Garage insulation and vapor barrier

[fortee9er]

Hi,
I need help in determining how to insulate my garage. I live in Houston, TX which is Zone 2 hot and humid. The garage is an older wood frame stand alone structure. All walls are exterior walls and there is no drywall on the inside.
The roof is a hip type roof and there is no ceiling it is all exposed.
My plan is to use dry wall or sbx to cover the walls once they are insulated.
There is no existing vapor barrier or radiant barrier.
I have installed a thru the wall air conditioner (33,000btu) but have not used yet it would be a waste of money at the moment.
What type of insulation system would you suggest?
Thank You

 

[Notgrownup]

It got to breathe, mine is tyvek on outside so I used R19 paper backed pink insulation stapled to the studs then covered my walls with OSB, I have about 10” of blown cellulose in the ceiling, I leave my unit running on 80 degrees. It’s not Houston but it was 102 withthe heat index today...Experts might chime in as far as the vapor barrier part and breathability of the bldg.

 

[tonyciambrone]

Is there housewrap?
What is the framing system?

 

[fortee9er]

No house wrapping. Wood frame construction.

 

[stm317]

There are three basic approaches.
1) You can close off an uninsulated attic section and make sure that it's properly vented (soffit/ridge vents or roof vents would have to be used with a hip roof). Then you'd insulate your walls and ceiling
2) You can spray foam everything (sealing the whole building up with no venting) as closed cell foam will act as a vapor barrier so long as it's a couple of inches thick. This is pretty much your only option if you want to leave the rafters exposed.
3) A combination of the two, where you have a vented attic with insulated ceiling, and spray foamed walls that act as a vapor barrier/insulation in one.

In a hot humid climate the common practice is to have the vapor barrier on the outside of the insulation which would be difficult to do at this point.

 

[DetachedGarage]

There are three basic approaches.
1) You can close off an uninsulated attic section and make sure that it's properly vented (soffit/ridge vents or roof vents would have to be used with a hip roof). Then you'd insulate your walls and ceiling
2) You can spray foam everything (sealing the whole building up with no venting) as closed cell foam will act as a vapor barrier so long as it's a couple of inches thick. This is pretty much your only option if you want to leave the rafters exposed.
3) A combination of the two, where you have a vented attic with insulated ceiling, and spray foamed walls that act as a vapor barrier/insulation in one.

In a hot humid climate the common practice is to have the vapor barrier on the outside of the insulation which would be difficult to do at this point.

I agree with #2. You may also want to consider Aero barrier before you do the spray foam.

 

[pmiranda]

Neat, I hadn't heard of Aero barrier before!

 

[kelpaso1]

Generally, if you heat for more of the year, the VB on the inside, and opposite if you cool for most of the year.