Wall Insulation Recommendations

[tworley]

Looking to insulate my 2-car garage. The ceiling is insulated already, as is the shared living space wall. The other two walls are exterior walls with 2x4 construction.

Looking at Rockwool RXCB351525. States R15 value and is fire rated. Its about $80 for a batt that covers 60 sq ft. A bit expensive, but its also a recycled material that has no fiberglass (a plus), has a slightly higher R-value than most other brands (R13) and they say can be cut/trimmed with a butter knife.

Any others I should be looking at? The garage currently is just above ambient temps in the winter. I will be installing a 6000w heater that I already have on hand. Probably wont drywall right away.

 

[LukesfirstJeep]

Two thoughts, what are you local building code requirements for residential walls? Although, this is your garage, I would insulate it like it was a inhabited space. Which leads me to my other thought, buy once cry once. After your walls are finished it's too late to replace or upgrade the insulation.

I've been in my house 35 years, and I think my walls are R19 total with 2x4 construction.

 

[FarFire70]

My garage was somewhat similar - once shared wall that's already insulated to the house. 2-car sized door.

I went with:

Johns Manville R-13 Wall Kraft Faced Fiberglass Roll Insulation 40-sq ft (15-in W x 32-ft L) Individual Pack

Cover that with OSB to protect it from spark and allow easier mounting of things to the wall (vs Drywall - plus no spackle).

It's made a huge difference!

A few years later I insulated the garage door with:

Expanded Polystyrene Board Insulation (1-in x 4-ft x 8-ft)

This made a huge difference on top of the wall insulation.

Posted about it here:

Thread 'Garage Door Insulation'

Nov 3, 2024

For those considering insulating your garage door - Do it!

Aluminum garage doors are a serious heat/cold sync!

I insulated all the walls in my garage and held off on the garage door for a year or more. I still felt a chill in the garage - even though the insulated walls made a big impacts.

I went with 1" Polystyrene Board Insulation for the garage door. Lowes #15358

https://www.lowes.com/pd/Common-1-i...ded-Polystyrene-Foam-Board-Insulation/3365576

Installed this a couple years ago and it make...

• FarFire70
• Replies: 11
• Forum: Shop & Tool Talk

• 

I don't run a heater unless I'm painting. Otherwise, maybe longjohns for a full-day stay in the garage for extra warmth but it's comfy most of the year for a few hours out there.

 

[tworley]

Two thoughts, what are you local building code requirements for residential walls? Although, this is your garage, I would insulate it like it was a inhabited space. Which leads me to my other thought, buy once cry once. After your walls are finished it's too late to replace or upgrade the insulation.

I've been in my house 35 years, and I think my walls are R19 total with 2x4 construction.

Minimum is r19 for inhabited I think. I'd have to dig deeper at a computer to verify. The issue becomes depth though, right? A compressed batt of r19 reduces the r-value

 

[tworley]

My garage was somewhat similar - once shared wall that's already insulated to the house. 2-car sized door.

I went with:

Johns Manville R-13 Wall Kraft Faced Fiberglass Roll Insulation 40-sq ft (15-in W x 32-ft L) Individual Pack

Cover that with OSB to protect it from spark and allow easier mounting of things to the wall (vs Drywall - plus no spackle).

It's made a huge difference!

A few years later I insulated the garage door with:

Expanded Polystyrene Board Insulation (1-in x 4-ft x 8-ft)

This made a huge difference on top of the wall insulation.

Posted about it here:

Thread 'Garage Door Insulation'

Nov 3, 2024

For those considering insulating your garage door - Do it!

Aluminum garage doors are a serious heat/cold sync!

I insulated all the walls in my garage and held off on the garage door for a year or more. I still felt a chill in the garage - even though the insulated walls made a big impacts.

I went with 1" Polystyrene Board Insulation for the garage door. Lowes #15358

https://www.lowes.com/pd/Common-1-i...ded-Polystyrene-Foam-Board-Insulation/3365576

Installed this a couple years ago and it make...

• FarFire70
• Replies: 11
• Forum: Shop & Tool Talk

• 

I don't run a heater unless I'm painting. Otherwise, maybe longjohns for a full-day stay in the garage for extra warmth but it's comfy most of the year for a few hours out there.

That is quite a bit cheaper than the Rockwool! My last garage was fully insulated minus the single garage door and I don't think it ever got below freezing in there. I use my garage space mainly on weekends. Yesterday morning it was a balmy 20 degrees in there

 

[FarFire70]

That is quite a bit cheaper than the Rockwool! My last garage was fully insulated minus the single garage door and I don't think it ever got below freezing in there. I use my garage space mainly on weekends. Yesterday morning it was a balmy 20 degrees in there

I posted some measurements of the outside vs inside in that thread I linked.

