Demilec Blown-In Insulation in San Antonio: What to Know First
Walt’s Insulation provides independent Demilec blown-in insulation service across San Antonio, and we work on it nearly every week. Most Demilec blown-in jobs, whether it’s a top-up over settled material or a full dense-pack wall fill, take one day from setup to cleanup, and we give you an upfront price before anything gets loaded into the hopper. We’re not a Demilec dealer and we don’t pretend to be one, but we know their products inside and out, and we’ve been fixing and installing them in Bexar County homes since 2000.
If you own a home with Demilec insulation and you’re noticing drafts, hot rooms, or energy bills that spike every July like clockwork, this page explains what we see in San Antonio and what it costs to make it right. Call (866) 751-4428 and you’ll get a live person, day or night.
How Demilec Products Fail - and How We Fix Them
Demilec makes solid insulation materials, but San Antonio’s heat, humidity, and occasional critter problem create specific failure patterns we’ve learned to spot fast. Here’s what we actually see on Demilec jobs around town.
- Heatlok HFO Pro settlement gaps. Demilec’s Heatlok HFO line is closed-cell spray foam, but when a previous contractor used Demilec foam in the roofline and left the attic floor with old fiberglass, the blown-in layer often settles to R-19 or worse within a decade. We see it in Stone Oak and Alamo Heights attics constantly: the foam is fine, but the blown-in top-up has compressed to where it’s doing almost nothing. We remove or fluff what’s salvageable and blow in fresh material to the right depth for our climate zone.
- Sealection 500 air gaps behind drywall. Demilec’s Sealection 500 open-cell foam can shrink slightly if it was applied during a humid stretch, which leaves hairline air channels behind finished walls. The symptom is a room that never holds temperature on north-facing walls. We dense-pack blown-in cellulose into those wall cavities from the exterior or through interior access points, filling the void without tearing out drywall.
- Moisture-wicking from foam-to-fiber transitions. Where Demilec foam meets blown-in fiberglass at the attic floor, condensation can form on humid San Antonio mornings when the AC runs hard. That moisture saturates the fiberglass, compresses it, and drops the R-value fast. We pull the wet material, fix the vapor transition with the right air sealing, and re-blow with fresh insulation that matches the existing R-value target.
- Rodent damage in Demilec-sealed attics. Demilec foam does not stop rats and squirrels. Once they bore through, they tunnel along the foam-fiber boundary and shred the blown-in material for nesting. We see this routinely in older neighborhoods like Jefferson and Monte Vista. The fix is removing the contaminated blown-in insulation, rodent-proofing the entry points, and then re-blowing clean material.
- Incorrect product mixing from a prior installer. Demilec’s two-part foam lines require exact mixing ratios. If a previous contractor got it wrong, the foam can become brittle and crumbly after a few years, sending dust and particles down into the blown-in insulation below. Homeowners notice a chalky film on ceiling vents. We evaluate the foam’s condition, and if it’s failing, we remove the damaged sections and re-insulate with a method that fits the home and budget.
Our Demilec Blown-In Insulation Process
Here’s how a Demilec blown-in job goes when you call us, from the first phone call to the final walkthrough.
- 1
Call and diagnosis over the phone. You talk to a real person, not a menu. We ask about the symptoms, the age of the home, and whether you know what type of Demilec product was installed. Most calls take under ten minutes.
- 2
On-site inspection and attic assessment. We show up in uniform, on time, and we actually get up into the attic. We measure current insulation depth, check for moisture, look for rodent activity, and figure out what’s failing and why.
- 3
Straightforward quote before any work starts. You get a written price that covers materials, labor, and cleanup. No vague “we’ll see how it goes.” The price we quote is the price you pay, and seniors and veterans take 10% off automatically.
- 4
The blown-in install. We set up outside, run the hose to the attic or wall cavities, and blow in cellulose or fiberglass to the target R-value for San Antonio’s climate. If it’s a top-up over existing Demilec foam, we work around it carefully so we don’t disturb what’s still doing its job.
- 5
Verification and cleanup. We check depth with a ruler at multiple points, not just one spot near the hatch. We clean up every stray piece of material in the house and yard. Then we walk you through what we did and why.
- 6
Done Right Promise follows the job. Every install is covered by our lifetime workmanship guarantee. If it’s not done right, we come back and make it right. No runaround, no fine print.
What Demilec Blown-In Insulation Costs in San Antonio
Blown-in insulation pricing in San Antonio depends on square footage, current insulation depth, and whether we’re topping up or starting fresh. Here are the ranges we typically quote for Demilec-related jobs.
| Job Type | Typical Range |
|---|---|
| Blown-in top-up over Demilec foam (1,500-2,000 sq ft attic) | $900 - $1,600 |
| Full attic re-blow after removal (1,500-2,000 sq ft) | $1,400 - $2,400 |
| Dense-pack wall insulation (single exterior wall) | $600 - $1,200 |
| Blown-in fiberglass (new construction or bare attic) | $1,100 - $2,000 |
| Rodent cleanup plus re-insulation | $1,800 - $3,500 |
What moves the price is attic access, existing material that has to be removed, and how much depth is needed to hit R-38 or R-49. We offer a free second opinion on any written estimate you’ve gotten from another company, and there’s no trip charge if you’re inside Bexar County. Call (866) 751-4428 for an exact quote.
Why San Antonio Homeowners Call Walt’s Insulation for Demilec Work
Walt Brenner started this company in San Antonio in 2000, after too many years of watching homeowners get sold insulation that didn’t match the South Texas climate. We’re still locally owned and owner-operated, with a published address and a license number you can look up. When you call, a live person answers every time, not a voicemail or an answering service.
Our technicians are background-checked and uniformed, so you know exactly who’s in your house. We work with Demilec products regularly, and we also install Owens Corning, Johns Manville, Knauf, Rockwool, CertainTeed, Icynene, and GreenFiber material, plus Reflectix radiant barriers when a home needs one. If Demilec blown-in isn’t the right call after we see your attic, we’ll tell you that and show you what is. We answer the phone live - talk to a real person, get a straight answer.
FAQs
Adding blown-in insulation on top of or alongside Demilec foam typically does not void the manufacturer warranty, as long as the installation doesn’t alter or damage the original foam application. As an independent Demilec service provider, we can’t speak for Demilec’s warranty department on every claim, but we work in a way that preserves existing material and document everything with photos.
Yes. We measure the current R-value of the foam and calculate exactly how much blown-in cellulose or fiberglass is needed to reach the total R-value target for San Antonio’s climate, which is R-38 to R-49 in most attics. We verify depth with a ruler at multiple points before we call the job done.
Most jobs are scheduled within a few days, and many blown-in top-ups can be done same-week. If you’ve got a real problem, like wet insulation or a rodent mess, we can often get a technician out within 24 to 48 hours. Call (866) 751-4428 and we’ll give you a straight answer on timing.
It depends on what the inspection shows. Settled blown-in fiberglass over intact Demilec foam is usually a top-up job, not a full replacement. Crumbly, brittle foam that’s shedding particles usually means the original install was done incorrectly, and that section should be removed and replaced. We’ll show you what we see up there and recommend the option that makes sense for your house and budget.
Yes. Many San Antonio homes have Demilec spray foam in the roofline and blown-in insulation on the attic floor, and both systems need to work together. We inspect both and make sure the air sealing, vapor control, and insulation depth all fit the design of the house, not just the spec sheet.
Written by Walt Brenner, Owner, Walt’s Insulation at Walt’s Insulation, serving San Antonio and nearby areas.