Green Air Duct Club · San Antonio Since 2009
Attic Insulation in San Antonio — R-Value Requirements for Texas Summers
Attic insulation in San Antonio is measured against one number: R-38.
That’s the Texas Energy Code minimum for Climate Zone 2, which covers all of Bexar County. R-value — a material’s resistance to heat flow — determines how much of that 140°F attic air pushes into your living space in July and August. We install to the R-38 minimum, and we measure your existing depth before any material goes down — so you know exactly what’s there and what’s being added.
- Measured Before Quoted
- R-38 to Texas Code
- Air-Sealed First
The R-Value Gap
San Antonio’s Housing Stock and the R-Value Gap
San Antonio’s older neighborhoods carry a predictable insulation shortfall.
Homes built in Bexar County before 1990 were permitted under a code that allowed R-11 or R-19 attic insulation. Those levels met the standard of their era — they don’t meet the demand of a cooling season that now runs eight to ten months a year. The insulation typically didn’t fail; it’s performing exactly as installed, at a level acceptable in 1978 that leaves a significant gap today.
Alamo Heights and Beacon Hill consistently show R-11 batt when we measure. ZIP codes 78201, 78207, and 78209 — concentrated pre-1980 housing — show the widest gap to the R-38 requirement. Even newer far-north developments were sometimes installed to an earlier code minimum that falls short of today’s standard. The gap shows up on the CPS Energy statement every summer.
From The Field · Ori Tarzi, Founder
What I Find When I Measure San Antonio Attics
“The number one thing that surprises homeowners is that their attic looks insulated. There’s material on the floor; it appears to cover everything. But when I take depth readings at multiple points — the corners, the eaves, the areas near the HVAC equipment, not just the center — the picture changes fast.
In a 1964 Alamo Heights home, the center measured R-14. Three feet from the exterior wall, near the top plate, it dropped to R-6 — the edge of the house, the zone that takes the most solar load, with almost no protection. Thermal bypass shows up constantly: conditioned air escaping through gaps at top plates, electrical penetrations, and recessed lights before it reaches the living space. New insulation over that gap still lets heat through.
That home needed air sealing at fourteen penetrations and a blown-in upgrade from an average of R-14 to R-38 before the assembly did what the homeowner assumed it already was. We always measure before we quote — the measurement determines the scope.”
Ori Tarzi
Founder, Green Air Duct Club
The Right Method
Blown-In vs. Batt Insulation for Existing San Antonio Attics
Batt insulation — pre-cut fiberglass or mineral wool panels — works well in new attic assemblies where joist bays are clear and uniform. In an existing San Antonio attic, bays rarely are: there’s existing loose-fill, HVAC equipment, ductwork, electrical runs, and framing irregularities that batts can’t fill around. Blown-in loose-fill fills around all of it — reaching corners, covering irregular framing, and layering over existing material that’s been assessed and confirmed clean. Cellulose performs particularly well in high-heat attics, settling less than fiberglass loose-fill and installing to a consistent depth we confirm with a depth ruler before the job closes.
What Every Job Requires
What Every Attic Insulation Job Requires in San Antonio
Every job is measured before installation and confirmed after — you see the before and after numbers.
Depth Recorded at Multiple Points
Existing depth is read across the attic floor at multiple locations — not a single center reading that overstates coverage.
Coverage Gaps Identified
Gaps are located at top plates, eaves, and floor penetrations before any new material is installed.
Attic Air Sealing First
Bypasses at electrical boxes, plumbing chases, and recessed lights are sealed where conditioned air escapes around the insulation layer.
Blown-In to Confirmed R-38
Material is installed to R-38 depth using a calibrated depth gauge — not estimated by the installer.
Post-Install Depth Readings
Finished depth is confirmed across the full floor, including the edge zones near exterior walls that are most often under-insulated.
Assess To Confirm
How We Assess and Install Attic Insulation
From a multi-point measurement to confirmed R-38 coverage — in sequence.
01
Diagnostics
We measure depth at a minimum of six locations across the attic floor, record every reading, identify coverage gaps, and note existing material condition. We inspect for thermal bypasses at top plates and penetrations — the gaps that let conditioned air escape around the insulation regardless of the R-value above them.
02
Implementation
Air sealing comes first — we close bypasses at electrical boxes, plumbing penetrations, access hatches, and top-plate gaps with foam and mastic. Then we install cellulose or fiberglass blown-in to R-38 depth across the full floor, including the edge zones near exterior walls that carry the highest heat load and are most often under-insulated in pre-1990 homes.
03
Post-Service Confirmation
We take post-installation depth readings and compare them to the pre-installation baseline. Every measurement is recorded; the finished depth confirms R-38 coverage at the required locations. We don’t consider the job complete until the numbers confirm what it set out to achieve.
Where We Install
Attic Insulation Across Bexar County
We work established inner-loop neighborhoods — Alamo Heights, Beacon Hill, Monte Vista, and the Near West Side — where pre-1990 homes consistently carry original insulation well below R-38, and newer developments in Stone Oak, Helotes, and along the far-north Loop 1604 corridor where depth was sometimes installed to an earlier code minimum. Available 24/7 across the full metro.
Bexar County & Surrounding Communities
- Alamo Heights
- Beacon Hill
- Monte Vista
- Near West Side
- Stone Oak
- Helotes
- Loop 1604 Corridor
- 78201
- 78207
- 78209
- Northwest Side
- Bexar County
Available 24/7
Schedule Your Attic Insulation Assessment
The first step is a measurement — not a quote. We measure your existing depth before recommending any scope, so you know exactly what’s in your attic, where the gaps are, and what it takes to reach R-38. We serve the full San Antonio metro.
Prefer email? Reach us at gr*****************@***il.com. Available 24/7 across the metro.
Common Questions
Attic Insulation in San Antonio: FAQ
The Texas Energy Code sets R-38 as the minimum for attic insulation in Climate Zone 2, which covers all of Bexar County. If your home was built before 1990, it’s likely insulated to R-11 or R-19 — the standard of that era. That shortfall is the most common finding we document when measuring San Antonio attics.
Age alone isn’t reliable — the meaningful test is depth. We take readings at a minimum of six locations, including corners and edge zones near exterior walls; a single center reading routinely overstates coverage. If your readings average below R-38, the system is carrying a heat load your HVAC compensates for every summer.
Not always. If the existing material is dry, free of contamination, and structurally sound, blown-in can be installed directly over it to reach R-38. If it shows moisture damage, pest activity, or contamination, removal is part of the scope before any new material goes down.
Air sealing closes the gaps at top plates, electrical boxes, plumbing chases, and recessed lights where conditioned air bypasses the insulation entirely. Adding insulation over an unsealed floor improves R-value on paper but doesn’t stop air moving through those penetrations. We seal first, then insulate, so the finished assembly performs at the R-38 the measurement shows.
Most residential jobs — including air sealing and blown-in installation — are completed in a single visit, with the diagnostic measurement at the start and the post-installation depth confirmation at the end both included. Homes with significant air-sealing needs or unusually large attics may require additional time, which we communicate during the initial assessment.
The reduction depends on the gap between your current level and R-38. A home moving from R-11 to R-38 in a climate that runs AC eight to ten months a year sees a more meaningful reduction than one moving from R-30 to R-38. We don’t quote a specific savings figure before measuring, because the starting point varies — but we confirm the before and after depth and the full R-38 coverage achieved.