Is R13 insulation in garage ceiling noticable vs Nothing?

[musgofasta]

My new house has an uninsulated garage (except for the 1 side attached to the house).

The ceiling is drywall over 2x4 framing with a large area above the drywall for storage. I want to insulate it, but then plywood or OSB over the top for storage. R13 is obviously all I can get in the ceiling and still get OSB screwed down.

Is R13 (and a new gable fan) going to be noticebly better than what I have now (zilch)? It's probably 120 degrees in the storage area now, and hotter than the outside air in the garage itself.

I think it could qualify for a sauna!

 

[Gary S]

R13 is going to make a world of difference. It that is all you can fit in, do it and you will never regret it.

 

[richashley]

I've got R-13 in mine and even without a gable fan it makes a huge difference.

 

[therealwormey]

R13 is going to make a world of difference. It that is all you can fit in, do it and you will never regret it.

ditto

 

[Falcon67]

I used R-13 in the old shop and could keep it at high 70s, low 80s with the underside of the roof deck at temps up as high as 160F.

 

[boiler7904]

When you say 2x4 framing, is it an attic storage style truss or just a 2x4 ceiling joist? If it's just 2x4 joists, they're way undersized for supporting any kind of weight safely.

First off, I'd switch to R-15 fiberglass batts. Every little bit helps.

You can also install a layer of rigid foam insulation on the plywood / osb floor and then another layer of plywood or osb as the actual floor surface. All depends on how much work you want to go to for extra insulation and how long you'll live in the house to make it worth the hassle to you.

I'm in a similar situation as you except the house is 5 years old with the osb floor down and filled with my wife's stuff. My plan is to take everything out of the attic, pull up the decking a couple sections at a time so I can install the batt insulation, reinstall the existing osb, install a 2" layer of rigid foam, and then another layer of osb. Sounds like a good winter project to me since the attic is the most empty at Christmas, it's 90-100 degrees cooler and I have more free time. Baby on the way this year means it probably won't happen for another year.

 

[malibu101]

Not trying be insulting, just saying..........
R-13 means it resists the transfer of heat 13 times better than nothing.
I think you'll be happy after it is done.

 

[spy604]

Not trying be insulting, just saying..........
R-13 means it resists the transfer of heat 13 times better than nothing.
I think you'll be happy after it is done.

Not exactly. R13 would be infinitely better than R0, and 13x better than R1 I would assume OSB sheathing and siding to be ~R1-2, so its about 6x-12x better.

 

[musgofasta]

I didn't know the R-value math worked like that, so I'm sure I'll be happy with the improvement.

I don't know the difference between attic storage truss and simple 2x4 ceiling joists, but it's strong enough for me to crawl around up there. There are diagonal bracing from the roof line to the ceiling joists if that helps differentiate.

I did pullups off the crawl space frame and there was no deflection, so I figured it's strong enough. Nothing heavy being stored up there anyway.

 

[boiler7904]

I didn't know the R-value math worked like that, so I'm sure I'll be happy with the improvement.

I don't know the difference between attic storage truss and simple 2x4 ceiling joists, but it's strong enough for me to crawl around up there. There are diagonal bracing from the roof line to the ceiling joists if that helps differentiate.

I did pullups off the crawl space frame and there was no deflection, so I figured it's strong enough. Nothing heavy being stored up there anyway.

The diagonal bracing is the webs of roof trusses. Roof trusses with a 2x4 bottom chord (horizontal member your drywall is attached to) are definitely stronger than a simple 2x4 ceiling joist.

 

[Jaguar Fan]

One thing to consider: contact a local mechanical engineer & ask. They have software to model the heat gains/losses for your specific area. It isn't just temperature; its also humidity and dew point. And - is your garage door insulated?

My guess is you can get a mechanical engineer to give you good answers very inexpensively (what you describe is not complex).

It isn't completely relavent to your situation, but you can read at the following link how over-insulating might not be the answer, either. It is just something I ran across this morning in my email in-box.

http://www.greenbuildingadvisor.com...5-3-frame-tips&utm_campaign=fine-homebuilding

 

[soob]

I added some blow-in insualtion to my house recently. I feel foolish for not doing the ceiling over the garage when I had the chance. Would not have been that much; the big-box home improvement stores will rent the machine if you buy 20 bags of $11 insulation. It may be a good alternative to the batt rolls. If you're worried about the height of the floor, you can raise it easily.

 

[WanderingSol]

I have the same situation, attached two car garage with no attic insulation. I insulated it this last January, 4" thick. First winter my garage did not go below freezing! In fact there were many more days it was comfortable to work in the garage. Last week we had high ninties all week, the garage stayed closer to high eighties most of the time. Considering how many more days (and nights) I could work in the garage since I insulated, it was well worth the $90 for insulation. A couple years earlier I replaced my two single overhead doors with insulated steel doors with a row of windows in the top panel. That too made a big difference and don't need to turn a light on during daytime.

Tim.

 

[WVBrady]

I didn't know the R-value math worked like that, so I'm sure I'll be happy with the improvement...

That's the theory. In real life the effect seems to be considerably less, but still well worth the effort.

 

[mark52621]

One of the barns on my farm is insulated fiberboard on the ceilings and walls. It is only R1.5, but it is much nicer than the uninsulated barns.

 

[musgofasta]

Well that was about as fun as a root canal, but mission accomplished.

A whole lot of blood, sweat and pain, but the ceiling is insulated. I was literally drenched from the heat up there, and cut myself on a few roofing nails poking through.

Pre-wiring for the fan is done, and it should be in this week. Even without the fan, You can tell a difference in heat level.

I'd say it went from "severely uncomfortable" to "hot but managable" in there! I'll take it.

 

[Todd.Brock]

I think you and I have a photocopy of each others garage. I have stuff in my attic and would be a major pain to pull it all out, but am thinking it would be worth it this winter. I have electrical wires running over my joists so blown in maybe the way to go. Although r-13 would work too.

 

[nate379]

Sister some 2x4s or 2x6s to the existing 2x4s to get more insulation in. It is where you loose the most heat. I have R60 in my house and garage and that isn't overkill. Only R21 in the walls to compare.

 

[bczygan]

Another thought for future reference. The best area for storage is in the middle of an attic space like that, where the most headroom is. If the roof pitch was great enough to provide extra headroom I would do the following. I would run the R13 unfaced batts in between the truss bottom chords, then I would run 2x6's perpendicular down the middle of the space at 2'o.c. and cover with 1/2" plywood after laying in R19 unfaced batts between the 2x6 joists and also covering all the R13 batts. This would create a storage area in the middle and give the entire ceiling R32. Note that all this extra load in thee middle of the span would make for only light weight storage.

 

[nate379]

I'd imagine so with only a 2x4 bottom chord. My trusses in the house and garage are 2x6 or 2x8 top chord (depending on location) and the bottoms are all 2x6. Even still was told by the inspector not to use for storage.

 

[musgofasta]

Gable fan went in last night. Piece of cake wiring, and a second noticable improvement in the comfort of the garage. Can barely hear it run with the insulation in place as well.

After getting it all insulated, I agree with above that there is only a long/narrow strip of usable storage before the ceiling height gets way too low. I may throw some additional unfaced insulation batts on around the outer section and only OSB floor the center of the garage around the crawl space.

But I'm satisfied with it for the moment.