Garage insulation question

[JK#2]

I dont post here ofter, just do a lot of reading. I have a standard 2 car garage with attic space. It dawned on me the other day while cleaning it out why it was always cold. Theres no insulation over it. Evidently, the previous owner removed all insulation for some reason (Pest control? there were a few cans of bug fogger up there). So my question is this: Do I put faced or unfaced insulation down between the joists? I'm not looking for living space type warmth, just a more comfortable area in the winter. Also, this attic space opens up to my kitchen attic space. Would a "barrier" between the 2 areas help with heating costs or is it not worth it?

 

[Zeke]

This should not share an attic over a living space for fire reasons. Wall it off.

Typically the face is towards where you are.

 

[JK#2]

This should not share an attic over a living space for fire reasons. Wall it off.

Typically the face is towards where you are.

So facing down onto the sheetrock?

Walling off the opening will be hard since thats the access to the rest of the attic space into the house.

 

[Zeke]

If you have SR you can just buy batts. I like the ones that are fully wrapped.

I won't say anymore on the firewall.

 

[eegger]

you should used unfaced or blown in type insulation. What kind of attic insulation does the rest of the attic have?

 

[JK#2]

you should used unfaced or blown in type insulation. What kind of attic insulation does the rest of the attic have?

right now its just sheetrock and joists, no insulation at all. I thought about blow-in but I need to keep some storage space up there.

 

[Rusted Nut]

Unless your garage roof is wood shingles without a vapor barrier, you do not want or need a vapor barrier in the garage ceiling. Wood shake, tile, and comp roofs all have vapor barriers. Used unfaced or blow in insulation.

I agree with Zeke on building a fire wall between garage and house. 5/8” type X drywall with one coat of mud works.

 

[billconner]

So facing down onto the sheetrock?

Walling off the opening will be hard since thats the access to the rest of the attic space into the house.

If there is a drywall ceiling in garage (and probably drywall on common wall with house) you're probably fine. Ceiling should be 5/8" type x, and just ordinary 1/2" on wall.

 

[billconner]

Attic/storage is and will remain uninsulated? Trusses or rafters? Attic accessed from house, not through garage? No flooring in attic, now or planned?

I think you're fine fire wise. I would put paper faced insulation - face down on drywall between ceiling joists - but it's a small issue. A tight fitting install with no gaps and no compression more important.

 

[Leaflessshadetree]

Faced insulation with the face down (and stapled along the edges). Another option is blown in over a vapror barrier. I expect you will notice a difference in the house. It will help a lot if you are heating the garage.

 

[stubbsrodandcustom]

I will tell you this from my experience. My garage is an attached 2 car built in the 70s, it is like yours where attic shares space as most attached do. With that. I had more insulation added to my house. 20" total insulation in the house, 10" in the attic space. I went blow in due to thats what the house already had installed plus when you buy enough bags they rent you the machine for free when I did it. I then had an attic stairwell added in the garage and decked about 10' up there, its very short under the trusses but army crawl to the back if you need to but I would do an attic stairwell first before insulating honestly but deck after. The decking squished the insulation down that was above the joists. I have complete ac and heat in my garage and it maintains very nice in there. Hope this helps.

 

[NUTTSGT]

If you're using it for storage or needing to go past it for storage, I think you will regret the (PITA) blown cellulose. I'd buy rolls of faced fiberglass and cut to length rather than pre cut batts.

 

[u2slow]

If there's poly between the drywall and ceiling joists, the VB is taken care of and you don't need facing on the batt insulation.

Since I put R22 in the shop walls, I'm going with R40 in the ceiling. Storage is not in the picture... I barely trust my own weight on these skimpy engineered trusses.

 

[PCMusicGuy]

I doubt it was removed by anyone. It is standard building practice to not insulate the garage ceiling or any garage exterior wall. I'd just do a bit of blown in and call it a day. It's likely that your garage has a exterior wall that is finished on the inside, and there are very few good ways to insulate that without tearing out and redoing sheetrock. Insulating the ceiling alone will definitely help.

 

[bigdav160]

What PCMusicGuy said. Insulation is for climate controlled space which garages are typically not.

