cooling down south texas garage

[blacktibby07]

whats the best option for lowering temperature in my garage? my garage is 30x20 detached from house, open attic rafters and open studs on walls, no insulation, no vents on roof, id atleast like it to stay close to outside temperature and not 20-30 degrees more, were barely breaking into the 80s right now outside and already getting unbearable in there

 

[Copymutt]

You've ready mentioned the deficiencies that make it retain heat. Insulate circulate the attic air or vent the pitch. You probably have too much humidity for a swamp cooler. AC is gonna cost you big time both for install and operation.
You might consider a run of culvert buried four or more feet and pull air through that. The longer the better, the bigger the better. If there's a shady spot locate the intake there.
Just my cheap showing
Jim

 

[blacktibby07]

vent the pitch? like install ridge top vent? and clueless on culvert, id have to see a picture

 

[75gmck25]

Either install a ridge vent, and/or several turbine vents so that there is somewhere for the hot air to get out. If you don't have any side vents on the lower part of the walls (most Texas garages I've seen do have them), you may want to also add screened vents in the walls.

Then try installing a large diameter ceiling fan over one (or both) garage bay(s), with the fan drawing air up. If you open the large garage door and turn on the fan it should keep hot air moving up and out the vents, and temps relatively bearable.

Installing a large window A/C unit should also be effective at cooling it down, but only if you install a ceiling, wall and ceiling insulation, and seals on the garage doors.

Bruce

 

[TRWham]

Ridge vent and perhaps a radiant barrier on the rafters. As long as air can flow into the bottom and through the bays between the rafters you can create quite a strong convective flow without a fan. Fans blowing on the occupants will also help.

 

[Falcon67]

Ceiling, insulation between joints, insulate walls, vent roof. Other than that, not much. 95 and 80% RH requires more than just blankets in the walls.

 

[slackdaddy1]

Need to separate the shop air from the attic air (Drywall the ceiling). Not sure from your description, does the "rafters" have a bottom cord, like a truss? If not you will need to install ceiling joists and drywall. closing off the attic will be the biggest change.
2nd would be insulating the ceiling, just a 6-8" of blown in on top of the ceiling.
Insulating and closing in the walls will not make much difference if the exterior of the walls is a light color.

Slack

 

[Falcon67]

Insulating and closing in the walls will not make much difference if the exterior of the walls is a light color.

Slack

LOL, my east/west walls are light gray. When they were barn red, the surface temp was 180F. Light gray, the most I've seen is 130F. Mostly the west wall - 3.5" fiberglass, OSB interior, inside wall 90F - typically. Wall insulation here makes a huge difference depending on sun exposure.

 

[6768rogues]

My brother has a building in FL and he put a big exhaust fan in the gable end.