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Green Building Bible, Fourth Edition
Green Building Bible, fourth edition (both books)
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    • CommentAuthorYanntoe
    • CommentTimeJul 29th 2019
     
    In the hamlet where I live, there is a community owned house which is occupied by a chronically unwell tenant.
    It's a stone/rubble walled property built in 1900 which looks to be in very good condition and the roof is in good nick with no evidence of water ingress. In 2015 the property was refurbed and double glazed windows were put in and the roof space insulated to current standards.
    The locale is one of the wettest in England and the prevailing weather comes from the West.
    The North West upper section of the West gable wall in one of the bedrooms is consistently damp and has been for some time, but now seems to be more problematic. As it's the gable end there are no gutters or downpipes.

    I suspect that the problem is one of condensation, but this suggestion is unlikely to be entertained by the "committee" who oversee the building unless there is some incontrovertible evidence that this is the case. The committee are of the tanking/concrete persuasion but at the moment are in the head scratching stage.

    So, I'd really appreciate any suggestions the Green Building Forumers have covering .....

    1) Could it be condensation or is there some other more likely cause
    2) How does one go about providing evidence that it is (or isn't) condensation
    3) If it is condensation what does one do about it (given that the budget will be small and the disruption will need to be a little as possible as the house is occupied by someone who is chronically unwell.

    All suggestions welcome.

    Thanks
    I
  1.  
    In my experience condensation is usually confined to the colder part of the year. Why do you think it is condensation?

    What is on the outside of the wall? If it is cement render are there any cracks in it that would allow rain behind the render and not let it out other than internally?

    Whilst you say the roof is in good nick has anyone been up there to check that all is as it should be and that any flashing on the gable end is OK and installed properly. Is there any any roofing felt under the tiles and is it in good order?

    Is the wall in the attic above the problem area in the bedroom also damp? If so then the problem is unlikely to be condensation.

    You say the wall has been consistently damp for some time. That implies that it was not always so (when did the problem start?). Was there an event or change that started the damp? e.g As a bedroom, did this room fall into disuse with the kept door shut whereupon damp was noticed after a period of time or is the room in constant use.
    • CommentAuthortony
    • CommentTimeJul 29th 2019 edited
     
    It is a simple matter to prove condensation in cooler weather, I silicone a small piece of glass to the wall using a ring of sealant on the wall. Next day take look condensation on the glass, if damp on the other side wet wall.

    I suspect condensation.

    I would drill the wall 5mm x 60mm deep, collect the dust, seal in a zip lock poly Baganda send it to me, may as well do five holes two in the problem wall, one in the other gable, two downstairs. Send the samples to me in the past, I will report % moisture content.

    How do you know the wall is damp?

    Tony
    •  
      CommentAuthordjh
    • CommentTimeJul 29th 2019 edited
     
    Posted By: tonyIt is a simple matter to prove condensation in cooler weather, I silicone a small piece of glass to the wall. Next day take look condensation on the glass, if damp on the other side wet wall.

    That sounds like an excellent, quick, simple test! :bigsmile: :bigsmile:
    •  
      CommentAuthordjh
    • CommentTimeJul 29th 2019
     
    There's nothing that prevents it being both condensation and rain penetration, of course :devil:

    To cure condensation, increase ventilation and temperature. Temporarily a blow fan heater on a lowish setting should cure it. Longer term, one or more of run the central heating warmer, open the windows more, do clothes drying outside etc.
    • CommentAuthorowlman
    • CommentTimeJul 29th 2019 edited
     
    <blockquote><cite>Posted By: djh</cite>There's nothing that prevents it being both condensation and rain penetration, of course<img src="/newforum/extensions/Vanillacons/smilies/standard/devil.gif" alt=":devil:" title=":devil:"></img>

    True, one of my clients had rain penetration on the gable wall (I assume solid), of a old Victorian farmhouse in an exposed location. Fortunately it was in an unused bedroom and we solved it with a clear sealant spray on the whole of the exterior. Not I add, the somewhat useless white spirit based stuff sold by builders merchants, but another product.
    •  
      CommentAuthordjh
    • CommentTimeJul 29th 2019
     
    I've found Stormdry to be effective, but full disclosure I've only used it indoors on the lime walls of my showers. The water does bead up and run off instead of penetrating the lime.

