Insulating overkill?

[Mark100]

Hello,

While I sit home and think about all the projects I cant get finished with this shutdown, I'm contemplating air sealing my new garage with spray foam. I am looking at the DOW great stuff spray kits online. I have seen some videos of people using the foam to seal each stud bay, top plates and bigger gaps prior to batt insulation. I will be heating the garage during the winter full time.

Is this overkill?

Should I just do the normal gaps and cracks?

Would there be a downside to sealing the studs to the osb? Wood expansion concerns?


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[PhantomEB]

Probably overkill but all I can say is with R22 in the wall, R16 door, and R50 in the ceiling, it don’t matter what it is outside, I am comfy inside my 24 square.

 

[acer66]

The greater your indoor temperature differs from the outdoor temperature the more it makes sense to go all guns blazing especially when you want do that 24/7.
Even small gaps and cracks can result in significant losses of your r values.

 

[matt_i]

Air sealing is big. Imo that's where most heat escapes.

I think you could get 80% of the way there with going wild with caulk tubes on the framing and it would cost several hundred less. Of course you'd have to do batts or other but the spray foam seems like the Caddy.

 

[u2slow]

While I sit home and think about all the projects I cant get finished with this shutdown, I'm contemplating air sealing my new garage with spray foam. I am looking at the DOW great stuff spray kits online. I have seen some videos of people using the foam to seal each stud bay, top plates and bigger gaps prior to batt insulation. I will be heating the garage during the winter full time.

The Dow Froth Pak? For the money, you can buy a LOT of rattle cans. I've taken to using batts or rigid insulation for everything (plus VB w/tuck-tape where applicable) and only use the spray foam for joints and crevices.

 

[Mark100]

The Dow Froth Pak? For the money, you can buy a LOT of rattle cans. I've taken to using batts or rigid insulation for everything (plus VB w/tuck-tape where applicable) and only use the spray foam for joints and crevices.

I was looking at the dow pro, it's like the regular rattle cans with tube attached but this is a gun and the cans screw on to it. Seems to have better control and can be cleaned after use.

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[Black Oak]

I' m the poster child for over kill . Fate blessed me with a mountain of free 2x2 and 2x4 stock , and ripped enough down to apply 2" x 2" stock on all studs and top/bottom plates . With 5" deep stud bays installed 1" rigid foam . Cut on the table saw , as tight as possible . Home Depot sells a small DIY spray foam kit that covers about 20 sq. ft. - comes in a small box . It was $39 . Then sprayed 4 corners , around the doors , etc. - and a few problem spots . It was a lot of effort for a marginal gain in R-value , but really helped air infiltration . That's what I was after .

 

[Mark100]

I went with 2x6 studs for a couple reasons. I plan on using r19/21 there. The spray foam would be to just seal the stud to the outside plywood and any gaps where they meet.

I' m the poster child for over kill . Fate blessed me with a mountain of free 2x2 and 2x4 stock , and ripped enough down to apply 2" x 2" stock on all studs and top/bottom plates . With 5" deep stud bays installed 1" rigid foam . Cut on the table saw , as tight as possible . Home Depot sells a small DIY spray foam kit that covers about 20 sq. ft. - comes in a small box . It was $39 . Then sprayed 4 corners , around the doors , etc. - and a few problem spots . It was a lot of effort for a marginal gain in R-value , but really helped air infiltration . That's what I was after .

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[scottydosnntkno]

is it attached to the house or detached?

either way, air sealing is really going to not be worth the money to foam the entire thing with an OHD. even on my brand new house, with brand new clopay 5 panel overlay doors (big $$$$$'s), with upgraded weather strips, with green hinges, and brush guards inside, on a windy winter day you can still feel a big draft coming in them, which negates all the air sealing i did to the garages when we built the house.

we used several hundred great stuff pro cans, and sealed each stud to the sheathing, between osb sheets, etc. and caulked the top and bottom plates to the floor and to eachother. and used the foam drywall adhesive so that was also all sealed up. my house blower doored better than my friends which was entirely done with 4" CSF that he spend 40k on.

while it will marginally help a little, in the long run for a garage its really not worth the expense. you might save $10 a month in heating, but if its a regularly used garage, every time you open the door you lose all the air sealing benefit.

