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Best way to insulate an existing attached garage?

Pony_Driver

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My 2 car garage is inset with my house, call it 50/50 for the two wall that share wall with room in my house. They are insulated but I'm 99.99% sure nothing else is, to include the ceiling. I would like to put insulation in the walls and over the ceiling so I can install a mini-split for moisture control.

The garage is finished and painted,.
"Best" meaning best without tearing everything out and starting over.

How would you go about it?
 
Is cost a factor? I know on my house, it's a '52 build and the insulation was poor at best when it was built. Sometime in the 90s I imagine they drilled through the brick in spots and injected it with foam? I would start with the ceiling first and if you want to DIY it, rent the blower from HD and blow insulation in, that will be your most bang for your buck on the ceiling. Make sure to install the Styrofoam soffit vents before you blow in insulation!
 
Cost is a factor as always or I'd just rip it all out and replace it. The house was built in the 90s. Blow in insulation is probably the easy answer for the ceiling, but what about the wall cavities?
 
Cost is a factor as always or I'd just rip it all out and replace it. The house was built in the 90s. Blow in insulation is probably the easy answer for the ceiling, but what about the wall cavities?

2x4 or 2x6 studs?
 
Can you cut into the wall at the top below the top-plate and fill the wall with blow-in?

I lived in an old ice-house and the walls were filled with sawdust. In our case, we cut a hole for a range exhaust and the sawdust just kept coming out of the hole. :D
 
(Untitled)

im having a local insulation company do my 30's era house with blow in cellulose(?) insulation, requires a 2" hole between each stud. the price for the entire house was reasonable so a couple walls should be cheap.
 
tear the sheeting off the inside and patch up all the holes in the studs that'll let MAUS move through the walls
then pack the shit with fiberglass batts

blow-in is a mess when you end up needing to fix anything
also a lot of times the ceiling will not be specced for supporting insulation if it wasn't insulated to begin with, so you might end up needing to put another layer of 5/8" drywall up in order to support the cellulose
 
I could drill a hole in the studs. Tearing it all out and putting in batts is a non starter. I would need another garage to to house all of my stuff while it was happening. How much does blow in insulation weigh? I don't want to rehang drywall there either. I don't mind sinking in extra drywall screws in the existing ceiling.
 
My dad drilled holes in the top of each section in his garage and blew insulation in as he didn’t want to gut his either. He never went back and closed the holes, but it’d be minimal work to do so.

You could do the same for the walls.
 
[486 said:
;n243801]tear the sheeting off the inside and patch up all the holes in the studs that'll let MAUS move through the walls
then pack the shit with fiberglass batts

blow-in is a mess when you end up needing to fix anything
also a lot of times the ceiling will not be specced for supporting insulation if it wasn't insulated to begin with, so you might end up needing to put another layer of 5/8" drywall up in order to support the cellulose

Man, reading this has me worried now. I’m not a drywall guy. My building is trussed 16” OC and I used 3/8” drywall in my ceiling. I LOADED every sheet with a shitload of GRK screws, but the guys that blew in the cellulose gave me about 12-14 inches of insulation.

Now I’m thinking all my lights and conduit need to come down and I need to do another layer of thicker drywall. Fuck!
 
Man, reading this has me worried now. I’m not a drywall guy. My building is trussed 16” OC and I used 3/8” drywall in my ceiling. I LOADED every sheet with a shitload of GRK screws, but the guys that blew in the cellulose gave me about 12-14 inches of insulation.

Now I’m thinking all my lights and conduit need to come down and I need to do another layer of thicker drywall. Fuck!

I wouldn't fuck with it unless it starts to sag.
 
im having a local insulation company do my 30's era house with blow in cellulose(?) insulation, requires a 2" hole between each stud. the price for the entire house was reasonable so a couple walls should be cheap.

Ive done 6 houses this way. You dont need a two inch hole. We do 1" holes at the top and bottom of the cavity between studs. Hopefully you dont have fire breaks. All the houses Ive done have had wood siding and we used the little plastic plugs that snap in and painted over. If the nozzle on the machine is bigger. Use a pastic funnel taped on the end to make it smaller.

Figure out how much you need the coverage is on the bags. You can always buy more than you need to get the free machine rental and then return what you dont use (per the HD counter guy).

Blow in from the bottom till it blows out the top hole youll know when its full. It comes in bagged compressed blocks, break it up as you put it in and make sure the chopper is keeping it loose. It wont take long to do that area. I did a 1800 sq ft ranch in two days.
 
