Another polyiso facer direction question
Hello,
I recently started installing 2 layers of foil faced polyiso insulation on my basement walls. One side has foil facing and the other side appears to have kraft paper facing. I started off facing both layers with the foil facing inwards toward the interior of the basement.
It occurred to me that a more durable assembly might be facing the outer layer so that the foil contacts the foundation wall and the inner layer foil still faces towards the interior of the basement (i.e. “back to back”). This would reduce exposure of the non-reflective kraft facing to any potential excessive moisture.
Does anyone have any thoughts on this? Am I overthinking this? Any feedback much appreciated.
Thanks,
Dave
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Replies
Sika, RMax, says that sandwiched together, the boards act as one. They also claim it does not matter in multiple questions about this on their product sheet.
I called and asked Henry as I was looking to use their EPS in my cathedral ceiling. They said it really didn't matter, but foil facing inward "open air space" if it matters at all.
Makes me wonder if the foil is just a stronger bond surface than the other side that has all the commercial print and we think there is a mechanical purpose?
If radiant heat actually occurs at the reflective side, you'd think reflective facing into the house keeps the conditioned air that direction.
Thanks Ryan. My question is really from a durability perspective. I think I would feel more comfortable with the foil facing the foundation wall. Since I am using two layers of polyiso, I can face the second layer of polyiso with foil towards the room.
The product I am using is Johns Manville AP foil faced polyiso.
Anyone see an issue with this?
Thanks,
Dave
I would rather not have paper in the middle of two vapor-closed layers (foil-foil) but in your case I think it's probably best to do so--paper facing in, foil facing the foundation and the interior space.