ICC 500-20 Standard for Design and Construction of Storm Shelters: What You Need to Know

Updates to ICC 500 Standard for Design and Construction of Storm Shelters: What You Need to Know

ICC 500 is a building code for storm shelters defined by the International Code Council. These codes are written to ensure the safety of people using and purchasing storm shelters, so customers can rest assured the storm shelters they purchase are built to the most rigorous standards.

Despite their obvious importance, did you know many storm shelter manufacturers use outdated codes? RemainSafe builds each of our current shelters in accordance with the latest edition of ICC 500 released in 2020. Before this, the most recent ICC 500 guidelines were from 2008, with minor updates in 2014.

ICC 500 Update Timeline

The quality of a storm shelter is dependent on how it can withstand anything a tornado can put it through. Science and weather are always evolving, and as we make new discoveries, building codes change to keep you safe. It’s vital to understand these codes and be certain the storm shelter is built and specifications developed using the most recent ICC 500 codes.

2002 –The International Code Council/National Storm Shelter Association (ICC/NSSA) Standard for Design and Construction of Storm Shelters was released, later to be called ICC 500

2008 – First edition of ICC 500 was released, under the name ICC 500-08

2014 – Revised edition of ICC 500 was released

2020 – The most recent edition of ICC 500 was released, often referred to as ICC 500-20

The 2020 edition of ICC 500 is often called ICC 500-20. In this updated edition, a few key design requirements were updated to optimize storm shelter safety. Here we will break down some of the most significant updates and additions.

Important ICC 500 Updates

In ICC 500-20, some existing design requirements have been updated to reflect more accurate and reliable safety protocols.

Section 303.3 Roof Live Loads and Wheel Loads

ICC 500-20 requires tornado shelters’ roofs to be designed to withstand minimum live loads of 100 pounds per square foot. If a shelter is in an area where debris may fall onto its roof, the roof live load weight capacity must be increased to accommodate the threat of debris.

Section 305.3.3 Impact Loads

ICC 500-20 adds criteria for determining whether laydown or falling debris hazards must be applied to the shelter in Section 305.3. ICC 500-08 only required debris hazards to be considered during siting. In ICC 500-20 the weight of debris must also be considered in the design requirements, and the shelter must be able to withstand at least two times the estimated weight of any debris that may threaten to fall on above-ground shelters.

This means shelters designed to new ICC 500 standards are built with falling debris in mind from the engineering and design stage, instead of just during installation.

Section 306.4.1.3: Anchorage for IPS

ICC 500-20 introduced anchoring guidelines for impact-protective systems. Impact-protective systems or IPS are defined by ICC 500 as “An assembly or device, subject to static or cyclic pressure… installed to protect an opening in the storm shelter envelope.” According to the ICC, devices that count as IPS include shutters, doors or other devices that pass impact testing. The new guidelines now require additional impact testing if any changes are made to the design of the IPS.

Section 504 Access and Egress in Community Shelters

The new code requirements state that community storm shelters that are designed for more than 16 occupants include an overhead hatch “access by an emergency stair, ladder or alternating tread device.” This means, in community shelters specifically, designers must include accessible secondary emergency exits overhead to be compliant with ICC 500-20.

New Sections in ICC 500-20

In addition to amendments to the original ICC 500 guidelines, ICC 500-20 also includes new sections that address regulations not covered in previous versions of the code.

303.2 Floor Live Loads

Previous editions of ICC 500 did not have weight restrictions for the internal floors of storm shelters. Storm shelters that meet ICC 500-20 code guidelines now state that “Community tornado shelter floors shall be designed for not less than the minimum uniform live loads for assembly occupancies in accordance with the applicable codes.” This means that flooring weight limits must pass testing under certain weights to comply with ICC 500. The specific weight requirements vary depending on applicable codes based on shelter type and intended occupancy.

507.3 Operating Hardware on the Unprotected Side

This new section of ICC 500-20 requires that the shelter’s operating hardware such as door-latching mechanisms must be able to be “locked, disabled or inactive, and shall not be susceptible to unintentional unlatching by debris impact” when located on the outside of the storm shelter. This means that any exposed mechanism that could cause the storm shelter door’s hardware to fail in impacted by debris, must be protected.

Request a Quote for an ICC 500-20 Compliant Storm Shelter Today

There are many more code requirements outlined in ICC 500-20. To learn more about storm shelter regulations, the full ICC 500-20 document is available for free on the ICC website. For a full list of updates made in ICC 500-20, the Federal Emergency Management Agency compiled a comprehensive guide available here.

To get a quote for an ICC 500-20 compliant commercial or community storm shelter, contact RemainSafe, we are happy to help.