Adding wall insulation to existing walls - Cold Climate

bagsanthony · Mar 6, 2026

I recently bought a property with a 28 ft x 36 ft x 13 ft pole "finished pole barn." Interior walls and ceiling are drywalled. I have recently beefed up the ceiling insulation. I have around R-45 fiberglass in there now. After experimenting and learning more about the place, come to find out, the past owner drywalled the walls and didn't put any insulation in there. Makes about zero sense. My plan of attack was originally to keep the space at 45-46 deg. unoccupied and bump up to 57-60 when working. The brutal winters of Western, NY and the cost of propane have me scratching my head.

I still want to insulate the remaining three walls but not looking forward to a drywall mess. I would like to maintain better temps and have the ability to maintain 55-60 degrees working temps better. However, with the existing drywall it is making the decision a little more difficult. Other members have suggested blown in insulation, drilling cavities to drop the loose-fill in. I'm skeptical of that in a very cold climate. The lack of a true vapor barrier is my worry. In a cold climate you def. want a good vapor barrier. What are your guys thoughts on this? It is my understanding that an injection spray foam is available. Any thoughts on this?

The Cobbler · Mar 6, 2026

bagsanthony said:
In a cold climate you def. want a good vapor barrier.

there's mixed feelings on vapour barrier in garages since there's not a lot of moisture inside from cooking, showers etc etc .
I would blow insulation in the walls and sleep well.
if you're concerned about vapour, a couple good coats on oil based on the walls will do what you need.

danski0224 · Mar 6, 2026

bagsanthony said:
It is my understanding that an injection spray foam is available. Any thoughts on this?

There is. Low expansion or retrofit foam.

I want to have it done, but it isn't cheap. Estimate was ~5k a couple of years ago for a 1400sf ranch.

They claim to be able to do it from outside and pull off one piece of siding around the perimeter. I have partial stone in front, and they said that they could drill holes in the mortar joints, doing it from inside would be better.

I know someone else that had fiberglass blown into the garage wall cavities from inside. They drill a 3" or 4" hole, blow it in, then install a foam plug that needs to be finished with drywall mud and tape. It worked, no idea on cost.

pcmeiners · Mar 6, 2026

"I know someone else that had fiberglass blown into the garage wall cavities from inside."

Blown cellulose is a better insulator, relatively cheap but blowing any insulation makes a mess. Making the hole, blowing the insulation and sanding dust from the hole repair needs a hefty cleanup. Did it on a few houses from the inside. One issue, it needs to be packed or else it settles a lot. Worth all the trouble though.

danski0224 · Mar 6, 2026

pcmeiners said:
"I know someone else that had fiberglass blown into the garage wall cavities from inside."

Blown cellulose is a better insulator

I am not 100% sure what was used. The homeowner said "fiberglass".

I did a garage ceiling (living space above) and used fiberglass above a fine netting, before drywall. You could hear it change as the void filled up.

I'm sure that there's all kinds of little technical issues with this approach, but putting 9" batts in a 12" space is definitely worse.

BurtEggley · Mar 7, 2026

I would look at it several ways.

1. Get a bid from a reputable drywall company to redo the walls. Add in the cost of the insulation and vapor barrier. I had a GC and his friend do my 23 x 30 garage sides and ceiling in one afternoon. That included the knockdown. Cost me all of $1800 15 years ago. You only have walls. The ceiling is done.

2. Get a bid from someone to remove and replace the siding. Lots of work or you can do it one panel at a time. You have all summer before next winter. Add in the cost of insulation.

3. Get a bid on blown in, but be aware, I have seen multiple cases over the years in real estate where people went to sell, had home inspections and the inspector discovered that the walls only were partially full, and what was there had compacted down, leaving the top areas empty as a best case and most of the stud bay empty as a worst case.

Then compare the 3 bids and the benefits.

fitter30 · Mar 7, 2026

Foam would give you a vapor barrier.

Fav Onefour · Mar 7, 2026

Is it typical stud wall framing? What exterior material? Does it have full sheathing?

Some of those answers might push your decision.

I know it seems intimidating to pull sheetrock and start over but maybe . . .
If the place is new to you, I'm guessing the wiring and various mechanicals could be updated for your own use of the space. If you pulled down the sheetrock, it would be a perfect time.

