Damp wall - what's causing it?

I have a damp wall in a flat I am refurbing to rent and I can't quite get to the bottom of why it is damp and therefore how to remedy it. It is a first floor room in a victorian house, I believe it is a single brick cavity. Outside, the affected wall is rendered up to the window sill level and then above that the brickwork is painted with masonry paint and the masonry paint has flaked off on the outside directly where the wall is affected on the inside.

The wall on the inside has been redecorated but immediately the paint has bubbled up and gone yellow due to the dampness coming back, and this seems to come and go when it rains. When initially trying to decorate it, it was sanded down to bare paster and appeared to be dry but I had terrible trouble even getting the paint to adhere to the wall, it would congeal as though there was something in the plaster reacting with the paint. The damp patch is only above the level of the render on the outside but doesn't go up as far as the ceiling. The house has a damp proof course so I don't think it is rising damp (or could it be?) and it isn't black mould so it's not condensation. There is no sealant around the window which is next to the damp patch which I will rectify but can't see this causing such a level of dampness to such a large area of wall.

Could the bricks have become porous therefore letting in water due to the wall being single brick? Could extending the render further up be a solution perhaps? Any advice would be gratefully received because I am at a loss as to the right trades person to call as I don't know the cause as there are no obvious leaks from gutters, pipes etc. I need to solve it quickly because I can't let the flat knowing this problem exists.
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Replies

  • redred Forumite
    666 Posts
    Hi Paintpot...it is tricky as the weather is very damp at the moment. I have refurbed a couple of houses, and I have found that the damp has sometimes been a problem - the thing is, the source tends to be close to the problem. You will need to dry the area out as much as possible. Any seal, such as paint will prevent it from drying fully. You may want to consider a few options. the first is stripping back on the exterior, and checking drainage outside. It could be something such as the sill that has come away from the wall. Try to see if there is a pattern to the damp that will show the size and shape of the leak. The good news is that once it is remedied it should remain so for sometime and you may be able to use a relatively cheap solution - I have had simple silicone seals resolve the problem such as yours which was very cheap. Good luck and hope you get it sorted soon!
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  • paintpotpaintpot Forumite
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    Thanks Red. I know it will be difficult for anyone to tell me exactly the cause but pointers to investigate etc are useful to me as it is bugging the hell out of me now :confused: The size of the damp is about a 1m deep strip that stretches the full length of the wall and is manifesting itself in the same place both inside and outside by damage to the paintwork. But how is the water getting in? There is nothing to strip off on the outside as apart from the masonry paint it is brick. I did manage to dry the plaster out inside and proceeded to paint it to "see what would happen" but now the wall is soaking wet again, probably weather related i.e. it dries out when it's fine and gets wet again when it rains as it is now. I will seal the window and see what that does. I assume the low level render is protecting the wall at the bottom from the damp getting in. The sill was deteriorating and crumbling, it's a concrete/stone type sill which I filled, sanded and painted so that is now watertight. Arghhh! I don't like playing this game :D
  • BonbonBonbon Forumite
    564 Posts
    Hi paintpot, jusy thought you'd like to know That I have the same problem and haven't found an answer yet. I live in a victorian solid brick house and have small damp patches that appear when it rains.I don't even have a window on my damp wall.I had new guttering put up and it didn't change anything, so I also look forward to any answers to this problem.
  • paintpotpaintpot Forumite
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    Hi Bonbon

    We shall both watch this space then. The house is split into flats and to be honest they have all had bits of damp like you describe but nothing to this extent elsewhere which really makes the flat uninhabitable until resolved as the paint is falling off within a matter of days so I couldn't let it to someone knowing this, and this is what would be the bedroom. I could hide it for a while using various methods but it would come back to haunt me. I have been advised I could plasterboard it but it's not a long term solution I don't believe.

    Any more bright ideas/advice out there please are very welcome.
  • adazeadaze Forumite
    623 Posts
    Whats the room directly underneath like (if its not yours, you could ask)? If thats damp too it could possibly be rising damp?
  • vetfredvetfred Forumite
    5.1K Posts
    You're right in not wanting to plasterboard over a problem especially as damp and water issues can eventually effect timbers etc and cause much more of a problem than it may be now. I'd call in a local builder/roofer or two and it shouldn't cost for them to give an opinion. I think a couple of experienced eyes are going to be your best bet really.

