Insulating Roof with Greenstar Panels
Hello,
We are in climate zone 2A and looking to convert our attic to a conditioned space. We would like to avoid spray foam at all cost. It looks like one code approved solution is to have exterior insulation and then using air permeable insulation on the bottom of the roof sheathing. Unfortunately our roof is still good so we can’t do that.
I found the following product from Florida (https://greenstarpanels.com/).
It basically creates a bottom-vent deck: creating an air space or rafter ventilation chute under the roof deck, outboard of the EPS insulation.
Does anybody have experience with this product. I can’t find much on it. It seems very easy to install. Too good to be true to be honest.
Thank you
Any
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Replies
It’s just foil faced EPS, nothing really special about it from my quick look at their site. You can get equivalent products from other manufacturers. I’d just use foil faced polyiso for this application myself, for better R per inch and material that is easier to find at suppliers.
Bill
Thank you Bill. Would you recommend this type of attic assembly in climate zone 2a as a way to get to a conditioned attic without the use of spray foam?
If you’re building a vented assembly, which I think is the case here, then it should work. I’d you’re planning to use batts on the interior to get up to a target r value, you need to keep to the ratios for your climate zone (with the rigid insulation as the “exterior” insulation) to avoid any moisture issues. In CZ 2A, it won’t be hard to keep to the proper ratio — although I’d have to look up exactly what the ratio is for that CZ as I’m more familiar with the more northern CZs.
Any roof assembly tends to be less critical when built as a vented assembly. It’s usually when you want an UNvented assembly that you really have to be careful how you build things.
Bill