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Yellow droplets on ceiling where stain block paint has been used ...

Discussion in 'Decorating and Painting' started by feisar32, 30 Sep 2021.

  1. feisar32

    feisar32

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    Hi

    New here and hoping someone might be able to give me an idea what's going on ...

    We have recently moved into what used to be my grandmother's old bungalow. She passed away in 2008 and the bungalow has been uninhabited ever since, although we've been doing extensive renovations over the past seven years.

    Previously (presumably over the course of several years), water had been leaking in around the chimney; we had a roofer install some flashing where there hadn't been any around the top and sides of the chimney. Where the water had been leaking and making the plaster beneath damp, there had been mould on the bedroom / kitchen side of the ceiling near the chimney breast.

    These were cleaned with fungicidal wash, painted with two coats of stain-block paint (can't recall the make, but could probably find out) before the roofer came in last year, so during some bad weather water staining had made it through. So again, after he'd been and once it was dry we cleaned it, applied two coats of the same stain-block paint, and then two coats of kitchen / bathroom emulsion.

    Despite this, even before we moved in, there seemed to be a regular sheen of moisture where that stain-block paint had been applied, on the kitchen side of the chimney, even if it hadn't rained for weeks.

    During this past summer, even when it hadn't rained for weeks, we have on a few random occasions seen clear droplets of yellow liquid on the ceiling on the bedroom-side of the chimney breast, where that paint had been applied; when wiped off, it does not stain. Now my wife has just messaged me to say she's seen the same on the kitchen side, which is the first time I'm aware of that happening.

    The droplets just seem to appear ... we don't notice regular dripping or anything like that which might indicate problematic quantities of water above

    I will check tonight when I get home, but each time this has happened since the flashing was applied around the top of the chimney, the plasterboard immediately above the affected area has not been obviously wet or even damp. I'm mystified ... unless there was some issue with the paint, I believe my Dad had had it for some time ... it's just odd that these droplets only seem to occur where that stain-block paint has been applied.

    Actually, one other potential factor: my Dad sprayed some expanding polyurethane foam between the chimney and the adjacent joist a couple of years ago. Last I looked it was not exhibiting any obvious sign of degradation.

    Does anyone here have any ideas what might be causing this, please ... ? As I said, I'm mystified but we need to sort it, as on the bedroom side the droplets could affect electrical equipment ...

    Edit: I should mention that, while my eldest son does smoke, he is not permitted to do so indoors. No-one else in the household smokes
     
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  3. Chivas69

    Chivas69

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    Do you have any pictures you could upload.
    If you can wipe away the droplets it sounds like they are coming from inside the room rather than above. Could it be condensation? Is it a flat roof?
     
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  4. feisar32

    feisar32

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    Hi

    Thanks for replying; yes I do, please see attached. It could potentially be condensation, I suppose ... the loft has been uninsulated, and the bungalow has been unheated, for several years. We now have heating in place and are starting to use it as the weather gets colder, but I've not yet had the opportunity to get the insulation sorted. That's a task for the very near future ...

    Just thought it was odd that the moisture only seems to gather on the areas which have been painted with the stain block (the images show it quite neatly as unfortunately the new emulsion was a slightly different colour to the old!) and seems to have some discolouration. Could that be a coincidence?
     

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  5. opps

    opps

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    It sounds like condensation.

    The walls in our bedroom used to be regular emulsion. One day the GF decided to paint them with waterbased eggshell. From that day onward when it is cold outside and the windows are closed, the vapour from breathing over night runs down the inner faces of the exterior walls.
     
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  6. Bosswhite

    Bosswhite

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    Stain block is basically a sealant, so condensation settles on it and cannot be absorbed, sounds like you need a Humidifier to dry out the atmosphere
     
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  8. Chivas69

    Chivas69

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    I'd say it's definitely condensation. I've seen this before on the top floor of a 3 storey flat. It had a flat roof and condensation would form where the steel joists would be. Ended up putting polystyrene wallpaper up and then blown vinyl on top. It helped but it still did it when it was cold out.
    I think insulating your loft will help massively with this as condensation sticks to cold surfaces. If you feel the ceiling is it much colder than the walls?
    As a test you could always put some insulation above this exact area and see if it stops the condensation. Just buy one roll until you're ready to do the lot.
     
    Last edited: 1 Oct 2021
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  9. RonnieE

    RonnieE

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    Looks very likely to be condensation to me.

    What is the ventilation like in that room? Does it have an extractor fan or trickle vents on the window?

    Is that surface cold to the touch? If so, humidity / moisture in the air could be reaching dew point and condensing on the surface, collecting as water droplets.
     
  10. opps

    opps

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    An easy way to test is to tape some bacofoil over the area. If condensation, the outer face of the foil will become wet. If damp, the underside of the foil will be wet.
     
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  11. feisar32

    feisar32

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    Thanks all for the replies; I believe you're right, as I temporarily put in one of those plastic units with the desiccant material inside, and while it hasn't resolved the problem it's reduced it quite considerably. There's no extractor in the room or trickle vents in the window, and while it's not yet that cold where we are, the weather's been miserable lately and the wind's been strong. Since we replaced the fascia and soffit all round with the soffit that's ventilated along its entire length, we do get quite a draught in the roof space ...

    I'm planning to lag the pipes this weekend, then can look to get the roof space insulated properly. In the interim I'll try your suggestions and report back when I have some results.

    Thanks again!
     
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