FM recently made changes to the ratings calculator within RoofNav and their Loss Prevention Data Sheets to reflect their partial adoption of ASCE 7-16. The main difference is that FM did not adopt the wind maps utilized by ASCE 7-16 and the 2018 International Building Code. This can cause wind design complications for FM-insured buildings.
On February 26, 2020, FM Global updated its Property Loss Prevention Data Sheet 1-28 “Wind Design” to reflect changes in its wind load determination methodology. It is important that the FM wind maps (and not the ASCE 7016 wind maps) are used when inputting the wind speed to obtain the correct wind pressures and wind uplift ratings needed when using FM’s RoofNav ratings calculator. Also, uplift pressures should be calculated per the applicable building code requirements for the project. It is suggested the more conservative of the two calculated design pressures be used.
Also, if you are certain that the project is NOT FM insured, it is highly suggested that you should not use the FM RoofNav ratings calculator to determine uplift pressures.
To view Carlisle’s presentation on this subject, click here.
If you have any questions about ES-1 and how they can be incorporated into your next roofing system, please contact your Luna & Associates Representative.