Fast, Reliable Spray Foam Insulation Across San Antonio
Spray foam insulation in San Antonio typically costs $1.80-$3.20 per board foot for open-cell and $3.50-$5.50 for closed-cell, with most whole-attic jobs running $3,800-$8,500 depending on accessibility and whether existing insulation must be removed first. We’re Envelope Insulation Co., and our Spray Foam Insulation in San Antonio crews work out of our local dispatch office here in the city. We answer calls live, 24/7, at (830) 529-7780, and we can usually inspect your attic within 24-48 hours. San Antonio’s housing stock is unlike anywhere else in Texas - 1950s-1980s slab-on-grade brick ranches built fast for military families, with original insulation that barely met code then and fails catastrophically now against 150°F attic temperatures. We know these houses because we’ve sealed and insulated thousands of them since 2016.
Why Envelope Insulation Co. Is San Antonio’s Preferred Spray Foam Insulation Contractor
We’ve sealed and insulated over 9,000 homes since 2016, every one with a written price before work started and a documented record when the crew left. In San Antonio specifically, we publish before-and-after blower-door numbers on every applicable job - a pressurization reading that shows, in one number, how much conditioned air your building envelope was losing before and after our work. Homeowners here read their three-star reviews as carefully as their five-star ones, so we’ll say directly: our reviews note that we show up on time, we text when the technician is en route, and we leave photo documentation that holds up when CPS Energy asks for rebate verification.
Our San Antonio office coordinates dispatch and scheduling locally. Calls are answered by a live person, not a voicemail loop with callback windows measured in business days. Background-checked, uniformed technicians arrive with the Haven Standard scope already written - flat price, written warranty, no work starts without both.
We also offer a Free Second Opinion on any written estimate from another contractor. Bring us a competing quote and we’ll read it with you, line by line, and tell you what’s actually specified versus what’s implied.
Our Spray Foam Insulation Services in San Antonio
Open-Cell Spray Foam
Open-cell spray foam in San Antonio attics runs $1.80-$2.80 per board foot installed. We use it primarily at roof decks and top plates in the city’s slab-on-grade ranches, where its vapor-permeability allows assemblies to dry inward while stopping the air movement that drives heat gain. In Climate Zone 2, the hottest residential code zone, an open-cell roof deck at 5.5 inches delivers roughly R-19 while forming a continuous air barrier - critical when your attic hits 150°F and your CPS bill shows the consequences. We source open-cell products from Icynene and Demilec, among others, with no proprietary lock-in that limits your options.
Closed-Cell Spray Foam
Closed-cell spray foam in San Antonio costs $3.50-$5.50 per board foot and delivers R-6.5 per inch with full vapor barrier properties. We use it at rim joists, garage ceilings, and in crawl spaces where ground moisture or exterior exposure demands impermeability. In San Antonio’s 1950s-1970s ranches, the rim joist where the slab meets the exterior wall is often completely unsealed - a detail builders skipped because natural gas was cheap and code didn’t require it. Closed-cell here stops both air and moisture transport. We do not spray closed-cell directly over existing fiberglass batts without removal; trapped moisture and hidden compression are failure modes we’ve documented too many times in homes near Lackland AFB and the old Kelly corridor.
Rim Joist Spray Foam
Rim joist spray foam in San Antonio slab-on-grade homes typically runs $800-$1,800 for a complete treatment, depending on linear footage and access. This is the single most skipped detail in the city’s ranch stock, and it’s the single biggest leak path that summer attic heat exploits. The rim joist is the perimeter band where your exterior walls sit on the concrete slab - in San Antonio’s military-era housing, it’s usually bare wood with maybe a strip of rotted fiberglass stuffed loosely. We flash this with 2-3 inches of closed-cell, creating both air seal and thermal break. Without it, your conditioned air exits at the base of every exterior wall while 150°F attic air enters at the top. The CPS Energy rebate documentation we submit includes rim-joist photos because the utility’s auditors know this leak path costs homeowners hundreds per summer.
