damp at base of wall built into hill

[maggie73]

My 1870's end terrace is built into a hillside and the back wall and some of the gable end wall in the livingroom are completely under ground. At the base of the corner where these two walls meet (roughly north facing) I get damp, to about 40cm high, about 60cm wide. it looks like surface moisture when it is damp, and i am assuming that this area is very cold (perhaps caused by moisture penetrating the retaining whinestone wall behind?) and the damp is perhaps mainly condenation, though there is a faint tidemark and no mould. there appears to be a cavity between the whin wall and a brick wall, which has been plastered. Below the suspended floor the joists are fine, though the ground below the floor at this corner feels damp and cold to touch. I am in the process of redecorating, with fingers crossed decor wont get too trashed too quickly. House was renovated in the sixties and I think there may be some concrete on the ground as well as some use of tar - dont really want to have to dig that up as very dry apart from the one corner. have lifted carpet and laminate and am going to sand floors, which should also help ventilate underground space. Question is:

If the decor gets damaged, or I get problems with rot in the joists, could i strip back the plaster from the brick to about 1m high on the walls affected, and have it replastered with lime and repaint with limewash? Or should I replaster the full height of the walls in lime plaster?

I guess that moisture is being pushed up the walls due to the concrete floors and I assume that lime plaster will allow any moisture in the bricks to evaporate naturally: I was given a quote for tanking to 1m but as I gather that this will just displace moisture, I am not going down that route.

 

[maggie73]

One year on, there is salt behind and through the lining paper, with a tidemark to about 50cm high and paper only held in place by the skirting board. The actual width has increased, and i think that condensation and moisture attracted to the salts is causing this. The cement plaster still seems solid when I tap it though. Joists still the same and feels quite well ventilated below the floor.
As the wallpaper is really bugging me, I want to do something about it, and probably within the next year as we are going to replace our back boiler in that room and open up the chimney, so will be redecorating anyway. The lining paper has been wetting up recently, but in hot weather, not when raining - is this down to high humidity being attracted to the salts on the wall?
I contacted The scottish Lime Centre for some advice and quotes for survey, and they say from my pictures and description that the problem is most probably ground water, and that visit will be £240 plus vat plus report £250-£500. Unsurprisingly I am wondering whether it is worth it as I could put that money towards good repairs. I was thinking of hacking off the cement plaster from the inside brick cavity walls on both walls under ground and having it replastered in lime, or putting in a dry wall, but the room is already small and dont want to lose any more inches! Obviously, I would like professional advice and a report, especially if i replaster and the problem is just as bad but it is an awful lot of money to spend.
So:
- Should I invest in the report?
- If not, should i replaster in lime - to the full height, or could I maybe go to say 1-1.5m high?
- Does anyone know rough prices for replastering in lime? The full area would be about 25-30m2 to the ceiling and i live in South lanarkshire, roughly 30 miles to Edinburgh and 40 to Glasgow.
- Also, would it be hard to get someone to remove a brick or two when the wall is exposed to see if there is debris lying between the cavity walls?
Hope someone can help, and hopefully tell me not to get a survey!!

 

[Moo]

Can't give advice, I'm afraid, but thought it might help if your problem were to be bumped up to the top again.

 

[andrew gayton]

can you post some pictures please?

 

[Gervase]

- Should I invest in the report?
- If not, should i replaster in lime - to the full height, or could I maybe go to say 1-1.5m high?
- Does anyone know rough prices for replastering in lime? The full area would be about 25-30m2 to the ceiling and i live in South lanarkshire, roughly 30 miles to Edinburgh and 40 to Glasgow.
- Also, would it be hard to get someone to remove a brick or two when the wall is exposed to see if there is debris lying between the cavity walls?
Hope someone can help, and hopefully tell me not to get a survey!!

If the report is being done just on the basis of pictures and a description rather than a site visit, I'd be tempted to save your money and get a surveyor with experience of old buildings to come and have a look. That may cost as much as the Scottish Lime Centre, but it may not.
I'd be wary of simply replastering without addressing all possible causes of moisture ingress, though lime plastering is certainly the best course of action once you've dealt with everything else. As Andrew says, some pictures would help.
As for plastering prices, they vary hugely, but you're looking at from around £35 a square metre for three-coat work, but some plasterers will charge much more!
Removing a single brick is a simple operation. Ideally, though, you'll need some means of looking into the cavity, which will mean an endoscope or similar. Know any friendly doctors? :wink:

 

[Nemesis]

I suspect the Scottish Lime Centre is a visit (says so in the post...) and possibly is a surveyor...

http://www.scotlime.org/

http://www.scotlime.org/trad_building.html

People:

http://www.scotlime.org/trad_survey.html

http://www.scotlime.org/trad_team.html

 

[Gervase]

Oops, misread the post and I hadn't seen the site - but having looked at it, I'd be happy to go with the the Scottish Lime Centre; their credentials are impressive and I'm sure you'll get sound advice. In the larger scheme of things, the money for the survey isn't a lot, and it will give you (one hopes) a definitive answer. What action you need to take to sort the problem could be as simple as replastering, or it could involve rather more, but at least you'll get advice which is tailored to an old building and which won't involve modern 'miracle materials' of dubious efficacy.

