Demilec Wall Insulation Nationwide | Walt’s Insulation

Demilec Wall Insulation in San Antonio: What to Know First

We provide independent Demilec wall insulation repair and installation across San Antonio, with most jobs completed in one visit. If your Demilec foam has settled, pulled away from studs, or stopped performing the way it did when it went in, we’ll tell you exactly what’s going on and what it costs to fix. Pricing runs honest and upfront, and a live person answers when you call (866) 751-4428.

Call (866) 751-4428

This page is for San Antonio homeowners who already have Demilec insulation in their walls, or who are weighing Demilec against other options and want straight answers from a company that has installed and repaired it since 2000. If that sounds like you, keep reading. And if you’d rather just talk it through, call (866) 751-4428 and ask for Walt.

How Demilec Products Fail, and How We Fix Them

Demilec makes good foam. But any insulation product installed wrong, or in the wrong wall assembly, will cause problems later. Here are the five most common Demilec-related wall insulation failures we fix in San Antonio homes:

• Heatlok HFO shrinkage at the top plate. Heatlok HFO is Demilec’s closed-cell spray foam line, and when it’s applied too thick in a single pass, the exothermic reaction cooks the foam and causes it to shrink back from the top plate. In San Antonio, where attic temperatures above 140°F are normal in July and August, that gap becomes a thermal bypass that pulls conditioned air right out of the living space. We identify the gap with a thermal camera, then trim and re-foam the affected bays with manufacturer-recommended pass depths.
• Sealection 500 settling in exterior walls. Sealection 500 is Demilec’s open-cell half-pound foam, and it performs well when installed at the right density. But if an installer dialed the proportioner wrong and sprayed it too wet or too dry, the foam can slump inside the cavity over several years, leaving voids and soft spots. The tell-tale sign is uneven wall temperatures you can feel with your hand. We core a small inspection hole, confirm the density issue, and either inject to fill voids or remove and re-spray the affected section.
• Aggregate incompatibility with older Demilec formulations. Some Demilec products from the 2000s and early 2010s don’t bond reliably to certain masonry primers used on San Antonio’s older limestone and brick homes. We see this in Alamo Heights and Monte Vista, where century-old exterior walls were retrofitted with foam years ago. The foam looks fine until you tap it and hear a hollow, detached sound. The fix is mechanical removal, proper surface preparation, and reapplication with a compatible Demilec system.
• Moisture trapping behind the vapor barrier. Demilec’s closed-cell foams act as a vapor retarder. When applied to the interior face of a San Antonio exterior wall without considering how humidity moves through the assembly, condensation can form on the back side of the drywall. We often find this in bathrooms and kitchens, where a homeowner re-insulated without reworking the ventilation. It’s a system problem, not a product defect. We address it by repairing or reconfiguring the wall assembly to breathe the way it should.
• Rodent and pest intrusion through unsealed penetrations. Demilec foam does not repel rodents. What it does do is make it harder to see where they’re getting in. Rats and mice will chew through open-cell foam in a matter of hours. We solve this by identifying entry points, removing contaminated foam, and reinstalling with proper exclusion work first, then new Demilec foam second. In older San Antonio neighborhoods like Jefferson and Beacon Hill, where alley-facing garages share walls with neighbors, we handle this constantly.

Our Demilec Wall Insulation Process

Here’s what a Demilec wall insulation job looks like from the first call to the final walkthrough:

1. 1
   You call (866) 751-4428. A live person answers, day or night. You’ll describe what’s happening. If it sounds like an emergency and you’re in our service county, there’s no trip charge to come look.
2. 2
   We diagnose the wall. We use a thermal imaging camera and a borescope where needed to see what’s actually going on inside the cavity. No guessing, no disassembly unless it’s required. Walt Brenner reviews the findings before any work is approved.
3. 3
   You get a straight quote. We’ll tell you what’s wrong, what it costs to fix, and whether OEM Demilec material or a quality aftermarket equivalent is the right call for your situation. We never push a full removal when a targeted repair will do.
4. 4
   We do the work clean. Drop cloths, shoe covers, sealed work areas. Our background-checked, uniformed technicians handle the material carefully and respect your house.
5. 5
   We verify the result. We don’t just fill the hole and leave. We re-scan the wall with the thermal camera and confirm the cavity is filled to the correct density. If it’s not done right, we make it right before we leave, not after you complain.
6. 6
   You get the Done Right Promise in writing. Every Demilec wall insulation job we do carries our lifetime workmanship guarantee. If it’s not done right, we make it right. No runaround, no expiration date.

What Demilec Wall Insulation Costs in San Antonio

Demilec wall insulation work in San Antonio typically runs between $1,200 and $4,800 depending on scope. Here’s what that looks like:

• Targeted cavity repair or re-injection: $350 to $900 per wall section, including inspection and thermal verification.
• Drill-and-fill retrofit for a standard 12-foot exterior wall: $1,200 to $2,200, depending on cavity depth and access.
• Full Demilec spray foam re-insulation of an average San Antonio exterior wall: $2,500 to $4,800, including removal of failed material where needed.
• Rodent damage cleanup and foam replacement: $600 to $1,800, depending on contamination and access.

The biggest drivers of price are cavity depth, how much old material has to come out, and whether we’re working from the inside, the outside, or through the attic. Every estimate is free, and we’ll give you a second opinion on any written quote from another contractor. Call (866) 751-4428 and we’ll get you a real number.

Why San Antonio Homeowners Call Walt’s Insulation for Demilec Work

We’re the one down the road. Walt’s Insulation has been locally owned and owner-operated since 2000, with a published address and a license number you can check. Walt Brenner grew up on the north side of San Antonio, not far from Brackenridge Park, and he still lives here. We’re not a franchise, and we’re not a call center routing your job to whoever’s closest.

When a Demilec product is the right call, we use it. When another brand makes more sense for the wall assembly, we tell you that too. We install and service materials from Owens Corning, Rockwool, Icynene, Johns Manville, CertainTeed, Knauf, GreenFiber, and Reflectix. That means we recommend what works, not what we happen to have on the truck. And every job, Demilec or otherwise, is backed by the Done Right Promise: lifetime workmanship, no fine print. We answer the phone live, talk to a real person, get a straight answer.

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