SpecTopics: Using the DORA Directory with ASCE 7 Calculations
To meet the IBC-required uplift pressures associated with the roofing assemblies, uplift pressures must be calculated in pounds per square foot (psf) and verified by testing.
The determination of the uplift should be completed by the designer of record or through his/her licensed engineer using ASCE 7. Once accomplished, manufacturers can confirm the assembly's compliance through uplift rating records.
The use of ASCE 7 is based on the adoption of the IBC, either statewide or locally.
IBC edition ASCE 7 edition
2018 and 2021 2016
2012 and 2015 2010
2003, 2006, and 2009 2002-2005
Once these pressures have been determined, it must be certified that the specified roof assembly has been tested following ANSI/FM 4474 in psf. These records are then listed on the DORA website.
Process Summary
It's simple to determine the correct roofing assembly for a specific building to meet the IBC:
1. Determine the building's uplift pressure using the ASCE 7 calculations, which should be completed by a locally licensed or qualified design professional.
2. Review the roofing assembly's "reported pressure", which is collected from manufacturers' results and ratings from ANSI/FM 4474 and listed on the DORA website.
3. Compare and verify the DORA listed pressures, which need to be equal to or greater than the ASCE 7 pressures.
Once the assembly has been selected and confirmed to meet the uplift pressures, it's important to read and carefully consider warranties to confirm that the wind coverage meets the building owner's needs and is easy to understand.
Keep in mind, when higher wind speed coverage is requested from the material manufacturer, additional enhancements may be necessary to qualify for the warranty, which will likely increase the cost of the total assembly and may increase the cost of the warranty.
To learn more about the DORA Directory, visit DORA's website.
If you have any questions regarding ASCE 7 or the DORA Directory, please contact Brian Chamberlain.
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