Damp Around Bay Window Roof

Discussion in 'Builders' Talk' started by Louise Smith 1985, Feb 10, 2024.

  1. Louise Smith 1985

    Louise Smith 1985 New Member

    Hi All,

    I am looking for some advice, my house is circa 1910 and I am having some issues with damp and mould around a bay window. The bay itself has a concrete roof and stone mouldings around the windows.

    I am experiencing damp and mould on the coving and plaster that was done 2 years ago.

    I am looking for some advice as to how this damp might be penetrating, it doesn’t look like it’s coming directly through the bay roof too me. Just to ensure I can get the right trades in and get it fixed once and not the wrong fix. It has been suggested to recoat the roof with a fibre based paint cromapol

    Photos show the issue.

    Thanks in advance


    Attached Files:

  2. Alan22

    Alan22 Screwfix Select

    Sometimes you get a cold spot, no insulation behind or a gap with cold air behind, the room not heated at some point and condensation gives you a damp surface just on that bit because it didn't get enough heat to dry out, clean and kill with a bit of bleach and warm water and with normal room temperature and ventilation now and then it dries out and stabilises.

    Much the same thing happens with a drip or cold air gap coming in on the other side so it's a total pain working it out.
  3. Louise Smith 1985

    Louise Smith 1985 New Member

    Thanks for the advice
  4. qwas123

    qwas123 Screwfix Select

    Please post pics:
    1. showing the roof itself - you can use a selfie stick from a bedroom window to reach out over the roof.
    2. the RH side of the bay from the ground up.

    You have penetrating damp - perhaps from a roof leak or maybe from penetration above the eaves causing damage that can be seen above the the mullion posts?
    One window head is cracked.
    In the bay interior on the LH side a crack can be seen in the surface plaster and cove.

    You have a great, with original features, cant (3-sided) bay.
    Is the house, front elevation wall solid or cavity?
  5. Louise Smith 1985

    Louise Smith 1985 New Member

    Hi, thanks for the advice the wall is cavity.

    Additional photos attached, I know the concrete is in a bad state / moss needs removing thanks

    Attached Files:

  6. qwas123

    qwas123 Screwfix Select

    Thanks for the pics.
    More damage can be seen above the RH mullion.
    The bay thats next to yours shows flashing where the roof meets the wall - do you have any similar abutment flashing?
    You say the roof is a concrete roof - whatever it is maybe its reaching the end of its long life?
    Its been surfaced with tar & gravel - you could try removing the present surface and re-surfacing.
    Any new roof should project at the edges, and have gutters.
  7. Louise Smith 1985

    Louise Smith 1985 New Member

    Thanks I was thinking a clean down and rceoat will ask roofers about installing gutters too thanks
  8. billysloke

    billysloke Active Member

    I don't want to contradict qwas123 because 1) he will start calling me his dear friend and "poster #8" and 2) he knows more than me, but your roof already projects a decent amount and appears to have quite adequate drip detailing, except for missing chunk on RH corner (viewed from front) plus there seems to be a crack all the way to roof level on the LH corner.

    Are you in a conservation area? If so you may not even be allowed to install gutters.

    Are you on good terms with your neighbours? Either side seems to have the same bay. Why not see whether they have (had) similar issues? Neighbour to right seems to have lead over the whole caboodle.
    stevie22 likes this.

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