I have a two story 1970s home that has basically storage rooms upstairs off the bedrooms where the roof angles down. Inside these rooms is the studs and insulation facing the exterior roof. Since they are angled the bat insulation keeps falling out. It was originally stapled, but has not held up. These rooms are pretty large and we use them for storage. There is an additional attic above the bedrooms.
What is the best way to fix this sagging without completely re-doing the insulation?
It can't be stapled as that has failed and the paper is in bad shape. Could I put foam board over the top and nail it to the studs holding it in place? This would probably leave gaps at the bottom and top due to the angle.