Insulating Florida detached garage

[mhand75]

Good morning,

Gotten a lot of great information from these forums over the years, but this is my first time posting. I moved into a house earlier this year that has a detached garage that I use as a woodworking shop. The shop has a Mr. Slim. mini-split, but it is not able to keep up in the summer. Temperature in the shop frequently got up to 95-99 this past summer.

I've had mini splits in two previous Florida garages before with little insulation and they've worked great. Those garages had a drywall ceiling with uninsulated attic above and uninsulated outer walls.

I'm not sure what best approach is for insulating the garage. I would like to keep the ceiling open.. it is only 7 1/2 feet hight and I'd like to run my dust collection piping in the rafters.

The options I was looking into:

1. Radiant barrier - would put the radiant barrier over the rafters. With the 2x4, this would give me a 3 1/2 gap.
2. Put batts between the rafters.

I was thinking the batts would be best, but I'm not sure what I would put over them after stapling them in place. Could I cover with OSB or something similar?

Open to any other ideas?

Also, there is no roof vent, but there are soffit vents, which seems odd? If I go radiant barrier, would I just close off the soffit vents? If I do batts, I'll put in a roof vent.

Details:
20x30 detached garage used as wood work Concrete walls
Asphalt shingle roof
Soffit vents
No roof vent
Mini split AC

Thanks for any advice.
Marcus

 

[mike93lx]

It is outputting cold enough air and just can't keep up eith heat gain/air leakage?

 

[My Old Tools]

My experience in Texas should be similar. Most of your heat gain is through the roof. 4 inch bats will help, but I went to 4" plus 8" in my latest shop and it really made a difference. The other option is spray foam of course.