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Green Building Bible, Fourth Edition
Green Building Bible, fourth edition (both books)
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    • CommentAuthorgravelld
    • CommentTimeFeb 24th 2018 edited
     
    Hi my name's gravelld and I'm a retrofitaholic. You might remember me from such threads as "Retrofit lean-to ridge detail, warm roof to EWI" and "Plinth detail - cavity wall" but this time I'm really ratcheting up the excitement to discuss door installations.

    The current house:
    - 1950s cavity wall
    - Rendered

    Highlights of this design
    - AT layer to be existing external render (plus possibly blowerproof/AT paint - depends on the quote!)
    - Door frame attached at head and sides by brackets, like with windows
    - Door threshold sits on Compacfoam

    This design is prior to confirming the manufacturers, so door width etc will have to be adapted.

    Hopefully this is obvious but the gap in the middle is where the door would be!

    Questions
    - Comments on the general ideas in the attached detail?
    - Can the same detail be used for doors or arbitrary size? I'm also installing a 4.5m slider which will be HEAVY
    - Is there a cheaper but almost as performant alternative to Compacfoam?
    - How should the external sill be attached so it can, er, be stood on?

    In case this isn't obvious I don't know what I'm talking about, so feel free to explain some basics.

    Refs/inspiration:
    - https://www.greenbuildingstore.co.uk/products/compacfoam-200/
    - https://retrofit.support/detail/88/ (sign up required to see full detail, https://retrofit.support/detail/version/613/image-file/ for closeup without labels)
      door.JPG
  1.  
    I have some Marmox Thermoblocks (http://www.marmox.co.uk/products/thermoblock). If I remember correctly from researching some years ago they are not as good as Compacfoam, but they mitigate the bridging somewhat. They are basically 2 thick layers of (?) GRP held aparat with pillars, and foam in-between. Imagine an ice-cream wafer where the wafers are GRP and the ice-cream is insulating foam with small load-bearing pillars! Whisper me if you want some. I thing they are about 70 tall, 100 wide and 450 long - ish.

    ''- How should the external sill be attached so it can, er, be stood on?''

    Depends - on a job I was working on, and where this detail is still t.b.c, there will be a French drain outboard of the cill projection. Our EWI sits lower at this point, and the alu cill will simply sit, 'flapping', as you have drawn it. There is a 'step' at the base of the Compacfoam, with a protruding brick layer. The cill and a bridging stone slab will sit on this 'ledge' and bridge the French drain, the cill in a waterproofing capacity and the slab in a load-bearing one. And I can't do computer drawings!
    •  
      CommentAuthordjh
    • CommentTimeFeb 24th 2018
     
    Posted By: gravelldCan the same detail be used for doors or arbitrary size? I'm also installing a 4.5m slider which will be HEAVY

    No, normal, side-opening doors are supported from the sides, primarily the hinge side of the frame. Sliding doors are supported from underneath by what must be an absolutely flat and level surface.

    How should the external sill be attached so it can, er, be stood on?

    The external sill is either attached to the front of the frame or built separately in front of it. It should be level with the door threshold to give any chance of making a level access either now or in the future. So the Compacfoam (or whatever) can run under the entire width of the frame.

    It's not clear how your airtightness layer connects to the door, especially around the brackets, nor how it can be built (i.e. sequencing).
    • CommentAuthorgravelld
    • CommentTimeFeb 25th 2018 edited
     
    Posted By: djh
    Posted By: gravelldCan the same detail be used for doors or arbitrary size? I'm also installing a 4.5m slider which will be HEAVY

    No, normal, side-opening doors are supported from the sides, primarily the hinge side of the frame. Sliding doors are supported from underneath by what must be an absolutely flat and level surface.

    Does that mean Compacfoam isn't even required for an "ordinary" side opening door?

    And does it mean the above detail is appropriate for a slider and not for a side-opener?

    I think the answer to both of those are no, because my references (which I forgot to post again [now added]) both use Compacfoam for side opening doors.

    Posted By: djh
    How should the external sill be attached so it can, er, be stood on?

    The external sill is either attached to the front of the frame or built separately in front of it. It should be level with the door threshold to give any chance of making a level access either now or in the future. So the Compacfoam (or whatever) can run under the entire width of the frame.

    Do you mean the width of the frame face-on, so the jambs sit on the Compacfoam? Above I'm only showing the threshold seal so there's no frame to touch the Compacfoam.

    Posted By: djhIt's not clear how your airtightness layer connects to the door, especially around the brackets, nor how it can be built (i.e. sequencing).
    At the bottom, tape from the parge coat on the plinth up and over the Compacfoam on the inside/upwards faces, then continuing underneath the threadshold seal assembly (whatever that is, manufacturer to be confirmed). Again, see reference above for what I (tried to) copied.