 

[Mark100]

The new additional garage is detached. I have two OHDs, a 10x10 and a 16x10. Both are good quality and insulated but they are still garage doors. The garage will store my boat and non-daily driver truck, so the doors will not be opened regularly in the winter.

is it attached to the house or detached?

either way, air sealing is really going to not be worth the money to foam the entire thing with an OHD. even on my brand new house, with brand new clopay 5 panel overlay doors (big $$$$$'s), with upgraded weather strips, with green hinges, and brush guards inside, on a windy winter day you can still feel a big draft coming in them, which negates all the air sealing i did to the garages when we built the house.

we used several hundred great stuff pro cans, and sealed each stud to the sheathing, between osb sheets, etc. and caulked the top and bottom plates to the floor and to eachother. and used the foam drywall adhesive so that was also all sealed up. my house blower doored better than my friends which was entirely done with 4" CSF that he spend 40k on.

while it will marginally help a little, in the long run for a garage its really not worth the expense. you might save $10 a month in heating, but if its a regularly used garage, every time you open the door you lose all the air sealing benefit.

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[NUTTSGT]

I'd say go for it.

IMHO, unless you are approaching R40 it's probably not overkill. Insulation is an investment. Every time you fire up the heat or kick on the AC, it's paying you back.


I'll be starting an garage expansion this summer, adding a 12x18 bay for my John Deere. I will be spray foaming (Great Stuff) the bottom and top of each stud cavity. I did this previously in the garage attic and again in the utility room of the house. It does stop air flow in the walls.

 

[scottydosnntkno]

The new additional garage is detached. I have two OHDs, a 10x10 and a 16x10. Both are good quality and insulated but they are still garage doors. The garage will store my boat and non-daily driver truck, so the doors will not be opened regularly in the winter.

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on a detached, its really not worth it then.

on an attached, the marginally less air leakage is beneficial to help mitigate the loss of residual heat from touching the heated house. if your getting 20k btu in thermal gain from the house, if you can cut even 2k btu or 10% of your loss your doing pretty good.but on a detached, where your getting no "free" thermal gain, and have two rather large garage doors, the doors are going to leak more air than you'll ever offset cost wise with the extra spray foam.

it would be akin to opening a window in the middle of winter, while holding a candle in your hand. sure the candle is giving off a little heat, but your losing 20x that much by the cold air blowing in.

plus, its all relative depending on where you live, heat source, etc.

our old house was 2900ft of living space (house and basement) and a 200ft garage that was heated with a 50k btu, 80% efficient hot dawg. it had a insulated door, but no ceiling or wall insulation and the door leaked air like crazy (visible light gaps) . our NG bill was ~160/mo on a budget plan(yearly usage split over 12 mo).

our new house, is 7,100 sq ft (including basement), with a 1200sq ft attached heated garage, and a 800ft attached heated garage, both sharing a 110k btu residential type furnace (98% efficient). all the latest and greatest, 2x6 with the air sealing i mentioned, r23 walls, r60 ceilings, EXTREMELY low air changes as noted. our new heat bill for NG? $220/month.

or, 5.1 cents/sq ft/mo vs 2.5 cents / sq ft / mo. so our new heat bill is literally HALF of our old one. 20 years newer construction makes a big difference.

my point is, if your going to pay say $80/mo to heat the new garage, spending $800 on spray foam to save $3/mo is going to take a really really long time to pay itself back.

 

[rayra]

Air sealing is big. Imo that's where most heat escapes.

I think you could get 80% of the way there with going wild with caulk tubes on the framing and it would cost several hundred less. Of course you'd have to do batts or other but the spray foam seems like the Caddy.

Yep and start at the very top and work your way down. That way if you run out you've at least got the most important part done.