Damp, old house, too many opinions!

[DorothyDove]

Our old house (1800s, single skin sandstone) has had a bit of damp in the living room. The old (30 years) damp proof course has come off and the insulation next to the wall was holding the damp in. So far had two experts and a conservation officer friend look round - friend says repoint in lime plaster, lime plaster inside, let the house 'breathe'. Both professionals (both of whom I've asked to do the above) say the wall will just get damp and make the room damp, one suggested a plastic membrane floor to ceiling and insulation, the other render to 150cm and breathable thermal board.

I'm now totally flummoxed - I was all set to go for a super sympathetic light touch option but no one seems to think it will work! How has everyone dealt with damp in their 200 year old+ houses and did it work for you? Would really appreciate some experiences!!

Take a step back and look at why it is damp.

Tackle the root of the issue. Are your rainwater disposal goods (guttering, down pipes, drains) all functioning as they should? Have you differing ground levels inside and out (higher outside) have you got cement render and / or pointing? These are the main causes of damp in old buildings

Introducing an impermeable membrane (or damp proof course, or hard cement) won't solve the problem, the moisture will carry on moving naturally through the capillaries of the porous stone and when it meets an impenetrable surface it'll crystallize, form salts and damage the stone further

Look on the historic England website under 'advice for owners'. Look also at the SPAB website and understand your issue before taking any steps to remedy it. And then employ a specialist builder who knows historic buildings

Thanks both. Poltergoose I feel your pain! These old houses are amazing but such a lot of work. Luckily we do have some money put aside to deal with this, just need to find someone who will quote for lime plaster rather than some kind of membrane!

iwant thanks - the main issue is the ground level is higher outside but not something we can remedy really as we'd have to dig a trench round the house! Guttering etc was all redone recently but pointing is definitely an issue. I've looked at SPAB and have a pretty good idea of what we ought to do - but the two guys who've been round are supposed to be specialists (loads of historic buildings in the area) and both have rattled me as they were very much against leaving it to breathe. Suppose I need to keep going until I can find someone to do what I'm asking it at least advise more along those lines!

You've both helped me strengthen my resolve and stick it out for more quotes along the lines of what I was thinking so thanks!!

Conservation officers are sometimes a bit lentil-weaving - but, were the two "Experts" people who sell damp-proofing?

If you invite into your home someone who sells damp-proofing, you can expect him to tell you to buy damp-proofing.

What was this old damp treatment that has "come off?" What is this insulation next to the wall?

We don't have sandstone round here, but adding plastic membrane to old houses will generally just hide and trap the water in the wall.

If the amount of water that can escape by evaporation and ventilation exceeds the amount that enters the wall by rain, ground and condensation, then the wall will be reasonably dry.

Presumably all three of them looked for sources of moisture such as raised ground level, gushing gutters, plumbing faults, wet washing, and poor ventilation?

Has it got a wooden floor? Has it got a cellar?

"the main issue is the ground level is higher outside but not something we can remedy really as we'd have to dig a trench round the house! "

Yes, that's the right action. You fill it with cobbles or pebbles (not gravel or fine material) so that water can drain through it and be led away to lower ground or a soakaway. It's a French Drain. The large stones prevent capillary action and allow a little air to contact the wall inside the trench.

Thanks pigletjohn - no wooden floor and no cellar - it's straight onto the earth which doesn't help, think there were flags originally but it's tatty concrete under the carpet now.

Original make up was stone, cement render, insulation, plasterboard, plaster. The insulation was wet and render dropped off the wall in most places when touched.

The guys who came claim to be listed building specialists - the damp proof guys do specialise in that kind of thing and I was probably a bit naive to think they wouldn't suggest full-on tanking etc. The others are specialist builders so not specifically damp proof pushers - or so I thought!!!

Oh yes conservation officer friend suggest a French drain but the SPAB website seems quite cautionary about using them! Argh!

The ihbc has a document on their website about French drains. I'd do that, and lime plaster.

I'm an old conservation officer - not all of us lentil weave pigletJohn!!!

the cellar, and the void under a wooden floor, is an airspace which can be ventilated. This causes water to evaporate off the exposed walls and to be carried away by ventilation. In a fairly modern house, one airbrick every two metres is enough, an old or damp house will benefit from more. They should be on all sides of the house so that whichever way the wind is blowing, there will be air movement in the void and water vapour will be blown away. The subfloor wall can therefore participate in the "evaporation and ventilation" process.

Additionally, a timber floor cannot transmit moisture to the walls like a solid floor sometimes can.

The surveyor we got when we bought our house claimed to be a listed building expert. Bollocks he was. Well, he might well have had a lot of experience with old houses but he still tried to put us in touch with his mate's damp proofing firm. How were your experts qualified?
We did the French drain thing in our old house - it is not that hard. Also, have you rung the SPAB helpline? I got them to help unpick the weird stuff our surveyor had said and why he had come to those conclusions, and it left me confident that the traditional methods were going to work better.

"straight onto the earth which doesn't help, think there were flags originally but it's tatty concrete under the carpet now"

eek!

That will make the room damp, and probably transmit it to the walls. It wants digging up and doing properly. If your friend is happy with a solid floor, it can incorporate DPM and insulation. You might need drainage under it which is outside my knowledge.

"stone, cement render, insulation, plasterboard, plaster"

eek!

All of that is wrong, apart from the stone. It is possible to dry-line with internal insulation, but doing that on a wet wall is outside my knowledge.

We had to dig a trench all the way round the back of our 1780s farmhouse. The garden at the back was almost up to the kitchen window level and the back of the house was horribly damp.

Now there is a 4 ft wide trench separating the garden from the house and the kitchen is lovely and dry. We also dug up the floor (original quarry tiles) and put down underfloor heating.

My friend has a trench - about 2ft wide, it's not where you walk so isn't a problem. V old cottage.

Oh wow, tons of useful replies. Thanks so much, I feel so much better and more resolved now! I'm going to reinvestiagte the French drain thing and push for quotes from the more 'artisan' builders I've found.

Poulter you could not be more right about undoing decades of bad work - so much in our house makes me think 'what the fuck???' And I do feel we owe it to the future of the house to put as much right as we can!

Thanks again all!!