GPS vs Polyiso for basement insulation
I am beginning a basement finishing project (basement was partially finished in the past, but not done well, had flooding and mold issues).
I am having a sump pump with perimeter drain installed, and then plan to insulate exterior walls and floor with rigid foam.
I am debating between gps (proboard 2″) and Polyiso (rmax thermasheath 3) for the insulation.
I am currently leaning towards Polyiso for the walls and gps for the floor, with the thought that the Polyiso on the wall comes with an air barrier in the form of the facing, but the GPS has a higher compressive strength for the floor (25 psi vs 20).
Currently thinking I would then put down a dimpled plastic liner above the GPS on the floor, followed by osb board for weight distribution, follow by rubber tiles to provide a soft top surface for the kids.
My questions are:
1. Is using the Polyiso on the walls a good choice? I read one article suggesting that it’s r value falls off if it gets colder than 50 F or wet, which my basement shouldn’t usually get that cold, but….
2. Are my flooring plans overkill? Should I skip the dimpled plastic or osb? Do I need something as a thermal barrier over the GPS on the floor for fire protection? If do, what can I use?
3. For hanging drywall in front of the Polyiso, can I use 2×2 instead of 2×4 studs to save space?
I live in South eastern PA.
Any thoughts or suggestions appreciated.
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