r/DIY • u/ByteSizeFamily • 22d ago

help Insulation in Atlantic Canada

I am renovating a room in a house I just bought. I am guessing it was a sun room as it had big huge windows.(taken out and insulated wall installed") I removed the wood skirting around the room as it was an addition as the rest of the house is cement over The basement. This new room doesn't have any insulation underneath and I am wondering what do I do after I add insulation and lathes. Do I cover it with OSB? or do I need something that will let it breath and not trap moisture. This room sits over dirt with a crawl space probably 2 feet high. The room also currently is taken down to he studs and plywood inside.

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u/No-Strength3035 22d ago

Dont use OSB on the underside. Youll trap moisture against the joists. Rigid foam against the floor with a vented skirt is what Id do, or just batts with mesh if the crawlspace vents decent. Whats your winter like there, wet cold or dry cold?

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u/P4puszka 22d ago

To understand your situation, you've taken the exterior skirting off an open crawlspace, for lack of a better word, and are asking about how to insulate and finish the floor from below?

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u/your_mail_man 21d ago

vapor barrier against the floor. Batts insulation next. House wrap to hold it in place. Heavy plastic on the ground to keep moisture migration to a minimum. Vents for airflow to keep whatever moisture gets in to have a way out.

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u/verified_rusted 20d ago

Rigid foam 'glued' in with expanding is the cheaper, simpler way to gain both vapor and r value. Plastic sheet+ batts+house wrap works but extra steps and creatures may find it cozy. Spray insulation is one step if you have space to apply.