Johns Manville Spray Foam Insulation Nationwide

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

Johns Manville spray foam insulation in San Antonio typically runs $1.50 to $4.50 per board foot installed, and most homes we quote are in the $2,800 to $9,400 range depending on the area and foam type. We’re an independent Johns Manville service provider, not a factory arm, which means we can tell you straight when a JM product is the right call and when a different brand fits the job better. This page is for San Antonio homeowners who already own a Johns Manville product, or are considering one, and want a crew that treats the attic like part of the house rather than a jobsite. If you need a written price, call (903) 437-9164 and a live person will answer.

Call (903) 437-9164

How Johns Manville Products Fail – and How We Fix Them

• JM Corbond III closed-cell shrinkage at the bond line. Corbond III is a solid product, but in San Antonio attics where daytime temperatures climb past 140°F, we see shrinkage at the seam between the foam and the roof deck when the original installer sprayed too fast or the substrate wasn’t dry. The foam pulls back just enough to open hairline air channels. Our fix is to cut back the affected area, re-spray with proper substrate temperature checks, and verify adhesion before we leave.
• Open-cell JM Spider or Corbond OC overspray on can lights and bath fans. This is the most common Johns Manville spray foam issue we walk into. Installers spray open-cell around recessed cans without the proper clearance, and the foam blocks ventilation, traps heat, and shortens fixture life. We cut the foam back, install the proper dam or barrier, and re-spray clean. Tell me what’s in that room, and I’ll tell you exactly what goes on the other side of the wall.
• Rim joist foam delamination with JM AP Foil-Faced polyiso used as a substrate. When spray foam is applied over foil-faced board that still has its facing dust or oxidization, the foam can delaminate within a season. This shows up in rim joist bays and crawlspace ceilings. We clean the substrate, lightly scuff where needed, and re-apply so the foam has a mechanical key.
• Wrong foam type for the San Antonio humidity cycle. A lot of Johns Manville owners end up with open-cell where closed-cell belongs, especially on roof decks and rim joists in older San Antonio homes along McCullough Avenue where eaves are tight. Open-cell is cheaper but it absorbs moisture in our humidity swings, which leads to musty smells and R-value loss. We evaluate the cavity and the use of the space before we recommend, and we put that recommendation in writing.
• Failed air sealing after open-cell settles or gets disturbed. Open-cell Johns Manville foam is soft. Rodents, roof repairs, or even someone crawling through the attic to run cable can tear it. The air barrier breaks, and the energy savings quietly slide. We can patch with matching JM open-cell, reinforce with closed-cell in high-traffic areas, and re-verify with a thermal camera before we wrap.

Our Johns Manville Spray Foam Insulation Process

1. 1
   Call and talk to a person. You call (903) 437-9164, and one of us answers. We ask about the room, the symptom, and the product you have or want. Then we schedule a visit.
2. 2
   Walk the job quietly. Neil Barron or a trained tech goes through the space before quoting. We measure, check substrate moisture, look at the existing Johns Manville product, and ask what’s in the rooms below. No tools come out until the written price is in your hand.
3. 3
   Written price before any work starts. You get the number on paper. That includes shoe covers, drop cloths, cleanup, and the photo of the cleanup before we leave. It’s not a surprise line item; it’s the price.
4. 4
   Prep the space. Drop cloths go across your hallway. Shoe covers go on at the front door. We tape off vents, cover stored items, and use quiet tools if kids are napping. The dog can stay home; we’ll tell you if we’re using a product that needs the family to step out.
5. 5
   Apply the foam correctly. We match the Johns Manville product to the job, spraying to the right depth and the right R-value, with the right substrate prep. We check adhesion as we go.
6. 6
   Test, clean, and show you. We verify with a thermal camera where it matters, clean the work area, snap a photo of the cleanup, and walk you through what we did before we leave. The 365-Day Done Right Promise means if it’s not right, we make it right. No debate.

What Johns Manville Spray Foam Insulation Costs in San Antonio

Most San Antonio spray foam jobs fall into these ranges:

• Rim joist spray foam: $1,400 to $3,200 for a typical 1,800 to 2,400 square foot home.
• Garage ceiling spray foam: $1,800 to $4,100 depending on ceiling area and whether you want open-cell or closed-cell.
• Roof deck spray foam (closed-cell): $5,000 to $9,400 for an average San Antonio roof deck, more for steep or complex roofs.
• Open-cell attic floor or knee wall touch-up: $1,600 to $3,800 depending on depth and access.

What moves the price is the foam type, the square footage, what’s already in the attic, and whether we’re fixing someone else’s work or starting fresh. You’ll have your exact number in writing before we touch a rafter. Call (903) 437-9164 for a free estimate.

Why San Antonio Homeowners Call Thistledown Insulation San Antonio for Johns Manville Work

We’re a Cedarwell-family company, independently owned and run by Neil Barron, and we’ve been doing this work in San Antonio for the better part of two decades. That means background-checked, uniformed techs on every job, a live person answering the phone at 2 a.m. if that’s when you call, and a written price before any work starts. We install eight insulation brands, including Johns Manville and Reflectix, because one product doesn’t fit every attic in San Antonio. When a JM product is the right call, we use it. When another brand fits better, we tell you that too. And every job carries our 365-Day Done Right Promise. If it’s not done right, we make it right.

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