Roof insulation for new house, R-50 flash and batt worth the $$$ vs. R-38 batt???
House details:
Located in Zone 5
-Basic rectangle Ranch style, 32’x68′
-2×12 Rafters with about 6/12 pitch
-2×10 ceiling/floor joists (attic/loft) in non- vaulted ceiling areas
-Vaulted area in middle of house (24’x32′ area with 24″ Glulam Beam) has no joists.
-We plan on using one side of attic for storage and the other as a loft.
-Also, planning on installing roof mounted solar panels
Insulation specialist came by and quoted us:
$4,100 for R-38 using Batts
$16,700 for R-20 (3″closed cell SF) w/ R-30 Batt Total RF= R-50
With such a big price difference is the added RF and air sealing worth it?
I like the idea of using the spray foam:
-Higher RF
-Air sealed and no roof venting
-Increase in Structural strength from wind uplift? (We are in a critical wind area)
I tried to keep post as short and to the point as possible but welcome any questions.
Thanks,
Jason
Replies
Jason, I did a very similar flash and batt install on my cathedral ceiling. I would expect that the cost of the R30 & R38 batts are nearly identical and the added cost of the flash and batt is 100% the cost of the spray foam. I am also in zone 5 and feel that the added benefit of the extra R value air sealing is well worth it and something that will pay for itself in a few years. Also of benefit is the ability to do an unvented roof assembly for your cathedral.
Ian, thank you.