For reference, my garage-shop was sheetrocked and insulated but poorly wired. Two 15A wall circuits was probably fine for their application back when it was built but I needed to update and add circuits. I wrangled around with options before finally deciding to bite the bullet and pull down sheetrock. The hardest part was the mental wrangling. Once I started tearing down the material, the project wasn't bad.
Walls are a whole lot easier than doing ceilings if you decide to do a DIY upgrade.

If you go that route, just do a vapor barrier. No more mental wrangling.

mepstein · Mar 7, 2026

If you are going to be there for a while, pull the drywall down, insulate and put up drywall or your favorite wall finish. In a couple years, you'll forget the hassle and expense but be glad you did it.

75gmck25 · Mar 7, 2026

In most cases, removing all old drywall and installing new is a fairly simple task for an experienced contractor. It seems like a lot of work for those who don't do it often, but it seems to really go quickly. And in a garage you don't need to pay for the highest level of final finish unless you want it really pristine.

Vapor barrier usually goes on the side of the wall that is the source of moisture, so above ground its usually just behind the drywall. However, as already mentioned, that may be different for a garage.

Spray foam in the entire stud bay would be the most effective insulation, but would probably cost quite a bit. You could also just "flash and batt" using a thin coat of spray foam first to seal it all and then mineral wool or fiberglass to fill the stud bay for the insulation value. I kind of like this idea better because once you spray foam the entire stud bay its a big mess to open it up to add wiring.

mm08822 · Mar 7, 2026

Look into getting a guy to demo all of the wall sheetrock and take away. This way, you aren't spent just getting everything demo'd. (Could even find a landscaper crew looking for some extra cash.)

Then you have a fresh slate for wiring, vb, insulation and choice of wall covering(s).

bagsanthony · Apr 26, 2026

Guys, I keep going back and forth on this.... with heating sparingly in very cold Western, NY I only paid approx. $400 all heating season this year. I really beefed up the ceiling insulation and added a couple of ceiling fans. I'm on the fence if this even warrants a full "tear-down" I keep going back and forth. Where it would really help would be the North Wall. I would aim my temp probe all around the building and the North Wall was always the problem child as you would expect.

I did have someone come and give an estimate to blow in dense pack cellouse insulation. He quoted me $5,000! I was not a fan of this price. I'm also on the fence on doing this with a 1990s pole barn that sweats, has no housewrap and the potential for trapping mositure. I have lived in Western, NY all my life and you really need a true vapor barrier here. I should point out that this space is a single bay partition of the barn. The adjoining space is 40 ft wide and has three large overhead doors. I have debated screwing the drywall project altogether and dumping my money into this space.... however, it would need a floor, insulation, wall covering, insulation, etc. It would be another big undertaking that I'm not sure is in the cards..

Another idea I had was what if I took 1-1/2" rigid foam board screwed it to the existing sheetrock and drywall over it? I would then use outlet extension rings to make it flush with the added layers and obviously long drywall screws..... or do I just go ahead and rip **** down little by little..... Suggestions and feedback appreciated!

pcmeiners · Apr 27, 2026

If your worried as to a vapor barrier a full coat of oil base will seal the moisture from traveling through the wall; latex will not stop vapor. Also unlike fiberglass dense packed cellulose stops air from traveling through it. Have a fully insulation garage (tiny bit bigger) a little above standard insulation amount, with a heat pump, cost close to $200 for the year heating and cooling, approx. the same weather .
Can't see taking down the wall board or adding another layer of insulation/drywall to insulate. Money much better spent on other things. As to insulation board the cost is ridiculous per board for an approx R 7.5 when cellulose will give you an R 13. Have you figured out how much it will cost with insulation board and new taped, and painted Sheetrock .

bagsanthony · Apr 28, 2026

pcmeiners said:
If your worried as to a vapor barrier a full coat of oil base will seal the moisture from traveling through the wall; latex will not stop vapor. Also unlike fiberglass dense packed cellulose stops air from traveling through it. Have a fully insulation garage (tiny bit bigger) a little above standard insulation amount, with a heat pump, cost close to $200 for the year heating and cooling, approx. the same weather .
Can't see taking down the wall board or adding another layer of insulation/drywall to insulate. Money much better spent on other things. As to insulation board the cost is ridiculous per board for an approx R 7.5 when cellulose will give you an R 13. Have you figured out how much it will cost with insulation board and new taped, and painted Sheetrock .

