How much insulation?

[bhalv]

So i have a 2 car attached garage that I'm probably going to have insulated in the next few weeks. The question is, being in southern Idaho, should I go with r30 or r40 blown insulation for the attic? I plan on using the garage for vehicle upkeep and various project throughout the winter and am trying to avoid freezing in the process. Any pointers would be helpful. Oh and i do not currently have a heater out there, but may add an electric unit in the future (I don't have gas available in my neighborhood)

 

[NIS240SHU]

I used to manage a team of energy auditors as the lead auditor so I'll chime in. The first thing you'll want to do is air seal any gaps between your attic floor's framing and the drywall with canned foam or air sealing caulk. This includes sealing any plumbing pipes, etc. Be careful of anything that produces heat. Next, go with the highest R-value of cellulose insulation you can afford. It's easy to do yourself and in my experience it's easier to do a good effective job with it then it is with blown Fiberglass. My house's attic is insulated to R-72 in places and I always have snow on my roof long after my neighbor's roofs are bare. PM me or post if I can help further explain.

Sent from my Nexus 4 using Tapatalk 4

 

[Falcon67]

X2 above - sealing things up is the first biggest bag for a buck. Then as much insulation as your wallet can stand. I only have R13 right now in the shop attic but I also caulked every seam in the ceiling OSB including where it meets the walls. That made a huge difference in performance. We did the same in the house last year and made a big difference.

 

[D KRAGER]

If you use blow in cellulose, go at least R40, it's cheap and it will settle. Go deeper than it says then after it settles you will still have enough.

 

[jimp]

Real world is never as good as in the lab, so I always exceed the obvious cutoff in the attached graph to make up for poor installation practice. However at some point you are wasting money on additional insulation, I stop at R40.

Again seal all leaks first.

 

[Pate]

I did my whole house at R-50. It was only a $300 upgrade (over R-40) for the garage and attic when the house was being built. Seemed like a good investment to me.

 

[NUTTSGT]

If you're in the attic space blowing it in, have the machine to do it, buying the bags, and getting dirty, you might as well spend a few more bucks on the extra bags and get the extra R10.

It will will only pay itself back in the long run.

 

[jvitez]

you might as well spend a few more bucks on the extra bags and get the extra R10.

It will will only pay itself back in the long run.

+1. I'm in climate zone 7 so ****** cold, so it was worth the small extra cost for me for go to R60 cellulose when we built our house. I'm planning on at least R50 when I do my attached garage.