Trusted Attic Air Sealing for San Antonio Homeowners
If you’re wondering how much Attic Air Sealing costs, in San Antonio it typically runs between $1,200 and $2,800 for a full seal on a 1,500 to 2,500 square foot single-story home, and most jobs are finished in a single day. That price is not a guess. We’ve been sealing attics across Bexar County since 2000, and we know exactly what San Antonio heat does to a leaky attic floor. The real problem is rarely what you can see from the hatch. It’s the dozens of small gaps around top plates, can lights, duct boots, and wire penetrations that let the air you paid to cool escape into a 140-degree attic by July. Walt’s Insulation fixes that. We’re the company down the road, not an 800 number. Call (866) 751-4428 and a real person answers, day or night.
We’re locally owned and owner-operated. Walt Brenner started this business over 25 years ago, and every job still carries the Done Right Promise: if it’s not done right, we make it right, no runaround. You’ll know exactly who’s walking into your house because our technicians are background-checked and uniformed, and they show up when we say they will. San Antonio’s summers demand a home that holds its cool air. If yours doesn’t, you’re paying for it every single billing cycle.
What Our Attic Air Sealing Service Includes
Air sealing is not one product. It’s a set of targeted fixes that close the pathways where conditioned air leaks from your living space into the attic, and where attic air gets pulled into your walls. Here’s what we actually do when we seal an attic in San Antonio, broken down by the specific areas we treat.
Attic Floor Air Sealing
Your attic floor is the ceiling of your living space, and it has far more holes in it than most homeowners realize. We locate and seal every gap where wiring, pipes, and framing pass through the drywall into the attic. These openings are hidden under insulation, which means they’ve likely been leaking for years without anyone noticing. Our crew pulls back the existing insulation section by section, seals each penetration with caulk or foam rated for attic temperatures, then replaces the insulation. This is the most common air sealing work we do in older San Antonio neighborhoods like Terrell Heights and Jefferson, where homes from the 1950s and 60s often have dozens of unsealed penetrations per room.
Top Plate & Penetration Sealing
The top plate is the horizontal framing member that sits on top of your wall studs, and it’s one of the leakiest parts of any wood-framed home in San Antonio. Where drywall meets the top plate, along interior and exterior walls alike, there is often a continuous gap that runs the entire length of the wall. We seal these joints with a foam sealant that expands to fill irregular gaps and stays flexible through decades of San Antonio heat and humidity swings. Every pipe, wire, chimney chase, and plumbing vent that passes through the top plate gets sealed too. On a typical 2,000-square-foot home, this is often where we find the equivalent of a window left open all summer.
Can Light & Duct Boot Sealing
Recessed can lights are notorious air leaks. Even the fixtures rated for insulation contact still allow air movement around the housing unless they’re properly sealed from below or boxed from above. We seal can lights with an approved method that prevents heat buildup while stopping the airflow, typically using a fire-rated enclosure or a high-temperature sealant depending on the fixture. Duct boots are the metal or plastic connections where your supply registers meet the ductwork, and they almost always leak at the seam. In San Antonio homes with flex duct, we regularly find boots that are loose, untaped, or gapped by a quarter inch or more. We seal every boot we can reach, at every register, before we call the job done.
Attic Hatch Sealing
The attic hatch or pull-down stairs is a surprising source of air loss. That thin piece of drywall or plywood over your head is usually completely uninsulated and rarely sealed. We weatherstrip the hatch opening, install a foam board cover or an insulated attic stair tent where practical, and seal the trim so air stops flowing around the frame. In San Antonio, where the attic can hit 150 degrees in August, an unsealed hatch acts like a small furnace door. Sealing it is often the single biggest bang-for-the-buck fix we make on an otherwise tight house.
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.
Brands We Service for Attic Air Sealing
Most of our air sealing work involves the insulation already in your attic, and we work with every material type on the market. That includes homes insulated with CertainTeed fiberglass batts, which we regularly pull back, seal under, and re-install. CertainTeed products hold up well in San Antonio’s climate, but the air sealing around them is what makes them perform. We know how to work with their batt systems without compressing the material or voiding any manufacturer warranty.
