Johns Manville Spray Foam Insulation in Converse: What to Know First
We provide independent Johns Manville spray foam insulation in Converse with same-day or next-day scheduling for most calls, and we publish your before-and-after blower-door numbers so you can verify the result in CFM50. Most Johns Manville open-cell and closed-cell jobs in a Converse home this size run between $2,800 and $6,400 depending on cavity depth, access, and whether the rim joists need treatment. This page is for homeowners who already have Johns Manville products in their building envelope and need spray foam installation, repair, or upgrade work done right the first time. Call (830) 420-0953 for a free estimate with a written price before any work starts.
How Johns Manville Products Fail - and How We Fix Them
- AP Foil-Faced Polyiso board separation in vented attics. The foil facing on Johns Manville AP series rigid boards can delaminate in Converse’s 100°F+ attic summers when installed without proper fastening patterns or when retrofitted over unsealed top plates. We remove the compromised boards, seal every top-plate penetration with targeted foam, then reinstall or upgrade to closed-cell spray foam directly on the roof deck.
- Corbond III closed-cell shrinkage at rim joists. Johns Manville’s Corbond III can pull away from sill plates in our clay-heavy Converse soils when seasonal foundation movement stresses the bond line. We cut back the shrunken foam, re-prep with primer where the substrate demands it, and reapply to the manufacturer’s lift thickness so the seal holds through expansion and contraction cycles.
- Intello Plus smart vapor retarder misinstallation in mixed-humidity zones. Converse sits in that tricky corridor where outdoor dew points swing 40 degrees between January and July; Intello installed on the wrong side of the assembly or without airtight taping becomes a condenser, not a retarder. We map the dew-point profile for your specific wall or roof assembly, then place the variable-perm layer where it actually belongs.
- Spider custom blown-in falling short of spray foam compatibility. Some Converse builders spec’d Spider fiberglass as a cost alternative to JM spray foam in 2018-2021 builds, leaving cavities that don’t meet modern air-barrier requirements. We don’t just blow more on top; we extract the underperforming material, air-seal the cavity with open-cell foam, and document the blower-door improvement.
- Formaldehyde-free batt compression at kneewalls and bonus-room transitions. Johns Manville’s formaldehyde-free batts lose R-value fast when compressed in odd framing, and in Converse’s older ranch conversions near Foster Road, that’s exactly what happens. We remove the compressed batts, build out proper dams and retainers, and spray open-cell foam to full depth so the thermal boundary stays continuous.
Our Johns Manville Spray Foam Insulation Process

- 1
Call and schedule. A live person answers, 24/7. We book a site visit, not a sales pitch.
- 2
Site assessment and blower-door baseline. We pressurize your home to 50 pascals and record the CFM50 reading. In Converse’s older stock, we often see 3,500-5,000 CFM50 before any work begins.
- 3
Written price and scope. Under Haven Standard Clause 1, you get a flat price, written scope, and written warranty before anyone lifts a tool. No exceptions.
- 4
Air sealing first, then insulation. Seal the leaks first. Then insulate. The numbers will tell you if it worked. We foam every top plate, penetration, and bypass before the main spray application.
- 5
Application and real-time monitoring. We monitor substrate temperature, ambient humidity, and lift thickness during application. For Johns Manville closed-cell jobs, we hold to 2-inch lifts and full cure between passes.
- 6
Final blower-door test and documentation. We run the pressurization test again, print your before-and-after report, and deliver your Documented Photo Record. The crew leaves when you have both in hand.
Before
AfterWhat Johns Manville Spray Foam Insulation Costs in Converse
Most Johns Manville spray foam jobs in Converse fall in these ranges:
| Open-cell spray foam, standard attic (1,200-1,800 sq ft) | $2,800 - $4,200 |
| Closed-cell spray foam, rim joist and crawl space | $3,400 - $5,600 |
| Closed-cell roof deck, full encapsulation | $4,800 - $6,400 |
| Garage ceiling spray foam (typical 2-car) | $1,800 - $2,900 |
| Removal and replacement of failed JM foam (per sq ft) | $1.20 - $2.10 additional |
What moves the price: cavity depth, access difficulty (steep Converse roof pitches or tight crawl spaces), whether we need to extract failed material first, and whether the job requires hybrid treatment with another brand like Reflectix for radiant barrier backup. We also source from Owens Corning, Knauf, Rockwool, and others if your assembly calls for a multi-material approach.
Call (830) 420-0953 for a free estimate. You’ll get a written price before any work starts, and a Free Second Opinion on any competing written quote you bring us.
Why Converse Homeowners Call Topside Attic Insulation Converse for Johns Manville Work

We’ve sealed and insulated over 9,000 homes since 2016, and Wes Okafor still runs the blower-door test himself on jobs where the numbers matter most. Our 365-Day Done Right Promise means if it’s not done right, we make it right, backed by the written scope and warranty you received before the crew started. Our technicians are background-checked and uniformed, and we don’t send anyone to your Converse home who hasn’t been trained on Johns Manville’s specific substrate prep and lift requirements. When a job calls for radiant barrier pairing or a hybrid approach, we also work with Reflectix and other major brands, so you’re never locked into a single product line that doesn’t fit your assembly.
FAQs
Installing spray foam over or adjacent to existing Johns Manville products does not automatically void manufacturer warranties, but coverage for the original product may be limited if the new installation alters the intended assembly performance. We document the pre-existing condition with photos and note all adjacent materials in your written scope so there’s a clear record if a claim ever arises. Call (830) 420-0953 and we’ll review your specific JM installation before quoting.
Most Converse appointments are scheduled same-day or next-day, with emergency response available for active air-barrier failures like separated foam or exposed cavities. We answer calls live 24/7, and you’ll get a text when your named technician is en route. Call (830) 420-0953 to check today’s availability.
Localized shrinkage or minor delamination can often be cut back and re-applied if the substrate is sound and the original foam hasn’t degraded chemically. Widespread failure, water damage, or foam installed before 2010 usually calls for full removal. We assess on site, show you the cavity condition in photos, and quote both options so you decide from evidence, not pressure. Estimates are free.
We source Johns Manville materials directly where the spec demands it, and we also use quality-compatible alternatives from Owens Corning, Demilec, and Icynene when the assembly performance calls for a different chemistry or density. We never substitute without documenting the change in your written scope. As an independent Johns Manville service provider, we select the material that hits the target blower-door number, not the one with the best distributor rebate.
You receive a printed blower-door report with before-and-after CFM50 readings, a Documented Photo Record of all work areas, your written scope with any deviations noted and initialed, and the 365-Day Done Right Promise warranty. These are delivered before the crew leaves, not emailed later or available on request. Haven Standard: Have it in writing.
Written by Wes Okafor, Owner & Lead Insulation Technician, Topside Attic Insulation Converse at Topside Attic Insulation Converse, serving Converse and nearby areas.