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Old 03-05-2015, 10:12 AM   #1
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Building Addition - Crawl Space

I am building a small addition to the back of my house in Ontario.
Excuse the crude drawing (best I could come up with).
I am interested in finding out how to insulate and protect the crawl space.
This space will have sides(not sure if its going to be lattice or PT boards - #2 on drawing).
Either way,it will be partially exposed to the elements.

In the photo attached, it shows the insulation I intend to use between the
16" centre joists. Covered with Comfortboard (#1 on my drawing).
There would be vapour barrier on top of the joists,under the T&G sub floor)
Im not sure if I should then cover the Comfortboard with thin PT plywood or perhaps Aluminum soffit ?
I then want to make sure I can seal all the gaps and spaces (to prevent mice infiltration etc). Suggested method ?

Is there any point in covering the crushed stone ground (#3 on drawing) with Poly sheet ?(or is this only beneficial in an enclosed,conditioned space?)

Any benefit to cover the 6"x6" posts and 2"x10"(x3) beams with Comfortboard and PT plywood ? (to further prevent transference of cold)?

Any assistance would be appreciated.

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Old 03-05-2015, 05:40 PM   #2
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In your area I'd be doing footings and a real foundation, not just building on post.
Far easier to keep the floors warm without the wind and additional exposure to the outside.
No 2X"s or 5/4 are rated for direct ground contact.
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Old 03-05-2015, 10:13 PM   #3
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Be sure to run your plan by the local AHJ. Plywood sub-floor has a perm rating of 0.70 (semi-impermeable) or so, usually no vapor barrier is required, check locally.

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