
Never Use 6 Mil Vapor Barrier in Crawl Space (Here's Why It Fails)
About this episode
If a contractor tells you 6 mil plastic is good enough for your crawl space vapor barrier, they're either lying or don't know what they're talking about. In this video, I'll show you exactly why 6 mil vapor barriers fail, what it's costing you, and what you should use instead.
📚 Get complete guidance in my Gold Award Winning Book "Crawl Space Repair Myths Busted" (https://amzn.to/3llnB1m)
📥 Download our Crawl Space Inspection Checklist:
https://buymeacoffee.com/csninja/extras
Join our Ninja membership to get early access to all our content: https://www.youtube.com/channel/UCIdzZrKCdyNf1Oh1cGjSYnA/join
Get a Free Estimate: https://crawlspaceninja.com/estimate
20% OFF DIY Products Code: "youtube"
Use at 🛠️ DIY CRAWL SPACE SUPPLIES:
👉 https://supply.crawlspaceninja.com
10% OFF DIY Mold Testing: https://fas.st/t/8cfyT8P3
⚠️ THE 4 MAJOR PROBLEMS WITH 6 MIL VAPOR BARRIERS:
1️⃣ TOO THIN - Tears easily with foot traffic, HVAC contractors, plumbers, and electricians going through your crawl space. 70-80% are damaged within 2 years.
2️⃣ PEST DAMAGE - Rodents, mice, rats, and possums tear through 6 mil plastic like tissue paper. They live underneath it, creating moisture, odors, and serious health hazards.
3️⃣ POOR SEALING - Most contractors just overlap the seams without taping. Moisture vapor still gets through unsealed seams, making it almost completely ineffective.
4️⃣ MOISTURE FAILURE - 6 mil is designed for vapor, not standing water. After heavy rains, it floats around, exposing dirt and allowing moisture to evaporate into your floor joists, causing mold and wood rot.
💰 HIDDEN COSTS OF 6 MIL PLASTIC (10-Year Total):
• Replacement every 2-3 years: $1,500-$3,000
• Increased energy bills: $3,600-$9,000
• Mold remediation: $3,000-$15,000
• Pest control & cleanup: $500-$3,000
• Structural repairs: $5,000-$25,000
• Insulation replacement: $2,000-$5,000
TOTAL: $15,000-$50,000+
Compare that to a proper 12 mil encapsulation system: $4,000-$8,000 upfront, lasts 20-25 years with minimal maintenance. That's only $300/year vs $667/year+ for 6 mil.
✅ WHAT YOU SHOULD USE INSTEAD:
• 12 mil solid vapor barrier OR 12 mil woven vapor barrier
• Proper vapor barrier seam tape (not duct tape)
• Mechanical fasteners (Christmas tree fasteners or Hilti nails)
• Double-sided butyl tape for wall attachment
• Crawl space dehumidifier (essential - plastic alone isn't enough)
**Contact Us:**
* Website: (https://CrawlSpaceNinja.com/)
* Schedule Free Inspection: (865) 659-0390
* DIY Store: (https://supply.crawlspaceninja.com)
* DIY Store Phone: (865) 321-9314
**Disclaimer:** This information is for educational purposes only. Consult professionals for specific advice. Some links may be affiliate links, which means we may earn a small commission at no extra cost to you.
#CrawlSpaceNinja #BasementNinja #CrawlSpace #VaporBarrier #CrawlSpaceEncapsulation #HomeImprovement #DIY #BasementWaterproofing #MoldPrevention #IndoorAirQuality #HomeRepair #CrawlSpaceNinja #6MilVaporBarrier #12MilVaporBarrier #MoistureControl #Dehumidifier #HomeInspection #RealEstate #HealthyHome #BuildingScience
Check out Michael's book, "Crawl Space Repair Myths-Busted" now available on Amazon!
Schedule a consultation: https://buymeacoffee.com/csninja/extras
Need help: https://crawlspaceninja.com or https://supply.crawlspaceninja.com
Get every episode summarized
Each time Crawl Space Ninja Show publishes, we email you a written briefing from the transcript — the topics, who appeared, and any specific claims, with the ad reads skipped.
Email me new episodesFree for 3 shows. No card needed.
Hosts & guests
No transcript yet
This episode has not been transcribed. Request it and it moves to the front of the queue.
More episodes
More from Crawl Space Ninja Show

Building Code Says 6 Mil Is Fine. That Doesn't Mean It's Good
Crawl Space Ninja Show

Why Fiberglass Under Your Floor Fails
Crawl Space Ninja Show

Gable Vents May Be HURTING Your Attic Ventilation
Crawl Space Ninja Show

Powered Gable Fans, Why They Almost Never Work
Crawl Space Ninja Show