Thanks a lot for your reply. This makes a lot of sense. I was just concerned about the cold metal surface condensing and leaking through. However, if this is well sealed and you apply the vapor barrier paint, I suppose the risk is minimal. Thanks! I really hate drywall and it would not be my first choice and have no interest mudding and taping!!!!

racecougar · Apr 28, 2026

bagsanthony said:
Another idea I had was what if I took 1-1/2" rigid foam board screwed it to the existing sheetrock and drywall over it? I would then use outlet extension rings to make it flush with the added layers and obviously long drywall screws..... or do I just go ahead and rip **** down little by little..... Suggestions and feedback appreciated!

That path seems like the worst, as you gain little insulation, have to drywall anyway, and lose interior space in the process.

Have you compared the price of tearing down the drywall, placing batts, and putting up your wall panel of choice (drywall, liner panel, plywood, etc.) vs an injected foam bid?

Denwood · Apr 28, 2026

This is a good applicaton for blown in cellulose. You can rent the blower and do it yourself via holes in your drywall...also easy to patch up. The trick is to find any horizontal fire stops in the wall and make sure you put holes at the top of each cavity. I did our entire (100 year old) house this way. We're in zone 7A, so winters down to -35C. Walls are drywall over plaster/lathe. Hole drilling was a LOT harder with plaster and lathe, but the cellulose part was done in just a few hours. Zero issues, and it's been 20 years. Vapor is not an issue really with garages, but cellulose is vapour permeable so not an issue really, particularly if the outside envelope is vapour "open" which yours likely is. If you take basic measures to seal up penetrations, I would not worry at all about vapour issues. Right now you have big vapour issues as warmer/moist air is condensing on your exterior walls behind the drywall. Air movement is greatly reduced if you get close to dense pack, and sound transmission will drop a ton...over 50% likely.

The nice thing about cellulose is that you will maintain a drying path in both directions out/in in your wall system. Closed cell spray foam is the only other way I would go, requiring drywall removal and $$$$.

Our treatment for the attics, was to do a flash/fill using 1-2" of closed cell to air seal everything, then R60 of cellulose over top. Air leakage via your electrical boxes in the ceiling and at the walls is likely quite high, and low hanging fruit if you're concerned about efficiency.

bagsanthony · Apr 28, 2026

Denwood said:
This is a good applicaton for blown in cellulose. You can rent the blower and do it yourself via holes in your drywall...also easy to patch up. The trick is to find any horizontal fire stops in the wall and make sure you put holes at the top of each cavity. I did our entire (100 year old) house this way. We're in zone 7A, so winters down to -35C. Walls are drywall over plaster/lathe. Hole drilling was a LOT harder with plaster and lathe, but the cellulose part was done in just a few hours. Zero issues, and it's been 20 years. Vapor is not an issue really with garages, but cellulose is vapour permeable so not an issue really, particularly if the outside envelope is vapour "open" which yours likely is. If you take basic measures to seal up penetrations, I would not worry at all about vapour issues. Right now you have big vapour issues as warmer/moist air is condensing on your exterior walls behind the drywall. Air movement is greatly reduced if you get close to dense pack, and sound transmission will drop a ton...over 50% likely.

The nice thing about cellulose is that you will maintain a drying path in both directions out/in in your wall system. Closed cell spray foam is the only other way I would go, requiring drywall removal and $$$$.

Our treatment for the attics, was to do a flash/fill using 1-2" of closed cell to air seal everything, then R60 of cellulose over top. Air leakage via your electrical boxes in the ceiling and at the walls is likely quite high, and low hanging fruit if you're concerned about efficiency.

Man, really appreciate your reply and how you explained this. And being that you're in a similar and even colder climate than Western, NY, your insight is great. I'm really leaning to this route now. People don't realize that an automotive shop/downtime to get into construction projects is killer. Plus we have too much exposed **** on our walls. Thanks man for your help!

bagsanthony · Apr 28, 2026

racecougar said:
That path seems like the worst, as you gain little insulation, have to drywall anyway, and lose interior space in the process.

Have you compared the price of tearing down the drywall, placing batts, and putting up your wall panel of choice (drywall, liner panel, plywood, etc.) vs an injected foam bid?

Yeah, I agree. I really leaning to the blown in cellouse. For my use as a repair shop, it's difficult for me to commit the time to rip the **** down and start a construction project. Plus I have too much junk on the walls. Cellouse looks to be my best option.

