Pole barn insulating question

[ChuckD035]

I know there are a ton of threads about pole barn insulation but not finding exactly what I want to know. I have a new 24x36 pole barn that only has the vinyl backed insulation on the roof. I am not trying to make this a living space, I just don't want it to be a sauna in the summer. I planned to just put 1.5 inch foam board between the girts and potentially cover it with OSB. My question is... will this even help if the area is still open to the outside air via the bird blocks and gable vent?

Thanks

 

[Chuckster in NJ]

Save your money on the insulation and install TWO ceiling fans....... The foam board has such a low R Value you probably won’t even feel the benefit of insulation.
A friend of mine has the same size building that is insulated and it gets hot during the summer...... I installed two ceiling fans for him and he loves them.

 

[ChuckD035]

OK. I just figured even something of low r-value would be much better than the bare metal which feels very hot to the touch when the sun is on it.

Thanks

 

[Chuckster in NJ]

Very true but the "investment" will not be worth it...... These tin cans get scorching hot in the summer and the only way to cool them down is to move the air. They are also *** biting cold in the winter and with a ceiling fan you can raise the temp 3-5*F on a sunny day with the fans circulating the "hot" air that is sitting high.

 

[ChuckD035]

Makes sense. I had already put up a few panels but I can move them over to the other corner where I plan to frame a room for a little extra r-value.


Thanks

 

[purediesel]

Call Bay Insulation, look them up on Google. I just called for a price on unfaced and the R19 was 55 cents a square foot. If your not looking for much this is a great option for probably cheaper than that foam board. Not to mention less work.

 

[fourbyford]

I would have to disagree with those saying the 1 1/2" foam board is useless... I initially installed a single layer of Dow (blue) foam board and could definitely tell a difference. I also have single walled garage doors... white painted steel and facing south. After I had a lot of the insulation up, it became obvious that the next issue was going to be the O/H doors. They radiated heat in summer and were ice cold in winter. So, this past winter, I added 1 1/2" insulation to them as well. I have detailed info in my thread if you're interested. I did go back and double up the foam board in my shop because, at some point in the future, I want to replace our current garage doors with premium 2 sided, insulated doors that are r18. It didn't make sense to spend the $$ for r18 doors with r7.5 walls, so, now they're r15 and covered with OSB.
Anyways, the foam board, in my mind, is a relatively inexpensive and quick way to improve your shop.

HTH,

...D

 

[fourbyford]

I'll add that I took care to "friction fit" each foam panel between the girts and made sure to force foam behind each post... used Great Stuff spray foam anywhere I thought it was needed. The air infiltration in my shop is virtually zero... except for around the garage doors, of course. I still need to work on fitting the doors and seals better but, what I have now is infinitely better than what I started with.

...D

 

[Azzkker]

If you install the 1.5" foil faced foam board, the infrared heat load will be greatly reduced over just installing regular blue or pink foam board. Use expanding foam sealant around each piece and air infiltration will be greatly reduced.

I initially tried interference fit on my Dow thermax 1.5" boards. Fit the first quarter in a hot October heat wave, but once it got into December and temps got into the teens the pieces had shrunk enough that they were loose fitting. I went back and cut an angel groove on the edges and used expanding foam to seal and glue them in. I did this on the 3" that was bookshelved on top. That eliminated all air movement from the walls. I then screwed the white metal tin onto the bookshelf runs leaving an air gap between the foam and the tin.

The airgap is important to mitigate temp bleed through contact.

 

[ChuckD035]

I'll add that I took care to "friction fit" each foam panel between the girts and made sure to force foam behind each post... used Great Stuff spray foam anywhere I thought it was needed. The air infiltration in my shop is virtually zero... except for around the garage doors, of course. I still need to work on fitting the doors and seals better but, what I have now is infinitely better than what I started with.

...D

Do you still have outside air coming in and out of your insulated area through gable vents?

 

[NUTTSGT]

If you have gable vents, you need to either close them off, not a good idea or create an attic space to take advantage of them.


Rigid foam is a great insulator, it just gets expensive getting to the point where it compares with a fiberglass batt. However, you can put it in the spaces, seal around it with expanding foam and come out with something decent.

R-value of the foam depends on what type you're using.

White polystyrene, EPS is around R-4.6 per inch.
Pink/blue board, XPS is about R-5 per inch of thickness.
poly-iso, generally foil faced is 5.8 and the foil facing should reflect heat back into the building if foil is facing center of building.

While these numbers seem small, it's the build up of layers that will make a difference. A 3.5" batt of fiberglass is generally R-11 or R13.

Foam board, at R-5/1" x 3.5 = R-17.5. But the cost is going to be more.

If it was mine, I'd put 1.5" between the girts/poles and siding. Put up a metal ceiling and blow insulation up there. Once that is done, come back and put some fiberglass in the wall cavity and cover them up.

No need to rush out, spend big bucks and have it done right now. It can be done in stages. . . . as time and funds permit.

Don't be afraid to look on CL to find an off brand of poly-iso.

 

[ChuckD035]

If you have gable vents, you need to either close them off, not a good idea or create an attic space to take advantage of them.