    Though If it is rainwater penetration I'd be more suspicious initially of some failed or poorly executed detail somewhere as PiH suggested, such as at the wall/roof junction, or a broken tile etc
    • CommentAuthorYanntoe
    • CommentTimeJul 29th 2019
     
    Thanks everyone.

    The area above the ceiling is vanishingly small as it's at the bottom of the gable - it appears dry.

    A roofer has had a look at the roof and can find no issue.

    If it was penetrating damp, I would expect it to be lower down the wall as the water would otherwise have to travel 650mm horizontally to get to the inside at the height it is. I would expect it to start at least 650 mm below the roof and track downwards. However it is only the top part of the wall that appears damp.

    I'll get the chaps to try the glass trick and may then see if they will drill holes as Tony suggests!

    I'll also lend them some humidity meters to see whether the room is cooler/wetter than others.

    Lets see what happens!

    Cheers
    I
  2.  
    Posted By: YanntoeI'll get the chaps to try the glass trick

    I'm not sure that will work in the (warm) summer

    Posted By: YanntoeA roofer has had a look at the roof and can find no issue.

    How well do you know the roofer

    Posted By: YanntoeI'll also lend them some humidity meters to see whether the room is cooler/wetter than others.

    That sounds like a good start

    I remember some years back I had a problem with water ingress from a gable end, long story short it was a misshaped tile up at the top and the water flowed down the flashing to a point where there was a badly installed part of the flashing. It was only found after striping the tiles off.
    • CommentAuthordbj
    • CommentTimeJul 29th 2019
     
    I have a west facing gable wall and finally slate hung it on the outside down to verandah roof at wallplate level ,to solve my condensation problems This was after trying all sorts of other potential remedies(chemical, repointing etc )Totally solved the problem which tended to show inside ( open unplastered stone wall) on through stones and around a window reveal. Managed to get some insulation on the outside of the wall behind the slates which probably helps. This solution of course requires a small slate overhang on the verges. Maybe a bit costly for you situation.
    •  
      CommentAuthordjh
    • CommentTimeJul 29th 2019
     
    Posted By: YanntoeThe area above the ceiling is vanishingly small as it's at the bottom of the gable - it appears dry.

    I don't understand that. The bottom of the gable suggests the eaves to me, but I doubt you mean that?

    As PiH says, how well do you know the roofer? If water got in near the ridge and made its way along the top of the wall under the tiles/slates it could easily appear on the inside of the wall near the eaves.
    • CommentAuthorYanntoe
    • CommentTimeJul 29th 2019
     
    I know the roofer very well and he is very good - indeed he worked on the roof in question - fixing the leaky chimneys! and roofed my extensions in local slate.
    He has checked inside and outside for signs of water ingress and can see nothing. Most of the Gable (in this case I mean the triangular bit at the top of the gable end wall) is above the ceilings and this is dry. However, when you get to the North West corner there isn't really any wall to see from above the ceilings and what there is, is dry.

    As to not seeing condensation in the summer, I certainly see it on my bathroom windows when someone's had a shower, or is the suggestion that if the wall is wet, in the summer, it can't be condensation?

    Hey Ho
    • CommentAuthortony
    • CommentTimeJul 30th 2019
     
    Sounds more and more like condensation to me
  3.  
    When did the evidence of the damp wall occur and what change caused the damp to occur or be noticed?
    • CommentAuthorYanntoe
    • CommentTimeJul 30th 2019
     
    Apparently the wall has "always" been damp, but is now "problematic" . I'm linking this to the arrival of the new tenants and the fitting of the double glazing around 18months ago.
    Interestingly, the bathroom window is now nearly always left open. The bathroom is next to the "damp" room. I should probably check whether they actually have an extractor fan!!
  4.  
    Posted By: YanntoeThe bathroom is next to the "damp" room. I should probably check whether they actually have an extractor fan!!

    And that it over runs the light switch off by 5+ mins and that it can't be disabled.

    What is the evidence of damp - black mould? wet patch on the wall? perception?

    If the problem is linked to new tenants then this leans towards 'lifestyle issue'

    Having said that I had black mould on a NW facing wall in a room that was little used by the tenants and under heated and kept with the door mostly shut. The building is stone/rubble built. The problem was solved by putting on 100mm EPS EWI. Actually instant fix. A few days for the wall to stabilise to the new temperature, a wipe down with dilute bleach and mould has never been seen since.
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