Garage is very tolerable with my setup. Like I mentioned, maybe longjohns for a full day to avoid 'cold skin but still mobile' effect. But it's about 50* even when mid-30* so I've definitely been t-shirt, hoodie, jeans for a couple hours without issue while moving.

I didn't check out the Rockwell but the insulation I posted would need some sort of covering since it is paper-based (fire hazard without a cover).

The insultation I posted separated really nice (like a good layered biscuit ) to fit around wiring within the walls. Install was fun with it, no headaches for me.

 

[Mike_H]

Spray foam. Just do it, and don’t worry about the cost. I think it’s R-8 per inch, so at 3.5 inches for a 2x4 wall, you’re looking at R-30 total.

My workshop is spray foamed and it is awesome. No wind penetration and it’s insulated enough I just keep my heat on all the time out there at about 65 degrees. Only adds about 25 bucks to my monthly bill.

 

[FarFire70]

Spray foam. Just do it, and don’t worry about the cost. I think it’s R-8 per inch, so at 3.5 inches for a 2x4 wall, you’re looking at R-30 total.

My workshop is spray foamed and it is awesome. No wind penetration and it’s insulated enough I just keep my heat on all the time out there at about 65 degrees. Only adds about 25 bucks to my monthly bill.

How easy is it to run new wiring or pipes for air lines in spray foam?

I'm asking it a curious person. Sounds like you have experience with the spray foam.

I've seeing the application and videos for folks with spray foam but I wonder how upgrades or future upgrades would require more work within the walls...

The traditional insulation I've mentioned just peels back if you need to add or work within the walls.

I'm not against the spray foam but something to consider and I'm curious about anyone who has dealt the foam because I've always had this underlying concern that it doesn't allow you to do this type of upgrade. If you have insight I would welcome it.

 

[Mike_H]

How easy is it to run new wiring or pipes for air lines in spray foam?

I'm asking it a curious person. Sounds like you have experience with the spray foam.

I've seeing the application and videos for folks with spray foam but I wonder how upgrades or future upgrades would require more work within the walls...

The traditional insulation I've mentioned just peels back if you need to add or work within the walls.

I'm not against the spray foam but something to consider and I'm curious about anyone who has dealt the foam because I've always had this underlying concern that it doesn't allow you to do this type of upgrade. If you have insight I would welcome it.

You would have to cut it away, and then add more over top of your new wiring or plumbing, or whatever. I don't know if you've done it, but adding a new run through an existing wall is kind of a pain in the butt anyway...

 

[FarFire70]

adding a new run through an existing wall is kind of a pain in the butt anyway...

Fair point

 

[NWPA Jeepy T]

You would have to cut it away, and then add more over top of your new wiring or plumbing, or whatever. I don't know if you've done it, but adding a new run through an existing wall is kind of a pain in the butt anyway...

If you plywood or osb the walls & screw it on, running wires/plumbing gets easier. If you foam, cut/tear out the foam where you'll be running, then Great Stuff or equivalent (I like Loctite foam) the voids. Foam, especially closed cell, requires less inches to get higher R value. Amazon sells diy kits

https://www.amazon.com/dp/B098R9NM5D/?tag=wranglerorg-20

 

[wigsajumper]

I prefer the Rockwool over fiberglass. Easier to work with. Personally I think it does a better job at sound deading. Supposedly the rodents dislike rockwool.

Insulated our camp with Rockwool this summer. I didn't use a butter knife to cut it but a nice 12" bread knife worked perfectly.

Should wear long shirt sleeves and something to protect your lungs.

 

[Mike_H]

If you plywood or osb the walls & screw it on, running wires/plumbing gets easier. If you foam, cut/tear out the foam where you'll be running, then Great Stuff or equivalent (I like Loctite foam) the voids. Foam, especially closed cell, requires less inches to get higher R value. Amazon sells diy kits

https://www.amazon.com/dp/B098R9NM5D/?tag=wranglerorg-20

Yeah, in my shop, I did OSB on the walls, and use conduit to move existing 220 outlets or as new circuits. Ran black pipe for my gas line externally too. It’s possible to get back into the walls, but low reward for the effort.

 

[tworley]

I looked at the spray foam. For a garage I spend a few hours in on the weekends it seems a bit costly. I wont rule it out, but I need to research it a bit more. I've only got the two walls (350 sq ft +/-) to cover. So it wont be too expensive going the batt route. I'll spend more time taking off whats currently mounted to each wall.

I haven't decided on walls yet; OSB or sheetrock. OSB would be nice to mount things to.