Rigid foam is a great insulator, it just gets expensive getting to the point where it compares with a fiberglass batt. However, you can put it in the spaces, seal around it with expanding foam and come out with something decent.

R-value of the foam depends on what type you're using.

White polystyrene, EPS is around R-4.6 per inch.
Pink/blue board, XPS is about R-5 per inch of thickness.
poly-iso, generally foil faced is 5.8 and the foil facing should reflect heat back into the building if foil is facing center of building.

While these numbers seem small, it's the build up of layers that will make a difference. A 3.5" batt of fiberglass is generally R-11 or R13.

Foam board, at R-5/1" x 3.5 = R-17.5. But the cost is going to be more.

If it was mine, I'd put 1.5" between the girts/poles and siding. Put up a metal ceiling and blow insulation up there. Once that is done, come back and put some fiberglass in the wall cavity and cover them up.

No need to rush out, spend big bucks and have it done right now. It can be done in stages. . . . as time and funds permit.

Don't be afraid to look on CL to find an off brand of poly-iso.

I wouldn't be able to create an attic space. We built it with a single slope roof to match the style of our house. I posted a couple pictures in an album on my profile so you can see what I am working with.

 

[NUTTSGT]

I wouldn't be able to create an attic space. We built it with a single slope roof to match the style of our house. I posted a couple pictures in an album on my profile so you can see what I am working with.

Looking at those, if it were mine, I'd add some foil faced poly-iso panels to the bottom of the rafters. Use these rigid panels as insulation and the space between the rafters open for ventilation.

Possibly, maybe add an inch between the rafters and another 1.5" on the underside.

 

[fourbyford]

... air through gable vents??

No! My garage has a vaulted ceiling and there are no gable vents... and won't be. It's all a conditioned space. I still need to add insulation to my roof to improve efficiency but it's livable as is...

(there is minimal insulation in the ceiling now... I will add to it)

...D

 

[NUTTSGT]

Are those rafters 2x4 or 2x6 ?

 

[fourbyford]

Not sure where that pic came from... my purlins are 2 x 8

 

[fourbyford]

OP...
Apologies... I've been running in and out of the house and, obviously, not paying enough attention to your question.

The foam insulation will reduce the transfer of heat through your walls. And, it sounds like you have the same insulation in your ceiling as I have in mine. It's not ideal but, isn't too bad.

While the insulation will help... air from outside the building will find it's way in (through your vents) and affect the temperature. As has been mentioned, you could create a dropped ceiling and add insulation above OR, you could eliminate the gable vents and other openings and work to make the entire space a conditioned one. My building is at least 15 years old (we've been here 7 years) and has never had gable (or any other) vents and hasn't needed them. Hopefully, next summer, I'll add dense pack cellulose insulation to the roof in my building and that should put me in good shape. If you don't (or can't) put in a ceiling with insulation, the entire space is essentially a conditioned space and the vents aren't needed.

HTH


...D

 

[NUTTSGT]

Not sure where that pic came from... my purlins are 2 x 8

OP's gallery.

 

[ChuckD035]

Are those rafters 2x4 or 2x6 ?

They are 2x6. Obviously I could't do a drop ceiling due to the garage doors but I could add the foam to the bottom of the rafters like you mentioned. The first 12ft section is without a garage door is going to be a fully framed in room with an 8ft ceiling and 2x6 walls with insulation. The rest of the garage is going to be mostly storage. I was just hoping to find and easy way to make it a little cooler that a sauna in the summer. Sounds like it might be a little more work than just the foam between the girts.

 

[TheJudge]

My father and I had (having) this issue still. Given, we started with just the bare interior of a 40x100 pole barn, and built the 40x40 shop from there. We found on the interior walls of the shop, that by putting up steel roofing, and creating that air barrier between the outside T111 and the inside of the shop actually helps a lot. We still need to put down insulation on the ceiling, and probably in between the studs of the back wall, but for now, it works like a charm.

Sent from my LM-G710VM using The Garage Journal mobile app

 

[tom-ky]

I would have to disagree with those saying the 1 1/2" foam board is useless... I initially installed a single layer of Dow (blue) foam board and could definitely tell a difference. I also have single walled garage doors... white painted steel and facing south. After I had a lot of the insulation up, it became obvious that the next issue was going to be the O/H doors. They radiated heat in summer and were ice cold in winter. So, this past winter, I added 1 1/2" insulation to them as well. I have detailed info in my thread if you're interested. I did go back and double up the foam board in my shop because, at some point in the future, I want to replace our current garage doors with premium 2 sided, insulated doors that are r18. It didn't make sense to spend the $$ for r18 doors with r7.5 walls, so, now they're r15 and covered with OSB.
Anyways, the foam board, in my mind, is a relatively inexpensive and quick way to improve your shop.

HTH,

...D

I did mine and think it was well worth it. I also have 2 ceiling fans. In my opinion it was well worth it.

 

[ChuckD035]

OK. One last question. When putting foam between the girts do I need to worry about moisture being trapped between the metal and foam or do the ribs allow enough airflow to keep it in check?


Thanks