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 Sherwood requires the right material specification, proper seam treatment, wall coverage, and mechanical fastening to provide lasting protection against moisture migration.
The thickness of vapor barrier sheeting, measured in mils, is one of the most significant specification decisions a homeowner or contractor makes. A 20-mil reinforced vapor barrier significantly reduces vapor diffusion and resists punctures from gravel, debris, and service personnel working in the crawl space.
Seam treatment is equally important to the material specification when it comes to achieving a functioning vapor barrier system. 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.
Covering only the floor and stopping the barrier at the wall-floor junction leaves the porous block or concrete foundation walls as an open pathway for moisture to enter the crawl space environment. 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.
The downstream benefits of a properly installed vapor barrier extend well beyond simply keeping the crawl space dry. If the barrier is incomplete or poorly sealed, a dehumidifier simply works harder against an unlimited moisture supply, running continuously and consuming excessive energy without achieving target humidity levels.
Every installation meets or exceeds Sherwood, WI building standards.
The materials we install in Sherwood are built to last decades, not years.
Full perimeter coverage is non-negotiable in our installation standard.
You receive documentation of your warranty before we leave the property.
A complete crawl space vapor barrier system starts with proper site preparation, including removal of debris and grading of the ground surface for maximum contact.
Upgrading from 6-mil to 20-mil sheeting with proper seam sealing delivers measurably improved moisture performance in most cases.
We install vapor barrier systems under flooring or as a standalone moisture management layer in unfinished basements.
This combination approach addresses both vapor diffusion and water management in a single installation.
Full crawl space encapsulation combines a complete vapor barrier system with a dedicated dehumidifier sized for the space to achieve and maintain target humidity levels year-round.
We offer post-installation inspections for vapor barriers installed by other contractors, as well as for our own older installations, to assess barrier condition, seam integrity, and wall coverage completeness.
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. That wall coverage made a huge difference in our humidity levels. Great work from a team that clearly knows what they are doing."
Our certified team is ready to assess your crawl space and provide a clear, honest recommendation
