Penetrating damp or condensation

Discussion in 'Builders' Talk' started by Cassas00, Nov 26, 2019.

  1. Cassas00

    Cassas00 Member

    I have some damp forming in my first floor bedroom bay window.

    https://i.ibb.co/LtJ3Kqc/IMAG2649.jpg

    That is in the left corner of the bay and there's a tiny amount in the right corner of the bay. I read this is a common issue with bays due to the 9" and 4" solid walls issue, if condensation.

    I've had the house since April, it's been empty since without heating (renovating). Windows been closed due to cold/rain. I do have a dehumidifier, but it's been on in the ground floor bathroom.

    I didn't have this issue in August when the rain was heavy and constant. It's been since mid November.

    I've had a couple of quotes about repointing and applying Thompsons breathable water sealant to the external brickwork, the pointing does look a bit weathered. I just don't want to throw money at the wrong problem.

    Is there anyway I can check if it's coming from the outside or inside? I heard about the foil/clingfilm test?

    Should I leave window open? Move dehumidifier to bedroom? I did read that best way to prevent condensation is to add insulation to the bay area but since I've only just had it re-plastered and skirting added I don't really want to go down this route. I read about anti-condensation paints?

    Also must note I'm having no condensation in the ground floor bay.
     
  2. Joe the Plumber

    Joe the Plumber Screwfix Select

    Anything painted over brickwork is a disaster. Bricks need to breathe, and there's no such thing as a breathable coating, in spite of all the advertising bullship.

    There will be a rational reason for your dampness (cracked mortar joint, damaged flashing, or indeed condensation, etc).

    Once you've found out what it is, you can repair it. But don't paint your house with snake oil.

    If it does need repointing, check if it's lime mortar or cement based (how old is your house?) You need it to be done with the same stuff.
     
    KIAB likes this.
  3. KIAB

    KIAB Super Member

    Post some outside photo's of the problem area.
     
  4. Astramax

    Astramax Super Member

    Can you post a photo of the exterior of the windows where the leak is located as it is more than likely to be a fault with the window installation.
     
  5. Cassas00

    Cassas00 Member

    From outside

    https://i.ibb.co/sKtqXV3/IMAG2665.jpg

    Close on main damp side

    https://i.ibb.co/z81Gqfy/IMAG2653.jpg

    Looks like small gap in mortar in that second photo.

    I'm just thinking why did the damp only show up now in November rather than August when driving rain was constant, unless it's taken this time to soak through?

    Victorian house, approximately 100 years old
     
  6. Cassas00

    Cassas00 Member

    Would you guys not recommend the water sealer? Maybe just repointing and seal around window?
     
  7. Astramax

    Astramax Super Member

    Would be worth filling that missing pointing as that seems to be in the area affected.
     
  8. Cassas00

    Cassas00 Member

    Yea, I'll definitely get that sorted. I've taped some clingfilm on the area, I'll check back in 24 hours to see which side is damp.
     
  9. Joe the Plumber

    Joe the Plumber Screwfix Select

    In answer to your question about water sealer, please also see my post, above. The previous owner of my
    house (built in 1911) painted it everywhere. It traps water in the bricks and when it then freezes in winter,
    it expands and blows the faces off them. I've got loads now that are damaged in this way.

    I can't think of any situation or problem to which 'water sealer' is the answer.

    Your house will need lime mortar for any re-pointing (and unfortunately it's not really the time of year to do it incidentally).

    You can get the right stuff, and plenty of good advice, here:

    https://www.lime-mortars.co.uk/
     
    KIAB likes this.
  10. KIAB

    KIAB Super Member

    Warmer weather would soon dry out a damp exterior wall.

    And water seldom takes a direct route going from A to B,it could be getting from a distance & workings it's way down to the problem area.
     
  11. Befair

    Befair Member

    It seems that modern Sovereign products do work and are breathable. Joe, perhaps previous owner applied cheap rubbish.
     
  12. Cassas00

    Cassas00 Member

    I have so much conflicting advice on the water seal, two quotes on the pointing have recommended it without me mentioning it. Even a damp specialist, who's done some previous work for me, has recommended it.
     
  13. KIAB

    KIAB Super Member

    It can cause more problems than it solves.
     
    Joe the Plumber likes this.
  14. Cassas00

    Cassas00 Member

    Yea, the thought of the brickwork spalling really puts me off. I think I'll go down the route of re-pointing, seal window frame externally.

    Then monitor the results of clingfilm/foil test.

    If penetrating the external work should solve it, I'll apply some damp seal paint internally, then emulsion.

    If condensation, a combination of heating, ventilation and use of the dehumidifier during winter months could solve it, if not I could board and insulate the bay window area.
     
    Joe the Plumber likes this.
  15. Joe the Plumber

    Joe the Plumber Screwfix Select

    How do they know which way the water needs to go? The previous owner of my house told me he'd painted it with 'Thompson's Water Seal'. I still can't
    think of a problem to which they are the answer.
     
  16. Cassas00

    Cassas00 Member

    So the cling film test didn't really show much, wasn't wet on either side but as only 24 hours. I've replaced with foil and will leave it longer.

    https://i.ibb.co/dPjcy5t/IMAG2668.jpg

    I've voiced my concerns about the water seal to both quoters.

    First one said

    Hi the face on the brick can blow off from frost being wet expanding, the paint will give the effect so the rains drips down with the stone it's so hard I personally can not see the face ever coming off in any condition of weather.

    Second one said

    EVERYONE ....has an opinion lol ....even the monks used olive/veg oil..... THOMSON a reputable company sells this product ...with an assurance of stone, bricks , blocks etc would not be affected.....me thinks theres too much internet youtube lol.... up to you mate ?

    NB more stonework is affected by car fumes /acid rain etc sulphur dioxide?
    my mix.......because of time of year cold/damp lime sand cem
     
  17. Cassas00

    Cassas00 Member

    Damp guy has said

    They have a valued point (about bricks blowing). My opinion is I would rather risk that happening than have a damp house.
    You can buy breathable double strength sealant but it’s expensive.
     
  18. Joe the Plumber

    Joe the Plumber Screwfix Select

    If your bricks were porous, the house would have been damp ever since it was built. Chances are if it's a problem with the wall, it will be from the lime mortar eroding and allowing water through, which it's supposed to do. It's a sacrificial material.

    Any spray on goo isn't going to properly resolve that. Re-pointing will.

    There may be some further information of interest to you here:

    www.heritage-house.org
     
    Cassas00 likes this.
  19. Cassas00

    Cassas00 Member

    Interesting site. Think I'll stay away from the sealer. Thanks all.
     
    Joe the Plumber likes this.
  20. kiaora

    kiaora Guest

    hi
    how do you tell the difference between damp patch and condensation ?
    simples !
    get key or coin or knife or similar,
    expose small surface area of plaster scratch off small square of plaster, ........

    result:
     

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