the perennial damp problem

I've been lurking here for a few weeks, and I've finally decided to take the plunge and ask for some help/advice from people who know what they're talking about (ie. you lot!). (Sorry this is so long. I wanted to get it all straight in my head so there is perhaps more detail than is really necessary.)

I'm in the process of buying this house and I'm getting very confused by all the conflicting things I've been told.

It's a 150-200 year old traditional stone-built terraced cottage -- probably limestone or sandstone, but it's hard to tell because the exterior is covered in a lumpy cement render -- and it's terribly terribly damp.

The chimney stacks on both sides (one of which belongs to a neighbour) are in bad repair. There are visible damp patches running down one gable wall. The attic was recently converted and they dry-lined the gable walls so you can't see any signs of damp up there, but I expect the stone walls are wet behind the board.

The guttering is full of plants and moss, and at the back of the house the downpipes simply stop halfway down, so that rainwater just runs down the wall.

There are small cracks in the cement render at the front and back.

There's a modern extension at the back, with a balconied terrace affair on its flat roof. The internal wall underneath where this flat roof connects to the old house is also damp.

The internal ground floor is no higher than ground level -- a cement yard at the back of the house, and a road right alongside the front of the house with no kerb (where presumably the DoT have kept on adding new layers of tarmac over the years so that it's now level with the floor).

The exposed stone fireplace/chimney breast has been re-pointed with cement, and coated with some kind of clear varnish, and the hearth itself has been boarded up with an electric fire plonked in front.

The ground floor is just concrete: concrete, with a layer of plastic on top, and underlay and carpet on top of that. Underneath the plastic the concrete is wet.

The mortgage valuation came back with a recommendation that we get it checked out by a damp/timber specialist. Unfortunately, where I live the only damp/timber specialists are people who have a vested interest in suggesting chemical DPCs. The damp/timber survey duly came back with a recommendation that we spend £3000 on an injected DPC throughout the ground floor, stripping off the plaster to 1.2 metres, and re-plastering with some kind of anti-damp anti-salt stuff, and, separately from that, also get the chimneys and gutters repaired. They didn't look at the floor.

The front of the house was bulging slightly so we had to get a structural engineer to come and look at it. He says we'll need to strap it to stop it from moving any further. I asked him to doublecheck the damp situation while he was there, because I didn't trust the damp survey. He agreed with their analysis, but also checked the floor -- and has suggested that we'll have to rip out the concrete and put down a proper DPM, lapped up the walls, before re-laying more concrete and proper insulation. He also agreed that we should have an injected DPC, because it turns out that he does trust the damp specialist.

So now I don't know what to do. I've talked to two different chartered surveyors, who both agree that we'll have to get a chemical DPC. (Again, as with the damp specialists, I don't know of any surveyors in my area who specialise in old buildings.) Everyone agrees that the damp specialist is great. I will apparently find it very hard to sell the house in future if I don't get a chemical DPC.

Based on what I've read on-line, what I think I need to do is:

1. get the chimneys, downpipes and guttering repaired.
2. strip out all the internal plaster and let the walls dry out.
3. get that varnish stuff off the chimney breast, re-point with lime, and reinstall a proper fire.
4. eventually, when funds permit, remove the cement render and replace with lime.

But I don't know what to do about the floor. Although it'll be fine to lower the ground level in the yard, I don't think there's any way I can lower the road level at the front of the house. The house is only a few metres above sea level so I'm assuming the water table is probably pretty high. Anyone got any ideas?

The structural engineer thinks it'll cost us £10,000 to sort out the damp problem. If the mortgage lender imposes a £10,000 retention then this will all be moot, anyway, because we won't be able to afford to buy it. If there's anything I can do to bring this figure down...

Not an expert....

It sounds like you have damp everywhere. It would be interesting to ask these damp experts you have spoken to how fitting an injected DPC is going to sort out the damp upstairs....

Water will be getting in through the cracked render and can then easily pass through the sandstone. With tarmic and concrete everywhere outside, there is nowhere for the ground water to evaporate so the house is basically standing in a puddle. From the pictures, it also looks like there is water splash issues from the road.

