Unconditioned, unfinished Colorado Garage advice
Hi!
I have an attached, but unconditioned garage in the greater Denver metro area (5B). The garage has a few soffit vents and a ridge vent. The garage is unfinished and when I bought it, just had open trusses and siding, no insulation or drywall anywhere except on the wall attached to the house (which is both insulated and drywalled). About a year ago I put R-15 rockwool everywhere except the drywalled-wall. I put it directly against the roof as well. The garage is a lot more comfortable in both winter and summer and I’m really happy with it. I’m not planning to drywall over the insulation.
In doing more research, I wonder if I messed up by not putting a vapor barrier? I think the answer is no, it seems since it’s not heated and rarely has people out there, humidity isn’t an issue so I think I’m fine.
The other question: it’s still pretty hot in the summer (just no longer excruciating), I’m thinking about putting in a gable and a gable fan. It seems a controversial issue, but I’m thinking as long as there’s sufficient vent capability, it won’t depressurize the house. I realize the gable fan will compete with the ridge vent, but I plan on putting a thermostat on the gable fan to only kick in when it’s at it’s hottest or when I’m out there. Am I way off track on all of this?
GBA Detail Library
A collection of one thousand construction details organized by climate and house part
Replies
I do not think you messed up with the garage insulation given your location. Consider that you live in a desert your chance of getting wet and staying wet loge enough for mold and rot seems very low.
Most people assume attics are vented to let the heat out in the summer but that is not the truth. Attics are vented to allow moisture to escape in the winter to prevent rot and mold.
I do not think power attic fans are affective at lowering attic temps. If you so the math the volume of air one would need to move to change the attic temp is 10 X the size of the proposed fan.
Walta
Hey Walta,
I agree and understand on the attic fans. In this case though, there's no attic per se, just a garage that could have an attic if it were closed up, but it's not.
In this case, the total size of the garage I calculated to be about 6000 cubic feet, I'm looking at a fan capable of 1,600 CFM, so it would be capable of changing the air in less that 5 minutes. Obviously heat removal is a more complicated set of math, but this seems like it would at least make it more comfortable while I'm working out there.
Am I still way off on this?