How much insulation in Texas?

13 years ago

I have a garage apartment above my detached garage. I had foam insulation installed on all sides. The contractor followed city code and made the garage ceiling (apartment floor) have enough foam for a R13.

Because this is Texas and because this is a detached garage, I'm concerned that this is not enough insulation for our summers.

To keep my electric bills as low as possible, what R-value should I have the contractor bring the garage ceiling to?

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Comments (7)

virgilcarter
13 years ago
Are the walls of the garage insulated or only the walls of the apartment above the garage?
mazelady
Original Author
13 years ago
Only the walls of the apartment above the garage.
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energy_rater_la
13 years ago
you should put foam on attic floor/ceiling
of room above garage. even if they only
use 2-3" of foam, you can put batts or
blown on top to equal R-38
the foam will do the air sealing...
do you have recessed lights in this room
over the garage? if so, then steps by foam
company need to be taken to deal with
foam around IC lights.

best of luck.
worthy
13 years ago
Duplicate Post

This post was edited by worthy on Tue, Mar 19, 13 at 20:15
worthy
13 years ago
The floor meets current Code requirements if you're in Climate Zone 2. How about the walls and ceiling? See 2012 International Energy Conservation Code below.

The bare legal minimum is not necessarily the optimum.

Here is a link that might be useful: Energy Code Requirements Texas
david_cary
13 years ago
Texas is a rather diverse climate. The vast majority of heat load for most a/c situations comes from the windows.

What is the temp of the garage? You might have west windows and commonly see 130 degrees or you might have no windows are rarely exceed 100.

At 100, r-13 is not horrible - only a 25 degree difference from room temp. At 130, you need far more than twice the r-value.
mazelady
Original Author
13 years ago
Our heat gets up to 101-102 in August. The apartment attic is foam insulated and I don't think it's vented. It had radiant barrier roof decking but the foam insulation invalidated that effort.

There are double paned windows on all sides - 3 on 1 side, large picture window on the other, and single windows on each end. The 3 windows on the west are mostly shaded in the summer and the east is partially shaded.

The garage ceiling is not sheetrocked. Would that improve the energy usage?

The window air conditioned unit is energy star rated. I had bought a 24000 btu unit but returned it for an 18000 unit per the foam insulation contractor's advice.

My concern is this past December, temperatures hovered around 29-39. The heater on the window unit ran a lot and my electric bill was $200 higher that month. This made me concerned for the summer weather which is more extreme.

I would like to keep my electric bill within $100 of the norm.