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Fixing damp problem

Discussion in 'Plastering and Rendering' started by Derek M, 6 Nov 2021.

  1. Derek M

    Derek M

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    My Dad has a problem with damp in a couple of places in his semi-detached house (probably built in the 1930's or 1950's, I'll check but I know it has solid walls as he couldn't get cavity wall insultation). At the back of the house next to the patio door there's a patch. The external wall has been coated with a sealed in recent years but my Dad thinks the damp probably got in the wall before it was sealed, so he's stripped back the wallpaper and cleaned up the black mould and hopefully that will let the plaster dry out before he redecorates, otherwise he'll have to strip the plaster back and replaster it.

    Then at the front of the house in the corner next to the front door there's a problem. He's stripped back the wallpaper there too and cleaned up the wall but he's not sure where the damp is coming from and he needs to work that out and fix the problem before redecorating. There's a water stopcock in that corner, so he's wondering if there might be a small leak in the pipe in the wall and the other side of the wall is the garage and there's a drain just outside the garage, so maybe that's the source of the damp, or he also wonders if it might just be water in the earth from the front garden.

    He found a company who claimed to be damp specialists and said they do free surveys but all they did was come out with a slightly better damp meter than my Dad has and stick it against the wall in a few places and say "Yeah, you've got damp there" (in addition to the two places I've mentioned already, they also said there was damp in the internal wall between the living room and kitchen, on the living room side at the end where it joins the external wall with the patio door). He asked them if they could tell what was causing the damp and mentioned the things he'd thought it might be but they just said he'd have to work that out himself and get the problem fixed and then they'd come back and remove and replace the internal plaster, which my Dad can do himself and even if he couldn't I'm sure a plasterer would do it a lot cheaper than this lot.

    I told my Dad he can't expect someone to come out for free and identify the problem for him and he'll have to pay the right person to identify the problem and fix it but I don't really know who that would be. Obviously if he can fix it himself he'd prefer that, so if you can give me some tips on how to identify the cause that would be great but otherwise if you can advise who we need to get in to do it that would be helpful.
     
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  3. JohnD

    JohnD

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    some photos of the damp patches would be useful.

    include something to show scale

    also, please show a photo of the whole wall, from gutter down to paving, to include all drains, downpipes, manholes and plumbing inside and out, and the airbricks. Mark the DPC with chalk or something so it is visible. Show the joint of doors and windows to the wall, inside and out.

    is the floor concrete?

    is it an extension?

    the wall coating probably prevents the damp from drying.
     
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  4. sxturbo

    sxturbo

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    Is the property rendered?

    What's the airflow like around the house?

    Any leaky guttering?

    Is the ground level outside lower than the dpc?

    It doesn't sound like rising damp as from your description it's very localised.
     
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  5. Derek M

    Derek M

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    Thanks. I'll get some photos when I'm next there. What's the DPC?

    Neither area is an extension. There's a porch outside the front door which was added about 30 years ago and there's no extension at the back, other than a utility room which is on the left of the house, adjoining the kitchen, whereas the damp in the rear external wall in the living room is on the right of the house, by the party wall with next door. Floors are all joists and floorboards, with carpets on top.
     
  6. Derek M

    Derek M

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    I think the airflow is pretty good. There's nothing blocking it in the front garden, which hasn't been concreted over for parking, and at the back (south facing) there's about 5ft of decking between the house and the lawn and the airbricks are exposed and clear of obstruction. There's a step down at the back of the house to the decking and likewise at the front of the house from the porch to the front garden.

    I don't think there's any leaky guttering, as my Dad would have mentioned it or fixed it if there was, but I'll check.

    I've got a feeling that the walls are rendered but I'll need to check that too.
     
  7. sxturbo

    sxturbo

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    Is the property rendered?

    Are the steps in the places where the damp is evident?
     
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  8. Derek M

    Derek M

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    I'm not sure whether it's rendered. I need to check that.

    The step at the back is outside the patio door, which opens on the left and the damp my Dad found is in the right-hand corner, although the people who came out said there was damp in the internal wall between the kitchen and the living room, near the left side of the patio door.

    At the front of the house the front door is on the left-hand side of the hall, then there's the porch (I think there's a small step between the house and the porch) and then there's the step down to the front garden. The damp is in the wall that adjoins the garage, on the right-hand side of the hall, so not really near the step.
     
  9. Derek M

    Derek M

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    I've got some more information and the photos now. The house was built in the 1930's and apparently the DPC is probably bitumen rather than lead. We can't mark it as it's below the walls. The exteriors walls are rendered.

    This is the inside rear right-hand corner of the living room, by the party wall.