Garage Ceiling Spray Foam
Garage ceiling spray foam in San Antonio runs $1,200-$2,800 for a typical two-car footprint, with closed-cell at $3.50-$5.50 per board foot or open-cell at $1.80-$2.80 if the garage is conditioned and drying is acceptable. San Antonio’s attached garages share a ceiling with attic space above - that attic reaches 150-160°F in July, and an uninsulated garage ceiling radiates that heat straight into bedrooms or living spaces on the other side of the drywall. We treat this as part of the building envelope, not an afterthought. Our crews document the before condition with photos, specify the foam type and thickness in writing, and include garage ceiling readings in the blower-door test when the attic is connected.
Spray Foam Roof Deck
Spray foam at the roof deck converts vented attics to conditioned, unvented space - a strategy that performs exceptionally well in San Antonio’s Climate Zone 2 heat. Cost ranges $3,800-$7,500 for typical ranch footprints, depending on deck area, pitch complexity, and whether existing insulation removal is required. We see this most often in Alamo Heights and Terrell Hills renovations, where homeowners want usable attic space and measurable efficiency gains. The key detail: top plates, can lights, and all penetrations must be sealed before foam touches deck. Our Haven Standard scope specifies this sequence explicitly - sealed first, insulated second, always.
What happens when you call
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A real person answersNo phone trees - you reach a local pro.
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You get an upfront price rangeHonest numbers before anyone is dispatched.
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A background-checked tech heads outLicensed & insured, dispatched right away.
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You approve before work beginsNothing starts until you say go.
Trusted Materials for San Antonio Conditions
We source spray foam from Demilec, Owens Corning, Johns Manville, and other manufacturers - no proprietary product lock-in that limits what we can recommend for your specific assembly. San Antonio’s semi-arid Climate Zone 2 conditions, with radiant heat gain dominating over humidity, mean open-cell roof decks dry effectively inward while closed-cell rim joists block the occasional driving rain that hits slab-on-grade walls. Our San Antonio warehouse stocks common densities and chemistries for fast turnaround; most jobs don’t wait on material delivery. We specify the exact product by manufacturer and density in your written scope, so you know what was specified versus what was sprayed.
Common Spray Foam Insulation Problems We See in San Antonio Homes
- Closed-cell sprayed over original 1950s-1970s fiberglass batts without removal. The compressed, degraded batts trap moisture against the drywall ceiling, and the foam hides the problem until stains appear. We remove and dispose of existing insulation before any spray application - it’s specified in every Haven Standard scope.
- Open-cell applied too thin on Monte Vista and Beacon Hill balloon-frame attics. These early-1900s homes have hollow wall cavities that communicate directly with attic space. Foam at less than full stud depth leaves channels for January blue northers to pull air through framing that summer never exposed.
- Rim joist and garage ceiling foam skipped or under-applied in slab-on-grade ranches. This is the leak path that destroys CPS Energy rebate eligibility - the utility’s air-sealing verification catches unsealed rim bands, and out-of-town contractors routinely miss it because they don’t know San Antonio’s housing stock.
- No pre- and post-installation documentation submitted for CPS Energy rebates. San Antonio’s municipally owned utility requires documented R-value readings and air-sealing verification. Contractors who don’t know this paperwork cost homeowners $500-$1,500 in lost rebates.
Pricing for Spray Foam Insulation in San Antonio, TX
Most spray foam insulation jobs in San Antonio run between $3,800 and $8,500 for whole-attic treatment, with smaller targeted applications at $1,200-$2,800. Here’s how typical scope breaks down:
| Application | Cost Range (San Antonio) |
|---|---|
| Open-cell spray foam (per board foot) | $1.80 - $2.80 |
| Closed-cell spray foam (per board foot) | $3.50 - $5.50 |
| Rim joist treatment (typical ranch) | $800 - $1,800 |
| Garage ceiling (two-car) | $1,200 - $2,800 |
| Whole attic removal + spray (typical 1,400-2,000 sq ft ranch) | $3,800 - $8,500 |
What moves you within these ranges: existing insulation removal and disposal, deck accessibility (steep pitches cost more), whether top-plate sealing requires deck removal, and the specific product specified. Every Envelope job begins with a written price - flat, itemized, no work starts without it. Call (830) 529-7780 and we’ll schedule a free inspection with written estimate, typically within 24-48 hours.
