Insulation between Purlins?

[diesel06]

Getting ready to start hanging foam insulation board I got for free. I got a 18 ft trailer load of fiberglass foam board insulation, most of it is 1.5 inches. I have a few pieces that are 3.5 inches thick. It was insulation for rubber roofs on big buildings. My question is can I just lay the board over top the outisde purlins or do I need to cut it down to fill the gaps in between then insulation over top

 

[sands35]

Either way. You could double layer it. One between and one over top. If you put it between with only 1 layer, you will have a thermal bridge through the purlin, so best to cover it if you are doing only 1 layer.

 

[diesel06]

i think i will have enought if i fill the gap in between, I have read some threads about putting insulation against the outside metal will cause condensation

 

[rodm1]

Don't go outside of the purlins wind will brake the foam down and the walls will make more noise when windy. I'm thinking of cutting the foam small then spray foam the edges in order to make an air tight seal. But concerned about rodents eating it.

 

[Autorotica]

Getting ready to start hanging foam insulation board I got for free. I got a 18 ft trailer load of fiberglass foam board insulation, most of it is 1.5 inches. I have a few pieces that are 3.5 inches thick. It was insulation for rubber roofs on big buildings. My question is can I just lay the board over top the outisde purlins or do I need to cut it down to fill the gaps in between then insulation over top

I bought a tractor trailer load of that same insulation for my shed from a roofer who was going out of business. The stuff I bought was from 1/2" thick to 4" thick. Nearly everything I bought was tapered. Put the insulation on top of the girts so it is not touching the metal. You want the metal to breathe.

I cut it to fit between my trusses at 48"OC. I tossed some nails in to hold the stuff up until I get the metal ceiling in.

Cut the insulation with a table saw. The gray covering has fiberglass in it, make sure to wear glasses/goggles and a respirator. I spent 5 hours in the shed today putting it on the walls.

If you have any other questions hit me up on email. [email protected]

Chris

 

[Autorotica]

Just realized you are in PA... If you are near 19520 you are welcome to swing by my shed and take a look at how I am doing mine.

Chris

 

[brownsmustang]

I bought a tractor trailer load of that same insulation for my shed from a roofer who was going out of business. The stuff I bought was from 1/2" thick to 4" thick. Nearly everything I bought was tapered. Put the insulation on top of the girts so it is not touching the metal. You want the metal to breathe.

I cut it to fit between my trusses at 48"OC. I tossed some nails in to hold the stuff up until I get the metal ceiling in.

Cut the insulation with a table saw. The gray covering has fiberglass in it, make sure to wear glasses/goggles and a respirator. I spent 5 hours in the shed today putting it on the walls.

If you have any other questions hit me up on email. [email protected]

Chris

How does the metal breath if you insulate over the top of the 2x4s vs between them. Wouldn't it still cause it to sweat?

Scott

 

[Autorotica]

How does the metal breath if you insulate over the top of the 2x4s vs between them. Wouldn't it still cause it to sweat?

Scott

Scott,

Maybe I didnt convey my idea correctly...

From the inside, my shed (pole barn) has the big 6" poles then 2 x 4's nailed horizontally every 2 feet and finally the ribbed metal is screwed to the 2 x 4. I am putting my 4' foam board insulation up against the inside of the 2 x 4's.

The bottom of the ribbed metal on the outside of the building is not completely sealed. The top of those same ribs is open to the vented roof space. The insulation keeps the outside air from reaching the inside of my shed but allows it to move along the metal.

Does this help?
Chris

 

[brownsmustang]

Scott,

Maybe I didnt convey my idea correctly...

From the inside, my shed (pole barn) has the big 6" poles then 2 x 4's nailed horizontally every 2 feet and finally the ribbed metal is screwed to the 2 x 4. I am putting my 4' foam board insulation up against the inside of the 2 x 4's.

The bottom of the ribbed metal on the outside of the building is not completely sealed. The top of those same ribs is open to the vented roof space. The insulation keeps the outside air from reaching the inside of my shed but allows it to move along the metal.

Does this help?
Chris

Lol, I've built quite a few pole barns so I know how they work. But unless your are sealing the foam to the steel it's not going to prevent the air from moving in the ribs of the steel just like if you put the insulation outside the purlins.

Scott