TRI-FLEX® 15 Synthetic Underlayment Data Sheet

Synthetic Performance Alternative to #15 Felt

TRI-FLEX® 15 synthetic underlayment exceeds the requirements of ASTM D226 type I and II and offers the benefits of a synthetic to traditional #15 felt users. Its higher coverage per roll means it goes down quickly. Because it is 10x stronger than #15 felt, costly blow offs are prevented. The product is mechanically fastened and may be used in conjunction with GCP self-adhered underlayments or alone.

It is totally recyclable, and contains post industrial recycled polymers, so it contributes to sustainabiliy and LEED.

TRI-FLEX® 15 underlayment acts as a secondary watershedding material below mechanically attached roof coverings. The product may be exposed for up to 60 days and may be used with asphalt shingles and most other roof coverings.

Product Description

TRI-FLEX® 15 underlayment is an engineered woven fabric, coated on both sides with polypropylene. The proprietary resin formula used in the walk and deckside surfaces create a slip resistant surface.

TRI-FLEX® 15 underlayment is available in 10 sq rolls (48 in. wide x 250 long).

    Features & Benefits

    Major benefits of TRI-FLEX® 15 underlayment vs #15 felt include:

    • Stronger - Its 10x stronger and prevents blow o s and tears in windy conditions
    • Higher Coverage per Roll - A 10 sq roll is 67% lighter than #15 felt, and covers 2.3 times the area
    • Fewer Laps and Fasteners - 30% more coverage per side lap than felt
    • Sustainable - TRI-FLEX® 15 underlayment is 100% recyclable, and contains post industrial recycled materials, and contributes to sustainability and LEED
    • Excellent temporary dry in - May be exposed for up to 60 days
    • Versatile - Suitable for use under asphalt shingles and most other major roof coverings
    • Custom Logo Available - The product can printed with a customer logo. Minimum order amounts apply. Please contact the GCP sales representative for details.
    • Local technical support - TRI-FLEX® 15 underlayment is backed by a team of local technical support personnel that help ensure every application goes smoothly.

    Product Advantages

    • Improved Slip Resistant Coating
    • Lighter and covers more area
    • Stronger and more durable
    • Facilitates faster and easier installation
    • Suitable for use under all major roof coverings
    • Custom Logo Printing Available
    • 25 Year Warranty

    Installation Guidelines

    1. The roof deck must be swept clean and be smooth and dry before installation begins.
    2. TRI-FLEX® 15 underlayment is laid horizontally (parallel to eave), starting at the bottom of the roof, with printed side up and with 4-inch side laps and 6-inch end laps. Side laps run with the flow of water in a shingling manner.
    3. TRI-FLEX® 15 underlayment should not be used at slopes less than 2:12, provided the slope is also acceptable to the primary roof covering. On slopes of less than 4:12, TRI-FLEX® 15 underlayment should be half-lapped a full 24 inches over the underlying course, shingle style.
    4. TRI-FLEX® 15 underlayment is attached to the roof with roofing nails or staples both having 1-inch diameter plastic/metal caps, spaced at 8 inches on center (oc) on both side and end laps in normal wind zones. In high wind zones or coastal applications, double the fastening to 4 inches oc. In all cases fasten at 24 inches oc down the middle of the roll in the field of the roof. Fasteners may be hand or machine applied. Staples without caps cannot be used.
    5. Where seams or joints require sealant or adhesive, use a high quality, low solvent, asbestos free plastic roofing cement meeting ASTM D4586 Type 1, Federal Spec SS-153 Type 1 (Asbestos Free). Consult your local GCP representative for more details.
    6. Install drip edge at eaves under underlayment and at rake over underlayment.
    7. Installation of the roof covering can proceed immediately following underlayment application. TRI-FLEX® 15 underlayment cannot be used as a primary roof covering. The product is not designed for permanent outdoor exposure. The installation of the final roof covering should take place within 60 days.
    8. For additional protection lay a single length of TRI-FLEX® 15 underlayment vertically in valleys and on hips prior to installing metal flashings (if used) and before installing horizontal underlayment. Return TRI-FLEX® 15 underlayment up all abutments at least 12 inches (more in heavy snow areas). Secure and trim to suit.
    9. Prior to loading roofing materials on TRI-FLEX® 15 underlayment it is recommended that roof jacks, toe-boards or a storage platform be secured to the underlying roof deck to prevent slippage of stored materials on steep sloped roofs. See OSHA Regulations (Standards – 29 CFR), Fall Protection Systems Criteria and Practices – 1926.502.
    10. Check local building code to ensure compliance in your area, as local building codes may vary.

