Insulating A Lean-to Off The Back Of My Garage. Need Advice On What Kind To Get - Insulation - DIY Chatroom Home Improvement Forum

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Old 04-11-2012, 01:22 PM   #1
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Insulating a lean-to off the back of my garage. Need advice on what kind to get

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!


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Old 04-12-2012, 08:13 AM   #2
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Old 04-12-2012, 09:00 AM   #3
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What size wall studs do you have?
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Old 04-12-2012, 05:41 PM   #4
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Originally Posted by spdorsey View Post
I live in California. Thanks for the replies!
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

Last edited by M3 Pete; 04-12-2012 at 05:44 PM.
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Old 04-13-2012, 11:32 PM   #5
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California has its own Energy Code. San Jose is in Zone 3C, requires R-38 in ceiling, R-25 in walls, pp. 13:

Call around for best prices......

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