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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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  1.  
    Our building control has asked us to raise our timber frame. Ideally we need a block that is close to 150 mm thick and around 300 mm high. H + H Celcon blocks have been recommended to us, but I can't see that the dimensions will work. Does anybody have any other ideas for similar blocks?
    • CommentAuthortony
    • CommentTimeJun 26th 2016
     
    Six inch laid fat they are 140mm + 10mm mortar, cut the ends off to 300 and buid in all off cuts
  2.  
    Sorry Tony, I don't completely follow. I was hoping for a large block that wouldn't require cutting. The 150 mm width is pretty crucial, but the 300 height could be slightly larger. And obviously the longer the better.
  3.  
    I don't know if thermal properties are important but what would probably happen over here is some shuttering of the dimensions you need and pour concrete, with a bit of rebar thrown in to make the builder feel structurally sound !! (otherwise could be called a ring beam)
  4.  
    Thanks @Peter! Yes, the thermal properties are important. I'm planning on putting a foamglas block at the bottom to make up 100 mm, then cement blocks on top to make up the next 300mm. I'll post a picture a bit later.
  5.  
    Here's a picture of what I was thinking.
      20160626 Plinth Detail.png
    • CommentAuthortony
    • CommentTimeJun 27th 2016
     
    Can't see the writing :(
  6.  
    Sorry, that's the transparent background. Hang on, I'll repost.
  7.  
    This should work...
      20160626 Plinth Detail.jpg
    • CommentAuthortony
    • CommentTimeJun 27th 2016
     
    I am presuming red is dpm and blue vb?

    I would prefer a combined vb/dpm on top of the floor insulation and running through the 7 N blocks, can't see why 7 N is needed ask engineer if 3.5 would be acceptable, foamglass in line with top of or all floor insulation, dpm stepped up inside of vertical insulation and out through it at g/l + 150mm

    I bet someone will want a dpm under the sole plate too.
  8.  
    Thanks Tony! The red is the DPM and the blue is the metal strapping to attach it to the concrete slab.

    The DPM is at the bottom as the insulation will be cork with a lime screed on top.

    We'll struggle to get the foamglas and insulation the same height as the cork is 200mm and the foamglas only 100mm.

    What's the benefit of having the DMP inside rather than outside the vertical insulation?
    • CommentAuthortony
    • CommentTimeJun 27th 2016
     
    That will hopefully prevent condensation causing it to sweat on the cold side.

    I would concrete the straps I and have them on the outside.

    I don't like hemp create supported on cork much.
    • CommentAuthorFred56
    • CommentTimeJun 27th 2016
     
    The 7N is a requirement of the timber frame standards as is the minimum height if the timber above ground level. I have done this and used 7N aircrete blocks, the ones that are extra long, 215 high and 140 mm wide (Thomas Armstrong Airtec7). A word if warning given to me by the block manufacturer's technical department was that their aircrete blocks do not fulfill compressive strength when laid flat or if cut. Building control, the timber frame supplier and the certifying structural engineer accepted the design.
    I reckon your external ground is too high relative to the internal finished floor level though.
    •  
      CommentAuthordjh
    • CommentTimeJun 27th 2016
     
    Is the hempcrete one solid lump filling the timber frame and extending both inside and outside of it? If so, I don't suppose I'd worry about the loading on the cork, though it would be worth checking.

    I'd be worried about hygroscopic materials and open space below ground level (expect the DPM to be holed at some time). I very much hope the drawing is oversimplified and isn't showing the French drain that will be there in practice? I'd also be the one that is keen to see a DPC under the sole plate and hempcrete too and I'd use a treated soleplate but then I'm an ignoramus.
  9.  
    Thanks @Tony - how do you mean 'concrete the straps'?

    @Tony & djh, yes, the hempcrete will be supported through the wall, so there should be very little weight on the cork.

    @Fred56 - yes, the external ground is high due to working with a height restriction. It is lower on other sides due to the site sloping somewhat.

    @djh - there is a large roof overhang and there will be an external drain.
    • CommentAuthortony
    • CommentTimeJun 27th 2016
     
    Concrete the straps into the slab whilst laying it.
  10.  
    @Fred56: the Thomas Armstrong Airtec 7 blocks look ideal. Problem is, they seem as rare as hen's teeth. They only seem to be supplying them to existing clients. Any idea where to get hold of them, if at all?
    • CommentAuthorFred56
    • CommentTimeJun 28th 2016
     
    I used to live in North Yorkshire and the factory was at Brompton on Swale near Richmond. They are a common brand in the local area and I bought from Yorkshire Independent at Leeming Bar. It's taken a while but I have found the invoice, price in Dec2011 was £1.74 plus vat each but you have to buy in full packs of 40. Full packs seems to be the only way to get them. The 100mm for internal walls were cheaper. They are both 620mm long. Armstrong seem OK, have used a lot of their lightweight aggregate blocks too, no problems to report.

    I live in Cornwall now so not in a position to locate them easily.
  11.  
    Thanks Fred! That was very kind of you to look up the invoice. I've struggled to get them down here. I'll see if I can follow up your previous suppliers.
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