TL-0004 — Slope Requirements Technical Letter
GCP’s underlayments (GRACE ICE & WATER SHIELD®, GRACE ICE & WATER SHIELD® HT, GRACE ULTRA™, GRACE SELECT™, GCP granular underlayment, Roof Detail Membrane™, TRI-FLEX® and TRI-FLEX® 15) are intended for use on sloped roofs and are not intended to be used as waterproofing on flat roofs.
A good rule of thumb is that the product is appropriate at whatever slope is normally acceptable for the specific sloped roof covering. For example, if the roof covering on a specific project is designed for slopes of 3 inches in 12 inches (7 cm in 30 cm) or higher, then GCP’s underlayments under that roof covering are also appropriate at slopes of 3 inches in 12 inches (7 cm in 30 cm) or higher.
GCP’s underlayments should not generally be used at slopes less than 2 inches in 12 inches (5 cm in 30 cm). Refer to product data sheets for further details.
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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 www.gcpat.com. 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: 2022-01-11