    If it's 1st floor as in you're upstairs (I know Americans say 1st floor for ground floor sometimes and I can't hear your typing accent!) then that would rule out rising damp or issues with the damp course I believe. As far as I know, what's known as rising damp isn't supposed to be able to go anywhere near that high? Certainly if it appears after rain then I too would agree it probably isn't because of condensation.

    I'm not in the trade do don't take my post as from anyone "in the know" but first off I'd want to make sure the guttering/weatherboard/ridge tiles/flashings were all doing their job.

    My uneducated guess for a potential problem is this: masonry paint. Victorian houses rely on the porous nature of their walls to breathe and evaporate out moisture but if the wall has been coated in an unsuitable paint which stops this then there may be a moisture balance issue. Where the paint has peeled, you say is where the damp is... so if it rains and all the in-tact paintwork above is focusing the water down to the "unprotected" area then maybe that's meaning there's a build up of moisture in a line across the wall.
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  • paintpotpaintpot Forumite
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    Sorry if I have confused everyone, it's actually a ground floor room :o to clarify.

    I have posted a picture below, sorry, if it's not sized properly. The affected area is directly above the radiator where the wallpaper has parted and extends about a meter high the full length of the wall i.e to the right. The black mould in the right hand corner is no longer an issue and was caused by something else. You can see how yellow the wallpaper is in places. I have now stripped this off but the yellow/damp has come back on the fresh emulsion.
    You can also see how close the window is to the affected area. The render on the outside goes up to the height of the window sill and then the masonry paint starts.

    16bk0p1.jpg
  • BobPropertyBobProperty Forumite
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    That's bad. I'd now be interested in a picture of the outside wall at the same place. Have the bricks been sandblasted or similar before the masonry paint was applied?
    Is the window a replacement for the original (I guess it is)? Picture of the window frame from the outside, bottom left would be appreciated.
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  • paintpotpaintpot Forumite
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    Yes it is bad! Hence my desperation!

    I haven't any photos of the outside. But to answer your questions:

    I have no idea if the bricks have been sandblasted etc. To describe, in various patches the masonry paint has flaked off, I used a wall paper scraper to pull the flakes off and then sanded and touched them in again but already they have bubbled and show yellow staining. But the patches are maybe only the size of an apple at most. If the window is not the original it is certainly fairly old by it's condition, it's single glazed and timber and I had to replace a piece of beading in the top pane. Otherwise they are in fine condition except you can see a hairline crack all round the edge on the outside where they are not sealed. The sill outside is stone/concrete or whatever it is and was very badly affected, it had a big hole in it and was powdery and that was the bottom left if you were standing outside and looking in.
    So what are you thinking bobproperty?

    Edit: if it helps to add this I don't know but a bit of history, this flat/house belongs to a friend of mine and is a BTL. In the summer I inspected it for her when it was with an agent as we were alerted to the fact it wasn't being looked after. The flat was in a terrible state and is being refurbed as the tenant has been evicted. The room affected with the damp is the bedroom but in the summer when I inspected it, it was flooded, literally an inch of water on the floor so the tenant was living in the lounge and never reported the leak - he said it was the fridge freezer with the leak but I didn't believe this due to the amount of water and the agent (as was) sorted the leak out but I have never known the cause of the leak since the agent was disposed of and I took over refurbing the place. The leak is what I believe caused the the black mould on the walls etc but not the existing problem as the mould has never reoccurred but this problem has and very very quickly. Also you couldn't see out of any of the windows in the flat for mould but nowhere else in the flat is there a damp problem but he never ventilated the place and he always, even in the summer had the heating on full blast. So despite the heat and there being a radiator directly next to the damp patch this hasn't dried the wall out, at times it has been dry but then it becomes wet again. It looked like there might be pipes channelled into the wall (very stange things go on in these sorts of houses believe me) but I chiselled out the plaster and there were no pipes so ruled that out as a cause.
  • BobPropertyBobProperty Forumite
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    paintpot wrote: »
    .....So what are you thinking bobproperty?......
    I'm thinking there's a fault with the brickwork/pointing or the frame/sill area which is letting water soak into the wall.
    A house isn't a home without a cat.
    Those are my principles. If you don't like them, I have others.
    I have writer's block - I can't begin to tell you about it.
    You told me again you preferred handsome men but for me you would make an exception.
    It's a recession when your neighbour loses his job; it's a depression when you lose yours.
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