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Strange small damp patches

Discussion in 'Plastering and Rendering' started by NickB_99, 21 Jun 2014.

  1. NickB_99

    NickB_99

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    Hi.

    Someone may have seen this before.

    I did some plastering last week and the skim seems mostly dry except for some strange small damp patches just in the corner.

    And a bit closer

    Underneath -
    I replaced a wood & glass partition between the hall and the lounge and built a wall with thermalites blocks.
    The bulk of the area on the right was dry lined with d&d plasterboard, leaving just a small strip about 4" wide up against the corner. (Where the damp is).
    This was filled with bonding and the whole wall skimmed with multi finish.

    The bonding went on last weekend and the skim on tues eve.

    There's no plumbing anywhere near and there was no obvious problem in the corner before.

    I'll leave it a bit longer to see if it clears, but the damp looks localised but very pronounced.

    Any ideas?
     
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  3. NickB_99

    NickB_99

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    Left the internal door open last night and it seems to have eased a bit.
    Maybe moisture from the bonding just taking its time to work out.
     
  4. roy c

    roy c

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    Should imagine that's the problem newby,,The bonding would have soaked up a lot of water and being thicker than the skim would take a bit longer to dry out.. If there was no damp before you did it then there shouldn't be any now,, ;)
     
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  5. NickB_99

    NickB_99

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    Thanks Roy.

    I'd expected more damp there, but was expecting a uniform strip about 4" wide, in line where the bonding was. I was surprised it was just little patches that were very pronounced. Not seen it before.
    I had wondered if putting pva over the damp bonding next day had perhaps sealed it a bit and then the damp could only get out in limited areas.
    Either way, I'm hoping it will clear on its own.
     
  6. HLangwick

    HLangwick

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    Hello,

    A little bit new to this forum business so not sure if this is the right place to post this, it seems related?

    We had a leak from the upstairs bathroom which has now been fixed. A lot of the old plaster from the room below was chipped off and taken back to brick (but not all) and we found an old bricked up window we didn't know was there. We have decided to keep and will be putting shelves in it.

    The plastering was done by pros about 2 weeks ago. It all dried out quite nicely except a few odd dark patches. These feel dry and a bit rough to the touch. Could this be something other than damp plaster and what should I do about it if anything? We are planning to tile over this and paint inside the old window.

    The house is a solid wall brick built cottage from the late 1700s. The outside of the house has 1 year old external insulation and brand new guttering so think we are all good from that point of view. Since the plastering has been done we have had the windows open 24/7 and the weather has been fairly warm and kind to us.


    Any help and suggestions much appreciated. I have tried to stick a couple of pics underneath.

    Cheers

    H

    http://media.diynot.com/220000_219666_79228_76006120_thumb.jpg

    http://media.diynot.com/220000_219666_79227_54114274_thumb.jpg
     
  7. ree

    ree

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    Your pics are more or less useless - they cannot be expanded. The site index has a posting pics procedure, or find instructions under ban all sheds user name.

    Pics of the outside wall will help.

    Sometimes the only response is to hack off the plaster from the area in question and then render in sand and cement and skim with board finish.
     
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  8. HLangwick

    HLangwick

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    Sorry about that I am still very new at this.

    I have attempted to add some more useful pictures now including the outside wall. But am still a little confused as to how best to include them in this post so. I have put them on gdrive. Here is the link:

    https://drive.google.com/folderview?id=0B35ddIp2AZDVMW92aVZFMHVuVDQ&usp=sharing


    sorry if that is a bit of a faff.

    Thanks again for all help

    H
     
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  10. ree

    ree

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    Thanks for the new pics , they are just the job.

    Is the external render applied over external insulation?

    Have you carefully examined the bathroom above for any signs of further leaks or any possibility of water getting into the wall? Is there a shower against that gable wall?

    The old opening had a lintel - was the lintel timber, has it been left in the wall?

    What damp (if any) was showing on the kitchen walls before renovation?

    How long after the leak repair was the wall re-plastered? What was originally leaking?
     
  11. HLangwick

    HLangwick

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    Hello here are my attempted answers:


    Is the external render applied over external insulation? Yes it is about 1 year ago.

    Have you carefully examined the bathroom above for any signs of further leaks or any possibility of water getting into the wall? Is there a shower against that gable wall?

    It was the join between the flexible pan connector and the stack which was badly installed during the external insulation work that was the source of the leak (nice I know). This has been fixed and it is all now bone dry. The shower is against another wall in the room upstairs so I don't think it can be anything from up there..


    The old opening had a lintel - was the lintel timber, has it been left in the wall?

    Yes it was and yes it was. If this was the cause of the strange patches it seems it would be concentrated around this area though?

    What damp (if any) was showing on the kitchen walls before renovation?

    There was a fair amount discovered once all the tiles fell of the wall but after the old plaster was chipped off we ran a dehumidifier in there for 2 weeks before any new plaster was added.

    How long after the leak repair was the wall re-plastered? What was originally leaking? as above..


    hopefully that is helpful and thanks for putting your brain to it!

    H
     
  12. ree

    ree

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    At some stage you will have to hack off the affected areas. Salts have been brought to the surface and they will not just go away or dissipate.

    At that time it would be best to replace the timber lintel with a concrete lintel or an angle iron. The wood is not the cause of the damp spots but its best out of he wall. It will retain moisture and attract fungal decay.

    A guesstimate would be that the leak, and the previous condition of the gable wall, have left the fabric in a long term damp condition that a few weeks with a humidifier would do little to shift.
    The moisture might have become trapped between the new render and insulation, and the interior plaster.

    Leaving the internal brickwork bare for say three months in a well ventilated kitchen will allow it to dry out but the key factor would be to render the wall as described above. The S&C render might not last long term but it will give some years of a clean surface.

    Decorating with emulsion would be the way to go.

    FWIW: the patches are not "strange" they are merely the common manifestations of salts on Gypsum plaster.
     
  13. HLangwick

    HLangwick

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    Great Thanks for the info.

    H
     
  14. NickB_99

    NickB_99

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    It's usual to start a new thread (topic), otherwise replies can get confusing whether it's for the original poster or not.
    And welcome to the forum.
     
  15. HLangwick

    HLangwick

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    ok, sorry about that..
     
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