Johns Manville Crawl Space Encapsulation & Vapor Barrier in Schertz: What to Know First
We provide independent Johns Manville crawl space encapsulation and vapor barrier service in Schertz, typically scheduling within 48 hours and completing most jobs in one day. Most crawl space encapsulation work in Schertz runs between $2,800 and $6,500 depending on liner grade, square footage, and whether the foundation needs active dehumidification. We do not start work without a written price, and we do not ask you to call for a quote to find out what the work costs.
This page is for Johns Manville owners in Schertz who are seeing moisture under the vapor barrier, noticing musty air migrating into conditioned space, or dealing with sagging liner seams in the crawl space. If you’re in the Sedona subdivision off FM 1518, the Selma area near I-35, or anywhere in the Schertz corridor where clay soils hold moisture and summer humidity stays above 70% for months, the ground conditions will defeat an improperly sealed encapsulation system. Call (830) 402-5240 for a free estimate with a written scope.
How Johns Manville Products Fail - and How We Fix Them
- JM CleanSpace liner seam separation at the perimeter bond. The CleanSpace 20-mil woven polyethylene liner relies on a double-sided butyl tape bond to the foundation wall. In Schertz, where expansive clay soils shift seasonally and create micro-movement at the sill plate, that tape can release within 3-5 years. We remove the failed tape, grind the foundation wall to bare concrete where needed, and reinstall with a mechanical fastening system - masonry screws with termination bars - before re-taping. The mechanical backup survives soil movement that adhesive alone cannot.
- JM Vapor Barrier Classic sagging between piers. The 6-mil Vapor Barrier Classic is specified as a ground cover, not a structural encapsulation liner. Homeowners who inherit it as part of a partial encapsulation often find it pooling water in low spots between piers, especially after the heavy spring rains that hit the Schertz area in April and May. We upgrade to a 12-mil or 20-mil woven product, install it with proper slack management and gravel ballast, and slope drainage to a sump or condensate pump if the grade allows.
- JM crawl space insulation batts dropping from the band joist. Johns Manville Kraft-faced fiberglass batts installed in crawl space ceilings lose their friction fit when relative humidity cycles above 60% repeatedly. The facing delaminates, the batt drops onto the vapor barrier, and the R-value goes with it. We remove the fallen material, treat any mold-affected framing with an EPA-registered fungistat, then install rigid foam board or closed-cell spray foam at the band joist - materials that do not absorb moisture and do not depend on friction to stay in place.
- JM TerraBlock degradation at the overlap seams. The TerraBlock floor insulation pad, when used in encapsulation systems, can compress and lose its thermal break at the seams where sheets meet. In Schertz crawl spaces with active rodent traffic - common near the greenbelt areas along Cibolo Creek - the edges get disturbed and the pad separates. We assess whether TerraBlock is still the right solution or whether a full encapsulation with sub-membrane drainage matting and wall insulation provides better long-term performance.
- Dehumidifier short-cycling due to oversized JM-supplied units. Some Johns Manville encapsulation packages specify a dehumidifier capacity based on national square-footage charts that do not account for the latent load of a Central Texas crawl space in August. The unit runs, satisfies its humidity setpoint at the sensor location, and shuts off - while perimeter areas stay damp and organic growth continues. We size dehumidification using actual crawl space volume, air leakage rate, and soil moisture conditions measured on site, not a chart.
Our Johns Manville Crawl Space Encapsulation & Vapor Barrier Process
- 1
Pre-work inspection and moisture mapping. We enter the crawl space with a thermal imaging camera, pinless moisture meter, and documentation tablet. We record wood moisture content at the sill plate, subfloor, and center joists; photograph existing Johns Manville liner condition, seam integrity, and any biological growth; and note pier spacing, ductwork obstructions, and electrical hazards.
- 2
Written scope and price delivered before work starts. Under Haven Standard Clause 1, you receive a flat price, written scope, and written warranty before anyone lifts a tool. No exceptions. If you have a competing estimate, we provide a free second opinion - we will read it with you line by line.
- 3
Material selection: OEM Johns Manville or quality equivalent. As an independent Johns Manville service provider, we have access to JM CleanSpace, Vapor Barrier Classic, TerraBlock, and associated tapes and fasteners. We also source compatible materials from Owens Corning, Knauf, and Reflectix when the application calls for it. We explain the trade-off and let you decide - no proprietary lock-in.
- 4
Air sealing first, then encapsulation. We seal the rim joist, sill plate gaps, and any penetrations for plumbing, electrical, and ductwork before the liner goes in. Seal the leaks first. Then insulate. The crawl space doesn’t care how thick the vapor barrier is if the air is still moving through it.
