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Slim
Joined: 05 Mar 2006 Posts: 6594 Location: New England (In the US of A)
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Posted: Wed Aug 02, 23 9:43 am Post subject: |
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I particularly appreciate dpack's caveats about the difficulty in generalizing advice about this kind of topic.
I don't know that my perspective from the climate here will apply there...
When I suggested perimeter insulation around the slab, it's with the assumption that there's no insulation under it, but that it sits on a reasonably drained/dry substrate. I also didn't clarify that I was envisioning foamboard going against the entirety of the slab's edge (with the primary goal of slowing heat loss to cold air above grade) but also burying it below grade, with high performance tape at the joints of the foamboard, to seal off the substrate from thermal wicking as well - well to slow it anyway. Here, that would mean splitting 4'x8" sheets of foamboard down the middle, and trying to cover 24" from exterior cladding down into a trench (or split in three and cover 16"-ish). Great care would need to be paid as to the location of any underground power, plumbing, etc.
Exposed foamboard can be covered with flashing.
This would help to limit the concrete from dipping below ground temperature, which is significant here, because air temperatures can be so low for so long over winter, and you may be able to consider the slab and the substrate below it as a bit of thermal mass. You could never expect a retrofit like that to get it to function the way a concrete slab does in a holistically designed passive solar house, but it could help reduce the heat wicking potential of the slab.
I agree that addressing drafts first will be much more bang for your buck. Heat loss via the concrete is nothing relative to cold air intrusion (and associated warm air escaping at the top of the "stack") |
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dpack
Joined: 02 Jul 2005 Posts: 46052 Location: yes
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Nicky cigreen
Joined: 25 Jun 2007 Posts: 9782 Location: Devon, uk
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Ty Gwyn
Joined: 22 Sep 2010 Posts: 4603 Location: Lampeter
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NorthernMonkeyGirl
Joined: 10 Apr 2011 Posts: 4618 Location: Peeping over your shoulder
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Nicky cigreen
Joined: 25 Jun 2007 Posts: 9782 Location: Devon, uk
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Nicky cigreen
Joined: 25 Jun 2007 Posts: 9782 Location: Devon, uk
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Ty Gwyn
Joined: 22 Sep 2010 Posts: 4603 Location: Lampeter
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Nicky cigreen
Joined: 25 Jun 2007 Posts: 9782 Location: Devon, uk
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