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Damp patches on walls

Discussion in 'Building' started by ajs123, 19 Mar 2021.

  1. ajs123

    ajs123

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    I have these patches on my walls. I've sealed the outside render, 2 coats of bullseye 123, 2 coats of masonry paint outside, same on inside walls with emulsion not masonry paint, yet the patches are still coming through.
    It is on a front facing wall, which are 3ft thick built in 1900s, doesn't occur in any other part if the house.
    Can anyone please give me an idea of what's causing this? (New sealant on downstairs windows, but not upstairs ones yet, windows 2 yrs old).
    Thank you.
     

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  3. KenGMac

    KenGMac

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    Suggest a very careful inspection of window seas between window and walls.

    That is a first port of call.

    Ken.
     
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  4. Wayners

    Wayners

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    Cavity tray problem maybe. This explains.

     
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  5. KenGMac

    KenGMac

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    Do not think they had Cavity Trays in "3 foot thick" walls built in the 1900s ?
     
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  6. Wayners

    Wayners

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    No. They didn't.. Oops.. Just going through posts quickly and not reading properly.
    Sorry...


    In that case you got troubles from above.
    I've fixed windows with foam and new silicone but when water appears to the side like in photo it could be water getting in higher up or coming through the bricks.
     
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  7. Bullet-Proof_Biscuit

    Bullet-Proof_Biscuit

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    I think the problem is you've just thoroughly sealed what were breathable walls.. Just think how is the moisture supposed to escape now other than the only porous side which is internal? Presumably there is no DPC and honstly 'sealing masonry' never does that, there will always be voids and cracks where rain/moisture can enter, this is fine originally because the porous lime mortar allowed an evaporation and drying route from the walls.

    Furthermore noting those patches are fairly high, I would be looking at the first floor walls / window openings as the source if they appear following rain.
     
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