 

[Nemesis]

Yes, impressve - a trust set up for the benefit of historic buildings in Scotland.

 

[chuckey]

Who owns the land ajacent to this problem corner? The best thing to do is to dig down to your foundations and install land drain pipes bringing them out through the gable end earth retaining wall. You will lower the water level and allow a certain amount of ventilation. You will only need access to this land during the "dig". When restored there will be nothing to be seen on the hillside.
Frank

 

[maggie73]

Thanks for all your replies - just what i didnt want to hear but knew i should invest in really!
Am only worried that I will spend a few hundred pounds to open a can of worms and find that it will cost thousands to fix..... Am trying to console myself that if we ever sell the house then we have a good survey on the damp problem, but if it is a damning report I may just want burn it and long to return to the days of blissful ignorance. However, in this case I think maybe we should spend the cash rather than trying a "fingers crossed" approach.

To answer the last question, we are the end terrace: at the back of the house there is a road, to the gable end there is public steps and to the front we have a thin public footpath along the terrace. All are immediately adjacent to the house, council owned and a mixture of concrete and tar. Would have to dig down at least 3m to get to any foundations and think would cost a small fortune?

 

[chuckey]

Not a good location for earthworks then, best to make that option 99. On a totaly different but relevant subject, you say the house is constructed of whin stone? Does this have "throughs" i.e. stones that go right through the wall? if it does then it would seem that you have a through, that, a, can leak water across it (if its not set at the correct angle) and, b, forms a thermal bridge from inside to outside so you would expect condensation to occur inside where there are throughs.
Could just be a bit of rubbish bridging the cavity.
Frank

 

[maggie73]

I dont know if there are any "through" stones as behind our plaster is the brick cavity wall (well, we think there is a gap between the whin and the brick). I am hoping it is rubbish bridging between the two walls - perhaps blown insulation fallen down from the attic??? otherwise my mind is whirring with the costs of pumps, excavating.... I did notice tonight at the top of the steps right next to our house there is a little water cover (maybe a stopcock though) and across the road behind our house a big old drain cover. If there are land drains below the tar road which are supposed to divert water away from the terrace and are not working, would we be able to push for the council to look into it? I know our terrace neighbour was "told" she had damp when she had a survey last year, and our neighbours across the steps also have damp. they have got lime plaster as well as their house wasnt "renovated" in the 60's. We are all built into the hillside, pretty much to first
floor.
Am sure it will all be fine - maybe it will be something simpleish like removing rubble and may not even have to lime plaster as it isnt a true external wall?
have kissed goodbye to the prospect of getting the new boiler anytime this decade.

 

[maggie73]

quick update.
Got the guys round from The Scottish Lime Centre, a chartered surveyor and a conservation technician and they were very helpful and assured me the house aint falling down. They reckoned that the renovation had been carried out correctly, ie damp proof course below sole plates, cavity wall etc to help prevent damp coming in from hillside and plenty of air vents. They were happy with the 'airiness' below the floor even though a couple of timbers were very damp. From looking at mortar joints (or rather the lack of them) which are full of wet muck at the bottom of the wall on the corner where the damp is evident, (the bottom of that outside wall is actually at ceiling height in the living room where earth retaining wall and gable end meet), they thought that dirt and debris has gradually been washed through the joints over time and is causing moisture to bridge onto the internal wall. It made sense as a neighbour advised that about 4-5 years ago water had been pouring down that road and then all the drains were fixed. the road was resurfaced 2 years ago, prior to which water used to pool just at the affected corner, and now the camber(?) of the road causes water to hit that corner, after which a dip in the tar diverts most water away from the back wall. They will write a letter advising as much, that I can send to the council, asking that they come and investigate for any leaks in service pipes, and to assess how the water flows to the corner. The surveyor suggested a small kerb or something along the back wall to divert water away, then hopefully wait for it to dry out. Nothing absolutely conclusive obviously and he said it would be trial and error, but he put my mind at rest and it didnt involve any money! (well apart from the visit)
I have now temporarily disguised our trashed wallpaper with a CD case, Tv and a pile of books, but forgot to ask about the salts coming to the surface of the plaster. The paper (especially that paper that is no longer attached to the wall and is held in place by a skirting board), really wets up periodically, quite often in prolonged dry weather and not always after heavy rain. Am i right in thinking that the salts attract moisture in humid conditions (cooking, clammy weather) and this is also contributing to the problem of the wet wallpaper? The paper seems to be acting like blotting paper!

Cheers.