The Concrete Masonry & Hardscapes Association (CMHA) has released Tornado Storm Shelter Prototypes Using Reinforced Concrete Masonry, a new manual providing architects, engineers and contractors with practical guidance for designing and building ICC 500-compliant tornado shelters.
Funded by the National Concrete Masonry Association Education and Research Foundation, commonly known as the NCMA Foundation, the report was developed through work led by the Masonry Institute of St. Louis. The institute brought together leading masonry engineers, code experts, mason contractors, field personnel and suppliers to ensure the concepts are technically sound and practical to construct.
"The strength of this manual is the caliber of professionals who contributed to it," said Mark Wilhelms, chair of the NCMA Foundation Program Review Committee and vice president of architectural sales at Best Block Companies. "CMHA brought together respected engineers, code experts and contractors to develop guidance the entire project team can use. It demonstrates how industry-funded research can address complex technical challenges and make masonry easier to design, specify and build."
The manual comes as severe storms continue to increase the need for structures that protect occupants during extreme wind events. Building codes require ICC 500-compliant tornado shelters in critical emergency operations facilities and most Group E educational occupancies within the 250-mph tornado wind-speed zone.
To help project teams meet those requirements, Tornado Storm Shelter Prototypes Using Reinforced Concrete Masonry examines three stand-alone shelter prototypes based on educational facilities, ranging from a smaller room to a large gymnasium. The prototypes use fully grouted, single-wythe, loadbearing concrete masonry walls and evaluate hollow-core plank, double-tee and steel-joist roof systems.
The manual addresses the complete structural system, including walls, foundations, roof diaphragms and the connections required to maintain a continuous load path under extreme pressure, suction and uplift. Contractor input also helped refine construction sequencing and field details.
"The masonry wall is generally not the most difficult part of a storm shelter," said Dave Gillick, who helped lead the manual's development. "The greater challenge is connecting the roof, walls and foundation so the structure maintains a continuous load path and resists uplift. The manual works through those conditions using three prototype buildings and three different roof systems."
The manual also outlines contractor responsibilities related to quality assurance, documentation, special inspections, structural observations and example costs for each prototype. It supplements CMHA's 2015 Storm Shelter Design Guide, which provides broader architectural guidance for a classroom-wing shelter.
By combining leading technical expertise with real-world contractor input, CMHA has turned NCMA Foundation-funded research into practical guidance that can help project teams confidently design, specify and build with masonry.
To download Tornado Storm Shelter Prototypes Using Reinforced Concrete Masonry or access additional technical resources, visit CMHA.org.
