A vapor barrier is a polyethylene sheeting system installed on the ground and walls of a crawl space or basement to block ground moisture from migrating into the structural environment above. A correctly installed vapor barrier in Lewis requires the right material specification, proper seam treatment, wall coverage, and mechanical fastening to provide lasting protection against moisture migration.
A mil is one-thousandth of an inch, and the difference between a 6-mil sheet and a 20-mil sheet is significant in terms of puncture resistance, lifespan, and moisture vapor transmission rate. For most homes in Lewis, IN, we recommend a minimum 10-mil product for general installation and a 20-mil product for spaces with high moisture loads or frequent access requirements.
Overlapping sheets by 12 inches or more at seams and securing them with butyl tape creates a continuous, mechanically bonded membrane that resists separation as the sheeting settles and moves over time. We use butyl tape exclusively for seam sealing, both because of its long-term adhesion to polyethylene and its resistance to moisture and temperature cycling.
This wall-to-sill coverage eliminates the vertical moisture migration pathway that accounts for a significant percentage of crawl space humidity in Lewis homes. The combination of floor coverage, properly lapped and taped seams, and full wall coverage to the sill plate creates a complete moisture envelope that dramatically reduces crawl space humidity and protects the wood framing above.
It also creates ideal conditions for mold and mildew growth on wood surfaces and insulation, contributing to indoor air quality problems in the living space above. A well-installed vapor barrier is also a prerequisite for effective dehumidifier integration in crawl spaces where mechanical moisture extraction is warranted.
Our installers are trained on manufacturer specifications for every product we use.
The materials we install in Lewis are built to last decades, not years.
We extend the barrier up every wall to the sill plate, closing the moisture entry pathway that floor-only installations miss.
Our vapor barrier installations carry a written warranty covering materials and workmanship.
We install reinforced polyethylene sheeting across the entire crawl space floor with full wall coverage and butyl-taped seams throughout.
Older thin-mil or damaged vapor barriers in Lewis, IN homes are common and leave crawl spaces with inadequate moisture protection.
Basement floors in Lewis, IN homes, particularly older poured concrete slabs, allow moisture vapor migration from the soil below year-round.
Drainage board integration is recommended for Lewis basements that experience both seasonal dampness and occasional liquid intrusion.
In high-humidity areas of Lewis, IN, a vapor barrier alone may not be sufficient to control crawl space moisture during peak summer months.
Inspection findings are documented with photos and a written report detailing any deficiencies and recommended corrective actions.
We measure the space, assess existing moisture conditions, document any existing barrier or mold, and identify all penetrations that will need to be addressed in the installation
Based on site conditions, we specify the appropriate mil rating, calculate material quantities, and plan the seaming layout for maximum coverage and minimum waste
Sheeting is laid, overlapped at 12 inches minimum, taped with butyl tape at all seams, and extended up all walls with mechanical fastening at the top edge
We walk through the completed installation with you, confirm all seams and coverages are complete, and provide written warranty documentation before leaving
"We had a previous vapor barrier installation that was barely 6-mil and had separated seams throughout. The humidity in our crawl space was unacceptable and we were starting to see mold on the floor joists. JCB Waterproofing and Construction came in, took out the failing old barrier, and installed a proper system that actually works. The difference in our indoor air quality was noticeable within a week."
"Very professional team that explained the difference between the grades of vapor barrier sheeting before recommending anything. The material quality and seaming were both done to a very high standard. We can already see the humidity meter reading dropping consistently."
"The crew extended the barrier all the way up the walls to the sill plate, which the contractor who did our original installation did not do. The proper wall-to-sill installation finally completed our moisture protection. Great work from a team that clearly knows what they are doing."
Contact JCB Waterproofing and Construction for a free site evaluation and written estimate for vapor barrier installation in Lewis
