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-   -   Garage insulation (https://ecorenovator.org/forum/showthread.php?t=4603)

Daox 10-21-15 07:35 AM

Garage insulation
 
Ever since purchasing my home, I've had grandeous visions of an insulated/heated setup for my detached garage (a mooney wall setup for those who know what that is)... Well, its 7 years later now and the farthest I've gotten is to staple up some plastic on the ceiling to keep the heat in while I got a heater going out there. I had to swap an engine one winter and that came in real handy. Needless to say I have higher priorities.

So, this morning I see the Menards ad on the table with an insulation ad on the front page. R-11 unfaced fiberglass for $5 after rebate. This would insulate my garage walls for ~$50. So, I'm seriously considering it. I realize that I"ll have thermal bridging issues with just shoving some fiberglass in the walls, but its a heck of a lot better than nothing and I'm not planning on heating it unless I'm out there working on stuff.

My questions are, what are the drawbacks of unfaced insulation for a typically unheated detached garage? Would it be best to put it up and then put plastic over the face (there is no external vapor barrier)? What about rodents? The mice love my garage as it is. Are they going to eat up/nest in the insulation? Is there a way to deal with that? Any other factors I should consider?

AC_Hacker 10-21-15 10:27 AM

Quote:

Originally Posted by Daox (Post 47560)
Any other factors I should consider?

From cellulose Moony wall to un-faced R11? That's quite a decline in gumption.

You're right, R11 is better than nothing. If the rodent problem is huge, you could staple metal screen around at least the bottoms of the cavities before you start, that could help.

But to actually get R11, each cavity needs to be air sealed.

I would think that a lot of concerns about moisture and condensation inside the insulating material wouldn't apply to a garage, because the continuing moisture release that is part of a home, will be essentially absent from a garage. So issues like trapped moisture inside insulation won't apply

Are you thinking to do a Moony wall out of R11? If that's your plan, then you could do the first layer, cover it with a plastic film barrier, and then go in to the horizontal structure and more R11 and more plastic film, and then a final layer of OSB for protection and to fasten shelves and tool hangers, etc.

As for mice, they've been on the earth since the dinosaurs, and they will still be here long after the human race has succeeded in devising a way to destroy itself.

So perhaps they deserve a little respect. In the long run they may actually be smarter (or at least more fit for existence) than we are.

Best,

-AC

natethebrown 10-21-15 12:11 PM

Quote:

Originally Posted by Daox (Post 47560)
Ever since purchasing my home, I've had grandeous visions of an insulated/heated setup for my detached garage (a mooney wall setup for those who know what that is)... Well, its 7 years later now and the farthest I've gotten is to staple up some plastic on the ceiling to keep the heat in while I got a heater going out there. I had to swap an engine one winter and that came in real handy. Needless to say I have higher priorities.

So, this morning I see the Menards ad on the table with an insulation ad on the front page. R-11 unfaced fiberglass for $5 after rebate. This would insulate my garage walls for ~$50. So, I'm seriously considering it. I realize that I"ll have thermal bridging issues with just shoving some fiberglass in the walls, but its a heck of a lot better than nothing and I'm not planning on heating it unless I'm out there working on stuff.

My questions are, what are the drawbacks of unfaced insulation for a typically unheated detached garage? Would it be best to put it up and then put plastic over the face (there is no external vapor barrier)? What about rodents? The mice love my garage as it is. Are they going to eat up/nest in the insulation? Is there a way to deal with that? Any other factors I should consider?

It sounds like your time is more valuable than anything. Just doing the batting will definitely save you quite a bit of time (as well as money) so go for it. As far as mice, get an outdoor cat. If you don't want a cat (can't blame you, I am lucky to have a neighbor with an outdoor cat), poison or traps always work.

randen 10-21-15 05:12 PM

Daox

It may be of interest to look into spray foam. This stuff will seal the garage up like a drum and prevent any problem with rodents. No plastic vapor barrier required. The products have now been around long enough that they are competitive with other more dated methods with superior performance. It wouldn't hurt to have some quotes done and maybe a cash for a Saturday morning deal may help.

Randen

stevehull 10-21-15 06:26 PM

Randen, - it is hard to beat fiberglass bats at those prices. Remember this is a garage, not a living space.

Here in Oklahoma, they get anywhere from $2-3 per sq foot for open cell foam at two inches thick. Yes, spray on foam IS tremendous and does block the wind, etc.

But a few cans of expanding foam in the bad spots (3 cans, $15 total), some fiberglass batts ($50) and some 2 mil plastic on top of that ($10) would be about as inexpensive (total < $100) and quick as you can get (literally a Saturday morning or afternoon project).

But you are correct - a foam quote is the way to tell . . . .



Steve

Daox 10-22-15 10:28 AM

Thanks for the input guys. I do agree its quite the lowering of standards. However, this is an out building. Its not heated 99% of the year. I have a propane heater for when I work out in the very cold weather. I typically don't even go through a 20lb tank in a year.

The eventual goal is to not heat the garage at all, it just be passively taken care of.

Daox 10-23-15 07:58 AM

2 Attachment(s)
http://ecorenovator.org/forum/attach...1&d=1445604798

I went and nabbed myself 10 rolls of fiberglass last night. Thankfully, I was able to stuff it all in the back of my Prius. Yay, only one trip to the store. They also had 4 mil plastic on sale for nearly half price as well. That made me quite happy to see as well.



http://ecorenovator.org/forum/attach...1&d=1445604798

This is my current storage area, my sunroom. I have a few projects to finish up in the garage, plus cleaning and reorganizing before I can start putting this stuff in the walls.


For now, I'm asking for some install advise. I know this isn't the optimal setup, but I want to make the most of what I have. AC Hacker mentioned that each cavity must be sealed up. How would you guys recommend going about that? Obviously, I have the 4 mil plastic for the inside. For the outside, just seal any holes with great stuff and/or caulk? Would acoustic sealant be a better choice? Tips please!

S-F 10-26-15 04:50 PM

The sealing needs to be at the plane of the air barrier. So I would attack any and all nooks and crannies that lead to the outside. What is the sheathing? If it's some sort of sheet lumber then you just seal the visible seams and then seal the stud/sheathing joint where the vertical seams are. You won't be able to properly seal the vertical seams without access to the outside of the sheathing but it should do a pretty good job. The only need for plastic inside is to protect the fiberglass.

Daox 10-27-15 11:10 AM

The sheathing is a tar impregnated particle board for the most part. Its not very sturdy at all. They used plywood in the corners for structural reasons.

I know right now the garage is horribly air leaky. Not much effort at all went into sealing it up, and I haven't done anything with it air sealing wise. This will be my perfect opportunity.

JRMichler 10-27-15 08:03 PM

I have some experience at sealing up and insulating a garage. That tar fuzzboard stuff cannot be sealed. It's more like a hard air filter than anything else.

My own garage walls never did get well sealed until I had 2" Styrofoam added to the outside and 2" foam dug down 2 feet around the perimeter. I had drywalled and taped the ceiling. That barely slowed down the air leaks. The ceiling got sealed when I pulled out the fiberglass batts and foamed the entire ceiling from above. Then the ceiling got insulated when I blew in about two feet of blow in fiberglass.

In your case, I'd just put in the batts, staple on the plastic and call it good.


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