If building control hear about you removing all the render from the walls inside, they will insist that you insulate internally and plasterboard which will either give you a thick impermeable layer or a very thick permeable layer. More cost and loss of room size, though it will reduce your heating bills.

A limecrete floor will just end up as a puddle if the water table is as high as it sounds it could be. A modern concrete / insulation / DPM floor will need to take the DPM through the walls to work properly which isn't going to be easy to do and will probably wreck the wall if attempted.

No easy / simple / cheap fix from what I can see. Sorry. Others might be more optimistic on what can be done.

I can't remember reading a more comprehensive description of just about every type of damp problem that can afflict a house! I hope this doesn't sound excessively pessimistic, but I hope you're getting the building cheap, and that you're going to salt away a generous "Solving-The-Damp" fund.

To begin at the beginning: your first actions must, of course, be to try and solve any and all obvious damp-exacerbation problems. Things like blocked or ineffective gutters, roof or wall leaks (flat roofs can be particularly suspect), and so on. Once you're certain that you've done everything needed to stop falling damp (otherwide known as rain) from getting in, then you can turn your attention to the dampness in the structure and to rising damp.

Rather than trying to reinvent the wheel, I'm going to direct you to the Agony Uncle section of this website: http://www.periodproperty.co.uk/ppuk_discovering_agony_uncle_archive_2009.shtml

Have a look through the current collection of articles, and through all the archives. You should find just about every type of damp problem addressed very authoritatively and clearly.

Always remember that managing damp is a step-by-step process. There's no point in trying every conceivable solution, all at once. The best place to start is usually with the cheapest of the options; see whether it works, and if not then move on to the next one. Obviously this can take a considerable time, because you have to wait a fair while after each treatment, to see whether the damp is drying out.

Once you've bought the house, you might like to prepare a list of your first planned steps, then post it here for comments and advice. As the old saying goes, "eat the elephant a spoonful at a time", and I think you'll get much more detailed comments from experts here than if you ask a blanket question about everything at once.

Good luck, and keep us in touch with progress.

Hi Im no expert either but have you had a word with the neighbours?they may have dealt with similar problems,looks to be a nice cottage if the damp can be fixed and the TT and MGP every year plus kippers cant be bad! phil.

I sincerely wish I could provide you with some solace here. Alas, not that easy.

I generally concur with what's already been said, and Penners makes a sensible suggestion in checking out the relevant Agony Uncle section. However, I don't think MdB is wholly right about building control insisting on internal insulation and dry lining if you choose to remove the offending render. As an existing building their interest is very, very limited - usually things such as loft conversions, electrical re-wiring, drains, alterations to chimneys, and digging up floors to re-lay them. That's pretty much it. If you're planning to re-plaster with lime (as would have almost certainly have been the case in its past) you are returning the building to its original state.

Chemical DPC's in old buildings seldom work except where it is used in ashlar stonework - basically it's all about a uniform line of resistance. If this house is made of a more rubble-type stone with earth - or lime - mortar, the chances are you'll never achieve a decent level of protection, and risk ramming the stuff further up walls where it finds a place in which the silicone barrier is weak.

The good news is that some of the remedial action necessary isn't that costly. Sorting out guttering and downspouts is easy to do whether fixing or replacing. Other issues may require a slightly, ahem, larger budget.

But remember: whatever the problem (and that bulging wall sounds like the biggest of all), you can sort it out. This, though, requires time and money.

Good luck, and keep us up to date whatever you decide to do.

C.

MdB said:

It sounds like you have damp everywhere. It would be interesting to ask these damp experts you have spoken to how fitting an injected DPC is going to sort out the damp upstairs....

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They said we'd have to get the chimneys and guttering repaired, separately from doing their chemical DPC.

A limecrete floor will just end up as a puddle if the water table is as high as it sounds it could be. A modern concrete / insulation / DPM floor will need to take the DPM through the walls to work properly which isn't going to be easy to do and will probably wreck the wall if attempted.

