Spray foam vs fiberglass roll in a mini barn

[willy3486]

My wife and I got a portable building,mini barn in the spring, its roughly about 400 square feet. I have the electric in and ready to think of insulation. Having insulation was not a option from the builder and due to space under it I will not be able to have any under the floor. But I have underpinned it like a mobile home. I also plan to do sheetrock and some kind of laminated floor. We have somewhat mild winters here in Tennessee and summers are hot and muggy. I am thinking of cooling it with one of the roll around AC units. The reason is we have a addition to our house that is about 250 foot that has fiberglass roll insulation that can be cooled with one of the roll around AC/dehumidifier units. I really don't want to run one of the 220 volt AC wall units ito cool this new building.


We plan to use this as a side business/retirement business building. We want to be able to cool it and heat it as economical as we can. So I had been looking at spray in foam. But with that I have to hire someone. My other options is getting foam sheets and cut to fit. I also can go the fiberglass route. With all that said is there that much difference between spray in foam and fiberglass roll? The difference in cost is not that big of a deterrent to get it. The biggest deterrent is I have money set aside to finish the building and having my tractor rebuilt, I want to pay off the cost of the tractor before I spend any more on the building. The issue is the tractor guy is taking a lot longer than he initially said. So in the long run does spray foam make it a lot easier to keep cool and heat?

 

[jack stand]

Your question regarding f/g vs. foam, cost aside your comparing the worst to the best. There's several degrees of the "worst" (fg), airflow through fg insulation is one, then there's installation details and depending on if you're including a rock wool type product in the mix.
I'd suggest cutting and fitting rigid foam with strict attention to sealing the wood to foam "joint" around the edges.
2nd hand foam is not hard to find and it's often polyiso from a commercial re roof job in full 4x8 dimension. This foam has the highest "r" value per inch of depth and is the same as closed cell spray in.
Foam would definitely be preferred for the floor if that's accessible from underneath for moisture reasons.

 

[jblnut]

Hiring spray foam will have it insulated and done quickly.

Fiberglass when installed properly should be just fine to do on more of a budget yourself but it takes time.

Used foam sheets are quite attractive as a diy deal because they insulated well when installed properly and can be quite budget friendly.

As far as heat/cooling sizing ..... The better insulated it is obviously the easier it will heat/cool. My 54x72x18 farm shop is completely cooled with a pair of little 5k btu window units. One in the office (14x16) and one in the shop part. I don't know how the shop one keeps up but it does. The building is well insulated with fiberglass blanets between the poles and 1-1/2" blue foam between the wall girts on the north, east and west sides (south is under a soon to be closed in and insulated lean)

If you want electric heat toss in a baseboard heater but if LP is your thing I'd look at a vented Empire heater designed for a fish house.

 

[willy3486]

I heard from one vendor I had checked with. His original quote was about two and a half times what fiberglass would run. I could do that. But once he saw I was interested and sent pictures the price doubled. I figured I could do fiberglass, install sheetrock and finish,do the flooring myself for that price. I still have one fellow to hear back from. I just can't justify the cost when it will not be used all day long.

 

[240sxguy]

PolyISO performs poorly in very cold climates, and the pink stuff loses 10% of it's R value over its lifetime. Sprayfoam doesn't have either of these problems FYI. It is, however, very expensive.

 

[willy3486]

I found a fellow who has white styrofoam sheets similar to the styrofoam thats used in packing peanuts. Its at a good price and it would need cutting and fitting in but I am ok with that. I plan to cover the walls and ceiling with drywall. How would this work? Only thing I was wondering is if it would heat up too much and release a odor or fumes when the sun hits the outside walls. It would be between the drywall and wood walls.