Which insulation to choose?
I'm to the point where I have to choose insulation and I know the knowledgable folks here will offer good advice as they have for me in the past.
I have a bid for blown in cellulose or fiberglass in the walls with cellulose in the attic and batts in the garage for $4500. I also have a bid for OC foam in the walls and blown in cellulose in the attic/batts in the garage for $5800. I don't think the foam quote is too out of line, but I'm wondering if it's worth the extra $1300. I would like an efficient home, but my budget is tight so I want to do what makes the most sense in the long term without breaking the bank now.
Here is some info that may help:
- 3000 sf heated
- 2x6 framing with 1/2" OSB with Tyvek
- Northwest Arkansas -- I'd consider this more of a Midwest climate but we definitely do more cooling than heating here
- Radiant barrier on the roof deck
- Vented roof (mostly turtle vents -- many -- and two copper dormer vents on the front)
- HVAC is 15 SEER 2-ton/3-ton system with an 80% gas furnace and, yes, it's in the attic (I tried, but there was simply no room to spare in the conditioned space and attic installs are typical around here)
- Is there any benefit to using the foam? My research would indicate that foam in the walls isn't such a great deal.
- I assume using any kind of foam on the rafters to moderate the attic would be pointless given that it's vented?
- If I go with foam, will I need to invest in an ERV as well? It's really not in my budget now or in the foreseeable future and I would hate to have to suffer with poor air quality and dry skin until it is. Also, I frankly do not want more holes in the roof.
- Can anyone speak to off gassing they've experienced with foam? I'm pretty sensitive to smells as well.
- Is foam really a better sound insulator?
I guess I'm just wondering if the extra cost for the foam is worth it considering all of the other decisions I've already made that are not conducive to a super tight envelope. The blown in stuff seems like it might make more sense but I'd like to hear what others think. Also, if anyone has an opinion on choosing blown in fiberglass over cellulose or vice versa, I'd love to hear it as well.
Thanks in advance as always.