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Yeah, we've already realised that limecrete won't be an option here. I'm wondering about digging out a floor void and inserting periscopic vents into the front and back walls. Although, if the water table is high enough that the floor void is simply an underfloor pool then this won't be an option either.

And how on earth would you take a DPM through walls that are already there? It looks like it'd be the only workable solution, but I can't see how anyone would do it.

Penners said:

I can't remember reading a more comprehensive description of just about every type of damp problem that can afflict a house! I hope this doesn't sound excessively pessimistic, but I hope you're getting the building cheap, and that you're going to salt away a generous "Solving-The-Damp" fund.

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Not that cheap. The Isle of Man is always in a sellers' market, so property prices are stupidly high. This is actually the only house we can afford on the whole island where we'd both be able to continue working from home. Anyway, that's a rant for another day...

Rather than trying to reinvent the wheel, I'm going to direct you to the Agony Uncle section of this website: http://www.periodproperty.co.uk/ppuk_discovering_agony_uncle_archive_2009.shtml

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I did actually spend a very instructive week reading every single entry in the Agony Uncle archive. Nothing there quite matched the ground level/water table/concrete problem.

Once you've bought the house, you might like to prepare a list of your first planned steps, then post it here for comments and advice.

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The problem I have here is that while we can just about afford to buy the house, we only have £10,000 for repairs + retention -- and no more than that available in the next 12 months. I need to know if the floor problem can be fixed, and vaguely how, so I can work out how much it could potentially cost. Better to know beforehand than get stuck with a damp house I can't afford to repair.

philpjuk100 said:

Hi Im no expert either but have you had a word with the neighbours?they may have dealt with similar problems,looks to be a nice cottage if the damp can be fixed and the TT and MGP every year plus kippers cant be bad! phil.

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The neighbour on one side hasn't maintained their house at all, by the looks of it. The neighbour on the other side got their side of the chimney stack repaired a couple of years ago, which I think has had the effect of pushing more damp through into the gable wall on what would be our side.

Kippers are always good!

christianb said:

But remember: whatever the problem (and that bulging wall sounds like the biggest of all), you can sort it out. This, though, requires time and money.

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Bizarrely, no-one seems that bothered about the bulging wall. The original surveyor said he thought the houses on either side were probably doing a good job of keeping it in check. And the structural engineer said we should strap it just to be on the safe side, but that he didn't think it was a huge problem. He was much more worried about the damp.

I think I'm going to take phil's advice and have a word with the neighbours.

christianb said:

However, I don't think MdB is wholly right about building control insisting on internal insulation and dry lining if you choose to remove the offending render. As an existing building their interest is very, very limited - usually things such as loft conversions, electrical re-wiring, drains, alterations to chimneys, and digging up floors to re-lay them. That's pretty much it. If you're planning to re-plaster with lime (as would have almost certainly have been the case in its past) you are returning the building to its original state.

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I'm not sure I'm right either but I believe that if you do more than 25% of the walls then you have to do the lot to the current regs. Our neighbours are in the process of having to do this due to a BC requirement though they are doing a complete renovation and did have BC throw the book at them for various reasons. The same goes for the floor. More than 25% and you have to do the lot to the latest regs. A CO would be interested in what its original state was. BC have no interest at all. IoM might be different of course.

piapiapiano said:

And how on earth would you take a DPM through walls that are already there? It looks like it'd be the only workable solution, but I can't see how anyone would do it.

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I believe you can cut a slice through the wall in sections and insert a DPM that way but I only vaguely remember hearing something about this once. Could be completely wrong and it doesn't sound an easy / simple solution to me if it is possible.

MdB said:

I believe that if you do more than 25% of the walls then you have to do the lot to the current regs. Our neighbours are in the process of having to do this due to a BC requirement though they are doing a complete renovation and did have BC throw the book at them for various reasons. The same goes for the floor. More than 25% and you have to do the lot to the latest regs. A CO would be interested in what its original state was. BC have no interest at all. IoM might be different of course.

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It's in a conservation area -- would that have any bearing on this?

