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Mould/Damp on ceiling Query

  • 17-07-2025 03:30PM
    #1
    CatFromHue
    Moderators, Science, Health & Environment Moderators Posts: 18,368 Mod ✭✭✭✭


    We had an extension put on in 2017/18 that extended the bedrooms out, roughly drawn below. This involved adding an air vent to the back wall as well. Over the last year or two I've been noticing mould starting to build up near the vent and a few spots of discolouration on the inside of the extension where the wall and ceiling meet. I'm worried that this might be more than just a bit of mould, the room is very warm naturally, and there might be a bit of a leak. There's a few cobwebs in the first pic but you can see the mould around the vent. Does that look like a bit of a leak?

    Room.jpg 20250717_145742.jpg 20250717_145745.jpg 20250717_145817.jpg


Comments

  • #2
    ted1
    Registered Users, Registered Users 2 Posts: 23,451 ✭✭✭✭ted1


    probably just a cold soy on the wall. I assume you clean the mould off when it’s appears.

    You could look at a electric/ mechanical vent with a built in humidistat



  • #3
    10-10-20
    Registered Users, Registered Users 2, Paid Member Posts: 9,161 ✭✭✭10-10-20


    Probably the block used for the closing the cavity at the top of both leafs. Even pumped cavity insulation suffers for the thermal bridge at that point.

    Monitor and Manage the RH and open windows when you can.



  • #4
    CatFromHue
    Moderators, Science, Health & Environment Moderators Posts: 18,368 Mod ✭✭✭✭CatFromHue


    Thanks for your comments. Below is a few close up pics of the affected area. It's the middle one that had me thinking is it more than just some mould.

    20250718_182714.jpg 20250718_182718.jpg 20250718_182733.jpg


  • #5
    whizbang
    Registered Users, Registered Users 2 Posts: 2,040 ✭✭✭whizbang


    Thats a water stain in last 2 pictures.

    Have a look up above in Attic.. Is this a flat roof ?



  • #6
    CatFromHue
    Moderators, Science, Health & Environment Moderators Posts: 18,368 Mod ✭✭✭✭CatFromHue


    This room had the extension put on so there's no attic or room above it. It's not flat as there's a small angle to it. Just got out the ladder and took a picture looking into the building and then from the window looking out. To my untrained eye it looks ok.

    20250719_143358.jpg

    20250719_143539 - p.jpg


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  • #7
    ongarite
    Registered Users, Registered Users 2, Paid Member Posts: 8,563 ✭✭✭ongarite


    To my untrained eye, the bottom tile to the right of the skylight is broken.

    It’s the finger width one, looks to be broken in half. And the tile beside it isn’t flush, sitting correctly because of the flat roof raised edging



  • #8
    10-10-20
    Registered Users, Registered Users 2, Paid Member Posts: 9,161 ✭✭✭10-10-20


    https://www.boards.ie/discussion/comment/123656408#Comment_123656408

    The skylight will have been fitted with a skirt under those tiles which should extend around 30cms from the edge of the frame, so that area should be well sealed. It should be checked all of the same.

    I wonder if it's leaking around where the flashing meets the render. That area is supposed to have the lead-work tucked into the wall with retention-clips fitted so that it's all tight, then sealed up afterwards. I can see where some of the render has been repaired over to the right of the soil downpipe.

    Here's an example of what I'm talking about, except you haven't lost the mortar/render.

    https://www.youtube.com/shorts/nLSHaEt3wdA



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