Vulca Seal Acrilay (Partially-Adhered) Underlayment

Fontana’s Vulca Seal Acrilay partially adhered peel and stick underlayment is an evolutionary product that combines SBS modified asphalt with a 3M acrylic adhesive. By using an acrylic adhesive, these products adhere four times better than asphalt-based adhesives, and last four times longer when attached to plywood decking. Due to the chemical makeup of the acrylic adhesive, Fontana has achieved the process of heat-welding the acrylic to the modified SBS material without the possibility of delamination. Acrilay has the ability to be installed in a wide range of application temperatures (40°F – 240°F) without the use of a torch in cold climates or sloppy viscous asphalt in hot conditions. When mechanically fastened over an adhesive area, the acrylic acts as a nail sealant thereby disallowing for any water penetration. The system is one of the most durable and longest-lasting adherable underlayment underclay or concrete roof tiles in the roofing industry. Vulca Seal Acrilay (Partially Adhered) is a single-ply field underlayment designed to withstand the worst of climate conditions while allowing moisture to wick out of wood decking. With 6” strips lining at the toe and head laps, the underlayment adheres directly to the deck or underlayment allowing for over 27 inches of floating underlayment between the adhesive strips. In a single-layered application, the bottom lap will have 2 inches of adhesive applied to the deck and 4 inches applied to the previous underlayment course. Double layer installation will lap fully over the previous underlayment course and be applied to the underlayment surface.


Vulca Seal Acrilay is the best way to protect your rakes, eves, and valleys from extreme weather conditions including winds exceeding 150mph and temperatures as low as 0°F.

Product Specification

Product Dimensions

Asphalt Coated Fiberglass Base ASTM D 4601  39.37” x 70’ 6”
Inorganic Steep Slope Membrane ASTM D 6757 236 sqft  (2sq Roll)


Product Testing


Thickness (mil) ASTM D 5147   60 mil
Max Load ASTM D 2523/D 1970   Pass
Adhesion to Plywood ASTM D 903/D 1970   Pass
Low Temp Flexibility ASTM D 1970   Pass
Tear Resistance ASTM D 4073/ D 1970   Pass
Moisture Vapor Presence ASTM E 96 Proc. BW   Pass
Self Sealability ASTM D 1970   Pass
Slip Resistance ASTM D 4918   Pass

Installation Instructions


20 Year Acrilay Warranty Download