    At the top/sides, tape from frame onto parge coat, also extra tape on the brackets to avoid air ingress around fixings etc.
    • CommentAuthorgravelld
    • CommentTimeFeb 25th 2018
     
    Posted By: Nick ParsonsI have some Marmox Thermoblocks (http://www.marmox.co.uk/products/thermoblock" rel="nofollow" >http://www.marmox.co.uk/products/thermoblock). If I remember correctly from researching some years ago they are not as good as Compacfoam, but they mitigate the bridging somewhat. They are basically 2 thick layers of (?) GRP held aparat with pillars, and foam in-between. Imagine an ice-cream wafer where the wafers are GRP and the ice-cream is insulating foam with small load-bearing pillars! Whisper me if you want some. I thing they are about 70 tall, 100 wide and 450 long - ish.

    ''- How should the external sill be attached so it can, er, be stood on?''

    Depends - on a job I was working on, and where this detail is still t.b.c, there will be a French drain outboard of the cill projection. Our EWI sits lower at this point, and the alu cill will simply sit, 'flapping', as you have drawn it. There is a 'step' at the base of the Compacfoam, with a protruding brick layer. The cill and a bridging stone slab will sit on this 'ledge' and bridge the French drain, the cill in a waterproofing capacity and the slab in a load-bearing one. And I can't do computer drawings!
    Thanks Nick, will look at those, if they are required.

    If your detail is shareable would be great to share it! Not 100% understanding the protruding brick layer.

    Will be a french drain here too.
  2.  
    ''If your detail is shareable would be great to share it! Not 100% understanding the protruding brick layer.''

    Sorry, the detail is not drawn.

    The 'protruding brick layer' is simply that the door casing sits about 40-50mm back from the external face of the brickwork. On top of the brickwork (set back that 40-50mm) is 75mm Compacfoam to take the weight of the sliding door. The cill and the 'bridge step' will sit on that 40-50mm lip.

    To clarify, when I said ''I have some Marmox Thermoblocks'' I meant I have some spare, kindly donated by a former client and available free or for a charity donation if you collect.
    •  
      CommentAuthordjh
    • CommentTimeFeb 25th 2018
     
    Posted By: gravelldDoes that mean Compacfoam isn't even required for an "ordinary" side opening door?

    I have some EPS 70 offcuts under mine. But it may depend on the particular doorset.

    Your detail is appropriate for nothing, IMHO.

    Do you mean the width of the frame face-on, so the jambs sit on the Compacfoam?

    No, from inside to outside.

    At the bottom, tape from the parge coat on the plinth up and over the Compacfoam on the inside/upwards faces, then continuing underneath the threadshold seal assembly (whatever that is, manufacturer to be confirmed). Again, see reference above for what I (tried to) copied.

    How do you construct that?
    • CommentAuthorgravelld
    • CommentTimeFeb 26th 2018
     
    Ok, looks like I need to start over then. Let's just say this is for side opening doors, as it sounds like you are saying there is no one-size-fits-all.

    So there's no need for Compacfoam and I can just mount an "ordinary" side hung door in the EWI layer, using angled brackets like for windows?

    Regarding the AT detail I added a link to the OP - https://www.greenbuildingstore.co.uk/wp-content/uploads/Compacfoam-FINAL-airtightness-detail-1024x1024.jpg
    •  
      CommentAuthordjh
    • CommentTimeFeb 26th 2018
     
    Posted By: gravelldSo there's no need for Compacfoam and I can just mount an "ordinary" side hung door in the EWI layer, using angled brackets like for windows?

    Posted By: djhit may depend on the particular doorset.


    Posted By: gravelldRegarding the AT detail I added a link to the OP

    That makes it clearer, thanks. That doorset has an aluminium threshold, whilst mine is timber. I can't tell from the photo how that threshold is thermally broken. Do you know what type of door it is? It doesn't match the detail shown for Progression doors at https://www.greenbuildingstore.co.uk/wp-content/uploads/Progression-Door-Details.pdf Apart from anything else they have timber under the threshold.
    Posted By: djhit may depend on the particular doorset.
    • CommentAuthorgravelld
    • CommentTimeFeb 28th 2018
     
    So it sounds like the threshold detail is much more dependent on the chosen product than, say, a window, am I interpreting that correctly?

    If so, something I need to revisit later. I realise I have to do this with *all* of the details I am documenting, but I'm just trying to get "the general idea". Maybe this is a waste of time and I have to commit to products?

    I don't know which actual door it was... I thought it was the Performance range but I might be getting mixed up.
    •  
      CommentAuthordjh
    • CommentTimeFeb 28th 2018
     
    Ha! The PDF details page is not found, so no banana yet. This is very typical of the difficulties when trying to get the actual details of whatever you actually purchase.
    • CommentAuthorgravelld
    • CommentTimeFeb 28th 2018
     
    Sorry - are you referring to a PDF details page for the Performance range?

    If so, it's unlikely I will be using a GBS joinery product tbh, so might be a little irrelevant. Really sorry if it's wasting your time. As above, I thought I could derive a general idea of what the detail should look like and merely refine it when I decide on the product.

    But it sounds like this is only feasible for certain designs and certain areas of a house, and for door thresholds which vary a lot is not really practical?

    If that's the case, are there general rules I can internalise for the rest of the detail, to "bolt onto" the threshold detail later?

    Specifically, can the frame for a side opening door be attached with brackets like with windows?
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