Insulating existing drywall walls in attached garage.

[MPOWERD]

I have an attached garage where only the attached wall is insulated. The remaining walls are finished (drywalled, taped, and bed, plus painted) but not insulated. The ceiling is easy as the attic space above is very tall and easy to put insulation down.

Is there a practical way to insulate these walls without tearing out the (just a few years old) drywall walls?

I did a forum search on this but came up empty...

 

[danski0224]

Blown in insulation.

Round holes are cut in the insulation, stuff is blown in, foam plugs are inserted and then covered with wallboard tape and drywall mud.

Things like irregular stud spacing and fireblocking can cause problems. The insulation can settle.

You will get a better job by tearing off the drywall and insulating normally.

Be sure to price the job out both ways.

 

[Higgins]

They will cut ~ 1 1/2" hole in the walls, and blow in the insulation! If your worried about the insulation settling, you can install some decorative trim over the holes, and paint the trim a decorative color! It's an easy project! That would allow you to add more if needed down the line!

It's a lot easier have someone blow in insulation as apposed to tearing down the drywall, installing insulation, install drywall, tape and paint! Not to mention the time! Or spend the $1,200 - $ 1,500 on top of the insulation cost!

 

[St-rider]

blown-in insulation can be done from outside also (if it's not brick). same way as from inside except the top piece of siding is removed, a hole in the wall put in, plugged and siding replaced.

 

[QMXcycle]

I just did blow in for my 24 x 24 detached. The main reason was cost. My walls are 2x4 studs so I could have had R14 with conventional fiberglass bats or R12 with weathershield blow in, the blow in was about 40% cheaper. I put up my vapor barrier then blew in through holes that I tuck taped after. It was a pain and took a long time but again, cost was the biggest incentive. The insulation did settle after a week or so but just a little. My plan is to cut holes next fall and top it up again, just to be sure, and blow a few more bags into the attic while I have the machine in my shop. It was easy, one man operation, I did the entire shop, walls and attic (40 bags) in 10 hours, it was messy though but it was also cheap. one thing to be weary of, you cant see whats going on behind that drywall, I noticed my insulation always got caught up on just about everything, wireing, potruding nails etc, if you dont remedy this you will wind up with pockets of no insulation.

 

[Scerb]

If you do blown insulation, you will need a professional machine to do it. The rentals at lowes/HD are not powerful enough to blow in walls, they are only good for open attic blowing.

You can get blown fiberglass which they say does not settle. Supposedly you can pack in Optima the most, making it settle the least although Insulsafe is a little cheaper and you probably wouldnt be able to tell any difference (especially since theres some guess work anyways blowing behind drywall).

 

[duneslider]

You can also have expanding foam blown in. It is more expensive but works great.

 

[James-W]

I guess it all depends on what you want and on what your budget is for the job. If you want to go cheap, then blown-in insulation would work out the best. Even though the blown-in insulation may get hung up and leave some areas where you have no insulation at all, overall the garage will be insulated much better than what it is now. If you want a first rate job and insulate the garage as best as possible, then you will need to remove the old drywall. It will definitely cost more money to do it that way, but I have a feeling that once it is done you will be happy you did it.

The spray foam insulation is wonderful stuff, the cost is rather high, but it works super good and it may be something you want to consider.

 

[Mr.N]

If you do blown insulation, you will need a professional machine to do it. The rentals at lowes/HD are not powerful enough to blow in walls, they are only good for open attic blowing.

It looks like the different stores carry different machines to blow in insulation.

Is there one insulating blowing machine form a home store better than the others?
Any ratings published?

I've seen an older unit that had a reducer for the end of the hose to blow into walls.

The AttiCat seem populare around here, but I've seen some older machines.

I like that the AttiCat give some numbers on installing in walls: Link
Walls - Bag Weight 28.5 Lbs.
R-Value
.....Minimum Bags Per 1,000 Sq. Ft.
.............Maximum Coverage Per Bag in Sq. Ft.
....................Minimum Weight in Lbs./Sq. Ft.
.............................Minimum Initial Installed Thickness in inches
....................................Installed Density Lbs Per Cu. Ft.
13...13.3 75.2 0.379 3.5 1.3
15...15.4 65.1 0.438 3.5 1.5
21...20.9 47.8 0.596 5.5 1.3
24...29.0 34.5 0.825 5.5 1.

I did read an article that suggested extending smaller tubing into the wall cavity and use a "flexable spa tubing" to help dispate the fill.

I think on a this old house they talked about drilling out a hole on the bottom & the top, fill from the bottom first.

 

[matouse3]

If you do blown insulation, you will need a professional machine to do it. The rentals at lowes/HD are not powerful enough to blow in walls, they are only good for open attic blowing.

Talk to the place you are renting from and see about the capability of the machine you are getting.

I rented from the local lumber yard, that machine had more than enough capability to blow into the walls of my previous house. I did from the outside since we were planning to side the building after the job. One hole in the bottom, one in the top- blow in the bottom first, stop when it starts coming out the top significantly, then top off using the top hole. I fabricated a round screen on the pole to stop the insulation from blowing out the top hole while i was filling from the bottom. Seemed to work well.

 

[matouse3]

You can also have expanding foam blown in. It is more expensive but works great.

I highly suggest against this type of insulation as I have had horrible experience with it. Yes, it is more expensive and I thought it was a a better option. My attached photo shows the results hidden behind my wall when I had to remove some drywall for an outlet installation.

 

[Mr.N]

Dense Packing, good video

Looks like this guy used a auto store tail pipe to help him

 

[jumpingryan]

I recommend spray foam, but it is probably best to not be a DYI job for a job that isn't open visibly.

A good contractor will make only small holes, and there is generally better coverage.

Blown in is better than nothing, but it can settle, and give uneven coverage. Uneven coverage is like having a giant hole in the wall, and can negate the effect of insulation as a whole....

Good luck!

R

 

[curly8888]

Spay foam is the only was to get 100 0/0 of your stud space
But. There is always a but, a customer of mine did it the guy doing the job probably couldn't run a paper rout
He pumped in way to much had the drywall buckle and popped All the screws. So he had to replace all the drywall anyway and saw cut the foam flush to the studs
Check references even go to a job they did to see the result
This was my only experience with spray foam

 

[HomeBrewA4]

I highly suggest against this type of insulation as I have had horrible experience with it. Yes, it is more expensive and I thought it was a a better option. My attached photo shows the results hidden behind my wall when I had to remove some drywall for an outlet installation.

have never seen this happen before with closed cell foam. Wonder if the guy didn't have his machine set up correctly.

I would do what is typically called a "drill and fill". Drill a hole in the top, fill it with either fiberglass insulation or cellulose.

I wouldn't even option out foam because depending how the product was stored before you get it, how warm it is on your rig, etc. all dictates its yield. You can either short a cavity or way over fill one.