Strengthen Existing Areas Against Extreme Wind Events During Remodels

Existing spaces that were not designed for resistance to the effects of a tornado can be augmented to provide additional protection for occupants as an interim measure.

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In the Best Available Refuge Area (BARA) – When You Don’t Have a Safe Room or Storm Shelter blog, we covered that a structure designed specifically as a storm shelter will provide reliable safety from an Extreme Wind event.

But what can be done about an existing space (not specifically designed as a storm shelter) to make it safer?

Existing spaces that were not designed for resistance to the effects of a tornado can be augmented to provide additional protection for occupants as an interim measure.

Efforts to strengthen an existing area are often undertaken during a planned remodel. While it’s important to note that exact performance of an augmented area can’t be known for sure (because it is part of a larger building system that was not designed for the increased forces applied during a tornado), strengthening measures are available to protect against flying debris.

Flying debris during a tornado causes damage to building components and is called “missile impact” by building design codes. The missile impact test historically used is a 15-pound, wood 2×4 shot from an air cannon at 100 mph! Increasing resistance to missile impact can significantly increase occupant safety in a tornado event.

There are a few things that can be done to address common deficiencies in school construction with respect to tornado safety. Here are a few suggestions that can increase student and staff safety:

Replace standard doors for door assemblies tested and rated for storm shelters.
Replace standard windows with shatter resistant windows rated for shelters.
Brace the tops of masonry walls to the roof deck and framing.
Reinforce roof framing connections to walls.
Add grout and reinforcement to existing masonry walls.
Supplement or replace roof framing and replace the roof deck with a concrete over metal deck system at short spanning roofs like corridors.

A Shive-Hattery structural engineer can work with you for an in-person assessment to customize an improvements plan specifically for your facility.

Follow our Extreme Wind Event biweekly-series intended to help walk you through identifying vulnerabilities and opportunities to improve safety: