How do I load thee?
Be prepared to address changes resulting from the 2016 edition of ASCE 7
The 2016 edition of ASCE 7, "Minimum Design Loads and Associated Criteria for Buildings and Other Structures," became available in June and replaces the 2010 standard. ASCE 7, issued by the American Society of Civil Engineers (ASCE), provides information that allows designers to determine various types of loads and load combinations on buildings. The 2016 edition is referenced in the 2018 editions of the International Building Code and International Residential Code.
Some wind load provisions in the new edition have changed dramatically from those in the 2010 publication. The loads on roof systems greater than 60 feet above grade are somewhat less than or equal to loads derived from the 2010 edition. However, for many roofs that are 60 feet or lower, the loads have changed substantially, and the roof zone layout is quite different. For those familiar with calculating loads in accordance with the 2010 edition, the transition to the 2016 edition will be easy. However, field crews will have a far greater challenge correctly installing attachments at the new roof zones unless designers make an effort to simplify the zone layouts.
The 2016 changes that pertain to the roofing industry include:
- New wind speed maps (including increased mean recurrence interval for Risk Category IV buildings)
- A new ground elevation factor in the velocity pressure equation
- Removal of the truncation of Kz below 30 feet
- Changes in roof pressure coefficients and zones for low-rise buildings
- The addition of pressure coefficients for rooftop photovoltaic (PV) panels
- Loads are now provided for rooftop equipment above 60 feet
- Additional Commentary regarding "open patches" in the surrounding terrain
Following is an overview of these additions and changes. I do not address changes that only pertain to primary structural elements such as beams, columns, shear walls and diaphragms that provide overall support and stability for buildings.
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