- 5
Installation, mechanical fastening, and dehumidification setup. Liner is cut, positioned, and secured with termination bars and masonry anchors at the walls, not just tape. Seams are overlapped 12 inches and sealed with pressure-sensitive tape rated for damp substrates. Dehumidifier is installed, ducted if needed, and set to maintain 50-55% relative humidity.
- 6
Documentation and closeout. You receive a Documented Photo Record of the completed work, including liner installation detail, sealed penetrations, and dehumidifier placement. If air sealing was performed, we provide before-and-after blower-door readings showing the change in building envelope leakage. The 365-Day Done Right Promise applies in writing.
What Johns Manville Crawl Space Encapsulation & Vapor Barrier Costs in Schertz
Most Johns Manville crawl space encapsulation and vapor barrier jobs in Schertz fall into these ranges:
| Scenario | Typical Range |
|---|---|
| Vapor barrier replacement only (ground cover, 6-12 mil, no wall sealing) | $1,800 - $3,200 |
| Partial encapsulation (ground liner + wall liner to sill, no insulation) | $3,500 - $5,500 |
| Full encapsulation with CleanSpace 20-mil, wall insulation, dehumidifier | $5,500 - $9,500 |
| Full encapsulation with active drainage, sump pump, and band joist insulation | $8,500 - $14,000 |
What moves the price: crawl space square footage and headroom (low clearance adds labor); number of piers and ductwork obstructions; whether existing Johns Manville material must be removed and disposed; mold or wood rot remediation needs; dehumidifier capacity and whether ducting is required; and whether the foundation needs a perimeter drainage solution.
Every estimate is free, written, and delivered before any work starts. Call (830) 402-5240 to schedule.
Why Schertz Homeowners Call Topside Attic Insulation Schertz for Johns Manville Work
We’ve been working the Schertz corridor for several years now, including jobs in the Sedona subdivision off FM 1518 where summer ground temperatures and clay soil moisture create conditions that test any encapsulation system. Wes Okafor and our crew have handled Johns Manville products long enough to know where the specifications meet Texas reality - and where they don’t.
Our approach is documented, not declared. You get a written price before work starts, a Documented Photo Record when the crew leaves, and before-and-after blower-door numbers on any job where air sealing is performed. The 365-Day Done Right Promise is in writing, not implied. If you need a material we don’t stock, we source from Owens Corning, Knauf, Rockwool, CertainTeed, Icynene, Demilec, GreenFiber, or Reflectix - no lock-in to any single manufacturer. Calls are answered by a live person 24/7.
FAQs
No. Johns Manville’s product warranties cover manufacturing defects in the original material, not installation modifications performed by independent contractors. As an independent Johns Manville service provider, we use warranty-safe practices: we do not alter the facing on Kraft-faced batts in ways that would void the original product warranty, and we document existing material condition before any work begins. If you have a specific warranty concern, bring your paperwork to the estimate and we will review it with you. Call (830) 402-5240.
Yes. We stock common Johns Manville encapsulation materials - CleanSpace liner in multiple widths, Vapor Barrier Classic rolls, TerraBlock pads, and compatible tapes and fasteners. For less common sizes or large-quantity orders, our distributor relationship typically yields 2-3 day turnaround to the Schertz area. If a Johns Manville part is back-ordered, we specify an equivalent from another manufacturer and explain the difference before substituting. Call (830) 402-5240 to confirm availability for your specific job.
Repair is cheaper only if the existing material is less than 3-4 years old, the damage is localized to one or two seams, and the foundation wall surface is still clean enough to achieve a new bond. In Schertz, we more commonly find that partial repairs fail within 18 months because the underlying soil movement or humidity problem was not addressed. A full replacement with proper mechanical fastening and dehumidification usually costs 40-60% more than a patch job but lasts 10-15 years instead of 2. We will show you both options in writing. Call (830) 402-5240 for a free estimate.
Most jobs are completed in one day. A full encapsulation with dehumidification typically takes 1-2 days depending on crawl space size and whether mold remediation or drainage work is needed. We schedule within 48 hours of your call and arrive on the confirmed date - under Haven Standard, you get a named technician and a text when they are on the way. Call (830) 402-5240 to book.
We are not exclusive to any brand. We service Johns Manville, Owens Corning, Knauf, Rockwool, CertainTeed, Icynene, Demilec, GreenFiber, and Reflectix products regularly. The right material depends on your crawl space conditions, not our supplier relationship. We explain the options and let you choose. Call (830) 402-5240 to discuss what makes sense for your job.
Written by Wes Okafor, Owner, Topside Attic Insulation Schertz at Topside Attic Insulation Schertz, serving Schertz and nearby areas.