Demilec Vapor Barrier Installation: The Inglewood Owner’s Guide
If your Demilec spray foam insulation is already in place and the vapor barrier portion has failed, torn, or was never properly installed, we stock Demilec-compatible vapor barrier materials on our trucks and typically complete the installation the same day. In Inglewood, expect to pay between $450 and $1,200 for a standard crawl space or basement vapor barrier installation, depending on square footage and whether we’re replacing an existing barrier or installing one for the first time alongside Demilec foam. Most homeowners discover the problem the same way: a musty smell creeping up through the floorboards, condensation on ductwork, or a crawl space that feels noticeably damp even during Inglewood’s dry spells.
Which Demilec Models This Applies To
Demilec’s spray foam lineup includes Heatlok HFO, Heatlok Soya, Sealection 500, and Agribalance, all of which perform their best when paired with a properly installed vapor barrier at the ground level. Here’s the compatibility gotcha most people miss: Demilec’s closed-cell foams (Heatlok series) act as their own vapor retarder at 2 inches of thickness, but they still need a ground vapor barrier below the crawl space to stop soil moisture from working its way around the rim joist and into the conditioned space. Open-cell products like Sealection 500 are vapor permeable, which means the ground barrier isn’t optional, it’s doing structural work.
When identifying the right vapor barrier to pair with your Demilec insulation, look for a 10-mil or thicker polyethylene sheet. For Inglewood homes with clay-heavy soil that holds moisture through the wet season, we recommend going to 12-mil reinforced poly. The OEM name on the barrier matters less than the thickness and the quality of the seam tape, but we can walk you through the option that makes sense for your specific Demilec product if you call us.
Signs Your Demilec Vapor Barrier Installation Is Failing
- Musty odor in the living space above the crawl space. When the barrier tears or pulls away from the foundation wall, soil moisture evaporates upward and carries that damp-earth smell with it. Demilec foam doesn’t stop this on its own.
- Condensation on crawl space ductwork or floor joists. In Inglewood’s mild winters, warm indoor air meeting cold surfaces below the house creates sweating. A barrier that’s intact prevents most of that moisture from ever reaching the framing.
- Visible standing water or consistently damp soil after a dry week. Inglewood doesn’t get much rain, so if your crawl space soil is still wet five days after the last storm, the barrier has lost its seal.
- Insulation pulling away from the subfloor or rim joist. Moisture weakens the adhesion on Demilec foam over time. The foam may look fine from the top, but the bond underneath has been compromised.
- Higher indoor humidity and warmer rooms in summer. When the vapor barrier fails, your Demilec insulation is fighting a losing battle against ground moisture. Rooms feel stuffy, and your AC runs longer than it should.
Replacement Cost & What’s Included
For a typical Inglewood home with a crawl space between 800 and 1,500 square feet, a full Demilec-compatible vapor barrier installation runs $450 to $1,200 installed. The range depends on three things: the square footage, whether the existing barrier needs to be removed and hauled away, and how much of the foundation wall needs to be covered for a proper seal. For homes near Morningside Park with older pier-and-beam foundations, we often find the rim joist area needs extra attention, which can push the job toward the higher end.
Every quote includes the 10-mil or 12-mil poly barrier, seam tape, mechanical fasteners or terminator pins, full coverage of the crawl space floor, and a 6-to-12-inch run up the foundation wall. We dispose of the old material. The work is backed by our 90-Day Done Right Promise, which means if the barrier pulls loose or a seam fails within three months, we come back and fix it at no charge.
DIY or Call Us?
You can safely inspect your current barrier by peeking through the crawl space access door with a flashlight. Look for tears, gaps at the seams, or areas where the plastic has pulled away from the wall. What you shouldn’t attempt is a full crawl space installation yourself. Working in a low-clearance crawl space with limited ventilation, while cutting and securing heavy poly sheeting, is physically demanding and easy to get wrong. A seam that’s not properly overlapped and taped will fail within months, and you’ll be back where you started. Our crews handle this every week. Most jobs are done in a single visit, and you’ll get upfront pricing before we start. Call (424) 622-5846 and a live person answers, day or night.
FAQs
With a 10-mil or thicker barrier and proper installation, expect 15 to 20 years of service in Inglewood’s climate. Thinner 6-mil barriers, which we see from time to time from previous contractors, often fail within 5 to 7 years. If you want us to check what’s under your house, call (424) 622-5846 for a free estimate.
Yes, if the damage is isolated to one or two small tears and the rest of the barrier is still pliable and intact, a patch with seam tape can extend its life by several years. If the barrier is brittle, has multiple holes, or has pulled away from the walls in more than one spot, replacement is the honest recommendation. We’ll tell you which one you need before any work begins, and you can use our $50 Off Any Repair Over $250 offer if repair is the right call.
Most Demilec-compatible vapor barrier installations in Inglewood take 2 to 4 hours for a standard crawl space. Larger homes or those requiring old barrier removal may take a full day. We complete most jobs in a single visit.
We stock 10-mil and 12-mil polyethylene vapor barrier sheeting, seam tape, and fasteners on our service vehicles, so we can handle most Demilec-related vapor barrier work on the first trip. We also carry Reflectix radiant barrier products. If your job requires something outside our standard inventory, we’ll have it within 24 hours.
If your Demilec insulation isn’t performing the way it should and you suspect the vapor barrier is the culprit, call us at (424) 622-5846. A live person answers 24/7, no voicemail. We’ll schedule a free estimate, show up on time, and give you a straight answer about what’s actually wrong under your Inglewood home. Neil Ashford and the Warmline Insulation Co. team have been serving Inglewood and the surrounding LA basin since 2011, and the work should speak for itself, and so should your energy bill.
Written by Neil Ashford, Owner, Warmline Insulation Co. at Warmline Insulation Co., serving Inglewood and nearby areas.