We Also Serve Cities Near San Antonio
Our Spray Foam Insulation crews work throughout Bexar County and surrounding communities, including Converse, Universal City, Schertz, and Helotes. Same written-price standard, same documented photo record, same CPS Energy rebate documentation for qualifying San Antonio-area homes.
Serving San Antonio, TX - Our Local Coverage Area
We’re based in the San Antonio area and know this community well. Use the map below to see our service coverage - if you’re nearby, we can almost certainly help.
FAQs - Spray Foam Insulation in San Antonio
Yes, spray foam qualifies when the job includes documented pre- and post-installation R-value readings and air-sealing verification submitted on CPS Energy’s forms. We handle this paperwork on every qualifying job - it’s included, not available on request. The rebate typically runs $500-$1,500 depending on scope and final R-value achieved. Call (830) 529-7780 and we’ll confirm your home’s eligibility during the free estimate.
Spray foam stops air movement while fiberglass only slows heat conduction, and air movement is the dominant heat transfer mechanism in San Antonio’s 150°F attics. A blower-door test - the pressurization reading we provide on every applicable job - typically shows 30-50% reduction in air leakage after spray foam at the roof deck and top plates. Fiberglass batts, even at theoretical R-value, leave gaps at framing and penetrations that summer heat exploits continuously. Call (830) 529-7780 for a free inspection and we’ll show you the leak paths in your specific attic.
Yes, original fiberglass batts must be removed before spray foam application. Compressed R-11 batts trap moisture when covered, hide degraded areas, and prevent proper adhesion of foam to the substrate. Our Haven Standard scope specifies removal and disposal as a line item before any spray work begins. We document the before condition with photos, remove the material, then seal and spray. The additional cost for removal and disposal in San Antonio ranches typically runs $0.75-$1.25 per square foot of attic floor. Call (830) 529-7780 for a written price that includes this step explicitly.
Yes, properly applied spray foam handles blue northers better than any alternative because it seals the air leaks that cold fronts exploit. Monte Vista and Beacon Hill balloon-frame homes have continuous cavities from basement to attic that act as chimneys in winter; foam at full stud depth in walls and proper thickness at the roof deck breaks these pathways. The same air sealing that stops 150°F attic air in July stops 25°F air infiltration in January. We verify this with blower-door tests that show the combined seasonal performance. Call (830) 529-7780 for a free estimate with written scope.
Closed-cell is usually the right choice for garage ceilings in San Antonio because it provides both air seal and vapor barrier in one application, and garages see more moisture variation than conditioned space. At 2-3 inches, closed-cell delivers R-13-R-19.5 while blocking the humidity that can migrate from garage to living space. Open-cell is acceptable if the garage is actively conditioned and drying to interior is designed for, but most slab-on-grade ranches benefit from closed-cell’s impermeability. We specify the product in your written scope with the reasoning documented. Call (830) 529-7780 for a free inspection and we’ll recommend based on your specific assembly.
Schedule Your Free Spray Foam Insulation Estimate in San Antonio
Every San Antonio job we take starts with a written price and ends with a documented record - photos, scope, warranty, and on applicable jobs, before-and-after blower-door readings. Our 365-Day Done Right Promise applies to all completed work: if it’s not done right, we make it right. Calls are answered live, 24/7. Schedule your free inspection and written estimate by calling (830) 529-7780. Wes Okafor and the Envelope Insulation Co. team will read your existing estimates with you, specify exactly what your San Antonio home needs, and put it in writing before anyone lifts a tool.
Written by Wes Okafor, Owner at Envelope Insulation Co., serving San Antonio since 2016.
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