Insulating a lean-to off the back of my garage. Need advice on what kind to get

spdorsey

I have an 18" wide x 9' deep x 6'6" tall room off the back of the garage. I re-framed 2 of the walls and shored it up, now I'm ready to insulate it to use as a small office.
Home Depot recommends R18 on the walls and R38 on the ceiling. Is this correct?
Also, where can I go to get this stuff cheaper? It seems that lining my roof with R38 will cost over $1000. That seems high.
I live in California. Thanks for the replies!

Windows on Wash

http://publicecodes.citation.com/ico..._11_sec002.htm

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joecaption

http://www.energystar.gov/index.cfm?...sulation_table

What size wall studs do you have?

M3 Pete

As Joe's map shows, California has five different zones in it.

I live in Zone 3 and have R19, because that's what the house came with. Might be nice to have more, but first I need to air seal the attic before it will do much good. But nearly everybody around here has the same thing.

Which begs the question, how airtight is this "lean-to"? If you have a drafty door and leaky walls/windows, going to the full recommended R value is not going to be good value.

And how are you calculating $1000 for an 18x9 roof? That's 162 square feet. Both of the R38 batts advertised on the HD site are exactly $1 per square foot.

This one is 64 square feet, look at the specs
http://www.homedepot.com/h_d1/N-5yc1v/R-202585891/h_d2/ProductDisplay

Gary in WA

California has its own Energy Code. San Jose is in Zone 3C, requires R-38 in ceiling, R-25 in walls, pp. 13: http://www.pge.com/includes/docs/pdf...ones_01-16.pdf

Call around for best prices......

Gary

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