Another Ceiling Insulation / Attic Ventilation Question for Unheated Garage

[BevoZ06]

My garage is currently unfinished with open ceiling joists. I will be insulating the walls and closing them in initially. Later when time and budget permit I plan to insulate the ceiling. I do not anticipate ever trying to heat the garage -- my objective is to insulate against 120+ degree temps in the summer.

The garage was constructed 19 years ago and, I guess, because it was left open and unfinished, does not have any roof or soffit vents. If I don't plan on installing any heating out there do I have to ventilate the roof? Everything I have read about vents and vapor barriers says it is primarily so vapor won't condense from the heated area to the unheated attic. I will have Kraft-paper faced insulation between the ceiling joists with the paper facing downward toward the floor of the garage. Thanks to everyone who has responded so kindly with answers to all my questions.

 

[Falcon67]

You're in Texas and your attic will easy get to 140+ and your roof deck can hit 160F in the summer. I have a house that was built in 2001 and it was half *** vented - plenty of soffit vents and no venting high on the roof. The shingles look more like they have been there 15 years than 10. First thing I did after we got moved was to cut 6 10" holes in the upper roof and install vents. Knocked 20F+ out of the attic.

1) do the ceiling cover first - the wall covering supports the edges of the ceiling panels. You can add insulation later up there - blow in is quick and cheaper.

2) put some kind of venting up there to move the heat out. Don't worry so much about cold - we don't have "cold" here. In fact, when I've been freezing my *** up here in Merkel, friends in Austin have been sipping brews on the patio down on 6th Street. Had to say much about what kind of venting without seeing the garage.

EDIT - looking at the pic in your other thread, I'd say put some soffitt vents along the sides and 1 or 2 vents on the back and/or side away from the driveway.

 

[BEAVO]

ok sorry to hijack thread but didnt want to start another if my question can be answered here if not i will start another thread..... so i live in ohio and my garage is also open... gets pretty cold here in winter and eventually it will be insulated and heated... so i guess my question is do i need vapor barrier on walls after insulation or the ceiling.... oh forgot to mention that theres no roof vents just vented at the soffitt thanks

 

[BEAVO]

anyone?

 

[Al Bundy]

ok sorry to hijack thread but didnt want to start another if my question can be answered here if not i will start another thread..... so i live in ohio and my garage is also open... gets pretty cold here in winter and eventually it will be insulated and heated... so i guess my question is do i need vapor barrier on walls after insulation or the ceiling.... oh forgot to mention that theres no roof vents just vented at the soffitt thanks

Yes you need roof vents and yes you need a vapor barrier.

 

[BEAVO]

on ceiling or walls or both and thanks for answering

 

[pattenp]

You should put vapor barrier on both walls and ceiling on the heated side of the insulation.

 

[pattenp]

To the OP:

You should vent attic space using soffit and ridge or gable vents. It also helps the life of the shingles.

 

[BEAVO]

You should put vapor barrier on both walls and ceiling on the heated side of the insulation.

thank you very much!!!

now my garage is 24x30 how many vents should i put on each side of the roof ridge? i have these how exactly are they put on thanks
http://www.homedepot.com/h_d1/N-5yc...splay?langId=-1&storeId=10051&catalogId=10053