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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.

PLEASE NOTE: A download link for Volume 1 will be sent to you by email and Volume 2 will be sent to you by post as a book.

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    • CommentAuthorRex
    • CommentTimeSep 6th 2019
     
    What ho one and all,

    When we bought the bungalow X years ago and before demolition, there was a detached garage, one side of which (double brick wall) was on the boundary. We did not demolish this wall. Beyond what was the rear of the garage, the previous owners had extended the wall about 15 feet.

    The top of the double brick wall was 'sealed' with a brick capping and to keep SWMBO happy, the wall was painted with a 'water resistant' compound and painted with masonry grey.

    After ten years, the brick that was the inside of the garage is flaking everywhere, as is the cement. But not every brick and not all the cement!

    I don't know when it was originally built, but is there such a thing as interior bricks that are 'softer' than external bricks?

    Is there a solution to prevent (reduce?) the flaking? And 'no', I am not going to replace the wall.

    Toodle pip and thanks

    Rex
    •  
      CommentAuthorfostertom
    • CommentTimeSep 6th 2019 edited
     
    Flaking (spalling) is due to some internal expansion forcing bits of the surface off. Two poss causes:

    a) Crystalisation of salts within the wall, mainly brought there by minerals dissolved in rising damp. As the damp dries out periodically, the water evaporates, leaving its mineral content as crystals, which are bulkier than their dissolved form. The expansion splits the masonry apart and flakes spall off.
    Another source of the minerals is in either the sand that the mortar was made of, typically unwashed sea sand, or in dirty mix water. This seems to be an endless supply of minerals, semi-dissolved in rising damp or rain-wetting, which brings the minerals close to the evaporating surface, crystalising there, as above.
    Freqently visible a crystaline fuzz growing on the wall face - called efflorescence.
    None of this will happen in a wall that's rarely full of water.

    b) Freezing. Again won't happen in a dry wall. Water in the wall freezes; ice is bulkier than liquid water so the same spalling can occur.

    Mechanically strong masonry can resist the expansion but may grow the efflorescent crystaline fuzz.

    One way or another, your wall is holding water content.
    • CommentAuthortony
    • CommentTimeSep 6th 2019
     
    Easy fix is to build a fence against it or climbing plant(s)
  1.  
    When the top was 'sealed' did that include a DPC?

    Seems likely to me that it's getting damp but then unable to dry out having been painted.
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