Denwood · Apr 28, 2026

bagsanthony said:
Yeah, I agree. I really leaning to the blown in cellouse. For my use as a repair shop, it's difficult for me to commit the time to rip the **** down and start a construction project. Plus I have too much junk on the walls. Cellouse looks to be my best option.

I did experiment with open cell injection (had one entire wall done this way), but in my opinion, cellulose is just as good, and likely a better fire barrier as well. It's also a lot cheaper and any DIYer can install it. HD rents the equipment out. Anytime I've had a wall open for renovation, closed cell makes a lot of sense as air sealing a 100 year old home is impossible, and the exterior ship lap has large gaps, with no effective air barrier. But, the closed cell requires a dedicated application truck to preheat chemicals and is the most expensive option out there. Vapour loading in a residential application is a much different animal vs a garage.

I pulled cellulose filled walls out during my last renovation (kitchen) and there were zero issues with mold, rot etc. (again, about 20 years since installation). The open cell injection insulated walls were a massive PITA to clean out. I had a steel shovel going at it for much, much longer than it took to vacuum up the cellulose.

For me, in your position, it would be cellulose 100%

It's a day project at best. If you do have a lot of water on the slab (that potentially makes it to your walls), you could cut up 6-12" or so on the walls and have closed cell foam done there, and do the rest with cellulose.

pcmeiners · Apr 28, 2026

As a note even densely packed cellulose settles after a couple years, with a 10 foot cavity height it will settle about 6" if packed correctly. As mentioned you need a hole around 1 foot from the top and bottom of each cavity, 4" hole size though they say 3"; if you go 3" it makes it more difficult to pack the cavities, and the hose will clog more often , very important to find all the chocks in the wall. Old houses have many chocks, thus empty spaces, this is where a IR gun would be nice.

With my mom's house she had a major fire in the basement of her balloon framed house. Only the basement and basement ceiling went on fire, the fire could not spread up the wall cavities. If not for the cellulose the fire would have spread via the wall cavities to the attic, and the house would have been totally engulfed with 10 minutes.

BurtEggley · Apr 28, 2026

also be aware that too much insulation may allow too cool a temperature late night and early morning in summer when it is humid if you get a lot of air movement in and out in summer to where you cannot dry the air out with the AC.

bagsanthony · Apr 28, 2026

BurtEggley said:
also be aware that too much insulation may allow too cool a temperature late night and early morning in summer when it is humid if you get a lot of air movement in and out in summer to where you cannot dry the air out with the AC.

This is 'heat only' in Western, NY. We really only "need" AC for about a month and half here (yes, it's sad I know) No need for AC in a shop

dcg9381 · Apr 28, 2026

BurtEggley said:
also be aware that too much insulation may allow too cool a temperature late night and early morning in summer when it is humid if you get a lot of air movement in and out in summer to where you cannot dry the air out with the AC.

Eh? The whole point of insulation is to prevent a temperature change compared to ambient. More insulation = less temperature change compared to ambient. No insulation - you'd be closer to ambient temperature.

Maybe I misunderstand and you're saying that if you open the door (evening) it would over-cool it and moisture would accumulate. Isn't that what the J-calculations are for? Make sure you don't shock cool your Yeti cooler in one shot?

I had one zero insulation shop. It'd do what you describe in the right atmospheric conditions without HVAC. No insulation doesn't prevent it.

The solution to this is an HVAC system that is properly sized or a split that can partially cool BTUs... OR an ERV/HRV. You're always going to have a potential moisture problem if you build a cooler without moisture exchange.

OP has R45 in the ceiling. That's the right order of operations. IR gun is my next go to.

BurtEggley · Apr 29, 2026

the issue happens all the time on this forum. Doesn't even cross the mind of people who live in lower humidity places and have pole barns. There are hundreds of posts on it. If at any point equipment with mass, like say a lathe, is cooler than the dew point, it will sweat. Better insulation does not stop heat transfer. It only slows it. If a pole barn sits vacant all night, and the equipment gets down to 60F and stays there until noon, say the temperature outside is 70F at 80% humidity, then the dewpoint is 63.5F. If that air gets into the space the heavy equipment will get a lite coating of moisture on it unless AC or a dehumidfier is run in the pole barn to drop humidity in that space. Before the greater insulation, the quicker heat transfer might have raised the mass in the pole barn / shop to slightly above the dew point and kept it there. All depends where this structure is, the weather there, if AC is going to be run in summer, and how much air transfer there is from the outside. If someone rolls up a big double door and lets in a lot of hot humid air at noon, and the lathe is still at 60F, it may sweat. One can slow the heat but if the pole barn has air exchange with the outside, you can't stop the moisture in the air from coming into that space.

