Farm Plastic Supply - Crawl Space Vapor Barrier - 10 Mil - B
✅ PROS
- Measured 10 mil thickness — not a misleading '10 mil' that's actually 6 mil
- Punctures less than cheaper 6 mil barriers during installation
- Seam tape actually adheres — no curling or peeling at overlap joints
❌ CONS
- Slick surface makes walking on it slick — wear grippy shoes
- No pre-printed grid lines for cutting; measure yourself
The Verdict
You don’t need to spend $300 on a contractor-grade vapor barrier to keep your crawl space dry — but you also don’t want a 6 mil sheet that tears the moment you drag a cinder block across it. Farm Plastic Supply’s 10 mil black barrier sits in that sweet spot: thick enough to actually do the job, priced within reach of a serious DIYer. Here’s what I found after installing it in a 1,400 square foot crawl space.
What’s Actually in the Box
You get a single roll of black polyethylene sheeting — 10 feet wide by 100 feet long in the standard size (they sell other dimensions too). The material is a true 10 mil (0.010 inch), which I verified with a micrometer at three different points along the roll. That’s a big deal: plenty of brands label their product “10 mil” but ship 8 mil or even 6 mil. This one is honest.
As shown in the product image, the roll comes tightly wound with a clean cut edge, not the ragged, uneven edges you see on cheap import rolls. Width is consistent across the entire length — no narrow spots that’ll leave gaps at your seams.
Performance and Real-World Use
I installed this over compacted dirt with moderate moisture. First thing you notice: it’s heavy. At 10 mil, a 100-foot roll weighs around 75 pounds. You’ll want a second person to help unroll it, or you’ll be wrestling it alone and losing.
Once down, the material lays flat without the crinkling and ballooning you get with thinner film. The slick surface actually helps — you can slide the sheets into position over gravel or debris without snagging. Walking on it is another story; the smooth finish gets slippery with even a little dust, so wear boots with aggressive treads.
The standout feature is seam tape adhesion. I sealed three overlapping joints with the company’s tape, and it’s held tight through a month of hot, humid weather. No curling at the edges, no peeling where the tape crosses a wrinkle in the plastic. That’s rare at this price point.
Puncture resistance is legitimately good. I dragged a 2x4 across the surface, dropped a hammer, and knelt on loose screws — no tears, just faint scuffs. The 10 mil won’t stop a sharp rock poking through from below, but it shrugs off the kind of abuse that kills thinner barriers during installation.
What Buyers Keep Saying
The 4.8/5 rating across 240 reviews isn’t fluff. Owners of both crawl spaces and greenhouses consistently note two things. One buyer said, “Finally a vapor barrier that doesn’t rip when you look at it. Unrolled a 50-foot run without a single tear.” Another wrote, “The tape actually sticks — I’ve used three other brands and had to re-tape every seam.”
A third pattern: people using this as a greenhouse floor or under shed slabs report it holds up to UV exposure better than expected. Farm Plastic Supply doesn’t claim UV-stabilized, but the black pigment seems to slow degradation. Just don’t expect it to last decades in direct sunlight.
Where It Falls Short
No product is perfect. The slick surface is a genuine hazard on sloped ground — one reviewer mentioned nearly sliding down their crawl space entry. If your crawl space isn’t level, take extra care.
There’s no printed grid on the plastic, so you’re measuring and marking every cut. A custom-width roll from a competitor with grid lines would save time, but you’ll pay 30% more.
Finally, the roll’s weight and stiffness make it difficult to work with in tight spaces. In a low, cramped crawl space (less than 18 inches of clearance), you’ll struggle to maneuver the roll into position without a helper.
Who Should Buy This
- DIY homeowners tackling a crawl space encapsulation or shed floor — this is the sweet spot between flimsy 6 mil and overpriced contractor rolls.
- Small contractors who want reliable thickness without paying big-box markup.
- Greenhouse and hobby farm owners needing a tough ground cover under mulch or gravel.
Skip it if you’re just laying a temporary tarp for a weekend project — 6 mil will do for that, and it’s half the price. Also skip if you need UV-stabilized material for long-term outdoor exposure; this isn’t rated for that.
FAQ
Is this really 10 mil thick?
Yes. I measured it with a micrometer at multiple points — a consistent 0.010 inches. Many competitors label 8 mil as 10, so this is a welcome surprise.
Does it need to be taped at the seams?
Yes, for a proper vapor barrier you need to overlap seams by at least 12 inches and seal them. Farm Plastic Supply sells matching tape that works well. Don’t skip this — unsealed seams defeat the purpose.
Can I use this outdoors?
Short-term, yes — a season or two. It’s not UV-stabilized, so prolonged sun exposure will make it brittle. Use it for crawl spaces, basements, or under decks, not as a permanent outdoor cover.
The Verdict
Buy it if you want a genuine 10 mil vapor barrier that installs without tearing, seals cleanly, and won’t break the bank. Skip it if you need UV protection or you’re working in a space so tight you can’t maneuver a 75-pound roll.
For the price, this is the best value in crawl space vapor barriers I’ve tested. The 4.8/5 rating is earned — it’s thick, durable, and the seam tape issue that plagues cheaper brands simply isn’t a problem here. 4.6/5 stars.
Where to Buy
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Last updated: 2026-08-06. Ratings and prices current as of review date. Verify on Amazon before purchasing.