TL-0009 — Fastener Sealability Technical Letter

GCP’s self-adhered underlayments (GRACE ICE & WATER SHIELD®, GRACE ICE & WATER SHIELD® HT, GRACE ULTRA™, GRACE SELECT™, Roof Detail Membrane™ and GCP granular underlayment ) are formulated to provide a quality seal around fastener penetrations. However, the quality of that seal can be significantly affected by the type of fastener used and the manner in which they are installed.

For best results, use smooth shank electroplated galvanized fasteners. Hand nailing generally provides a better seal than power activated nailing. Do not install the fasteners through the underlayment over unsupported areas of the structural deck, such as over the joints between adjacent structural panels. In addition, the fasteners should be installed as straight as possible so the membrane is not torn. It is important that the temperature at the time the fasteners are installed through membrane is 40°F (5°C) or higher for optimum sealability. If fasteners are removed leaving holes in the underlayment, the membrane must be patched with a round piece of membrane extending past the damaged area 6 inches (150 mm) in all directions. Underlayments may not self-seal open fastener penetrations. | North America Customer Service: 1 877-4AD-MIX1 (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. Grace Ice & Water Shield, GCP granular underlayment, Grace Ultra, Grace Select, and Roof Detail Membrane are trademarks, 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.

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GCP Applied Technologies Inc., 2325 Lakeview Parkway, Suite 450, 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: 2022-05-06