I have a 24' x 30' detached garage in northern MI that I use for storage/workshop etc., It has no AC or Heat and I don't plan on adding (I also have a heated attached garage). About 10 years ago I insulated the 2x4 walls with fiberglass bats and then closed them off using exterior grade siding (LP smart side) on the interior walls for hanging cabinets, yard tools, aesthetics etc.,
The garage has a full perimeter soffit vent (1.5' overhang) on all 4 sides. In had NO ridge or gable vents. I had a new roof (asphalt shingles) put on several weeks ago and a ridge vent added. I was hoping it would help with the humidity, it did not (depending on the day). I need the attic space for storage (I added a pull down ladder and closed in most of the roof 'floor' with 1/2" OSB)
I decided to add 1.6" foil faced foam insulation boards to the underside off the roof joists, creating a continuous channel from soffit vents to the ridge. I'm completely enclosing the top so that the 'interior' of the attic peak is no longer exposed/open to the ridge. It will only be R10 (no heating plans as noted). I'm about 65% complete (it's time consuming maneuvering the panels through the beams, cutting around beams, fitting, taping etc.,).
It's still humid (on days) and the temp gets pretty warm in the space. In hindsite I'm concerned that since the foam board is also a vapor barrier I will trap exhaust gasses. There's a gator with plow stored in the garage that gets backed in and warmed up after starting in the garage. I've never notice an exhaust issue with the old 'no roof vent' setup as the gasses either went out the soffits or permeated the roof/shingles, there was never any lingering smell.
I'm thinking about adding a powered vent (louver style) at the gable peak at the back end of the garage or possibly some inline ducted vents that would direct air from pickup points near the gator and/or at the peak of the attic space. I'm leaning more towards the ducted vents since I don't like how the 'louvers' don't seal well from what I've researched.
Appreciate any experience, expertise or opinions!!
Thanks!
The garage has a full perimeter soffit vent (1.5' overhang) on all 4 sides. In had NO ridge or gable vents. I had a new roof (asphalt shingles) put on several weeks ago and a ridge vent added. I was hoping it would help with the humidity, it did not (depending on the day). I need the attic space for storage (I added a pull down ladder and closed in most of the roof 'floor' with 1/2" OSB)
I decided to add 1.6" foil faced foam insulation boards to the underside off the roof joists, creating a continuous channel from soffit vents to the ridge. I'm completely enclosing the top so that the 'interior' of the attic peak is no longer exposed/open to the ridge. It will only be R10 (no heating plans as noted). I'm about 65% complete (it's time consuming maneuvering the panels through the beams, cutting around beams, fitting, taping etc.,).
It's still humid (on days) and the temp gets pretty warm in the space. In hindsite I'm concerned that since the foam board is also a vapor barrier I will trap exhaust gasses. There's a gator with plow stored in the garage that gets backed in and warmed up after starting in the garage. I've never notice an exhaust issue with the old 'no roof vent' setup as the gasses either went out the soffits or permeated the roof/shingles, there was never any lingering smell.
I'm thinking about adding a powered vent (louver style) at the gable peak at the back end of the garage or possibly some inline ducted vents that would direct air from pickup points near the gator and/or at the peak of the attic space. I'm leaning more towards the ducted vents since I don't like how the 'louvers' don't seal well from what I've researched.
Appreciate any experience, expertise or opinions!!
Thanks!