Damp patch? & whats the remedy

Discussion in 'Building' started by danped, 16 May 2014.

  1. danped

    danped

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    Hi,
    I've got this patch on the inside of the house, on an external cavity wall. When we moved in the previous owner said it was down to lack of air circulation as they had a large bookcase in front of it.

    We don't have a bookcase there but we have a desk. The patch was previously more extensive and higher up the wall, we have since painted over it and it has reappeared at the bottom of the wall only.

    Any ideas what is causing this and how to get rid of it?


    Thanks,
    Dan
     
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  3. footprints

    footprints

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    Yes it's a dead spot for air circulation chances are it's even worse behind the cupboards either side.

    You need to make the surface warmer or increase air flow.

    One answer I found behind a wardrobe was to paste the radiator insulating foil you fit behind rads to reduce heat loss to the wall, it made the surface warmer so condensation did not form.
     
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  4. ree

    ree

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    As above, heat and ventilation are the enemy and the remedy for condensation.

    Do you have a rad in the room, a trickle vent, an air brick or a fire opening?
    Do you have cavity insulation?
    And is this a ground floor room?

    Perhaps a pic of the whole wall with the desk pulled back/

    Given that the Torus skirting is modern, and there's a line of decorators caulk, perhaps the plaster has been replaced previously?

    footprints,

    I'm glad, and interested, to hear that foil was a solution for you. However, most reports are that rad foil is not the answer, in fact that it may worsen the effects of condensation.
     
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  5. danped

    danped

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    Thanks for the replies.

    the wooden bits either side are the legs of my desk, there's not much more to see if I pull it back.

    I have two rads in the room, and a fire opening. This is a ground floor room - the main living room.

    The reason I was asking is I am actually planning on having cavity insulation but I was concerned this problem might be accentuated. As part of the CWI I will need a trickle vent installed. There are air bricks under the floor - it is a suspended floor.

    So from what you have said it sounds like cavity wall insulation may help this problem by keeping the wall warmer.

    Let me know if you still need a wider picture of the wall.
    Thanks.
     
  6. ree

    ree

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    Given that you propose cav insulation, its in your interest to have a proper pre-injection inspection. In particular, they must view inside the cavity for any blockages or snot bridging - (they must also inspect the condition of the cav ties).

    Google details of the above inspection checklist and procedures.

    You appear to have sufficient heat and venting - the long view might be to remove the damaged plaster, perhaps all that wall plaster, and replace with a remedial render. However, that would come after any wait and see what effect your Cav insulation etc has on any future condensation.

    FWIW: did the seller make any mention of these issues on the house sale Disclosure document?
     
  7. danped

    danped

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    I'll check the inspection is done properly for the CWI. The plaster is in pretty good nick tbh. Perhaps the skim is slightly blown in a few spots. Ht seller didn;t declare any issues on the document. I don't think it is a big issue. I just want to make sure CWI doesn't make it worse.
     
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