racecougar · Apr 29, 2026

That's when you smack the guy that opens the door and lets all the humid air in.

pcmeiners · Apr 29, 2026

bagsanthony said:
This is 'heat only' in Western, NY. We really only "need" AC for about a month and half here (yes, it's sad I know) No need for AC in a shop

Thing with NY weather if you want rust free tools you need to run a mini split 24/7. Well you think of the AC cost, except mini splits cost very little to run, especially the air condition part. Basically you only need to have it cool to a bit higher temperature than possible dew points. My AC part cost around $10/month, for me that is dirt cheap for rust free tools and dry air to work in.

bagsanthony · Apr 29, 2026

pcmeiners said:
Thing with NY weather if you want rust free tools you need to run a mini split 24/7. Well you think of the AC cost, except mini splits cost very little to run, especially the air condition part. Basically you only need to have it cool to a bit higher temperature than possible dew points. My AC part cost around $10/month, for me that is dirt cheap for rust free tools and dry air to work in.

how well does the mini split heat your shop and what are the dimensions of your shop? I'm skeptical of electric heat/heat pumps in cold climates for heating. Forced air gas-fired is the most reliable and cost effective (just my opinion)

pcmeiners · Apr 30, 2026

Shop is 36x30', 10' high, when it was -7°F it was uncomfortably hot standing close to the unit, as to the general comfort level in the shop, no different than any other winter day. True large gas heaters will heat up faster but mini-splits are not meant to run very intermittently, mine are on 24/7.

My unit in the garage is the 12k low temperature unit.....

https://www.goodlifehvac.ca/images/Fujitsu_LZ_Series.pdf

bagsanthony · Apr 30, 2026

pcmeiners said:
Shop is 36x20', 10' high, when it was -7°F it was uncomfortably hot standing close to the unit, as to the general comfort level in the shop, no different than any other winter day. True large gas heaters will heat up faster but mini-splits are not meant to run very intermittently, mine are on 24/7.

My unit in the garage is the 12k low temperature unit.....

https://www.goodlifehvac.ca/images/Fujitsu_LZ_Series.pdf

Thanks for the info. I am actually considering something like this for the house since i have no central AC/ and would like to offset propane heating costs when I don't burn wood. thanks!

pcmeiners · Apr 30, 2026

slight correction, shop is 36x30'

bagsanthony · May 1, 2026

Denwood said:
I did experiment with open cell injection (had one entire wall done this way), but in my opinion, cellulose is just as good, and likely a better fire barrier as well. It's also a lot cheaper and any DIYer can install it. HD rents the equipment out. Anytime I've had a wall open for renovation, closed cell makes a lot of sense as air sealing a 100 year old home is impossible, and the exterior ship lap has large gaps, with no effective air barrier. But, the closed cell requires a dedicated application truck to preheat chemicals and is the most expensive option out there. Vapour loading in a residential application is a much different animal vs a garage.

I pulled cellulose filled walls out during my last renovation (kitchen) and there were zero issues with mold, rot etc. (again, about 20 years since installation). The open cell injection insulated walls were a massive PITA to clean out. I had a steel shovel going at it for much, much longer than it took to vacuum up the cellulose.

For me, in your position, it would be cellulose 100% It's a day project at best. If you do have a lot of water on the slab (that potentially makes it to your walls), you could cut up 6-12" or so on the walls and have closed cell foam done there, and do the rest with cellulose.

Awesome information. One question, wouldn't you want dense-filled cellulose in this case as opposed to your standard loose fill? It's my understanding the loose-fill will settle and doesn't seal as good in a wall application. I don't know of a DIY dense system that HD will rent.

Denwood · May 1, 2026

bagsanthony said:
Awesome information. One question, wouldn't you want dense-filled cellulose in this case as opposed to your standard loose fill? It's my understanding the loose-fill will settle and doesn't seal as good in a wall application. I don't know of a DIY dense system that HD will rent.

