DIY Doctor

Insulated Concrete Base for Garden Room

Postby yogi2dab » Mon Apr 27, 2020 9:47 am

Good morning all,

I’m not sure if this is the right place for this kind of question but here goes. I’m drawing plans for the build of a summer house in my garden. I want to have insulated concrete slab (under slab) for the floor to make full use of the space and 2.5m height restriction. I understand that insultation board goes around (vertically) the perimeter of the wooden frame for the base and within (horizontally), then you pour the concrete into the insultation, thus the insultation encases the concrete slab underneath and around the sides. Once it sets, you then remove the wooden frame. I can’t find an answer to how you then finish the sides where insulation was placed vertically around the wood frame? If you take out the frame, the insultation will then be in direct contact with the soil. You could pull the DPC up to protect it but then the second question is what about the walls because you can’t put walls directly only the insultation around the edges, can you? You could do away with the insultation around the perimeter but then a cold bridge would be created and make insulation underneath pointless! Here is a link to a guide I found that explains what I’m trying to achieve. I know that with extensions/new builds, the insulation is held in place by a few courses of brickwork but surely this is not the case for a garden room.Hopefully someone can help me with this one and offer their advice of experience. ... 019/10/03/
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Simply Build It

Postby stoneyboy » Tue Apr 28, 2020 9:13 pm

Hi yogi2dab
Looking at the link you gave the walls are built on the edge of insulated floor slab - the timber frame remains in place.
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Postby oliveretoe » Wed Jul 01, 2020 6:38 pm

Hi there, I was wondering what you ended up doing with this issue, as I am wondering EXACTLY the same! Am at the point of laying insulation, and not sure how to get round this.......(using the same guide)
Any advice would be appreciated......?!
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