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PETEX 15 Synthetic Roof Underlayment Installation

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PETEX-15 is a synthetic roof underlayment and is designed and manufactured to replace #15 traditional asphalt roofing felt; shingle only application. PETEX-15 is considered a vapor barrier and must be installed above a properly ventilated space.  Follow all applicable building codes.


SITE PREP:  All protrusions from the deck area must be removed and the deck shall have no voids, damaged or unsupported areas.  The deck surface should be free of debris, dry and moisture-free.



APPLICATION: PETEX-15 must be covered by asphalt shingles within 30 days of application. For slopes from 4/12 to 7/12 PETEX-15 is laid out horizontally (parallel) to the eave with the printed side up. Horizontal laps should be 4“ and Vertical laps should be 6” and anchored approximately 1” from the edge. For low slopes 2/12 to 4/12, double coverage is recommended, vertical end laps should be 12” overlap and anchored 1” in from the edge. Roof slopes greater than 7/12 pitch must be installed with Plastic Cap and Nails and recommend to be anchored in each location as printed on product.



FASTENERS: Same day coverage with asphalt shingles - If PETEX-15 is covered within 24 hours of installation, it can be anchored with corrosive resistant 3/8” head x 1“ leg roofing nails (ring shank preferred, but smooth leg roofing nail is acceptable).  Note the installations instructions for roof slopes greater than 7/12 pitch above. DO NOT USE STAPLES: use of staples will void warranty.



ANCHORING: All anchoring nails must be 90 degrees to the roof deck, tight with the underlayment surface and the structural roof deck. For extended exposure (30 days), driving rain or strong winds, double the lap widths as a minimum. The use of a compatible sealant between the laps, or using a peel and stick tape is highly recommended.


Where seams and joints require sealant or adhesive, use a high quality, low solvent asbestos free, plastic roofing cement meeting ASTM D-4586 Type 1 (Asbestos Free) Federal Spec SS-153 Type 1 (Asbestos Free). Acceptable alternatives are butyl rubber, urethane, and  EDPM  based  caulk  or  tape  sealant



EXTENDED EXPOSURE: If PETEX-15 product will be exposed longer than 24 hours and up to 30 days then product must be attached to the structural roof deck using a minimum 1” diameter plastic or metal cap roofing nails (ring shank preferred but smooth leg nails acceptable). Plastic Cap and Nails are defined as a minimum 1” (25mm) diameter plastic or metal cap with either; ring shank nails (preferred) or smooth leg nails (acceptable). Miami Dade approved tin tags/metal caps are also acceptable, recommend for best performance with the rough edge facing up. For 30 day exposure anchoring on every printed position is required. PETEX-15 is not designed for indefinite outdoor exposure.



Follow OSHA guidelines for steep slope installation. Slip resistance may vary with surface conditions from debris that accumulates, weather, footwear and roof pitch. Failure to use proper safety gear can result in serious injury. Depending on roof pitch and surface conditions, blocking may be required to support materials on the roof.