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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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    Looking for a contractor to remove damp cavity wall insulation on a property in South Wales that has been retrofitted with EWI?
    • CommentAuthortony
    • CommentTime5 days ago
    It will dry out now , may take a while and empty cavities will negate the EWI if they are draughty, that would be normal too.
    The water soaked the cavity following a roof leak and destroyed all the internal dot and dab plaster.

    We want to put the plaster back on but need to either dry the CWI and give a certificate or remove it..

    I'm not putting a warranty on it as it should have been removed when they did the EWI?
    Hi VE, can you clarify? Are you saying that EWI was done when it was known that there was *wet* CWI in the cavity? If this is the case then that was arguably ill-advised although, as Tony points out, the CWI should ultimately dry out (although the speed and consistency of the drying-out will depend on the detailing and completeness of the EWI). If, for example, 'industry standard capping details' have left a cold strip along the top of the bedroom walls at the eaves, the top of the wall may take much longer to dry out.

    This brings us to a difficult issue re EWI on cavity walls. You'll find much discussion here and in other places about thermal by-pass 'leaving EWI out in the cold', and the attempts needed to ensure that this does not happen. Closing the cavities and, of course, closing the original cavity vents are obvious ones, but some leakage will remain. So... *although insulation is very rarely a draught-stopper* a lot of us suggest that CWI will go a small way towards reducing air movement - and thus thermal by-pass - in the cavity.

    So, if your CWI is absolutely *wet through* it probably does need to be taken out *but replaced by (graphite) EPS bonded beads*. I would not recommend leaving the cavity un-filled.

    As far as CWI removal it is a lot of years since I last tried to find a CWI removal contractor. At the time, from the replies I received, it became clear to me that none of the firms I contacted had a 'cavity hoover'. The installation job had maybe taken half a day off ladders, and the guesstimate for the removal job - removing individual bricks and 'poking it out with a stick' was over a week on scaffolding - a very different and much more costly proposition. Things may have changed now - there may be some sort of suction method, but never having seen it tried I wonder how easily soaking-wet agglomerated 'ex-fluff' would suck up a tube.
    No the EWI must have been fitted previously but not known if any issues.

    The policy holder (insurance work) advised they had a roof leak that saturated the cavity. It's the last house on a run of 5 and takes all of the water and is felt roof

    We were tasked with redoing the internal plaster and decorations but advised to do so either the cavity needs to be dried (I'm not warrantying the drying as I don't think it should have been left in) or it gets extracted.... then we can do the repair works
    • CommentAuthorjms452
    • CommentTime4 days ago
    If it is insurance work you may be restricted but If it was my house I'd be focusing on a lasting solution for the roof.

    When you remove the cavity wall insulation (fibreglass?) the walls will still take a fair while to dry (weeks to months?).

    What is the EWI made of - phenolic won't like getting saturated.

    Posted By: Nick ParsonsSo, if your CWI is absolutely *wet through* it probably does need to be taken out *but replaced by (graphite) EPS bonded beads*. I would not recommend leaving the cavity un-filled.

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