We also work extensively with homes that have Icynene open-cell or closed-cell spray foam, and with Demilec spray foam products like Heatlok HFO. If your attic has an existing spray foam application that wasn’t done right, or if you have foam in the roofline but the attic floor was never sealed, we can identify exactly where the leaks are and fix them without disturbing the foam. Same goes for GreenFiber blown-in cellulose, which settles over time and hides gaps that were never sealed in the first place. Whether you have any of these or something else entirely, we know how to work with it.
We’re not a manufacturer’s rep. We’re a sealing contractor. The brand in your attic matters less than the gaps under it, and those gaps are what we’re trained to find.
Signs You Need Attic Air Sealing Right Now
- Upstairs rooms that never cool down in summer. If your upstairs stays 8 to 12 degrees warmer than downstairs in July, conditioned air is escaping somewhere. The attic is the first place we look because heat moves upward, and any gap in the ceiling plane becomes an exhaust vent for your AC.
- Energy bills that climb every June. San Antonio electric rates from CPS Energy don’t need any help from a leaky attic. If your summer bills keep rising even when your thermostat setting hasn’t changed, your home is losing conditioned air faster than your AC can replace it.
- Dust on furniture within days of cleaning. Air leaking from a dusty, unconditioned attic carries fine particulate into your living space. If you dust on Monday and it’s back by Friday, your attic air is moving through your ceilings and walls.
- A hot hallway near the attic hatch. Stand under the hatch on a August afternoon. If you feel warmth radiating down, the hatch is unsealed and uninsulated. That’s a sign dozens of smaller leaks exist elsewhere that you can’t feel as easily.
- You can see daylight around light fixtures or plumbing pipes in the attic. On a bright day, walk the attic and look down at the floor. Any light you see from below is a direct air path into your home. Those are gaps, and every one of them can be sealed.
Our Attic Air Sealing Process - Step by Step
We don’t rush, and we don’t skip steps. Here’s how a typical attic air sealing job goes in San Antonio from start to finish.
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Initial inspection and pressure diagnostic. We start with a walkthrough of your attic and a look at your existing insulation. When it makes sense, we use a blower door test to quantify how leaky the house is before we start. This gives us a baseline number we can improve against, and it tells us where the biggest leaks are hiding.
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Attic prep and insulation management. We move the existing insulation carefully, section by section. We don’t walk over areas we haven’t looked at, and we protect any ducts, wiring, and plumbing we encounter. If we find rodent damage, water damage, or mold, we stop and tell you before proceeding.
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Sealing every penetration and gap. Working top plate to top plate, we seal wire holes, pipe penetrations, and framing joints with the right material for each gap. We use fire-rated caulk around flues and can lights, expanding foam for irregular gaps, and rigid materials where an air barrier is needed. Nothing gets skipped for speed.
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Hatch, drop-down stair, and register treatment. We weatherstrip and insulate the hatch and attic stair assembly, then seal each duct boot from the attic side. This is detail work, but it’s where a lot of San Antonio homes lose the most air.
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Final walkthrough and a written summary. We show you exactly what we sealed, where, and why. You get a walkthrough before we leave, and the work is covered for life under the Done Right Promise. If anything ever fails, we come back.
How Much Does Attic Air Sealing Cost in San Antonio?
A whole-house attic air sealing job in San Antonio typically runs between $1,200 and $2,800 for a home up to 2,500 square feet, similar to our Attic Air Sealing in Houston. Smaller jobs, like sealing just an attic hatch and a handful of top plate gaps, can start around $400 to $700. Larger homes with complex mechanicals, multiple can lights, or an existing spray foam roofline run higher. The average single-story home in Alamo Heights, Stone Oak, or the Northeast Side lands right in the middle of that range.
What affects the price most is attic accessibility, how much existing insulation has to be moved and re-installed, and the number of penetrations. A 1960s ranch in North San Antonio with original wiring and a dozen can lights will take longer than a 2010 build with tight framing. What matters is that our quotes are itemized and upfront. No mystery line items, no surprise change orders. Every estimate is free, and if you have a written estimate from another company, we’ll give you a free second opinion. We’ll tell you honestly whether their scope covers what your attic actually needs. And remember, seniors and veterans always get 10% off with us, no expiration.
