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    • CommentAuthorMHicks
    • CommentTimeNov 20th 2017
     
    I'm close to starting to fit my EWI (250mm EPS) to our solid wall new build. I'd like - and I think it is perfectly sensible to - run the EPS straight past the DPC into the trenches with no faffing about with starter track, drip details, 'basetherm' or suchlike. I've researched here and elsewhere and I'm pretty sure it's the way to go. BUT... Is my local BCO going to accept this? He's overworked and down here in Pembrokeshire we don't do no newfangled stuff, full-fill cavity is seen as pretty avant garde, I'm not sure he's even seen a solid wall/EWI newbuild before.

    Any tips on how I can persuade him my plan is ok?
    • CommentAuthorgyrogear
    • CommentTimeNov 21st 2017
     
    Well, you could tell him that that is how *mine* is done, LOL

    :bigsmile:

    gg
  1.  
    You could find another *Welsh* example where a BCO has approved it, and point him there.
    • CommentAuthorMikC
    • CommentTimeNov 21st 2017
     
    I'm interested to know how you get on, as I am intending to do the exact same thing. I'm in Carmarthenshire, but still at planning stage.
    • CommentAuthorDarylP
    • CommentTimeNov 21st 2017
     
    @MHicks,
    You are probably sensible, but you need to prove it! Is your BCO LA or AI?
    Breaching the DPC is a big no-no in their book, for obvious reasons.
    Can you give him/her some case-studies, or other evidence, to tick that box, and satisfy them?
    Being 'overworked' may benefit you....:devil:

    Good luck....:wink:
    •  
      CommentAuthorfostertom
    • CommentTimeNov 21st 2017 edited
     
    Fundamentally, two issues:

    1. EPS is non-wicking (doesn't 'soak' water upward) - unlike bricks etc which consequently need a dpc to intercept that.

    2. EPS doesn't mind being wet, even permanently saturated, in the ground - just like bricks etc. Its insulativeness doesn't even reduce all that much when saturated.

    Though of course it's better if not saturated (just damp is fine). Good way to ensure non saturation is to put a perforated french drain in the bottom of the trench incl backfilling the trench with clean sharp aggregate that water can readily drain down through, to the pipe. Ideally run the EWI right down to bottom of found level.

    There are recommendations to switch from EPS to closed-cell insulation such as XPS, below ground, in the belief that closed-cells don't absorb water, unlike EPS's largely open structure. Experience shows that closed cells do in fact slowly absorb water, then never dry out - unlike EPS which readily dries out.
    • CommentAuthorMarkyP
    • CommentTimeNov 21st 2017 edited
     
    have you had a chat about the EWI yet? Was your EWI detailing specified on your BC drawings submission? Might be a non-issue.

    when I looked into this I couldnt find any EWI system manufacturers who did a continuous EPS from footing to eaves. But I think this is just path of least resistance in a trade which is somewhat DPC obsessed. I think a lot of home owners will also have at least a little knowledge of DPCs, and would probably baulk at the idea of bridging it. All in there's probably little industry demand for the continuous EWI method, so no one has invested in a BBA approval for it. All the BBAs and detail drawings I saw showed seperation at DPC for the plinth layer, some also specified XPS and also various "waterproofing" methods. None of which seem necessary.

    we discussed this recently in another thread, in the very worst case, where BCO wont budge, you could run a plinth course of EWI level with DPC, run a plastic DPC along the top of the EPS, and then continue with above DPC layers and use a push in drip bead. You might even then get away with forgetting the push in drip and just rendering the whole lot.
    • CommentAuthorMHicks
    • CommentTimeNov 21st 2017 edited
     
    Posted By: ferdinand2000You could find another *Welsh* example where a BCO has approved it, and point him there.


    I've looked, but again there's nothing round here.

    Posted By: DarylP@MHicks,
    You are probably sensible, but you need to prove it! Is your BCO LA or AI?
    Breaching the DPC is a big no-no in their book, for obvious reasons.
    Can you give him/her some case-studies, or other evidence, to tick that box, and satisfy them?
    Being 'overworked' may benefit you....http:///newforum/extensions/Vanillacons/smilies/standard/devil.gif" alt=":devil:" title=":devil:" >

    Good luck....http:///newforum/extensions/Vanillacons/smilies/standard/wink.gif" alt=":wink:" title=":wink:" >


    He's local authority.

    Case studies - I haven't found anything official, just a wealth of (sound) opinion (see Tom below) which doesn't have much value as far as he is probably concerned.

    Posted By: fostertomFundamentally, two issues:

    1. EPS is non-wicking (doesn't 'soak' water upward) - unlike bricks etc which consequently need a dpc to intercept that.

    2. EPS doesn't mind being wet, even permanently saturated, in the ground - just like bricks etc. Its insulativeness doesn't even reduce all that much when saturated.

