How can I effectively insulate my 2×10 floor joist cavities to regulate temperature and maintain comfort in my basement?
Asked by Aubree Ambrose 
3 months ago
Last Updated: September 24, 2024
How would you go about insulating those 2×10 floor joist cavities? My basement is all insulated and drywalled, with the supply and return ducts in place. I had to take down the ceiling for some rewiring and ductwork, and I couldn’t help but notice how warm those floor joist spaces are in the summer, and how chilly the tile floors get in the winter. I’ve been eyeing mineral wool for its soundproofing and fire-resistant qualities, but it’s only 5 inches thick. Should I use that against the floor and leave a 4.5-inch gap between the insulation and the new ceiling? Or should I just go all out and fill the cavities with a full 10 inches of R30 fiberglass?
If you can’t, go for two layers of mineral wool to make up for the difference in thickness.
If the outside walls and foundation area are insulated, you’re all set. Tiles will feel colder underfoot in winter simply because… if you had radiant floor heat, that would be a game changer. Insulating won’t hurt, but it’s just extra money.
You know, you can totally fit two layers of mineral wool in one stud cavity.