Attic Air Sealing Near San Antonio - Our Service Area
We’re based right here in San Antonio and we work all over Bexar County, from downtown and the East Side up through Shavano Park, Timberwood Park, Converse, and beyond. We run crews throughout the metro every week, so most areas within the loop and the outer band see next-day or same-week availability. If you’re comparing companies, we’re the one down the road with a published address and a real local owner, not a franchise. We also serve surrounding communities and can point you to our sister pages for Attic Air Sealing in Houston, Attic Air Sealing in Spring, and Attic Air Sealing in The Woodlands if you or someone you know needs work further out. And if you’re starting fresh with your whole attic, start with our home page to see the full range of insulation services we offer.
Serving San Antonio, TX - Our Local Coverage Area
We’re based in the San Antonio area and know this community well, and we also provide Attic Air Sealing in Pasadena. Use the map below to see our service coverage - if you’re nearby, we can almost certainly help.
Frequently Asked Questions - Attic Air Sealing in San Antonio
Attic air sealing is the process of closing the gaps, cracks, and penetrations where conditioned air escapes from your living space into the attic, or where hot dusty attic air gets pulled into your home. It’s the essential first step before adding or upgrading attic insulation because insulation slows heat transfer but does not stop air movement. Without air sealing, most insulation underperforms by 20 to 40 percent. In San Antonio’s climate, this is the difference between a home that holds its cool air and one that fights to stay comfortable all summer.
Most single-family homes in San Antonio are fully sealed in one day, typically six to nine hours depending on attic size and accessibility. Homes with complex mechanicals, steep rooflines, or extensive existing insulation may take a second day. We’ll tell you the expected timeline in writing before we start, and we don’t leave until the work is done and the attic is left cleaner than we found it.
A full attic air sealing job in San Antonio generally runs $1,200 to $2,800 for homes up to 2,500 square feet, with smaller targeted jobs starting around $400. The final price depends on attic accessibility, the number of penetrations and can lights, and how much insulation we need to move. Call (866) 751-4428 for an exact quote. Estimates are free, and if you already have a written estimate, we’ll give you a free second opinion.
Yes. We regularly work in San Antonio attics that have Icynene open-cell or closed-cell foam and Demilec Heatlok HFO spray foam roofs. The air sealing process changes when foam is present because it’s structural to the roofline, and we adjust our methods accordingly. We never disturb existing foam, and we focus on sealing the areas the original installer left unfinished.
In most cases, yes. We keep same-day and next-day appointment slots open for San Antonio homeowners with urgent situations, like a failed hatch seal letting 150-degree attic air pour into a bedroom. Call (866) 751-4428 and a live person will answer 24/7. No voicemail, no answering service. We’ll tell you honestly if we can get there today.
Every attic air sealing job we do in San Antonio is covered by our lifetime Done Right Promise. If the work we did isn’t holding up, we come back and make it right, no charge, no runaround. That’s the guarantee Walt Brenner has stood behind since 2000, and it applies to every job we complete, not just the ones where something goes wrong.
Not much is required. Clear access to the attic hatch or pull-down stairs, and move anything fragile from closets and hallways near the hatch. Our technicians will handle everything else, including moving insulation and protecting your floors and HVAC equipment. We’ll walk you through the day’s plan when we arrive, and you’ll get a summary of everything we sealed before we leave.
Schedule Your Attic Air Sealing Service in San Antonio Today
Don’t let another San Antonio summer paycheck vanish into your attic. Call (866) 751-4428 today for a free, no-obligation estimate on attic air sealing. A real person answers, 24/7. We’ll schedule a walkthrough, give you an upfront price, and if you already have a written quote from anyone else, bring it in and we’ll give you a free second opinion. This is the one down the road, doing it right since 2000.
Written by Walt Brenner, Owner at Walt’s Insulation, serving San Antonio since 2000.