Man, reading this has me worried now. I’m not a drywall guy. My building is trussed 16” OC and I used 3/8” drywall in my ceiling. I LOADED every sheet with a shitload of GRK screws, but the guys that blew in the cellulose gave me about 12-14 inches of insulation.

Now I’m thinking all my lights and conduit need to come down and I need to do another layer of thicker drywall. Fuck!

Youll be fine as long as it doesnt get wet, but 3/8 drywall is going to sag if it gets wet anyway. Youre 16" on center and that insulation is only a couple pounds per square foot.
 
It can be blown in the walls also a 2" hole near the top in-between each stud is all that is needed and it has more R value than batt insulation
 
Youll be fine as long as it doesnt get wet, but 3/8 drywall is going to sag if it gets wet anyway. Youre 16" on center and that insulation is only a couple pounds per square foot.

I counted my screws as well...I have 35 GRK screws in each sheet. :laughing:
 
I counted my screws as well...I have 35 GRK screws in each sheet. :laughing:

brand of screws really doesn't matter in drywall
all it's doing is holding a sheet of paper that contains a bunch of gypsum

you did put them in without tearing through the paper, right? :flipoff2:
 
[486 said:
;n247036]

brand of screws really doesn't matter in drywall
all it's doing is holding a sheet of paper that contains a bunch of gypsum

you did put them in without tearing through the paper, right? :flipoff2:

90% of them, yes. Some of them got away from me.
 
lol
when I was hanging my 5/8 I put screws in every inch to two inches

mainly because that shit's waaaay fucking heavy and I kept popping them through
we'll see how well it holds up

ETA:
it was 1/2" with maybe 10" of blow in atop it, 24" OC and it was sagged down maybe 1/8" between studs
 
Some good and some bad info going on here....
3\8 lid????:homer:
2 layers of 5\8 to hold up insulation on the lid???:homer:
2" centers??:lmao:
carry on home depo warriors
 
Some good and some bad info going on here....
3\8 lid????:homer:
2 layers of 5\8 to hold up insulation on the lid???:homer:
2" centers??:lmao:
carry on home depo warriors

nonono it is a layer of saggy ass 1/2 and a layer of very poorly installed 5/8
half the screws weren't doing anything, you try holding 3/4 your body weight on your head while operating a drill and putting way too long of screws into way too dried out of wood
 
You answered the time old question....
As Larry said























You can't fix stupid!:flipoff2:

Reskinning a lid is simple math layer 1 + layer 2 thickness plus add say 3\4-1" for the working end of the fastener.
using a QUALITY rock gun makes it much easier.
(not rocket science)
Guys break the membrane due to either wrong tools or operator error.
And tapers h8 it.
Same with any gap +1\8" ...

My rockers could hang and hold a sheet with 6 nails....
Of course using a lift makes it idiot proof:lmao:

Op you doin this or writing a check, seems like you are doing it.
 
Last edited:
Reskinning a lid is simple math layer 1 + layer 2 thickness plus add say 3\4-1" for the working end of the fastener.
.
but then you add into the equation that I got a 25lb bucket of 2.5" coarse thread screws for 20 bucks
and the house seems to be mainly framed with white oak

least it ain't ca :flipoff2:
 
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[486 said:
;n247484]
but then you add into the equation that I got a 25lb bucket of 2.5" coarse thread screws for 20 bucks
and the house seems to be mainly framed with white oak

least it ain't ca :flipoff2:

Next time make a "T" out of 2x and use it to hold the sheetrock up. Ive hung many 5/8s board overhead by myself this way. Easy peasy.
 
The real question is... do you have a vapor/water barrier around the outside?

My garage is T1-11 directly on the studs on two walls, and tar paper on the other two walls. Everything I have read suggest if I throw insulation in there i am going to get into wood rot issues...
 
The real question is... do you have a vapor/water barrier around the outside?

My garage is T1-11 directly on the studs on two walls, and tar paper on the other two walls. Everything I have read suggest if I throw insulation in there i am going to get into wood rot issues...
Sprayfoam the inside of the T11/studs, put in 3/4" to 1" of closed cell, then put your batts inside of that.

Aaron Z
 
The real question is... do you have a vapor/water barrier around the outside?

My garage is T1-11 directly on the studs on two walls, and tar paper on the other two walls. Everything I have read suggest if I throw insulation in there i am going to get into wood rot issues...
1930s thinking:
don't run a vapor barrier on the inside, and a permeable enough inside sheeting so you get enough airflow through the wall to dry up any condensation
 
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