Insulation Plan - Western NY Auto Repair Shop

[bagsanthony]

Guys, after a ton of back and forth I have decided to properly insulate the walls in my 1993 built pole barn (28X36X13 HIGH) in Western, NY. The previous owner had installed drywall however no insulation in the walls (with the exception of a very crude 1 ft layer of fiberglass near the base of the floor). I'm really happy I decided to go this route to address proper air sealing and fix/ install any new wiring. The building has no house wrap and I'm looking to see if my insulation plan is a good plan or if there is something better.....

I understand that closed-cell spray foam is the way to go, but frankly, it's not in my budget. With this being a working shop, I have aimed to tackle a section at a time without any downtime to my everyday car repairs. Here's what I had in mind:

• 2" foil-faced foam board installed on the face of the wood girts (screwed with foam board washers) then seal/tape all seams
• Over the foam board, I would then lay in roxul mineral wool (R-15)
• The foam board used prior would be my vapor barrier as long as it well sealed.
• Utilize the existing 2x4 horzontal pieces to re-install drywall. I understand I will most likely have to remove a couple to drop each foam board section in.

Does this seem like a good plan? I went this route to allow for an air -gap (1-1/2") between the metal and the foam board and to have continuous insulation. I have also seen the foam board directly against the metal, installed between the girts.... I was skeptical with this approach due to the lack of house-wrap... Please let me know your thoughts. Feel free to offer something completely different as well. Thanks guys!

 

[theoldwizard1]

Put your insulation money where it will have the most effect ! Ceiling/roof

Get a quote from a spray foam contractor to just do the "joints".

 

[bagsanthony]

Put your insulation money where it will have the most effect ! Ceiling/roof

Get a quote from a spray foam contractor to just do the "joints".

We’re all set with the ceiling. It has r-45 - 50
And drywalled

 

[theoldwizard1]

We’re all set with the ceiling. It has r-45 - 50
And drywalled

Insulating the walls will not give you a lot of "pay back" once the ceiling is done and leaks are stopped.

Get a quote from a spray foam contractor to just do the "joints".

 

[bagsanthony]

Insulating the walls will not give you a lot of "pay back" once the ceiling is done and leaks are stopped.

Get a quote from a spray foam contractor to just do the "joints".

I disagree 100 percent. I plan on being at this property for 25 plus years… no questions asked wall insulation improves comfort and makes a building feel better and is worth it in Western Ny fighting the wind and cold 7 months per year

 

[theoldwizard1]

I disagree 100 percent. I plan on being at this property for 25 plus years… no questions asked wall insulation improves comfort and makes a building feel better and is worth it in Western Ny fighting the wind and cold 7 months per year

Okay ! Still get the joins foamed first. Even if you have to wait to complete the insulation. Worth the cost.

 

[beltfeed]

I disagree 100 percent. I plan on being at this property for 25 plus years… no questions asked wall insulation improves comfort and makes a building feel better and is worth it in Western Ny fighting the wind and cold 7 months per year

Very true. I live in the same area as the OP. Last winter the wind howled out of the west for most of the winter. Temps were from 0 to 20F for probably 8 weeks total When I say howl that was 20-40 MPH mostly nonstop. Good insulation on the walls helps to keep that cold air out. Your doors will probably be your biggest leak point. Try to add the best seals around the doors that you can.

 

[Prospecter]

You might consider dense pack cellulose. It can be blown in behind the drywall, or as a "Mooney Wall" if you don't have a finished wall.

 

[bagsanthony]

You might consider dense pack cellulose. It can be blown in behind the drywall, or as a "Mooney Wall" if you don't have a finished wall.

Thanks not a fan of the cellulose in direct contact with the metal siding. Everyone I’ve talked to says not a good idea. I like the foam board/ rockwool since they are great for managing potential condensation which is a concern in cold Western NY

 

[Mainiac Mat]

I may be misunderstanding your plan... but be sure you're clear on the vapor barrier.

The vaper barrier goes on the warm side (the inside for your situation) to prevent warm moist air from passing through the wall and condensing on the inside surface of the exterior sheathing. This is where trapped water will cause mold/mildew in the wall.

If you put the foam board on the outside, and the mineral wool inside of that, you will have warm moist air pass through the sheet rock and the mineral wool and condense on the inside foil surface of the foam board. This trapped moisture will mildew and stink, or worse start black mold and make you sick.

I'm pretty sure you want to put the foam board inside the mineral wool. Or, install poly sheet inside the mineral wool.

 

[jack stand]

I put 1 1/2" in between the wall girts like you suggested, then another layer on top of the girls for a 3" layer that interrupted by the girts but achieves a very good air seal. I would recommend that rather than trying to cut the foam very tight. Just allow for a minimum 1/4" gap around the perimeter or in between foam panels.
Go on Amazon and the foam guns that take the big screw on cans can be had for well under $20 and you can only use what you need a then start again unlike the "straw" cans where you have to use and it all once.
Be sure to slide the foam behind your vertical 2x4's as shown in your picture.
From everything I've heard, 3" of foam is enough depth-r value to have the dew point be within the foam. Supposedly where you want it for condensation concerns. Then fill it the rest (or most of) the wall cavity with the mineral wool like you suggested.
You'll have a very nicely insulated shop, winter be dammed!

 

[bagsanthony]

Thanks man! Just want to make sure I’m understanding correctly… you’re saying:

- first one layer of 1-1/2” foam board between the girts with the foam board in contact with the metal siding. Cut 1/2” smaller to leave 1/4” gap of spray foam all around. Do this instead of laying foam board on the girts ( with an air gap to the metal)

- I would then fill the rest of the cavity with R19 / R21 roxul. No need for plastic vapor barrier over roxul since the foam board sealed is used?

 

[Mike65]

Where are you in western NY? My wife & I lived in East Bloomfield, Canandaigua & Gates for a combined 8 years & the wind in the Winter is no joke.

 

[jack stand]

Thanks man! Just want to make sure I’m understanding correctly… you’re saying:

- first one layer of 1-1/2” foam board between the girts with the foam board in contact with the metal siding. Cut 1/2” smaller to leave 1/4” gap of spray foam all around. Do this instead of laying foam board on the girts ( with an air gap to the metal)

- I would then fill the rest of the cavity with R19 / R21 roxul. No need for plastic vapor barrier over roxul since the foam board sealed is used?

Yes, the only difference in what I did 18 years ago was I used tyvek under the metal on the girts.
Foam was not in the plans at the time and I had to stuff it in-between like you'll have to do also. I found that scoring the outside of the foam
*panel would allow me to get longer (l-r) panels in as once flat it "closed" itself.
The tyvek may have helped sliding in the foam but planning the direction that you work (with the seam in the metal that can catch the leading edge of the wall foam) you should be fine. Properly sealing the edges to the framing is just as good of an air seal.


*my foam had a tar paper type cover on each side and it's p-iso, used take off from a commercial re roof. Iirc $7 for a 4x8x1.5 sheet.

 

[bagsanthony]

Where are you in western NY? My wife & I lived in East Bloomfield, Canandaigua & Gates for a combined 8 years & the wind in the Winter is no joke.

I’m in Sweden just outside of Brockport