    This is the inside rear left-hand corner of the living room, next to the kitchen.

    This shows the step outside the patio door, with an airbrick either side.

    This is the airbrick near the party wall.

    This is the airbrick near the kitchen/living room wall.

    This shows the drain and pipes, near the side of the kitchen furthest from the living room.

    This is the inside front wall where the damp is. It affects the wall behind the bookcase and the paper has been stripped there too, as you can see above the fire extinguisher.

    This is the same wall before the wallpaper was stripped, showing it bubbling underneath.

    This is in the corner of the inside front wall, showing the stopcock (that plug socket isn't connected!)

    This is the inside of the porch, with the damp the other side of the wall below the window.

    This shows where the porch joins the original external wall.

    This is a closer shot of the airbrick inside the porch.

    This shows the front external step and the step from the porch to the house.

    This shows the front drainpipe and two gullies. The rear one goes to a drain and the front one goes to a soakaway under the front lawn. The damp is on the other side of the wall which the drainpipe is attached to.

    These are a couple more shots of the drainpipe and gullies.

    This is the front wall showing where the airbrick is.

    This is a closer shot of the airbrick.
     
    Last edited: 21 Nov 2021
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  11. sxturbo

    sxturbo

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    How long has your dad lived there?

    Is it a sudden problem? Looks like it's been going on for a while.

    These houses need to breath, most damp issues are caused by lack of ventilation and condensation.

    Is the render original or has it been added? If it's been added it may well be cement and it needs to be lime.

    Or it could be the paint is stopping the wall from breathing.

    There isn't any immediate faults showing in the pics other than lots of damp in places

    I would advise on a drain survey just incase one has failed.

    The air brick in the porch really needs fresh air through it. But this isn't going to be possible so an additional air brick should be added outside of the porch.

    The render could well be bridging the dpc and causing the issues. I'm unsure how one would check this, without removing chunks of it
     
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  12. foxhole

    foxhole

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    You have several problems, external ground level is high is some areas, render will hold onto moisture while the cracks you have will let it in, rain down pipe too short soaking wall, porch area provides no ventilation to exterior slowing any drying process.
     
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  13. Derek M

    Derek M

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    He's lived there about 40 years now and I think the porch has been there for about 30 years. I don't think this has been a problem before, but of course there may have been some minor damp in the wall that wasn't evident beneath the wallpaper until recently. I think the wallpaper was changed about 10 years ago and there wasn't a problem then.

    The render has been added (I'm not sure exactly when but it was quite some time ago) but that's true of most of the houses in the street. Wouldn't the company doing the rendering have known to use lime rather than cement? How would he check what it is? It stops about 1-2 foot short of the bottom of the wall, as you can see by the black strip where the airbricks are, so I don't think it can be bridging the dpc.

    If exterior paint stops walls breathing, what do people use instead?

    I'll recommend that he gets a drain survey done. Should he just google for a specialist drain survey company?

    There is a window in the porch which is left open in the summer so maybe if that's left open all year round that will be sufficient but I'll suggest he fits an exterior air brick.
     
  14. Derek M

    Derek M

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    Which areas is the external ground level high?

    I can see how the crack in the rear wall to the right of the patio door could be letting in moisture and causing the problem in that corner, so I'll tell him to get that sorted.

    The rain down pipe above the drain at the back can be easily extended to avoid water splashing on the wall there, so I'll get him to do that too, although that's not where the damp patches are.

    I'll get him to sort out the porch ventilation too.
     
  15. sxturbo

    sxturbo

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    There is different types of paint and most consumers don't really know and are generally oblivious.

    Old walls need to breath, especially single skin ones.

    Something like this should be used to paint on the walls, (there's also lots of other info on the site you mind find useful)

    https://www.lime-mortars.co.uk/breathable-paint/exterior-paint


    In the 70's 80' and 90's people weren't hugely interested in conservation, cement replaced everything and very few would advise lime render, even today most people try and slap cement onto old walls.

    The lower bricks painted in black has been rendered, you can see there is a step, and the white render is down either touching it or very near it. This could well be a point of water ingress.

    Though it doesn't explain for the damp around the front door where the porch is.
     
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  16. Derek M

    Derek M

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    Thanks. Hopefully he'll know what it was painted with. If it wasn't a breathable paint and/or the render is cement, how much do you think it would cost to get someone to remove the paint / render and re-do it?

    Would it be worth just getting the render removed from the lower bricks painted in black and re-rendering and painting that first to see if that solves it?
     
  17. sxturbo

    sxturbo

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    It'll be a fortune to remove the paint and or render.

    Really you need to get a proper Ric's surveyor to have a look.
     
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