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"All walls must be cavity walls" - true or false?

Discussion in 'Building Regulations and Planning Permission' started by d000hg, 10 Oct 2019.

  1. d000hg

    d000hg

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    We've been speaking to several BC and energy assessment people around a large heated log cabin I've mentioned previously is going in our garden.
    I'm trying to get a grip on what the big issues will be and in broad strokes how we might address them and want to get someone on board who is sympathetic to the design and works with it rather than just following the same approach they always use on more traditional designs.

    The solid 70mm wooden walls come up quite often, in regard to part L (insulation etc) and also part C (moisture). One guy told me that basically, any new wall MUST have a cavity regardless of other considerations. He seemed to be saying we'd have to put a damp liner on the walls, then an air gap, then an insulated layer inside a stud wall, which all seemed a bit overkill.

    Do the regs put explicit rules on HOW you do things, or only what the end result is? In this case, is a cavity required explicitly, or is it just a typical way to meet certain requirements?
     
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  3. Notch7

    Notch7

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    I realise you may not want to hear this but solid interlocked log cabin construction is not very suitable for the UKs damp climate.
    The interlocking traps water which is the cause of long term damp and rotting.

    The best timber frame construction method is to:

    build a studwork frame
    clad it with sheathing board
    cover with membrane which makes it weathertight
    Fix 50 x 25 vertical battens at say 600mm centres
    Fit cladding.

    Once the breatheable membrane is on, the structure is waterproof and windproof.
    The battens create a cavity
    The cladding is the visual external finish. It doesnt matter if it leaks, the water runs out of the cavity. The cavity allows airflow so helps the cladding to dry out.

    For more info go to the tyvek housewrap site -it provides downloads with construction details.
     
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  4. d000hg

    d000hg

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    Thanks, but this is already on order (deposit paid, expected in a few weeks) based on approved planning permission so we're stuck with it :)

    Log cabins are very popular in the UK right now (typically as garden rooms and the like) and the company we use offers a 10 year guarantee which implies they are fairly confident. Though I suppose it depends what lifespan you are expecting - 10 years, 50, 100+. People probably don't build these things thinking whether it will still be there after they die, unlike a house. I think we'd be happy viewing it as a 20 year 'disposable' structure. And I suppose treating the wood is crucial as well.

    If we were doing this all again I might be tempted to go with your route above but it's academic now. Not to say it's not interesting, though. It'd be very interesting to do a cost breakdown of both because that was a key factor in going log rather than brick - your option sounds like it might come out comparable to a cabin actually.
     
  5. mrrusty

    mrrusty

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    We have been visiting log cabins at fisherground farm in Lakes http://www.fisherground.co.uk/ for 25+ years and the cabins are just as good as the day they were put up. Interlocked logs although I think more like 100mm thick. We were there when they were built. You do of course need to make sure the interlocks are the correct way round...

    They are totally dry and also surprisingly easy to heat and keep warm. I guess they don't meet BR for permanent occupation, but for sure they are good enough.
     
  6. d000hg

    d000hg

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    I assume solid wood, and the interior of the main walls are not clad or anything?

    I wonder how they got away with that; surely such buildings aren't exempt for BR? Oh unless they escape under the 50m2 rule
     
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  8. ^woody^

    ^woody^

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    False
     
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  9. tony1851

    tony1851

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    Today's minimalist post...^
     
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  10. ^woody^

    ^woody^

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    Au contraire, earlier ....

    Im on a roll.
     
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  11. d000hg

    d000hg

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    I don't mind brevity
     
  12. d000hg

    d000hg

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    Just not very good at it
     
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  13. DIYnot Local

    DIYnot Local

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