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Making an Extra Thick Insulated Garden Shed Wall With Lots of Overhang?

Discussion in 'Home and Garden' started by SquirrelMadness, 14 Sep 2019.

  1. SquirrelMadness


    Joined: 30 Aug 2014

    Posts: 464

    Hi. I initially designed the wall to be double 12mm ply/OSB on the exterior totaling 24mm but now found out that timber is a thermal "weak spot" in terms of insulation so figured it would be better to add exterior insulation to the building wedged between the ply/OSB?

    Here's what I got:



    So the timber is build on a single skin brick layer. There is already overhang on the inside of about 20mm.

    Am thinking of splitting those 2 12mm sheets and wedging insulation board in between.

    Complete with the battens and render cladding this would leave a pretty big overhang.

    Layers would go like this:


    Would the bricks and concrete slab and timber framework be able to take the weight of this overhang?

    That piece of "wood" you see in the top pic would be screwed to the base of the timber framework so the Celotex and plywood can rest on it without putting too much pressure on the edge of the brick.

    Also the framework studs are 400mm spaced and will be filled with acoustic rock wool which isn't as thermally good, hence the added external PIR boards idea.

    Yes posted on DIYnot with no replies so giving OCUK a try lol

  2. Bar


    Joined: 9 Apr 2004

    Posts: 2,539

    It should be structually sound enough - as long as the top is secured robustly and you have lateral joists holding the walls together at the top. The more important question is do your victims volunteers really make that much noise...
  3. Derek W


    Joined: 1 Oct 2008

    Posts: 11,705

    Location: Glebe Park

    I think you're over complicating things. Just keep the outside for your external finish. Put your rockwool between the studs and put on an insulated plasterboard with integral vapour control layer on the inside. It'll reduce your cold bridging but it means that you'll also reduce your internal room size by 50mm.
  4. koolpc


    Joined: 2 Dec 2004

    Posts: 12,408

    Location: Under The Desk, Wales