I have a walk-in attic off my bedroom that goes above the garage. The attic wasn't venting at all so I recently installed a solar fan to help reduce the heat in the summer. Since it wasn't venting properly before the fan install all my fiberglass insulation on the backside of the interior wall needed to be replaced. The attic itself is not insulated - only the walls on the bedroom/bathroom. I pulled all of the fiberglass insulation from between the studs and I was going to just replace it with newer fiberglass insulation. But I'm thinking about just going with foam board insulation since it's more resistant to mold growth (?) and not just replacing the fiberglass insulation.
My plan was to just stack a few pieces of 2" foam board over the existing foam board between the studs and use spray foam to seal the gaps around it.
Can I just use foam boards vs fiberglass?
There is existing foam board on the backside of the interior drywall. Can I just stack a few layers of 2" foam board on top of the existing reflective boards or do I need to create space between?
If I need space between them - Can I leave it empty or do I need to fill it with fiberglass or something else?
Or Do I just go with fiberglass insulation and place it back in between the studs and call it a day?
Thank you for any help.