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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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    • CommentAuthorgravelld
    • CommentTimeNov 9th 2017 edited
    I received the attached detail from an EWI system provider.

    Is it normal to have a gap like this between above and below DPC insulation? Seems wrong to me.

    The explanation they have given is:

    The gap here is to allow for the expansion of the different insulation types & renders, the maximum depth is approx. 3mm

    I've not seen this mentioned before so I was wondering if this was best practice?

    3 - Insulation board
    7 - Silicone render
    8 - Base profile
    9 - "Anticipated line of DPC" (shouldn't that be a DPM if it's just a line?)
    10 - XPS
    11 - Polymer plain render
    13 - Sealing tape and low modulus silicone (can't see that lasting long)
    I've not seen this before either - but if you are using their "system" and you want any guarantee they may offer then if you don't put the gap in then that will be their get out of jail free card!!
    Of course if you don't use a different type of insulation and render above and below DPC (and why would you?) then presumably there would be no need for a gap.

    A question - Is an EWI system just a fancy name for industry standard products batched together and sold at an inflated price? :devil::devil:
    • CommentTimeNov 9th 2017
    What is (9)?

    And (13) and for that matter everything else?
    13 is Compriband (expanding tape - other trade names exist).

    9 is almost certainly dpc level.
    • CommentAuthorMarkyP
    • CommentTimeNov 10th 2017 edited
    not planning on using this detail on my plinth.

    you state that the manufacturer says "The gap here is to allow for the expansion of the different insulation types & renders"

    I'm guessing they are proposing XPS below DPC? Maybe other waterproofing measures and renders? Having followed the discussions on here on plinth EWI, I'm convinced it's not necessary to "waterproof" your below DPC plinth, quite the opposite actually. I intend to use EPS below DPC, the same render basecoat as used above DPC though perhaps applied a tad thicker. As you've seen on my EWI thread I'm not using a 100% system method, no warranty, lots of DIY. So I'm not constrained to follow manufacturer's detail below DPC.

    had I more time, I would have a carried a single thickness of EPS from footing to eaves, no DPC, no seperation. I just didnt have time to excavate so decided on a base track to get the main walls done this year, plinth will be retrofitted next.
    • CommentAuthorgravelld
    • CommentTimeNov 10th 2017
    Yes, I assumed it must be because XPS is used.

    They also talk about using a different render. For above ground, silicone. For below ground a "polymer plain render".

    I'll put some words to the numbers.

    BTW Marky, this particular firm has also said they find PVC starter rails aren't robust enough... thoughts?
    • CommentAuthorgravelld
    • CommentTimeNov 10th 2017
    Nick, not sure what they mean by "sealing tape" (tape covers a multitude of things!) but hopefully it's something like compriband...
    • CommentAuthorMarkyP
    • CommentTimeNov 10th 2017
    Posted By: gravelld

    BTW Marky, this particular firm has also said they find PVC starter rails aren't robust enough... thoughts?

    mine hasnt broken yet! I could maybe see alu being preferred by a gang of crash, bang, whollop installers but havent had cause to regret using PVC as yet. Now the adhesive has set the base isnt really doing much.
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