    Though of course it's better if not saturated (just damp is fine). Good way to ensure non saturation is to put a perforated french drain in the bottom of the trench incl backfilling the trench with clean sharp aggregate that water can readily drain down through, to the pipe. Ideally run the EWI right down to bottom of found level.

    There are recommendations to switch from EPS to closed-cell insulation such as XPS, below ground, in the belief that closed-cells don't absorb water, unlike EPS's largely open structure. Experience shows that closed cells do in fact slowly absorb water, then never dry out - unlike EPS which readily dries out.


    Yep, this seems to be the case Tom and what you've outlined is exactly what I plan to do. But I need to convince the guy that it's right.

    Posted By: MarkyPhave you had a chat about the EWI yet? Was your EWI detailing specified on your BC drawings submission? Might be a non-issue.

    when I looked into this I couldnt find any EWI system manufacturers who did a continuous EPS from footing to eaves. But I think this is just path of least resistance in a trade which is somewhat DPC obsessed. I think a lot of home owners will also have at least a little knowledge of DPCs, and would probably baulk at the idea of bridging it. All in there's probably little industry demand for the continuous EWI method, so no one has invested in a BBA approval for it. All the BBAs and detail drawings I saw showed seperation at DPC for the plinth layer, some also specified XPS and also various "waterproofing" methods. None of which seem necessary.

    we discussed this recently in another thread, in the very worst case, where BCO wont budge, you could run a plinth course of EWI level with DPC, run a plastic DPC along the top of the EPS, and then continue with above DPC layers and use a push in drip bead. You might even then get away with forgetting the push in drip and just rendering the whole lot.


    I briefly spoke with the BCO about EWI and the DPC a while ago and wasn't encouraged. He was extremely skeptical of using EPS ('poor r-value') and suggested that the DPM that was protruding through the solid wall be turned UP the wall 'at least a couple of inches', stuck to the wall and rendered over.

    The push in drip bead/dpc actually sounds like a good solution to this - giving the appearance of something traditional... I like it. Thanks!
    • CommentAuthorgravelld
    • CommentTimeNov 21st 2017
     
    Nice summary Tom.

    Have BRE never done any research on this?
    • CommentAuthorCWatters
    • CommentTimeNov 21st 2017 edited
     
    I briefly spoke with the BCO about EWI and the DPC a while ago and wasn't encouraged. He was extremely skeptical of using EPS ('poor r-value') and suggested that the DPM that was protruding through the solid wall be turned UP the wall 'at least a couple of inches', stuck to the wall and rendered over.


    Rendering over the DPC/DPM? Last time I looked at this you weren't meant to render over a DPC and render below a DPC had to be a special type of render.

    http://www.rend-right.co.uk/durability/

    http://www.rend-right.co.uk/wp-content/uploads/2011/08/Durability-6.gif
  2.  
    Posted By: MarkyPin the very worst case, where BCO wont budge, you could run a plinth course of EWI level with DPC, run a plastic DPC along the top of the EPS, and then continue with above DPC layers and use a push in drip bead. You might even then get away with forgetting the push in drip and just rendering the whole lot.

    +1

    Oh and I agree with what FT said above
    • CommentAuthorgoodevans
    • CommentTimeNov 22nd 2017
     
    I'm in the middle of this conversation with my proposed BCO at the moment (whether he is selected as the actual BCO depends on the answers to several questions I have given him :bigsmile: ). My suggestion is a small 75mm downturn of the DPM/DPC as it comes out of the blockwork (the top of which is 150mm above ground) - his first suggestion is a 1m upturn just to make sure no moisture gets past travelling up the wall. My concern is ensuring that any water that has got into the structure can pass safely down past the DPC so we will not be agreeing on the "1m high swimming pool lining". I'll let you know if he buckles (so far he's done quite well on the other questions so I'm hopeful).
    • CommentAuthorDarylP
    • CommentTimeNov 22nd 2017
     
    LA BCOs are not the 'enemy', but paid to help and advise where possible, whilst ensuring the buildings meet the Building Regs.
    Agreed some do take a rigid approach, but most are sensible.... :bigsmile:
    • CommentAuthortony
    • CommentTimeNov 22nd 2017
     
    Goodevans, it would be insane to have any upturn and I fully agree with you
    • CommentAuthorgoodevans
    • CommentTimeNov 23rd 2017
     
    Yes Daryl - I think that's true - and as I've not done this before I'm hoping they will stop me doing anything stupid. So far the proposed bco has past all the tests - this one may be just a little beyond his comfort zone.
    • CommentAuthorDarylP
    • CommentTimeNov 23rd 2017
     
    ... then give him a 'crutch' to help him into his 'comfort zone'...? :bigsmile:
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