Johns Manville Crawl Space Encapsulation Nationwide

Johns Manville Crawl Space Encapsulation: The West Hollywood Owner’s Guide

We stock and install Johns Manville-compatible crawl space encapsulation systems in West Hollywood, with most complete installs running $3,800-$6,200 depending on crawl square footage and whether the foundation walls need rigid foam board. Same-day service is available when we have your liner spec in stock, which we do for the common JM widths used in the 90046 and 90069 ZIP codes. Most West Hollywood homeowners discover their encapsulation has failed when they notice a musty smell returning after months of dryness, or when their dehumidifier runs continuously without pulling the relative humidity below 60%.

Call (213) 306-2607

Which Johns Manville Models This Applies To

Johns Manville produces crawl space liners under their CleanSpace-compatible polyethylene line, typically sold in 12-mil, 16-mil, and 20-mil thicknesses with reinforced polyester-cord scrim. The part number you’re looking for is printed on the white tape seam edge, formatted as JM-CS-XXXX where the last four digits indicate width and mil rating. The 16-mil, 20-foot-wide roll is what we encounter most often in West Hollywood crawl spaces built between 1925 and 1955, the bungalow stock off Harper Avenue and the duplex courts near Melrose.

Aftermarket equivalents exist from Viper and Stego, but Johns Manville’s scrim pattern is proprietary, and mixing liner brands at seam overlaps can void the vapor-barrier warranty. We carry both OEM JM rolls and Viper Woven as a field-tested alternative when the original spec is discontinued. If your existing liner has the silver-tape seam treatment with the JM logo stamp, that’s a 2018-or-newer production run, and the 20-mil replacement is your direct match.

Signs Your Johns Manville Crawl Space Encapsulation Is Failing

• Condensation beads on the liner underside. This means the vapor barrier’s perm rating has degraded, or the seam tape has delaminated, letting soil moisture pass through. In West Hollywood’s clay-heavy soil near Beverly Boulevard, we see this where the original installer skipped the perimeter drainage mat.
• Musty odor returning after prior elimination. Your encapsulation system was designed to hold relative humidity below 55%; if the smell is back, the seal is breached. We trace this to failed pier-wrap tape more often than liner punctures.
• Dehumidifier running 18+ hours daily. The unit is compensating for a barrier that no longer blocks the 10-15 gallons of daily soil evaporation typical in a 1,200-square-foot crawl. The dehumidifier isn’t broken; the encapsulation is.
• White chalking or embrittlement on the liner surface. This is UV-stabilizer degradation, even in a dark crawl space, caused by the fluorescent work lights used during original installation. JM liners with this pattern usually date to 2012-2016 production lots.
• Sagging or pooling at low points. The liner has separated from the foundation wall fastening strip, often because the original installer used generic construction adhesive instead of JM’s butyl-rubber termination tape. Water follows the path of least resistance and collects where the seal broke.

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After

Replacement Cost & What’s Included

In West Hollywood, a full Johns Manville crawl space encapsulation replacement typically runs $3,800-$6,200 installed. The lower end covers a 600-800 square foot crawl with straightforward access and intact wall fasteners; the upper end includes 1,000+ square feet, new rigid foam board on foundation walls, and pier wrapping where the existing piers were never sealed originally.

Our price includes the JM liner roll, butyl-rubber termination tape, seam tape, drainage mat where the soil grade requires it, and labor. We do not charge separately for the blower-door test when encapsulation is bundled with attic air sealing, which is common in the older West Hollywood housing stock. Every job closes with a Documented Photo Record and, when applicable, before-and-after blower-door numbers showing the envelope improvement. The 365-Day Done Right Promise applies to all encapsulation work, and the written scope specifies the exact JM mil rating and square footage before anyone enters the crawl.

DIY or Call Us?

Homeowners can safely inspect their own crawl space for the symptoms above, but we do not recommend DIY replacement. The work requires extended time in a confined space with limited egress, and the butyl-rubber termination tape demands a heat gun and seam-roller technique that takes practice to execute without gaps. More critically, West Hollywood’s pre-1960 crawl spaces often contain abandoned knob-and-tube wiring and deteriorated cast-iron sewer lines that a homeowner shouldn’t disturb without training.

What you can do: photograph the JM part number on the liner edge, measure your crawl’s square footage, and note any standing water before calling. We’ll bring the correct roll width and mil rating to the estimate, so you’re not paying for a return trip. Call (213) 306-2607 for a written price before any work starts, Haven Standard Clause 1.

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