FRSA Tile Underlayment Testing Confirms Concerns - October 2021

Tue, Nov 30, 2021 at 8:00AM

Mike Silvers, CPRC, Silvers Systems Inc. and FRSA Director of Technical Services

Self-adhering manufacturer’s product approvals showed relatively low uplift resistance for these underlayment systems. The highest of those we found provided resistance of 45 psf with the safety factor of 2 accounted for. This means the product should have resistance of 90 psf during testing. The resistance stated in these product approvals would not meet the American Society of Civil Engineers (ASCE) 7-16 requirements in many areas of Florida.

FRSA was concerned that this prescriptive application was being used to circumvent the more restrictive ASCE 7-16 compliant requirements of the 6th Edition FRSA-TRI Florida High Wind Concrete and Clay Tile Installation Manual. The manual has prescriptive methods for two ply hot mopped systems that include greatly enhanced fastening for the #30. For all other underlayments you need a product approval that meets the resistance values for your specific job based on the tables in the manual or engineering calculations that are based on ASCE 7-16. Read more

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