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Green Building Bible, Fourth Edition
Green Building Bible, fourth edition (both books)
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    • CommentAuthortony
    • CommentTimeAug 18th 2019
    Re 0.1 for walls, I like 0.1 or less and diminishing returns depend on over what period the finances are calculated. Any decent life of the building makes a nonsense of diminishing returns and as soon as you look at costs of retrofitting you start crying.

    Many of the homes that are being built now will have to be further insulated before 2050 at huge cost.
    • CommentAuthorTullich
    • CommentTimeAug 18th 2019
    I'm 36 and this will be the last house I ever live in. I've designed it so it can be extened in two directions to increase the size of the living area and add a bedroom and bathroom easily. Infact, it was designed to be larger, and then trimmed back to what i'm actually building now.

    I have to get the materials right now for where building efficiency will be in 20 years time, so maybe 0.1 Uvalue walls from the get go aren't a bad idea....
    • CommentAuthortony
    • CommentTimeAug 18th 2019
    • CommentTimeAug 18th 2019 edited
    Posted By: TullichDoes anyone think it would be worthwhile splitting this into two threads, one for floor construction and one for wall construction?

    I doubt it at this stage. With hindsight, it might have been better to start two separate threads originally, but I think most people on here read most threads and will join in if they have anything to contribute.

    I'd suggest that the next thing to do as regards the floor is to contact a few engineers that specialise in passive slabs and see what they have to say about what's practical and what the likely costs are.

    Probably similar for the walls, but you've more chance of getting a supplier to provide the condensation calcs etc as part of their supply, or their bid for supply.
    • CommentAuthorTullich
    • CommentTimeAug 18th 2019
    Thanks djh. I'm not really much of a forum user, so i'm never quite sure what the form is.

    On the list to contact re slab design are TSD and Monson. Any recommendations for other SE's specialising in this area appreciated.

    • CommentAuthorGreenPaddy
    • CommentTimeAug 19th 2019
    I'm probably not understanding your design approach, but as regards structural engineers, I think I saw you mention that you have a SE on board already? I'm guessing he's from the timber frame company, as you mentioned the need to get another SE to cover the entire build (foundations AND frame), which would be correct in that case.

    If you get a specialist SE who does fully insulated rafts, you'll need to be sure he also will cover (or do an SER for) the whole building, or you'll need a 3rd SE...costly, and very confusing as to who has what responsibility.

    If you're still unsure about ground bearing/solid slab versus suspended, one thing that might help make up you mind is (as has been mentioned a few times) the fact that the finished floor level will be much higher for a suspended floor as opposed to a ground bearing...like 300mm higher, assuming you don't want the solem to be below external ground level. Can you adjust scaping to allow for that? Probably need a planning amendment at some point to cover that.

    Also, building over the winter (as your timing suggests - design, warrant approval, start maybe Nov if lucky), likely the suspended timber floor will go in as the first stage, prior to the frame...keeping the floor joists and it's insulation dry for a couple of months would be challenging.

    Ok, so that's not very helpful in terms of moving you forward!!

    So here's my tuppence worth, as someone who designs and builds low energy houses in the Highlands...keeping it simple in terms of who you can get to do the work, and supply materials, rather than just looking simple on a piece of paper...

    - strip foundation, prob 600 wide, 200 deep, at a depth of around 600mm below grade, steel mesh on bottom.
    - blockwork underbuild (could be 100mm if not doing 140mm frame)
    - 150mm compacted type 1 solem
    - DPM over sand (are you in a radon gas area - check)
    - 300mm EPS70 with 50mm kingspan vertically against the inside of the block underbuild
    - second DPM over the EPS, mainly to stop the water from the concrete running through the EPS gaps
    - steel mesh set on stools with 80mm top cover
    - cable tie your UFH pipes to the mesh (if you want UFH)
    - 125/150mm C35 concrete
    - timber frame (can be 100mm don't need 140mm structurally)
    - walls; plasterboard/25x50 battens/VCL/rockwool/OSB/125 PIR/battens/cladding
    - add 100mm EPS on ext face of block underbuild and render it (use your offcuts from slab)
    - roof; plasterbaord/25x50 battens/VCL/300mm JJI/full fill with wool32/22x150 sarking boards/highly breathable membrane

    Lots of ways to skin a cat (sorry PETA supports), but the above will be understandable by any SE, most contractors, BSO's, gives Uval 0.1 or very near, no condensation, no cold bridging so very low psi values for your SAP calcs, and something you have half a chance of getting started this year.
    • CommentAuthorTullich
    • CommentTimeAug 19th 2019
    The design approach is a bit haphazard.