 

[LukesfirstJeep]

Minimum is r19 for inhabited I think. I'd have to dig deeper at a computer to verify. The issue becomes depth though, right? A compressed batt of r19 reduces the r-value

Depth can be an issue. There were two different insulations for 3 1/2 walls when I built, in 1998 One had a significantly higher R value than the other. I chose the one with the higher R. Compressing a 6" insulation in a 3 1/2" cavity defeats the purpose.

I don't know what permits, if any , are required where you live, but many municipalities frown upon flammable material, like OSB, to be used for finished walls. The last statement is a "Do as I say, not as I do" thing. I installed 6" fiberglass insulation in my garage ceiling, and covered it with foil covered foam board. By today's standards, this is frowned upon.

 

[tworley]

Depth can be an issue. There were two different insulations for 3 1/2 walls when I built, in 1998 One had a significantly higher R value than the other. I chose the one with the higher R. Compressing a 6" insulation in a 3 1/2" cavity defeats the purpose.

I don't know what permits, if any , are required where you live, but many municipalities frown upon flammable material, like OSB, to be used for finished walls. The last statement is a "Do as I say, not as I do" thing. I installed 6" fiberglass insulation in my garage ceiling, and covered it with foil covered foam board. By today's standards, this is frowned upon.

I've already got my outlets and panel mounted and protruding out 1/2" to account for some sort of wall cover. I don't think I want to re-do those to try and increase cavity size

R15 is all I can find for 2x4 walls. I'm leaning more and more to the Rockwool. The local Lowes has 55 bags in stock too.

I've seen multiple houses in my subdivision with OSB walls. I recall looking for the code a few years ago and IIRC, only a shared living space wall required 5/8" fireproof gypsum. I dont recall any language for just exterior garage walls.

 

[B1Toad]

The nicest garage I ever saw had sheetrock first then real plywood (not OSB) all the way around the bottom up to 4' high. When I built mine I didn't want sheetrock and didn't want to spend the money on real plywood so I used OSB. The city did require the OSB on the common wall to be 5/8" but 1/2" was OK everywhere else.

My insulation was Ecobatts R-38 in the 12" ceiling and I believe R-21 in the 2x6 walls, keeps it pretty cool in the summer which is the main objective where I live.

Before closing up walls consider running some empty conduits into J-boxes with blank covers for future things like welders and EVs.

 

[BlueC]

A compressed batt of r19 reduces the r-value

Correct. You also need to know faced vs unfaced moisture barrier for your local area. Do it wrong, and you'll build up moisture behind it. Fiberglass will be easiest, blown will be cheapest if you're putting up walls, mineral (rock) wool will be most effective and will also aid in noise insulation.

I looked at the spray foam. For a garage I spend a few hours in on the weekends it seems a bit costly. I wont rule it out, but I need to research it a bit more.

I don't like spray foam in wall cavities of existing structures. In an open garage, especially a metal frame, not that big of a deal. In a new structure that's built super tight, maybe. But I've seen spray foam put in existing wall cavities wreck a few houses. The first time I saw it was in a house built in the '80s. The owner had been talked into insulating with spray foam. Well, apparently there was a leak somewhere that no one knew about until it blew out at the bottom of his exterior wall about a year or two after insulating. A home inspector had found another area that was doing the same, so the homeowner was attempting to have the foam removed, and that was going to be a major job. Since then, I've had a few home inspectors tell me about damage done by spray foam. I know leaks happen in any wall, but the foam seems to hide it until it's too late.

 

[tworley]

I bought the R15 rock wool. Picking it up this afternoon.

Still trying to figure out if a vapor barrier is required. My current shared living space wall does not have a vapor barrier. I tore out one section of drywall last year to repair a drain vent pipe and there was no vapor barrier. Only a thin, silver, cardboard type material in front of the existing insulation. I installed a coax outlet in our living room on the opposite side of the house that is an exterior wall and that too did not have a vapor barrier. Only the same thin, silver cardboard type material and existing insulation.

 

[DuckNut]

Spray foam. Just do it, and don’t worry about the cost. I think it’s R-8 per inch, so at 3.5 inches for a 2x4 wall, you’re looking at R-30 total.

My workshop is spray foamed and it is awesome. No wind penetration and it’s insulated enough I just keep my heat on all the time out there at about 65 degrees. Only adds about 25 bucks to my monthly bill.

Spray foam insulation was big here in FL and elsewhere for several years.

Now it has turned ugly. Insurance companies are starting to claim these are uninsurable.

My feeling is it is good stuff overall. If is gets wet, it is horrible. It will never dry out, rot everything it is in contact with. Absolute destruction if it gets wet.