Are you intending to run heating or A/C in garage? Then insulate it. If you are not then inulation will have a placebo effect only.

 

[NUTTSGT]

What PCMusicGuy said. Insulation is for climate controlled space which garages are typically not.

Are you intending to run heating or A/C in garage? Then insulate it. If you are not then inulation will have a placebo effect only.

On the contrary, insulating an attached garage does more than give a placebo effect. If you insulate and keep the doors shut, it will hold some heat and can be 10-15° warmer inside than the outside temps. If you're one of those that opens your garage door and leaves it open all day, than you are wasting your money.


While 10-15° may not seem like much, consider one wall of your home facing a warmer exposure than the rest. It'll help with heating your home in the winter. It's much like a business having a double door in the entry way.

 

[bigdav160]

Where is your heat source? Perhaps up north where you have deep footings? I imagine Oklahoma it's slab on grade and the ground isn't significantly different than the air temp. I don't think I've seen garage doors with seals near me.

 

[Jeepster04]

right now its just sheetrock and joists, no insulation at all. I thought about blow-in but I need to keep some storage space up there.

Are you saying your entire house is not insulated in the attic? Why are you worried about the garage?

You can at least fill up the space between the joists and still have storage space on top of the joists. Use blow in, no vapor barrier.

On the contrary, insulating an attached garage does more than give a placebo effect. If you insulate and keep the doors shut, it will hold some heat and can be 10-15° warmer inside than the outside temps. If you're one of those that opens your garage door and leaves it open all day, than you are wasting your money.


While 10-15° may not seem like much, consider one wall of your home facing a warmer exposure than the rest. It'll help with heating your home in the winter. It's much like a business having a double door in the entry way.

My garage stays in the high 40's/low 50's unless the temp outside drops into the low 20's/teens. Ive used an IR temp gun and the concrete is always around 50F in the winter. I rarely heat it with a couple electric heaters when I'm out there. R13 in the walls and maybe a bit over that in the attic.

 

[racecougar]

Where is your heat source? Perhaps up north where you have deep footings? I imagine Oklahoma it's slab on grade and the ground isn't significantly different than the air temp. I don't think I've seen garage doors with seals near me.

The slab is a serious heat sink here in MO; meaning it provides some heat in the Winter and some cooling in the Summer. It's amazing how little heating/cooling is needed with a well insulated garage here.

Are you saying that garage doors do not have seals in Texas?

 

[Ak Jim]

Saying “well we just don’t do that here” is no excuse to not doing things better.

 

[NUTTSGT]

Where is your heat source? Perhaps up north where you have deep footings? I imagine Oklahoma it's slab on grade and the ground isn't significantly different than the air temp. I don't think I've seen garage doors with seals near me.

Footers are at frost depth, local depth. Heat source, nothing other than the heat from the vehicle engine.

 

[Mike65]

I will tell you this from my experience. My garage is an attached 2 car built in the 70s, it is like yours where attic shares space as most attached do. With that. I had more insulation added to my house. 20" total insulation in the house, 10" in the attic space. I went blow in due to thats what the house already had installed plus when you buy enough bags they rent you the machine for free when I did it. I then had an attic stairwell added in the garage and decked about 10' up there, its very short under the trusses but army crawl to the back if you need to but I would do an attic stairwell first before insulating honestly but deck after. The decking squished the insulation down that was above the joists. I have complete ac and heat in my garage and it maintains very nice in there. Hope this helps.

I noticed from the times I have been in our attic that it is open to the space over the carport, & there is no insulation over the carport just over the living space in the attic. Should I insulate it or close it off?

 

[stubbsrodandcustom]

I noticed from the times I have been in our attic that it is open to the space over the carport, & there is no insulation over the carport just over the living space in the attic. Should I insulate it or close it off?

Honestly if your garage is insulated in the roof, and the house is, the carport really doesn't need to be. You could wall it off if your wanting to but I see no benefit on you doing anything to it unless your wanting to separate the spaces in the attic etc. My buddy has a lift in his garage, he used the attic above his carport for storage since he lost all his other attic space. He just decked it and let it ride. Works great.