I believe you can cut a slice through the wall in sections and insert a DPM that way but I only vaguely remember hearing something about this once. Could be completely wrong and it doesn't sound an easy / simple solution to me if it is possible.

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I went a-googling after replying to your post, and it turns out a retrofitted physical DPM is done like this: http://www.dampdecay.co.uk/index.php/gallery?func=viewcategory&catid=13&startpage=2

I wonder how that would work in an uneven stone wall?

piapiapiano said:

It's in a conservation area -- would that have any bearing on this?

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Outside yes, inside no - I think....

piapiapiano said:

Bizarrely, no-one seems that bothered about the bulging wall.

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The bulging wall may not be much cause for concern - or it may be. It all depends on when the bulge happened, and whether it's stopped happening.

It's far from unusual to see mis-shapen masonry on period properties. But so long as the masonry in question is now in a stable state, this can often be ignored.

Ideally you'll need to secure some telltales to the wall, to see whether it's still moving.

The stacks could be wet for a number of reasons: rain could be coming down an uncapped chimney; the flashing where the roof meets the stack could be faulty; cement render on the stack could be cracked and allowing water to percolate down below the roof level.
The faulty guttering and lack of downpipes are certainly making a major contribution to the dampness of the building - water running down the wall is going to saturate the wall. Fix that and you'll have removed a major source of damp.
The cement render is going to be a major contributor to the damp. Water enters the cacks in the render and can't get out again, saturating the structure of the wall. Often the only way it can get out is inside, leading to damp patches and rotten joist-ends and lintels.
Flat roofs are notorious for leaking; so much so that many insurance companies refuse to cover them. They can be made watertight with the right materials and a competent contractor, however.
External surface levels don't help, but the house looks as though it's on a hill, so most of the water will run down and away from your walls.
The varnished stone fireplace is hideous, but can be stripped fairly easily. The stack will need some ventilation, which will help alleviate damp, and it's not clear that it has any at the moment.
The damp floor is probably condensation - if you have a layer of plastic over concrete, the concrete will be wet under the plastic. Given that you're on a hill and not at the bottom, a high water table is unlikely, so fix all the other sources of penetrative damp and your floor should be dry.
Bulges can be worrying but they can also be benign. You need to establish how long the bulge has been there. Is there any sign of recent cracking in the external render or internal plaster? Old cracks full of dirt and dust aren't a problem - it's recent movement that's worrying. It's something pretty basic that your structural engineer should have addressed.
Your damp specialist is at best naive and at worst a charlatan, whatever the locals might think. An injected DPC in rubble stone does not work. End of. A physical DPC can be inserted, but it would be a massive job, cost nearly as much as the house and be of dubious merit. Your structural engineer may be a fine engineer, but I'd wager he knows bugger-all about damp.
A chartered surveyor is no yardstick of expertise with old prperties. Most have cut their teeth on modern buildings and many haven't a clue about the qualities of traditional stone buildings. That's why the two you've seen have recommended injected DPCs. If you are unsure and need a competent survey, look in the 'seeking specialists' section of this site for surveyors with expertise with traditional buildings. S/he will have the clout to argue with a mortgage company against any imposed retention.

Gervase, thank you! That was all very reassuring. You're right, the house is on a slight incline, so the water should be running away from it at the front (although I suppose there'll be an issue of splashing from passing traffic). I hadn't even considered that. Or that the wetness under the plastic would be condensation.

And I totally agree that the varnished fireplace is hideous. The house we're renting at the moment has a big limestone fireplace -- unvarnished -- and it looks very lovely. Very typical of old Manx properties. I can't understand why anyone would want to cover it with something that would make it look permanently wet.

The cement render is going to be a major contributor to the damp. Water enters the cracks in the render and can't get out again, saturating the structure of the wall. Often the only way it can get out is inside, leading to damp patches and rotten joist-ends and lintels.

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So are you saying that getting that cement render off is a priority? I confess I was thinking of just patching up the cracks as a temporary fix, and waiting until I had enough funds to pay for a new lime render before properly sorting it out.

Couple of rambles...

