no need for them.
Sometimes you see air bricks/outside ventilation at a higher level in some houses, but they are usually not really necessary and can let cold draughts in

gemmacots

The house does currently have a dpc, I am just concerned that a damp specialist will say it needs a new DPC which I have read online that they’re not even worth doing. I am more concerned about the fact that I may have to dig up all of the cement in the ground level if there is no membrane under the cement as how would we deal with this otherwise? Although we still don’t know if this is the cause. Thanks everyone for your replies, much appreciated  

Grotdog

Few, if any RICS surveyors understand even the most basic of things about damp. Yours is typical - membrane under concrete pushes moisture sideways into the base of walls. In situations where it replaces a suspended floor, it just puts more stress on the walls and can create cold patches, which attract condensation - ie, the symptoms of 'rising damp' that doesnt even exist. All those holes and dpc's that were injected were just fraud - they never did work, and have done nothing except damage the brickwork. As FreeBear says, ping prong cattle prod meters are useless - if said rics surveyor used one, his report isnt worth the paper its printed on. You dont need a 'damp' surveyor - you just need a good building surveyor that understands these things. Reading other forum members comments - they all seem to know more than the rics surveyor you quote - and they're right.  If you have nay doubts, get a copy of The Warm Dry Home book - its on the heritage house website - and all is explained. (out of stock but new stock arriving from printers next week).  Any other queries, shout - but stop worrying. Your biggest issue is to get constant gentle heating and ventilation into the house, and any issues should start to go away. 

Albermarle

Grotdog said:

Few, if any RICS surveyors understand even the most basic of things about damp. Yours is typical - membrane under concrete pushes moisture sideways into the base of walls. In situations where it replaces a suspended floor, it just puts more stress on the walls and can create cold patches, which attract condensation - ie, the symptoms of 'rising damp' that doesnt even exist. All those holes and dpc's that were injected were just fraud - they never did work, and have done nothing except damage the brickwork. As FreeBear says, ping prong cattle prod meters are useless - if said rics surveyor used one, his report isnt worth the paper its printed on. You dont need a 'damp' surveyor - you just need a good building surveyor that understands these things. Reading other forum members comments - they all seem to know more than the rics surveyor you quote - and they're right.  If you have nay doubts, get a copy of The Warm Dry Home book - its on the heritage house website - and all is explained. (out of stock but new stock arriving from printers next week).  Any other queries, shout - but stop worrying. Your biggest issue is to get constant gentle heating and ventilation into the house, and any issues should start to go away. 

What you say is largely in tune with the usual comments made on this forum about so called damp surveyors.

However you do seem to have a rather personal interest in the above book and website in bold above, according to your post in 2022.

 but something I've been very involved with over the years - we run a Chartered Survey company, and I've written the book on dampness in homes - and the effect that temperature has on the building fabric. I'm sure Martin won't mind me mentioning the name of the book - its out on the 17th Sept, and pre-orders are being taken - called The Warm Dry Home and available on our website - just look for the Heritage House website.

FreeBear

Grotdog said: As FreeBear says, ping prong cattle prod meters are useless - if said rics surveyor used one, his report isnt worth the paper its printed on.

Don't think I've ever used the term "ping prong cattle prod meters", nor said they are useless. In the right hands and used with a modicum of thought, they can be used to locate areas that need closer investigation. But one needs to understand that the readings are not absolute and all sorts of contaminants will give false readings.

Some RICS surveyors understand the limitations of these moisture meters and give measured comment on potential problem areas.