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Green Building Bible, Fourth Edition
Green Building Bible, fourth edition (both books)
These two books are the perfect starting place to help you get to grips with one of the most vitally important aspects of our society - our homes and living environment.

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    • CommentAuthorjanzon
    • CommentTimeMar 3rd 2019
     
    I have a stone house built in the 1890s that have damp upstairs walls on both gable ends.

    I have had the roof looked at thinking there was a leak somewhere but that hasn't helped.

    I was beginning to think the rendering was at fault, letting water in with nowhere to go but through the wall,so I looked online for ideas when I came across a site with very strong views on rendering old houses and associated damp problems.

    https://www.heritage-house.org/damp-and-condensation/types-of-damp-what-have-i-got/damp-problems-caused-by-cement-render.html

    Has anyone had similar problems or any views on the opinions expressed in the above site?
    •  
      CommentAuthordjh
    • CommentTimeMar 3rd 2019
     
    I agree with what it says about cement render. Not with what it says about EWI, although obviously the job needs to be done properly.
  1.  
    Wot djh said + 1
    •  
      CommentAuthordjh
    • CommentTimeMar 3rd 2019
     
    Posted By: janzonI have a stone house built in the 1890s that have damp upstairs walls on both gable ends.

    I have had the roof looked at thinking there was a leak somewhere but that hasn't helped.

    Is the damp inside or outside? Which way do the gables face and where are you (how exposed)? It sounds like it is rendered but what with? And how long has it been like this?
    • CommentAuthorjanzon
    • CommentTimeMar 3rd 2019
     
    The damp is on inside, the wallpaper is getting visibly wet after heavy rain.

    House is in a very exposed area on top of a hill in the NE, gables face roughly East & West with the east side worse affected.

    It is rendered with cement I believe, not smooth but a kind of knobbly effect. The problem has been getting steadily worse over the last few years with me thinking I had solved the problem with roof repairs.
    •  
      CommentAuthordjh
    • CommentTimeMar 3rd 2019
     
    Posted By: janzonThe damp is on inside, the wallpaper is getting visibly wet after heavy rain.

    Ouch! If it easy to make the association between rain and damp inside, that suggests some direct path for water to flow from outside (or above) to inside, rather than just rain penetrating through the stonework from outside. A photo might be useful. Is it damp in patches or everywhere? Near the top of the wall or the floor etc?

    It is rendered with cement I believe, not smooth but a kind of knobbly effect.

    Is it some kind of dash? Wet dash rather than dry dash. Harling, or whatever.
    • CommentAuthorowlman
    • CommentTimeMar 4th 2019
     
    @ djh
    I sounds like a tyrolean render finish, most likely with a sand and cement scratch coat underneath.
    • CommentAuthorjanzon
    • CommentTimeMar 4th 2019
     
    djh

    The wet patches start in a squarish pattern on the top half of the wall in a bedroom on the first floor (i.e not the ground floor).

    I don't know what kind of render it is. It sounds like owlman could be correct
  2.  
    Is the plaster directly stuck onto the inside of the stone, or is there an air gap and then a lath-and-plaster wall lining? (Does it sound hollow when tapped)

    We had damp where the air gap between the stone and the back of the lath-and-plaster had been blocked and bridged (by a previous owner filling it with insulation).

    Have you access to tap the render on the outside and see if that also sounds hollow? Cement render can trap water behind it which eventually freezes and detatches the cement in patches, which collect more rain behind them and channels it into the wall . Ultimately that requires to be re rendered.

    Old stone walls naturally dried a little to the inside, the houses were massively ventilated by open fireplaces so were not damp. The lime pointing needed regular maintenance. As time went by many of our neighbours were cement rendered to 'fix' that.
    • CommentAuthorgyrogear
    • CommentTimeMar 4th 2019
     
    Posted By: WillInAberdeenthe houses were massively ventilated by open fireplaces so were not damp


    +1

    and richer owners would hang "carpets" (tapisseries = tapestries...) on the walls!

    (and I doubt that they heated anything like as much WE tend to, these days...).

    gg
    • CommentAuthorjanzon
    • CommentTimeMar 4th 2019 edited
     
    Posted By: WillInAberdeenIs the plaster directly stuck onto the inside of the stone, or is there an air gap and then a lath-and-plaster wall lining? (Does it sound hollow when tapped)


    Doesn't sound hollow so my guess it that it is stuck on to the stone with an underlayer as described above by owlman.

    There some kind of metal strip to start the render off around doors, windows etc.
    • CommentAuthorrevor
    • CommentTimeMar 4th 2019
     
    We have renovated and added extension to a 1750's stone farmhouse. Previous owners had pebbled dashed the exterior sand cement and cement render interior with finish plaster coat. The house was damp and plaster cracked. When we hacked off the pebble dash we could see fine cracks in the surface and underneath, the wall was wet. Rain driven by the wind (we are also in a very exposed area) getting in through the cracks and then not able to escape. We built a wrap around extension around the old building with only gables ends ending outside. The external walls were battened out, levelled between with a lime render and EWI added followed by cedar cladding with an air gap between it and the insulation. Internally the stone was rendered with lime plaster and soon to be painted with a clay paint.

    One stone wall was left exposed as a feature but is within a glass conservatory and acts to store captured solar gain in the mass of the wall.

    The 2 chimneys are soon to be fitted with wood burners with direct air feed to them via ducts in the floor. We have aimed for a low leakage house so have MVHR so it replaces the natural ventilation it once had from the chimneys.

    The stone or rather the mortar between it has to breathe so you have to leave the stone exposed and point up with a lime mortar or EWI it, as we have done or lime mortar render.

    Unfortunately many builders/plasterers do not know how to deal with old stone buildings and those that do, can charge a good price for lime work. Our plastering took quite some time as coats had to "cure" before the next and in all involved 5 coats. The internal lime work cost in the region of £70 per sq M so compare that with conventional hard wall plastering and you can see why old buildings end up with inappropriate materials.
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