Polyiso for basement
I am about to embark on the basement insulation. I have a question about polyiso. After much reading I was so sure about putting xps 2″ rigid foam against walls and rim joist.
I read the gba, several other forums and as I understand, the steps are – clean the basement walls, clean rim joist, place rigid foam, seal with great stuff, place xps with foam glue on walls, tape the seams, seal the edges with great stuff, leave a inch gap and frame with stud walls.
I have a few questions and will greatly appreciate anyone guiding me through this. Thanks a lot in advance for your time and patience.
1. Can I use polyiso faced with aluminum – if so will the foil go facing with concrete or towards the interior?
2. Must I leave the 1″ gap between foam and studwall?
3. Will placing a perimeter drain with a gradient along the entire basement and letting it drain out in one corner help if moisture accumulates – or am I overcomplicating it in a newbee fashion?
4. One more question – if I am going to leave a little space between stud wall and the rigid foam, is there any mileage in stuffing the stud bays with unfaced fiberglass?