Mystified by damp

Discussion in 'Other Trades Talk' started by tamsin, Jul 26, 2021.

  1. tamsin

    tamsin New Member

    we are completely mystified what is causing this…any thoughts of what angle to go down now will be greatly appreciated. We’re pulling our hair out about it!!

    1930s house, 1st floor, external wall. When we stripped the wallpaper (18months ago) there was a layer of polystyrene under it, so clearly had been an issue before.

    Generally appears when it’s raining, although it does appear when it’s just cold. When it is raining, it’s appears VERY quickly, almost too fast.
    - we’ve had the roof redone
    - cutters are all clear
    - dehumidifier to try and draw it all out
    - damp meter is not showing any damp present (?!)
    - exactly the same damp pattern patch will appear
    - it does disappear and dry out
    - cold to touch, not wet, wallpaper isn’t bubbling off at all.
    - it starts about a third of the way down the wall to the bottom
    - no damp on the same wall downstairs
    - no pipes in that area

  2. Abrickie

    Abrickie Screwfix Select

    Several external photos of that area would be of immense help :)
    Jord86 likes this.
  3. Wayners

    Wayners Screwfix Select

    Cavity wall I guess.
    I do wonder if water getting through and cavity trays would fix?
    Outside photos will help
  4. Jon Dennis

    Jon Dennis New Member

    Can you go into your loft and look down the cavity to see if there is anything bridging it?
  5. Abrickie

    Abrickie Screwfix Select

    Have you tried, there are inconvenient things like wall plates, rafters/trusses, felt/membrane, etc in the way :D
  6. Jon Dennis

    Jon Dennis New Member

    I can look down the cavity on my house, it has a cut roof, use a camera and you don't have to get your head in there. Just make sure it doesn't drop down the cavity. You can get cheap endoscopes for your mobile phone.
    Last edited: Jul 28, 2021
  7. Nev Hope

    Nev Hope Active Member

    Check out the window reveal….. it’s awfully narrow for a cavity
    tamsin likes this.
  8. Hell68

    Hell68 Member

    External brickwork? Had similar in one of my bedrooms. Repointed and not had a problem since.... fingers crossed!
  9. tamsin

    tamsin New Member

    Thanks for comments, it isn’t a cavity wall.
    External is rendered, we still have scaffolding up from roof so can’t get any good pics.
    Render isn’t blown, there is a slight visible crack coming from the corner of the window. Could that be causing it, even though most of the damp mark inside is above the crack?
    Thanks all!
  10. Nev Hope

    Nev Hope Active Member

    Wouldn’t now be the ideal time to take a photo, you could use the scaffolding

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