Fiberglass insulation hangers for under roof deck
I’m having trouble finding fasteners for hanging fiberglass insulation from sprayed-on polyurethane foam in a conditioned attic conversion application.
The stack will look like:
sprayed polyurethane foam
——–|—-|—-|—-|—-|—-|—-|—-|—- <- fasteners pushed into foam fiberglass insulation to cover foam to meet code and increase total insulation value ————————————————– Attic conditioned air space The hangers need to be: -Thermally insulating so the R40 insulation used here at 7000′ in Colorado is not shorted out -Able to anchor into the sprayed polyurethane foam at one end, and hold low density fiberglass batts at the other It looks like: http://www.twistfix.co.uk/products/insulation-fixings/plastic-insulation-fixings-product.html Might work, but they are not available in the US. It looks like the pin on the following product is too smooth to hold low density fiberglass if the head is glued to the polyurethane foam, and if inserted the other way, the pin might fall out of the polyurethane: http://www.midwestfasteners.com/products/swproducts/insulationfasteners/nonwelde d/ihangers_nylon.php Most of the hangers I find have some sort of metal in them, and if my calculations are correct, this is a really bad idea for this application. For example, it looks like 10d nails on 1′ centers will lower an R40 ceiling to R27! The best thing I have found for this application so far is a screw type drywall anchor without the internal screw: http://www.toggler.com/products/snapskru/overview.php. I would screw them into the polyurethane through the fiberglass, then pull on the outer layers of the fiberglass to hide the anchor. The biggest problem I see with these is that they are so short, I’m concerned I won’t get enough bite into the polyurethane. A related question: does any know how much I can shorten the nails coming through the roof sheathing without reducing the integrity of these fasteners used for a tile roof? after the 10d nail calculation I referred to above, It looks like these nails will have a significant affect in system R value. Dave
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