Roof Vapor Retarders Safeguard Against Vapor Migration and Prevent Vapor Flow
The proper installation of a vapor retarder in the roofing system safeguards against vapor migration and prevents vapor flow upward into the insulation.
Americover offers roofing vapor retarders that can withstand extreme temperatures, and are highly puncture and tear resistant. Many of the vapor retarders and vapor barriers can be customized to reduce in-field seams or manufactured with fire retardant to meet building codes.
Roof vapor retarders prevent things like the following:
- ice under the membrane
- soaked insulation facers
- destabilized insulation
- rusting roof decks
- dripping water down screw-fastener threads
- compromised fiber board and perlite integrity
- mold on organic facers
- loss of adhesion on adhered systems
Common Questions About Roof Vapor Barriers
What is a roofing vapor barrier, and why does my roof need one?
A roofing vapor barrier is installed beneath the roofing assembly to block water vapor from migrating into the roof deck and insulation. Without it, vapor condenses when it hits a colder surface, leading to trapped moisture, decking rot, and mold.
What characteristics make a quality vapor retarder?
Performance and perm ratings are the main factors in selecting a quality vapor retarder. The purpose of a vapor retarder is to reduce the movement of water vapor in the roofing systems. Typically, these materials must have a perm rating of 1.0 or less to be successful. Poorly constructed vapor retarders can contribute to the destabilization of insulation, rusting, dripping water, and loss of adhesion to systems.
Where does the vapor barrier go in the roof assembly?
It’s installed on the warm side of the insulation — the side facing the building’s conditioned interior — so vapor is stopped before it reaches a colder surface where it would condense.
What thickness should I use?
Thickness depends on exposure and traffic during installation; heavier mil options resist punctures and tears better on roofs with rooftop equipment or foot traffic. Your rep can match mil thickness to your specific deck and climate conditions.
Do roofing vapor barriers need to be fire retardant?
Some roofing assemblies and local building codes require a fire-retardant liner. Check your project’s code requirements before selecting a non-FR product.
Call us for free samples and/or Pricing on our speciality roof vapor retarders.Give Us A Call
High Quality Roof Vapor Retarders
String Reinforced Plastic Sheeting
Dura-Skrim® Reinforced Plastic Sheeting is a heavy duty construction and agricultural film excellent for both indoor and outdoor applications requiring an exceptionally strong material.
VAPORBLOCK® Vapor Retarder
VAPORBLOCK® is a high performance crawl space vapor barrier designed to retard moisture migration through concrete slabs-ongrade. VAPORBLOCK® vapor barriers exceed ASTM E-1745 Class A, B, and C requirements.
HDPE / LLDPE / PVC
Americover custom-fabricates vapor barriers in HDPE, LLDPE, and PVC for roofing applications — cut and configured to the exact dimensions of each project. Material selection depends on the job: HDPE for puncture resistance, LLDPE for flexibility on complex roof geometries, PVC for chemical and weathering durability. Every barrier is built to fit the roof, not forced to fit a standard size.
Vapor Barrier Blue
Vapor Barrier Retarders are composed of polyolefin resins to create a puncture-resistant vapor barrier for use under concrete slabs to stop moisture migration and reduce mold, mildew, and fungus.
Vapor Barrier Yellow
Vapor Barrier Retarders are composed of polyolefin resins to create a puncture-resistant vapor barrier for use under concrete slabs to stop moisture migration and reduce mold, mildew, and fungus.
Pro Crawl Barrier
Pro Crawl Barrier is a 10 mil Class 1 Vapor Barrier with a high gloss white finish offering low permeability and excellent tensile strength to protect the building fabric from moisture vapor damage. Roll size is 10′ x 100′.
Vapor Retarder Tapes
A vapor barrier is only as strong as its seams. Americover’s tape lineup — R25B, Butyl Tape, and Vapor Tape — closes every seam, lap, and penetration in a roofing vapor barrier system so moisture never finds a way through. Each brings a different bond to the job: aggressive elastomeric contact, permanent high-tack butyl, or polyethylene-backed tape that strengthens over time. Match the tape to the seam, and it holds for the life of the barrier. Not sure which tape fits your project? Call 833-261-6501.
R25B Seaming Tape
R25B Tape is a single-sided synthetic elastomeric adhesive tape that bonds instantly to polyethylene and polypropylene sheeting, providing a weather-resistant seam seal built to hold up in direct sunlight.
Butyl Tape
A double-sided, high-tack butyl rubber tape with a reinforced cloth carrier that creates a permanent, airtight bond across roofing vapor barrier overlaps without the rubberband effect that plagues non-reinforced butyl tapes.
Vapor Tape
A 12 mil polyethylene backing tape with a pressure sensitive adhesion system that seams roofing vapor barrier panels with a bond that strengthens over time.
EnkaMat® Moisture Drainage Solution
EnkaMat® is a 3D nylon filament mat that serves as a moisture-mitigating, noise-reducing underlayment in roofing systems, extending the life of the structure beneath it. Its open matrix allows airflow and drainage beneath ballast or membrane roofing, relieving hydrostatic pressure and protecting the waterproofing layer from wear. For roofing applications, place it beneath zinc panels or ballast materials, cut it to fit, and mechanically fasten if required.
Check out our online selection of specialty plastic building solutions. Contractors and distributors are eligible for special pricing and volume-based discounts on select products, call us at 760-237-8786. Our online inventory is just our retail selection, which means we can often source items you may not see here.Give Us A Call
Contractors and Builders Talk About Americover
When you partner with Americover, you benefit from our industry and product application knowledge. But don’t take it from us. Take it from those in the building industry who have relied on our quality and reliability over the years.
Roof Vapor Barrier Resources
Americover’s Product Catalog
Browse our full inventory of vapor barrier and crawlspace encapsulation liner products.
Guide to Selecting an Effective Vapor Barrier
Everything you need to know about choosing and installing a vapor barrier.
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