I am not going to call anybody out. My math does the talking for me.
Can I compress insulation?
- Thread starter StaggeringGoat
- Start date
I am not going to call anybody out. My math does the talking for me.
bczygan
Well-known member
I'm a builder. We have always avoided compression to get maximum R value for the products we had, which were designed for standard 2x4 and larger 2x6 spaces. Now, with higher fuel costs, people are trying to find ways, and manufacturers are following with products, to optimize R value in these spaces. To a builder it all comes down to dollars and cents. And so it is for most of us. If the OP does some calcs, he can determine the best use for the materials he has available based on their cost and quantities. He may want to also consider using this thicker material in his ceiling, especially if it is un-faced. Yes, you can get higher R values by compressing FG insulation to a point. With new material at retail prices is it cheaper to compress a batt made for a thicker wall, than using the new higher density materials made for that wall? I don't know. Do the math and find out.
rsa
Well-known member
Make your wall cavities 6.5" thick.
ddawg16
Well-known member
Kevin C
Well-known member
I purposely went with 2 x 4"s for my walls. However I still want to get the maximum R value in that cavity, so for me this is good info.
Why not frame it out to 2 x 6's? I'm facing the wall with 2" foam sheeting. The goal is to reduce thermal breaks. Its ends up the same thickness as a if I had used 2 x 6's but should insulate a lot better.
Spacers is a option for the OP, assuming that adding 60 or so 2" x 2" x 8' spacers does not add too much to the cost. I would guess about $ 200 or so in materials.
There has been much disagreement mostly based on initial assumptions and the difficulty of trying to explain concepts over the internets. If we were all in the same room I have no doubt we could agree on common ground. I don't see any "******* match" in this thread. So don't go trying to make out something that has not been there. This thread should end so go Copper on the another thread.
Kevin C
Well-known member
Pretty mild climate. The garage will be standing for a long, long time so I dont have a problem with spending a few extra dollars on something I will get a lot of long term usage out of. I would rather over-insulate and have a shop that's easy to heat and cool than have any regrets later. Once the sheet rock is up its hard to make changes.
The context of my statement is maximum R value using fiber glass insulation bats The cost difference should not be that much. For the fiber glass I'm looking for R15 in my 2 x 4 walls.
If I was going crazy, I would get the walls spray foamed. What ever I end up doing, it will be done to code for an occupied building ( I'm in zone 4 , marine that should be R13 + R 3.8 or R20).
On top of the studs I plan on putting 2" foam to insulate and help with sound dampening. The goal is to reduce thermal bridging. Even the concrete floor has R10 insulation under it.
We will get cold snaps in the mid 20's. I eventually plan on using some solar heating. We do have occasional hot weather. The past week it stayed in the high 90's ( high of 102f). This is all about having a comfortable shop.
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Kevin C
Well-known member
Falcon67
Well-known member
FWIW in a shop sense - recommended here is R49 attic, R13 walls. The shop is 960 sq/ft and has R13 in the 2x4 walls and R13 in the ceiling. The ceiling is just faced batts laid between the joists as the OSB was already up. There's room for more (joists are 2x12), but I was on the cheap, get 'er done. Ceiling is OSB with joints caulked. Walls are OSB, kraft stapled to the studs before the OSB went on the walls. Door is uninsulated steel 16x7 with "R3" 1/2" foam board in the panel spaces. The building has 5 windows 2-0x3-0 double pane low E. Man Door is steel insulated and foamed in. Ceiling height is 8'. 24x40, long walls face nearly north/south. 3 windows N, 2 S, big door is S.
It's been cold for us - barely 45 on Saturday, 40 Sunday, 30s and overcast last two days, every night mid 20s except Monday AM when it was 18F. Last night in the building - no heat - it was 50F. That is the coldest it's been this winter and it's usually 55. Turned on the 17K BTU electric and the 28K BTU propane and in 30 minutes it was 66.
It's been cold for us - barely 45 on Saturday, 40 Sunday, 30s and overcast last two days, every night mid 20s except Monday AM when it was 18F. Last night in the building - no heat - it was 50F. That is the coldest it's been this winter and it's usually 55. Turned on the 17K BTU electric and the 28K BTU propane and in 30 minutes it was 66.
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