Johns Manville Wall Insulation Nationwide | Walt’s Insulation

Johns Manville Wall Insulation in San Antonio: What to Know First

Wall insulation using Johns Manville products in San Antonio typically runs $1,800 to $4,200 for a standard single-story home, depending on whether we’re doing injection foam into existing walls or batt insulation during new construction or remodel. Most jobs are completed in one day, and we’re an independent Johns Manville service provider, not a factory outlet or authorized dealer. We just install the products correctly and stand behind the work for as long as you own the house.

Call (866) 751-4428

This page is for San Antonio homeowners who either already have Johns Manville insulation in their walls and are dealing with drafts, hot rooms, or higher bills, or are planning to install Johns Manville products and want someone who actually knows the material. If that’s you, call (866) 751-4428 and a real person answers, day or night.

How Johns Manville Products Fail, and How We Fix Them

• Compressed fiberglass batts in exterior walls. Johns Manville ComfortTherm batts are wrapped in plastic, which is great for handling but creates a vapor barrier on the wrong side in a San Antonio climate. We regularly see homes where moisture got trapped against the wall cavity, the batt sagged, and the top six inches of the wall lost all R-value. The fix is pulling the old batt, checking for moisture damage, and reinstalling with proper air sealing before the new insulation goes in.
• Blown-in JM Spider settling in wall cavities. Spider is a spray-applied fiberglass that works well until it’s installed too wet or too fast, which happens more than manufacturers like to admit. In San Antonio’s July humidity, improperly cured Spider has a documented tendency to slump toward the bottom plate. We’ve opened walls in Alamo Heights and found the bottom third dense and damp while the top two-thirds was nearly bare. Our fix is re-blow or switch to injection foam, depending on the framing.
• Injection foam shrinking around windows and door headers. When JM injection foam, often sold under their Corbond or AP-Foil adjacent lines, gets installed in wall cavities without proper temperature control, it can shrink as much as 3 percent in the first year. That leaves a thermal gap exactly where you notice it most, around windows or where plumbing runs through exterior walls. We re-inject and verify fill with a thermal camera before we close the wall.
• JM Kraft-faced batts installed backward. This one shows up in homes flipped by volume contractors. The kraft paper should face the living space in San Antonio’s hot-humid climate, because we’re cooling more than we’re heating. Time after time, we find it facing the exterior sheathing, trapping condensation inside the cavity. It’s a fast fix for our crew: reorient or replace, then re-seal any penetrations before the drywall goes back.
• No air sealing behind the insulation. This one applies whether it’s Johns Manville ComfortTherm, Spider, or any other product in their line. Insulation slows heat transfer, it doesn’t stop air movement. If the wall has unsealed top plates, electrical penetrations, or cracked sheathing, the JM product gets blamed for a problem it didn’t create. We seal first, then insulate. That sequence matters more than the brand.

Our Johns Manville Wall Insulation Process

1. 1
   We ask about the comfort pattern, not just the product. Which rooms get hot first? When do you notice the heat, morning or afternoon? That tells us more than the product label ever will.
2. 2
   We inspect the existing Johns Manville material. We look at what’s in the wall, how it was installed, and whether it’s even the right product for that application. Sometimes the insulation is fine and the problem is duct leakage or a bad radiant barrier.
3. 3
   We size up the fix, OEM versus quality aftermarket. Johns Manville’s warranty covers manufacturing defects, not installation. If the product is fine, we’re not going to sell you a replacement. If it’s failed, we’ll show you why and discuss what goes back in, whether that’s another JM product or something better suited to the wall.
4. 4
   We do the work without tearing your house apart. For drill-and-fill or injection jobs, we work from the outside through small plugged holes or from the inside with minimal drywall cuts. We cover floors, we mask off the work area, and our techs wear shoe covers.
5. 5
   We verify with a thermal camera. You can’t see insulation performance with your eyes. We scan every wall we touch before and after to confirm the cavity is full and there are no gaps around framing or outlets.
6. 6
   We clean up and walk you through what we did. You get a plain-English explanation, not a sales pitch. Then we register the work under our lifetime Done Right Promise, which means if something isn’t right, we fix it. No fine print, no runaround.

What Johns Manville Wall Insulation Costs in San Antonio

Drill-and-fill injection foam into existing walls usually lands between $2.50 and $4.00 per square foot of wall area. That works out to about $2,800 to $4,800 for a typical 1,400-square-foot ranch home. New construction or remodel batt installation runs lower, usually $1.00 to $1.80 per square foot installed, labor and materials included. Blown-in Spider or similar spray-applied fiberglass for wall cavities sits in the middle, around $2.00 to $3.00 per square foot.

What moves the price: accessibility, whether we’re working from inside or outside, how much old material has to come out first, and whether there’s any moisture or mold to remediate. Every quote is upfront and fixed. No surprise line items when you get the bill. Call (866) 751-4428 for a free estimate, and if you already have a written quote from someone else, bring it in. We’ll give you a straight second opinion.

Why San Antonio Homeowners Call Walt’s Insulation for Johns Manville Work

We’ve been doing this since 2000, and we’re the one down the road, not a franchise with a rotating crew. Walt Brenner grew up on the north side of San Antonio, not far from Brackenridge Park, and he learned the trade at San Antonio College before spending years in attics and crawl spaces figuring out what actually holds up in South Texas heat. When you call Walt’s Insulation, you get a live person, 24/7. Not a voicemail. Not a call center. We answer the phone live, talk to a real person, get a straight answer.

Our technicians are background-checked and uniformed, so you know exactly who’s walking through your door. Every job carries the Done Right Promise, our lifetime workmanship guarantee. If it’s not done right, we make it right. And while Johns Manville is our primary wall insulation product line, we also work with Reflectix and other trusted manufacturers including Owens Corning, Rockwool, CertainTeed, Knauf, Icynene, Demilec, and GreenFiber, so you’re never stuck with a single brand if another one makes more sense for your walls.

FAQs: Johns Manville Wall Insulation in San Antonio