Gervase is certainly bang-on about damp proofing contractors. Or at least most of them. As it happens, I know one who really understands old buildings and wrote a letter for me to pass on to the mortgage company (who had imposed a retention) explaining that you'd have to be an idiot to stick a chemical dpc in an old building like mine. It did the trick.

Second, there's a big difference between old settlement cracks (which have ceased to expand) and bulging walls. Or at least there is as far as I'm concerned. I was in the splendid little French town of Chinon a year or so ago and noticed one of the buildings on the historic Rue Voltaire (connections to Richard the Lionheart, Joan of Arc, etc) had its entire first floor being kept together by loops of builder's band. This, as far as I'm concerned, is no way to ensure the future of an historic monument. Or even a charming little cottage in the Isle of Man.

Finally, I'd make the removal of cement render a medium priority. But definitely do it when you can - much as I'll eventually get around to removing what remains of the damn stuff on my own cob cottage.

C.

Probably totally irrelevant, but my last place was a 1950s brick cavity wall bungalow. My surveyor found damp, and recommended a damp treatment company, who stripped the internal plaster and injected chemicals. I'm totally convinced that it was a complete con, that cost me a lot of money, and ruined my enjoyment of the house, and led to stress and ill health. If there was a damp problem at all, it was more likely related to things like the concrete path at damp course level, that the surveyor didn't even pick up in his report :evil:. If they can't get it right with a relatively modern house, what hope is there with something older and more specialised?

piapiapiano said:

Gervase

The cement render is going to be a major contributor to the damp. Water enters the cracks in the render and can't get out again, saturating the structure of the wall. Often the only way it can get out is inside, leading to damp patches and rotten joist-ends and lintels.

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So are you saying that getting that cement render off is a priority? I confess I was thinking of just patching up the cracks as a temporary fix, and waiting until I had enough funds to pay for a new lime render before properly sorting it out.

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I reckon it's a priority. Onced the guttering is fixed and the flat roof sorted it's the biggest hinderence to the house drying. There's little point lime plastering the inside whilst the outside is stuffed by the cement render. Agree with Gervase about everything else, all spot on.

You need a plan with a house like this, or it will be a money pit. I think you need to get the figures right and think how long you plan on staying in it and work out if you are going to get your money back. It's a 10K job to get it right I should think and that's not pocket change for a mid-terrace.

M.

Matt and Gervase are the experts here so you have some good advise - especially compared to mine ;-)

I would agree with Matt and Gareth. In particular I would suggest removal of impermiable materials to be a high priority, so that the house has the chance to breathe.

However, to take a different slant on matters:

You are aiming to purchase and the advice you are getting here (and what I hope you had in mind anyway) involves tackling the works in a different way to those previously suggested and adopted by the lender as appropriate. The most important thing at present is that you have to assess which will cost more. The reason is that as a prospective purchaser you need to decide whether to revise your offer. Buying a house and the price paid for it is not a scientific calculation and many factors can influence the negotation. Therefore use the information you have gathered, find out which approach costs more and use it for negotiation purposes. It sounds as if there is a retention so use this as a bargaining point.

If you can get the retention lifted in some way then do so, but if you can live with it or get it deducted from the price then you can still purchase.

Once you have purchased and the lender chooses to check up on things (or you decide to get the retention monies back) then is when you will have to explain that prior to purchase you were going to adopt the advice given (and forming the basis of the retention/conditions, etc), but after moving in got other advice that you decided to follow. You may have a slight battle on, but in most instances I have been involved with this approach works. In fact most of the time they do not check up in conditions anyway. Retentions are a bit trickier, but nonetheless they can be sorted out and released provided you can demonstrate that the original problem is resolved.

You may also like to refer to the RICS leaflets including the one on damp that are somewhere here on this site. There is plenty of other published material discussing this matter and advising against injecting stone walls.

On one of my jobs at present I did not want thick brick walls injected (a Grade II* building) and when the builder (who was unsure) spoke to the Sovereign Chemicals rep he advised against injecting old thick brick walls! His argument was that not only could he not guarantee the injection would work, but if it did then the bricks below the new 'DPC' would suffer greater dampness retention and be more liable to frost damage, etc.

