Vented attic, thin dry fiberglass, simple ranch
- Usually start with
- Air seal, then blown-in to R-49
- Why it fits this climate
- Lowest cost per R on a large lid under a hot roof
Match the attic you have
Best Insulation in San Antonio
The best insulation in San Antonio is the one that fits the attic you have in Climate Zone 2A. A vented ranch ceiling, a foam roof deck, and a bare garage lid under a bedroom are three different answers. Brand names do not settle it. The assembly does.
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A climate chooser for these attics
Bexar, Comal, and Guadalupe Counties are IECC Zone 2A. Kendall County, which is Boerne, is Zone 3A. Attic ceilings in the 2021 IECC are R-49 in both, with the R-38 eave exception where that section applies. Walls are where Zone 3 asks for more. Use the row that matches the house, then read the service page before you book.
Start here, then confirm on site
3 to 4 inches already there, hatch leaks
- Usually start with
- Seal, then top up toward R-38 or R-49
- Why it fits this climate
- ENERGY STAR's Zone 2 retrofit add for that starting depth is R-38
Cut-up roof or a plan for an unvented attic
- Usually start with
- Open-cell spray foam on the deck, plus the listed covering
- Why it fits this climate
- The foam is the air barrier. Soffit vents close on purpose.
Wet, soiled, or crushed fill
- Usually start with
- Remove, seal, then new insulation
- Why it fits this climate
- New material on failed fill keeps the moisture or the smell
Bedroom over a garage
- Usually start with
- Seal and insulate that lid. Foam if the bays are blocked.
- Why it fits this climate
- That bay can be hot while the main attic looks acceptable
Empty 2x4 walls
- Usually start with
- Dense-pack, or batts if the wall is open
- Why it fits this climate
- Zone 2 wall target is about R-13. The attic still comes first on most calls.
Boerne address in Kendall County
- Usually start with
- Same attic logic, higher wall target
- Why it fits this climate
- Zone 3A. Nights run cooler on the plateau than at the San Antonio airport.
| Situation | Usually start with | Why it fits this climate |
|---|---|---|
| Vented attic, thin dry fiberglass, simple ranch | Air seal, then blown-in to R-49 | Lowest cost per R on a large lid under a hot roof |
| 3 to 4 inches already there, hatch leaks | Seal, then top up toward R-38 or R-49 | ENERGY STAR's Zone 2 retrofit add for that starting depth is R-38 |
| Cut-up roof or a plan for an unvented attic | Open-cell spray foam on the deck, plus the listed covering | The foam is the air barrier. Soffit vents close on purpose. |
| Wet, soiled, or crushed fill | Remove, seal, then new insulation | New material on failed fill keeps the moisture or the smell |
| Bedroom over a garage | Seal and insulate that lid. Foam if the bays are blocked. | That bay can be hot while the main attic looks acceptable |
| Empty 2x4 walls | Dense-pack, or batts if the wall is open | Zone 2 wall target is about R-13. The attic still comes first on most calls. |
| Boerne address in Kendall County | Same attic logic, higher wall target | Zone 3A. Nights run cooler on the plateau than at the San Antonio airport. |
What to ask any contractor
Ask these on every bid, including ours. A contractor who changes the subject is telling you the scope is thin.
1. What R-value, at what settled depth, on which product chart?
Blown-in without a chart is a pile of bags. The code points at the manufacturer's settled R-value.
2. Will you air seal before the new layer covers the ceiling?
If the answer is no, you are buying depth and keeping the leaks.
3. What happens if you find vermiculite, wet fill, or knob-and-tube?
The right answer is stop, test or call an electrician, and reprice. The wrong answer is we will blow over it.
4. Is this number a phone guess or a scope after someone was in the attic?
Use our calculator for a range. Do not treat any phone price as final, from us or anyone else.
5. Does this address need a City of San Antonio permit?
Ask. Requirements depend on the work. We will not invent a permit rule to sound careful.
6. Which utility meter is on the house?
CPS Energy, New Braunfels Utilities, GVEC, and Bandera Electric Cooperative do not share one rebate page.
Where to go next
Pick the page that matches the row you chose. Each one has the process and the limits. The calculator gives a range. The assessment is the written version.
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Questions about choosing
No. A vented ranch wants a sealed ceiling and blown depth. A cut-up roof that will be unvented wants foam on the deck. The best product is the one that matches that assembly.
Past a continuous R-49 on a vented Zone 2 attic, more depth helps less than fixing the holes and the thin bays you skipped. R-60 is in the DOE band. It is not a reason to ignore an open hatch.
Any contractor. If they will not name the R-value, the product, the can rating, and what happens when they find vermiculite, keep looking. Those answers are the job.