Damp Concrete Floor and Chimney Flue Lining

[MarkPurle]

Hi,

We are just in the process of purchasing a Cornish Cob built cottage from circa 1700 and thought we would have a full survey done for peace of mind
We haven't receieved the full report yet but the Surveypor informed us that the lounge floor which is concrete has a damp problem and he recommends replacing with a properly damp proofed floor or cover in flag stones.
There is no damp in the cob walls nor timber.
The outide of the cottage is cement rendered (not ideal) and the inside is plaster.
Anyone out there who can offer insights/recemendations from your experiences. We are concerned that if we chanegd the floor/stop any natural evaporation it will push the damp to the next point of absorbancy i.e. the walls.
We have visited the property twice and could not smell no damp at all so just wondering how much of damp problem it is really.

The final point is there is an open fire that we have seen working on each visit, the surveyor tells us the chimnety flue is not lined, so bare cob, and is a serious fire risk and we must get it lined - any comments?

Many thanks from a period proprty beginner

Cheers
Mark

 

[worms]

Bumping this one back to the top. Welcome MarkPurle - hope you are still with us, as it takes a few days for first posts to appear!

Plenty of folks on here have faced similar issues to yours, so I am sure the advice will come along shortly! Meantime have a trawl through the old posts as there are a lot of previous discussions on this and some people who have done heroic work on their cob properties.

 

[Penners]

Hi Mark and welcome.

I'm a little concerned about your surveyor's report. Is he/she an expert in period buildings?

Damp in a concrete floor but none in the adjacent cob walls sounds a difficult situation to achieve. I'm no expert but given that (as I understand it) the concrete will be less permeable than the cob, this sounds unlikely. Did the surveyor actually state that the cob walls are free from damp, or did he/she say something like "...so far as I was able to ascertain"?

The most usual scenario is for a concrete floor to force damp to migrate sideways and wick up the walls. The reverse situation sounds - as I said - unlikely.

Do the cob walls stand directly on the earth, or is there a masonry plinth supporting them? If the latter, this might be more of a believable situation.

 

[MatthewC]

Hi Mark

You want to investigate a limecrete floor, with tiles or limestone flags; don't seal the floor as that would negate the whole point. This would be breathable and allow moisture under the floor to escape. I did this in my kitchen and am very happy with it; see my blog (blue spot on right) for April/May 2011.

You should ask your surveyor for more details on what he means by a "damp problem", especially if you don't smell it (or see it?). The suggested "properly damp proofed floor" would actually have the same effect as the concrete it would replace, i.e. drive the damp to the walls. The very suggestion indicates that your surveyor does not really understand dampness in old buildings...

What sort of plaster do you have inside? Is it pink?

You are right that the cement on the outside walls is not ideal; when it cracks, it will let moisture in behind but then that moisture cannot get out! Result: cold and damp walls. I remember Cornwall from my earlier days: 40mph fog, horizontal rain... I can see why the wall got rendered!

Matthew

 

[Penners]

You are right that the cement on the outside walls is not ideal; when it cracks, it will let moisture in behind but then that moisture cannot get out! Result: cold and damp walls.

I also suggest that this situation is particularly undesirable with cob, which can deteriorate if permanently wet.

 

[MarkPurle]

Thanks again everyone, I should recieve the full written report in the next day or so, I'll check the wording carefully.
The info I shared on the blog was from a verbal discussion straight after his survey.
Keep you updated
CheersMark

 

[Penners]

When you get the report, Mark, be careful about reproducing any sections of it here. Surveyors tend to wrap their reports up in confidentiality and copyright clauses.

 

[stuwlam]

If your surveyor is not a specialist in period properties I'd be very careful about what he says. In my experience of trying to sell a period property which had a full survey done on it by a prospective buyer, the surveyor (clearly not a specilist in period houses) made a lot of ridiculous statements and in some cases made statements which were just plain wrong. Result was that our potential buyer ran a mile. I'd seek out a local specialist surveyor if I were you.

 

[Toast Chimney Lining]

Hi, I would highly recommend having a Chimney CCTV survey completed. As with most listed, period or thatched properties this type of service has become ever more increased because of the dangers and hazards created from old age, damaged and worn chimney’s namely Carbon Monoxide leakage, spilling, poisoning.

Regards
Toast Fireplaces

 

[Penners]

Carbon monoxide is odourless, but unless I'm much mistaken there's a slight whiff of commercial interest in the air.

 

[Toast Chimney Lining]

Yes Carbon Monoxide is odourless, just some friendly advice. I am not nation wide but there are alot of experts in this field who can assist and advise on the best course of action to re-line a chimney.