Damp, cold bedroom wall with serious condensation problems

Discussion in 'Builders' Talk' started by Alicegal, Aug 9, 2019.

  1. Alicegal

    Alicegal Member

    We have just bought a very old, tiny stone cottage which used to be a stable. My daughter's room is at one end of the house. The thick stone, gable wall has been cemented over (there's no way we can remove this). Inside her room, this wall suffers terribly from condensation problems. In winter beads of water coat the walls, even with ventilating the room and heating. Unfortunately we have lpg gas (no choice) which costs a fortune. It is far too expensive to leave the heating on low all night in the winter to keep the wall dry. I'm really worried about my daughter sleeping in this wet, damp room. What could we do to this wall to stop this massive condensation problem? The walls are incredibly thick - typical of a stable/building built in the 1800s. Would insulating the wall alleviate this? The existing plaster on this wall is bulging, crumbly and soft - obviously from being constantly wet every winter. Any advice would be greatly appreciated, thank you!
  2. koolpc

    koolpc Well-Known Member

    Obviously you need to hack off the plaster. If there is no water coming in from outside i would insulate the wall.

    I have done this myself. Batten walls, insulate, vapour barrier, plasterboard and then plaster.

    In the mean time, buy a dehumidifier. They are superb.
    Alicegal likes this.
  3. Alicegal

    Alicegal Member

    barneydog likes this.
  4. Alicegal

    Alicegal Member

    Thank you very much for your advice, we will do just that!
  5. koolpc

    koolpc Well-Known Member

    Some will say to buy insulated plasterboard and stick that to the wall by dot and dab. I am not confident of that approach. Battening gives the boards a solid base. Of course, you could even apply insulated plasterboard to the battens instead of ordinary plasterboard. Of course, still putting insulation in between the batterns too.
    Alicegal likes this.
  6. Alicegal

    Alicegal Member

    Thank you so much!
  7. glob@l

    glob@l Active Member

    A guy (joiner) near me stripped the lathe and plaster back to the bare stone walls. He built a stud partition slightly away from the stone leaving a space between the stone and stud partition for ventilation, insulation boarded between the studs, taped and silicon sealed all joints and then plasterboarded. Does this sound like a good or bad idea?
    Alicegal likes this.
  8. b4xtr

    b4xtr Active Member

    Insulating is a very good idea but you also need a vapour barrier
    Alicegal likes this.
  9. Alicegal

    Alicegal Member

    How do you create a vapour barrier?
  10. koolpc

    koolpc Well-Known Member

    Once you put the battens up, and then the insulation, you stretch out a continuous plastic sheet across the whole area. Nice and taught. Pinned in place.

    Then you attach the plasterboard / insulated plasterboard. You then have a vapour barrier. WP_20141123_002.jpg
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  11. Alicegal

    Alicegal Member

    Thank you, that's very helpful.
    With our wall being a cemented gable end wall, would the insulation between the batons not draw moisture from outside and end up wet behind the plastic? Could trapped moisture cause deterioration of the external wall since it might be trapped between the stone and plastic sheet? Sorry for questioning - you can probably tell I'm a novice! Did you leave a gap between your external wall and the insulation to allow air to circulate, or is your insulation pressed right against the wall between the batons please? How much floor space do you think you lost in building your new internal wall? I'm asking as our daughter's room is already quite small. Thanks so much for your help!
  12. koolpc

    koolpc Well-Known Member

    It was pushed up against the wall. The amount of space i lost was approx 80mm in total. Hardly anything.

    Obviously you have to make sure no water is coming from the outside first as otherwise the insulation will rot. The wall has to be dry.

    What you described in your opening post was condensation. Warm air falling on a very cold surface which condenses.

    I have insulated 2 walls in different houses like i mentioned above. We moved house so i did it in the 2nd houses living room. It made a difference to the warmth too.
    Alicegal likes this.
  13. koolpc

    koolpc Well-Known Member

    I would do some research online about insulating a solid stone wall. In theory, no water should be coming into the house through the wall. Hopefully the outside is well pointed or rendered?
    Alicegal likes this.
  14. Astramax

    Astramax Well-Known Member

    I believe sospan has a lot of knowledge re stone walls, he may be along later and be able to help you.
    Alicegal likes this.
  15. koolpc

    koolpc Well-Known Member

    Wallrock could be another option too. Or something similar
    Alicegal likes this.
  16. Alicegal

    Alicegal Member

    The wall is very thick, old stone as the house used to be a small stable. At some point, the previous owner cemented all over it as apparently this wall is exposed to the wind and rain.
  17. Joe the Plumber

    Joe the Plumber Well-Known Member

    If water is getting through the wall from outside, it's almost certainly being trapped between the concrete and the stone and can't escape back into the atmosphere outside because of the concrete.

    I'd have a good look outside and see if there are cracks in the concrete allowing water through.

    If so, the ideal solution will be to remove all the concrete and re-point the stones. As the place is old, the mortar will definitely be lime, which is lovely stuff, still easily available and perfect for the re-pointing.

    That will then make the wall watertight again for many years and should also solve the damp problem. It might well make the house more valuable too.
    Dam0n and Alicegal like this.
  18. koolpc

    koolpc Well-Known Member

    I lived in a solid stone buit house. Condensation was a nightmare as outer walls obviously had no cavity thus extremley cold. Waem air inside would condense on the cold wall.

    You have to check first to see if water is seeping in from outside first.
    Alicegal likes this.
  19. Alicegal

    Alicegal Member

    Thanks so much everyone. We're going to attempt insulating two of the three bedroom walls that are exposed to the elements in the hope this prevents condensation from forming. These two walls have bulging, crumbly plaster with tiny damp spots dotted on them, so they are the worst. We are removing the draughty old single glazed windows and replacing with double glazing. I realise this could also cause condensation as the room will be warmer, so we will make sure to open them on a daily basis for ventilation. Strangely, the other bedroom, which is smaller, doesn't suffer much from condensation. Perhaps it is just the side of the house which is most exposed to the elements.
  20. Alicegal

    Alicegal Member

    I'd like to do that, but we're worried what the cement might be hiding! The surveyor suggested leaving the cement for this reason, and trying to insulate that wall instead. The seller said that he put the cement on to protect the side of the house from the elements. It's only on one side and above a small extension on the ground floor. We'll have another look to see if any water could be seeping through the cement.

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