It will be hard to DIY a proper dense pack with the rental equipment. However, you can get closer if you take your time. Some settling at the top of the wall cavities is not the end of the world. I will say though that cellulose left in place for some time will bind to itself with just atmospheric moisture. I've seen this in attics when removing cellolose loose fill that has been there for some time. It tends to "crust" up a bit on the surface likely due to the interaction between cellulose fibers, borates, and moisture. The more fire stops in your walls (mine had them every 3 feet as it was historically balloon framed) the less issues you'll have with settling. You can drill an extra hole(s) in each cavity if they are open for 13 feet (likely not in your pole barn) and blow then in starting at the lowest hole, blocking, then going to the higher one to get better coverage.

If you hire out the cellulose blow-in using a contracter with the proper high pressure machine, fill tubes etc. that can get you to a higher density. I don't think you'll get there with the HD rental stuff. If you take a step back though, it's a garage, not a house so DIY in my book is just fine. If you want to maximize performance, hire it out....but for how much of a gain??

pcmeiners · May 1, 2026

For dense packing.....

With a machine from HD or Lowes the instruction state to drill holes 2.5", which will result in taking longer to fill the wall cavities, the hose will clog often and it will not pack as good. To dense pack drill the holes close to the hose diameter, not the nozzle size, do not use a nozzle if it has a size anywhere around 2.5", it is just too damn small. Drill holes approx. 1 ft front top, 1 foot from bottom. Save all the drilled out wood or Sheetrock which are used to repair the drilled holes. Fill the holes until the machine bogs down, until the cellulose does not flow, if you do not do this the cellulose will settle much more and you lose much of its insulation and fire stop ability. If you do not dense pack and stop filling once the holes are filled it will settle >25% over time. Even densely packed cellulose will settle in several years but 6" is much better than >25%
To repair the holes, place the Sheetrock pieces you drilled out below the surface of the hole, joint compound over that, wait a week, sand, more compound and sand again, compound again, finish sand. Before I place the Sheetrock pieces in the holes I go around each holes with a sharp utility knife blade, beveling off any edge which is above the wall surface so that there are no high spots when compounding, if you do not do this it will take a lot of compound and sanding and a lot more dust, and lastly you will like see where every hole is once painted.

DGersic · May 1, 2026

bagsanthony said:
I still want to insulate the remaining three walls but not looking forward to a drywall mess. I would like to maintain better temps and have the ability to maintain 55-60 degrees working temps better. However, with the existing drywall it is making the decision a little more difficult. Other members have suggested blown in insulation, drilling cavities to drop the loose-fill in. I'm skeptical of that in a very cold climate. The lack of a true vapor barrier is my worry. In a cold climate you def. want a good vapor barrier. What are your guys thoughts on this?

My house was built with open cavities, the only insulation was some 3/4” thick fibre board on the outside walls, under the cedar siding. Interior walls are plaster over rock lath.

Wanting insulation, and not wanting to destroy my siding, or my plaster, I went with blown in cellulose.

The first step was carefully cutting every nail and the old layers of caulk and paint, then removing the top course of siding. This gave us access to the fibre board.

Every 16”, a 3” hole was drilled through the fibre board. The insulation blower packed every cavity full.

The siding was then nailed back on. I did have to caulk and repaint the house afterward. This was 20+ years ago, I’ve since repainted the house again.

A recent bathroom remodel opened up one of those exterior walls, and you can see that the cellulose did not settle.

The demo guys did break it up some, and chunks ended up on the floor.

Denwood · May 1, 2026

DGersic said:
My house was built with open cavities, the only insulation was some 3/4” thick fibre board on the outside walls, under the cedar siding. Interior walls are plaster over rock lath.

Wanting insulation, and not wanting to destroy my siding, or my plaster, I went with blown in cellulose.

The first step was carefully cutting every nail and the old layers of caulk and paint, then removing the top course of siding. This gave us access to the fibre board.

Every 16”, a 3” hole was drilled through the fibre board. The insulation blower packed every cavity full.

The siding was then nailed back on. I did have to caulk and repaint the house afterward. This was 20+ years ago, I’ve since repainted the house again.

A recent bathroom remodel opened up one of those exterior walls, and you can see that the cellulose did not settle.

The demo guys did break it up some, and chunks ended up on the floor.

I think with a typical wall (particularyl plaster lathe, with exterior shiplap there is a ton of structure/nails etc. to stabilize a blown in stud cavity from settling as well. Excellent post though as you can see how the wiring got in the way on one of the cavities!

