Insulating my detached garage has me baffled!!
Hey everyone! I’ve been learning a lot on this site, but haven’t been able to piece together a plan to address the project I’m working on.
I’m looking to insulate my detached garage, which previously had a mold issue. I’d like to use green materials, however, moisture and budget take priority.
Detached Garage (35’x25’)
4c climate (marine)
1 story (plus “attic like” space)
No plumbing or gas, has electricity
45 degree roof pitch
15’ from soffit to roof line
Straight pitch roof, no valleys, hips
Soffits are not vented, however there are visible gaps between roof deck and soffits
Roof is vented
Ceilings used to have faced R19, no drywall, insulation was removed during mold remediation.
Rafters are 16 on center, 2×6, so not a lot of room there.
My primary concern is to keep the RH down since it is very moist where I live. I plan on having a dehumidifier, and may add heat later as I use in the space year round.
From my understanding there are two potential ways to approach this project, air sealing and using baffles. I don’t know what is the best method for my situation.
If using baffles… I would plan to add vents in the soffits, run baffles up to the roof ridge, fill the rest of the rafters with as much insulation as possible and cover with drywall.
If air sealing… Seal the roof vents, soffits and any other leaks. Then add rigid insulation to all exterior walls, seal insulation and cover with drywall.
I’d really like to know what approach would give the best results in keeping the building dry. Budget isn’t much, expensive materials aren’t realistic for me. I’d much appreciate being pointed in the right direction by folks who have understanding of the challenges that marine climates present.
GBA Detail Library
A collection of one thousand construction details organized by climate and house part