    Code Approvals

    • Complies with AC-188 Acceptance Criteria for Roof Underlayments.
    • Meets the requirements of Florida Building Code, Approval
    • Complies with ASTM E108/UL 790 for use in the installation of Class A asphalt glass fiber mat shingles and Class C asphalt organic felt or metal shingles
    • Meets ASTM D226 physical requirements of Type I and Type II

    Precautions and Limitations

    • Consistent with good roofing practice, always wear fall protection when working on a roof deck.
    • Slippery when wet or covered by frost, debris or dust.
    • Do not fold over the roof edge unless the edge is protected by a drip edge, gutter or other flashing material.
    • Check with the manufacturer of the metal roofing system for any special requirements when used under metal roofing. Do not install directly under roof coverings especially sensitive to corrosion, such as zinc, without providing proper ventilation.
    • Do not install under copper, Cor-Ten®, or zinc metal roofing in high altitudes or in the desert southwest. These roofs can reach extremely high temperatures due to the low reflectivity, high absorption, and high conductivity of the metals.
    • Provide proper roof insulation and ventilation to help reduce ice dams and to minimize condensation.
    • Repair holes, fishmouths, tears and damage to product. TRI-FLEX® 15 underlayment does not self-seal open fastener penetrations.
    • Do not use uncapped staples!
    • Do not install fasteners through the product over unsupported areas of the structural deck, such as over the joints between adjacent structural panels.
    • Do not stretch Do not use uncapped staples! underlayment during installation. The product should be pulled taut, but should not be stretched.

    Product Data

      10 SQ ROLL
    Roll length 250 ft (76.2 m)
    Roll width 48 in (1.05 m)
    Roll size 1,000 ft2 (92.9 m2)
    Roll weight 20 lbs (9.1 kg)
    Rolls per pallet 48

    Performance Properties

    Color (front/back) Black/Black  
    Weight 20 lbs (10 sq roll)  
    Tear strength  MD 36 lbs; CD 36 lbs ASTM D4533
    Accelerated aging Pass (no damage, cracking, chipping) ICC-ES AC48
    Ultraviolet resistance Pass (no peeling, chipping, cracking, flaking) ICC-ES AC48
    Water ponding Pass (no percolation) ASTM D779
    Pliability Pass (no cracks) ASTM D226
    Water transmission Pass ASTM D4869
    Tensile strength MD 66 lbs; CD 49 lbs ASTM D828
    Thickness 7 mils ASTM D3767 | North America Customer Service: +1 (877) 423 6491

    We hope the information here will be helpful. It is based on data and knowledge considered to be true and accurate and is offered for consideration, investigation and verification by the user, but we do not warrant the results to be obtained. Please read all statements, recommendations and suggestions in conjunction with our conditions of sale, which apply to all goods supplied by us. No statement, recommendation or suggestion is intended for any use that would infringe any patent, copyright or other third-party right.

    TRI-FLEX is a trademark, which may be registered in the United States and/or other countries, of GCP Applied Technologies, Inc. This trademark list has been compiled using available published information as of the publication date and may not accurately reflect current trademark ownership or status.

    © Copyright 2018 GCP Applied Technologies Inc. All rights reserved.

    GCP Applied Technologies Inc., 2325 Lakeview Parkway, Suite 400, Alpharetta, GA 30009, USA
    GCP Canada, Inc., 294 Clements Road, West, Ajax, Ontario, Canada L1S 3C6
    This document is only current as of the last updated date stated below and is valid only for use in the United States. It is important that you always refer to the currently available information at the URL below to provide the most current product information at the time of use. Additional literature such as Contractor Manuals, Technical Bulletins, Detail Drawings and detailing recommendations and other relevant documents are also available on Information found on other websites must not be relied upon, as they may not be up-to-date or applicable to the conditions in your location and we do not accept any responsibility for their content. If there are any conflicts or if you need more information, please contact GCP Customer Service.

    Last Updated: 2023-06-28