Stephen
(aka 'Agony Unc')

Just to support what Gervaise said, our hallway was sodden when we bought, but is now bone dry. The downpipes from the gutter used to stop an inch from the ground, but now run off to a soakaway, and the plastic sheet and carpet were lifted from the stone floor, removing the condensation problem.
Removing cement render is a job you can do yourself with a £40 hammer drill and a ladder, although being so close to the street may cause you complications. There is a chance that the brick or stonework beneath will need repairs, but if you do the job carefully there should be the chance to stop and get advice if things look too bad. I have no idea how much lime rendering will cost where you live, but we found someone who did a very good job on our house, which has a much bigger frontage than yours, for just over £3000 plus materials.
Keep in mind the fact that these houses must have been pretty dry and comfortable to live in when they were first built. You just have to undo the years of neglect.

I decided to be proactive and went up to talk to the neighbour this very evening. The house on the right is owned by a reclusive schizophrenic, so I didn't go and talk to him (apparently I'll have to go through the police to contact his family to find out about repairing the contiguous guttering at the back).

The house on the left is owned by a lovely lady who was very annoyed to discover that her chimney had only been half-repaired. She showed me all the damp patches that have recently popped up in her house, despite having a chemical DPC put in a couple of years ago (the bank insisted on it when she bought it).

The good news is that her ground floor is wooden floorboards suspended over a void with just earth beneath. And it's dry. So the limecrete option could be on the cards once more. The bad news is that she wants to get the floorboards out and have it tanked. I may introduce her to you lot, if we actually complete on the purchase.

The other good news (if you look at it from a certain angle) is that "our" house flooded last weekend. The firemen had to go through her house and break in through our back door, apparently. This, I think, explains why the concrete was wet when the structural engineer went in a couple of days later. I assume the flooding was caused by the excessively heavy rain, bad guttering and the blocked drain.

The not-so-good news is that the now-defunct oil-tank pipe, which runs under the concrete floor from the front to the back of the house, leaked at some point in the past -- and previous tenants have complained to this good neighbour about an oily smell emanating from the floor. So we'll definitely have to dig it up at some point.

The other not-so-good news is that she had to replace all the lead pipes when she moved in, so that's something else we'll have to find out about.

Oddly enough, it's all seeming more doable tonight.

Matt Green said:

There's little point lime plastering the inside whilst the outside is stuffed by the cement render.

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You make a good point!

You need a plan with a house like this, or it will be a money pit. I think you need to get the figures right and think how long you plan on staying in it and work out if you are going to get your money back. It's a 10K job to get it right I should think and that's not pocket change for a mid-terrace.

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That's why I'm here -- to find out what needs to be done urgently and what can be postponed, and to get an idea of what I should be getting quotes for. I wish I could just drag this entire forum with me in an indignant huddle to explain things properly to all these surveyors and specialists.

Fortunately, we have exactly 10K to spare for it. I'm going to rely on the charity of friends, family and freecycle for all the furnishings.

DaveBrigg said:

Removing cement render is a job you can do yourself with a £40 hammer drill and a ladder, although being so close to the street may cause you complications.

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We were just up there tonight, having a nosy round the outside of it, and you could peel the waterproof paint off the exterior with your fingers. I couldn't tell what the lumpy render underneath it was, though. So that's another puzzle to solve: how does pebbly lime render differ from pebbly cement render?

Stephen said:

I would agree with Matt and Gareth. In particular I would suggest removal of impermiable materials to be a high priority, so that the house has the chance to breathe.

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Okay. That's a lot of people in favour of making that a priority. I'll move it to second place on my list (after chimneys and guttering).

Therefore use the information you have gathered, find out which approach costs more and use it for negotiation purposes. It sounds as if there is a retention so use this as a bargaining point.

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We realised this a few hours ago, and got very excited when we totted up all the things wrong with it that might be useful for negotiations. As you say, it's a case of making it look as bad as possible to the vendor, and as good as possible to the bank.