When we purchased our 100 year old home it was empty and being partially reno'd for a few months. We blew from the inside (outside clad in brick lower story, cedar shakes, top story) which was a LOT easier than dealing with outside. Keeping the hole saw "rounds", patching was pretty simple too

Due to all the fire stops, we ended up with 3 holes typically per stud bay.

The real game changer though was doing the flash and fill in the attics because a ballon framed plaster/lathe home will leak a ton of air via the tops of the walls where gaps in the lathe create massive air leaks. 1-2" of closed cell in the cleaned out attics completely sealed up all those issue from the tops of walls (including exterior walls) and all the ice damming issues, frost in the attic etc. disappeared 100%. Then it was easy to blow R60 cellulose over top DIY.

Similar issues would exist in a garage at the tops of walls, and electrical boxes etc. at the ceiling.

Seabornman · May 1, 2026

I'm in a similar boat in central NY. I decided a cold climate heat pump was my best option, as we don't have access to natural gas. I have a 3 ton unit in a 32x64x12 foot building. It maintained a minimum of 53 degrees when it was below zero outside. The unit is at one end and the thermostat was set at 60. I spent a lot of time caulking to air seal. I still have some more to do. As far as your walls, I used kraft faced batts, which aren't much of a vapor barrier. I don't have water and don't plan on bringing wet or snowy cars in. Cooler air can have less water vapor and there'd be less drive to the exterior. So far so good.

bagsanthony · May 6, 2026

Denwood said:
It will be hard to DIY a proper dense pack with the rental equipment. However, you can get closer if you take your time. Some settling at the top of the wall cavities is not the end of the world. I will say though that cellulose left in place for some time will bind to itself with just atmospheric moisture. I've seen this in attics when removing cellolose loose fill that has been there for some time. It tends to "crust" up a bit on the surface likely due to the interaction between cellulose fibers, borates, and moisture. The more fire stops in your walls (mine had them every 3 feet as it was historically balloon framed) the less issues you'll have with settling. You can drill an extra hole(s) in each cavity if they are open for 13 feet (likely not in your pole barn) and blow then in starting at the lowest hole, blocking, then going to the higher one to get better coverage.

If you hire out the cellulose blow-in using a contracter with the proper high pressure machine, fill tubes etc. that can get you to a higher density. I don't think you'll get there with the HD rental stuff. If you take a step back though, it's a garage, not a house so DIY in my book is just fine. If you want to maximize performance, hire it out....but for how much of a gain??

Thanks man for all the help and everyone here! A part of me is going back and forth. What I didn't mention was the barn is broken up into two partitions. There is this current side (single bay where my two-post lift currently is) and an additional three bays (unfinished no floor) I have thought about putting the money into the other three bays as it would give me more working room and use the existing single bay for storage. Little by little I would finish the three-bay space, rather than retrofitting and the insulation non-sense. It would be a clean slate to work with. Feedback appreciated!

bagsanthony · May 6, 2026

The left three bays (three 10 ' x 12' overhead doors) and the interior

Fav Onefour · May 6, 2026

Nice building. No soffits.

It's one of those buildings that isn't really great, but it's sure as heck a lot better than nothing. I'm thinking the insulation investment should be kept to basics. In the sheetrocked bay, is the wall cavity properly done at the bottom? It may be hard to determine, but I'd be looking for concrete that continues to the outer skin etc. I've seen polished t**ds where the guy put up interior walls and poured the new concrete up to the new wall. Insulation on dirt would lead me right to the cheapest option possible.

I certainly wouldn't go nuts and tear out the interior just to insulate. If you want to go high end, I'd be looking at updating the building before that investment.

bagsanthony · May 6, 2026

Fav Onefour said:
Nice building. No soffits.

It's one of those buildings that isn't really great, but it's sure as heck a lot better than nothing. I'm thinking the insulation investment should be kept to basics. In the sheetrocked bay, is the wall cavity properly done at the bottom? It may be hard to determine, but I'd be looking for concrete that continues to the outer skin etc. I've seen polished t**ds where the guy put up interior walls and poured the new concrete up to the new wall. Insulation on dirt would lead me right to the cheapest option possible.

I certainly wouldn't go nuts and tear out the interior just to insulate. If you want to go high end, I'd be looking at updating the building before that investment.

you guessed it - the cheapest option! The concrete stops at the interior wall

Adding wall insulation to existing walls - Cold Climate

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