    I designed the house and an architect digitised my drawings and submintted my planning application. PP's been granted and I've contracted a SE to do the whole building SER, who's worked with my architect before. There's no TF supply co. The frame will be site cut and erected by me and some friends in the trade. I'm looking for a SE to design the slab only, info to go to my SE as above. Ground works will be completed by a local contractor (my neighbour). There will be very little in the way of bought in labour. I'll be taking a mini sabatical to break the back of the build and get it to wind and watertight. Then i'll get back to my day job and can work inside in the dry. So not exactly a standard approach then!

    Your sections sound excellent and are definitely buildable. I'm pretty well set on wall and roof designs at this point. A minor ammendment needed to PP for a change in dimensions if changing from EPS to PIR for the EWI as discussed earlier in the thread. Just the slab or suspended floor to figure. I'm going to get on the phone now and see if there's any interest on the SE side, which will probably decide which route I follow. Your make up above is v. Interesting and i'm grateful for the info given you're in the trade and workimg in the area.

    I'm led to believe my building warrant won't take long to come back as it should be a rubber stamp and pass job. November is too late to start....

    Apologies for the brief reply - back at the office again today!

    Thanks again. Keep you posted.
    • CommentTimeAug 19th 2019
    Posted By: GreenPaddyIf you get a specialist SE who does fully insulated rafts, you'll need to be sure he also will cover (or do an SER for) the whole building, or you'll need a 3rd SE...costly, and very confusing as to who has what responsibility.

    Could you explain that a bit more, please? I had one engineer for the foundations (Hilliard Tanner) and one for the wall structure (Paul Rose). Neither of them took responsibility for the other's work AFAIK and that didn't seem to cause any problems. FWIW, supplier's SE was responsible for the metal-web joist 1st floor and yet another SE was responsible for the curved timber frame roof.
    • CommentAuthorGreenPaddy
    • CommentTimeAug 19th 2019
    djh - If using an SER, then that struct engr checks all the calcs, loadings etc, so it's bound as one design. It may be different in England, but sounds like Tullich has understood this, given his comments above explaining his use of SE's.
    • CommentAuthorTullich
    • CommentTimeAug 19th 2019
    Hi Both,

    I have a very red face this morning....

    I'd never actually discussed the raft/slab idea with my SE, assuming (incorrectly) that it would need seperate specialist input. Turns out he's done dozens of them and, what's more, he's confident he can engineer a diyable solution that doesn't use proprietary forms for the edges. It's looking likely that we'll have a bespoke solution shortly using standard sheet EPS and some clever shuttering.

    I'm incredibly excited. Updates to follow.
    • CommentAuthortony
    • CommentTimeAug 19th 2019
    Love it 👍
    • CommentTimeAug 19th 2019 edited
    Posted By: GreenPaddydjh - If using an SER, then that struct engr checks all the calcs, loadings etc, so it's bound as one design. It may be different in England

    I don't even know what an SER is, and a search finds 'SER Scotland', so yes I guess it is different in England. For that matter, Wikipedia doesn't know what it is either, so it seems to be a closely guarded secret.

    Seems like good idea at first glance though.

    Ah, there's an explanation at http://www.aed.consulting/design-certification-ser-certificate/

    edit: Tullich, that's very good news. Hope you make rapid progress now.
    • CommentTimeAug 22nd 2019 edited
    Posted By: Tullichi've decided after a lot of reading and head scratching to go with the REMOTE wall model as discussed here previously
    Very good choice. I missed your original mention of 19 April
    Posted By: Tullichthe REMOTE wall concept, and the excellent video series produced by the Cold Climate Housing Research Centre
    Wasn't aware of CCHRC - excellent - thanks.

    I found the REMOTE video, no time to watch it all, but curious to know why my own favourite method has the name REMOTE!? Can you enlighten me?
    • CommentAuthorTullich
    • CommentTimeAug 22nd 2019
    Outside insulation

    Slightly tenuous, but good to give a build type a name I think! The video series whilst looking a bit dated is excellent for the self builder. Take a look at CCHRC's "Integrated Truss Frame" (roof truss manufacturers in this country take note of the potential to expand into this area!) and the adjustable piles/steel ringbeam they use in lieu of conventional founds on the Tundra. Excellent stuff.

    In a similar vein there's also the PERSIST wall:


    Oh, along with Matt Risingers "Perfect Wall" as seen on YouTube.
    • CommentAuthorTullich
    • CommentTimeAug 22nd 2019
    I'm now busy trying to wrestle a D score on our SAP calc into something more respectable....
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