Johns Manville Spray Foam Insulation Nationwide | Walt’s Insulation

Johns Manville Spray Foam Insulation in San Antonio: What to Know First

We install, inspect, and service Johns Manville spray foam insulation throughout San Antonio, and most open-cell or closed-cell jobs go from first call to finished installation inside a week. Pricing is straightforward: you’ll typically see $1.80 to $3.50 per board foot for open-cell and $2.75 to $5.50 per board foot for closed-cell, depending on the surface and depth. We’re an independent Johns Manville service provider, not a manufacturer rep, which means we tell you what the product actually does in a South Texas attic, not what a brochure says it does. If you own a home with existing Johns Manville foam and need an honest assessment, call (866) 751-4428 and a real person answers.

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How Johns Manville Products Fail and How We Fix Them

Johns Manville makes solid spray foam lines, including the Corbond III and JM Corbond Performance series. But San Antonio’s climate does things to spray foam that other markets never see. Here’s what we run into most:

• Corbond III closed-cell shrinkage at roof deck seams. San Antonio attics hit 140°F in July. We regularly see Corbond III pulling away from rafters by a quarter inch after five to seven years, especially on south-facing roof decks off Culebra or Stone Oak. The foam cures hard, and repeated thermal cycling separates it from the wood. The fix is a targeted re-foam of the seam gaps with a compatible closed-cell product, then a fresh thermal check. Patching beats full removal in most cases.
• Open-cell odor retention after rodent activity. Johns Manville open-cell foam is porous, which is what makes it an air barrier, but that porosity also traps odor. If squirrels or rats get into a Helotes or Alamo Heights attic, the smell they leave behind embeds in the foam and does not air out. Ours is the phone call after weeks of candles and no change. We cut out the affected sections, sanitize the cavity, and reinject fresh JM open-cell.
• Improperly cured installs from out-of-town crews. This is a big one. We pull foam from attics around the Medical Center and Leon Valley that was sprayed too thick in a single pass by crews chasing volume. Johns Manville specifies max lift thickness, and when it’s exceeded, the foam can smolder, off-gas, or develop a permanent tacky center under the cured crust. We evaluate, remove what’s bad, and re-spray to spec.
• JM Corbond Performance open-cell sag in vaulted ceilings. Open-cell isn’t structural. On steep vaults in places like Terrell Hills, we see foam delaminating from the underside of the roof deck when the framing flexes or the original installer skipped the JM adhesion primer. The symptom is visible gaps at the ridge line. Re-foaming those sections with the right surface prep solves it.
• Failed rim joist applications near slab moisture. San Antonio sits on clay soil that pushes moisture up through the slab edge. In crawl spaces and pier-and-beam homes in Olmos Park, we’ve seen closed-cell foam at the rim joist develop a waxy sheen and lose bond because the substrate was damp at application. Johns Manville foam does not forgive damp wood. We correct drainage, dry the cavity, and reapply, and this time it stays put.

Our Johns Manville Spray Foam Insulation Process

Here’s exactly what happens when you call us about Johns Manville spray foam work in San Antonio:

1. 1
   Call and talk to a person. Someone answers, day or night. We ask about the space, the symptoms, and what you’ve noticed. If it sounds like a straightforward afternoon job, we’ll tell you that over the phone.
2. 2
   On-site assessment at your published-address home. A background-checked, uniformed tech arrives, checks the existing JM foam depth, adhesion, and moisture conditions. Headlamp on the corners. Notes taken. No sales pitch.
3. 3
   Straightforward options, not a pressure menu. We tell you what can be patched, what should be removed, and what doesn’t need touching. OEM Johns Manville foam is used where the warranty or spec demands it. Where an aftermarket product matches or beats the performance, we say so and price it accordingly.
4. 4
   The work. We prep, protect, spray, and trim. No overspray on your soffits, no foam where it shouldn’t be. We run a thermal camera when it’s done because that’s how you verify coverage, not with a pat on the back.
5. 5
   Cleanup and the Done Right Promise. We leave the space the way we’d want it left. If it’s not done right, Walt’s Insulation makes it right. Lifetime workmanship, no runaround. That’s the whole deal.

What Johns Manville Spray Foam Insulation Costs in San Antonio

Real numbers for real jobs in Bexar County:

• Rim joist spray foam with JM closed-cell: $900 to $2,200 for a typical 1,500 sq ft home
• Open-cell attic ceiling in a 1,200 sq ft attic: $3,800 to $6,500
• Closed-cell roof deck (same attic size): $6,500 to $11,000
• Garage ceiling with JM open-cell: $1,400 to $2,600
• Spot repair or re-foam of failed sections: $500 to $1,800 depending on access and depth

What moves the price: foam type, depth, the condition of existing foam, and access. Closed-cell runs higher per board foot but gives you more R-value per inch and a vapor barrier, which matters when San Antonio humidity pushes 90% in May. We give you a written number upfront, free second opinions on any competitor’s estimate, and no trip charge inside our service county. Call (866) 751-4428 and we’ll give you a straight answer.

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

We’ve been locally owned and owner-operated since 2000, founded by Walt Brenner, who grew up on the north side near Brackenridge Park and learned this trade at San Antonio College before spending years figuring out what textbooks and manufacturer cut sheets miss. Our techs see Johns Manville foam every week in every neighborhood from Schertz to Somerset. When an install doesn’t make sense for the climate, we say so, even if it means steering you toward a different approach. And if your home has other insulation brands like Reflectix radiant barrier, we handle that too. You get background-checked, uniformed techs, a published address and license number, and a live person who answers the phone 24/7. We answer the phone live, talk to a real person, get a straight answer, this isn’t a franchise arrangement, and it shows. The Done Right Promise stands behind every job. $40 off any repair over $200, free second opinions, and 10% off for seniors and veterans, always.

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