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Building Upgrades to Further Protect Against Severe Thunderstorms

Severe thunderstorms cause billions of dollars in insured property damage each year. Resilient commercial structures built using stronger construction methods can better withstand severe weather by reducing building damage, inventory loss, and business interruption caused by severe weather 

Start Building Upgrades!

We can’t stop severe thunderstorms, but we can strengthen building components to better prepare for them. Upgrade now and be Thunderstorm Ready!

Checklist: Business Thunderstorm Prep & Upgrades 
Annual maintenance tips and upgrades to protect your business. 

1. Strengthen your roof against severe weather.

The roof is the first line of defense against severe weather. Severe thunderstorms produce winds of at least 58 mph. These winds can damage an improperly designed or maintained roof cover leading to leaks that can damage inventory, machinery, tools, and belongings.

  • Replace your roof with a FORTIFIED Roof, designed to prevent avoidable wind and water damage with just a few additional methods and materials. Based on decades of IBHS research, this roofing standard helps keep your roof on and water out during severe weather. 
    • Here’s how a FORTIFIED Roof works: 
      • Stronger roofing system to better protect against high wind. 
      • Roof flashing tested for wind and used to secure the perimeters of low-slope membrane roof systems. 
      • Gutters and downspouts tested for outstanding performance against wind.   
      • Sealed roof deck to keep rain from seeping through the cracks of the roof deck boards on a steep-slope roof even when shingles are lifted or blown off. 
      • Roof-mounted equipment for increased wind pressures. 
      • Impact Resistant and Pressure Rated Skylights in hail-prone regions to withstand water intrusion and large impacts.  
    • How do I build to FORTIFIED? 
      • Visit or to learn about the standards and the designation process. 
        •  Determine the level of resilience you want to achieve (FORTIFIED Roof, FORTIFIED Silver, or FORTIFIED Gold). 
        • Complete an online application. 
        • Work with a third-party evaluator provided by IBHS to verify compliance with the standards. 

2) Upgrade to wind-rated commercial doors.

Large openings including commercial overhead, roll-up, and sectional (garage) doors are among the most vulnerable parts of a building during a tornado. High winds in a tornado can push the doors inward, allowing pressure to build inside the garage and push up on the roof and surrounding walls—often resulting in major structural damage to your building. 

  • Purchase wind-rated commercial doors 
    • Hire a licensed contractor to properly select and install a wind-rated overhead door.
      • When available, consult the building’s structural drawings to identify the design wind design pressures. Look for doors tested to one of these standards: 
        • ANSI/DASMA 115 Standard Method for Testing Sectional Doors, Rolling Doors, and Flexible Doors 
        • The Florida Building Code TAS 201 (Impact Test Procedures), 202 (Criteria for Testing Impact & Nonimpact Resistant Building Envelope Components Using Uniform Static Air Pressure), and 203 (Criteria for Testing Products Subject to Cyclic Wind Pressure Loading) 
      • Once the door is installed, ensure it shows a label with the wind rating. Remember—don’t peel off the label! 
2. Wind-rated rollup door

3) Upgrade to impact-rated windows and doors.

Windows and doors with glass can be shattered or damaged by flying debris during high winds or even large hail greater than 2 inches in diameter.

  • Purchase windows and doors that test to ASTM E1996 for small missile impacts. 
3. Upgrade to Impact Rated Windows and Door Label

4) Get a wind-rated lightning protection system.

Lightning, which occurs in every thunderstorm, can cause a power surge to costly electrical equipment that can’t handle the extra voltage.   

  • Utilize a lightning protection system designed and installed for wind resistance in accordance with FEMA guidance on rooftop attached lightning protection systems in high-wind regions.  
B3- New lightning protection

5) Invest in a commercial backup generator.

Severe thunderstorms can cause power outages that may interrupt your normal business operations.

  • Purchase a backup generator properly sized to operate critical utilities necessary to maintain vital business operations.  
Generator for emergency electric power. With internal combustion engine.

6) Protect critical equipment

Heavy rain from thunderstorms can cause flooding that could penetrate your business and damage critical equipment. Additionally, winddriven rain can seep through vulnerable building components such as windows and doors, leaving inventory and other valuables exposed to water.

  • Elevate electrical and mechanical equipment and connections necessary to operate critical systems above the 500-year flood level, if known, or 3 ft above the base flood elevation (BFE) for the property. 
  • If the equipment cannot be sufficiently elevated as described above, permanent dry flood protection such as flood gates, walls, doors, or similar devices should be used to prevent water intrusion to the heights described above. Flood depth, duration, velocity, and condition of water should be considered (including floating debris). 
  • Move and elevate inventory and important documentation away from windows and doors in the event water penetrates the openings.  
Water damage from rain, snowmelt or pipe burst coming from multiple cracks and leaks in concrete wall and ceiling. Selective focus.

7) Install a tornado safe room or storm shelter.

A tornado safe room is designed to provide the best protection from winds up to 250 mph and flying debris, even if the building around it is severely damaged or destroyed.

Severe Weather Shelter Area Sign On White Background


8 Install protective screens over HVAC units

HVAC units (whether they are on the roof or located elsewhere) can be severely damaged by hail, leading to energy loss, complete malfunction of the unit, and potential business downtime.

  • Install hail guards on air conditioner condenser fins, air intakes such as fans, and any other vulnerable components that, if struck by hail, can impair the operation of the unit.  
    • Incompatible hail guards could affect performance or damage the system. Discuss hail guard options with the HVAC unit manufacturer to determine the best protection system for your individual units.  
8- Install hail-netting-cross-stitched

9) Upgrade to impact-rated cladding systems

Cladding systems can be damaged by hail and flying debris during severe weather.

  • Install reinforced brick, stone, or concrete-fiber board siding that can better withstand the impact of hail. 
Construction worker installing stone on architectural facade of new building. details of construction industry

10) Upgrade to steel gutters and downspouts.

  • Hail impacts can easily damage popular gutter materials like vinyl and aluminum.
  • Upgrade to steel products, which are more durable against hail impacts.
Roof gutter on a new tiled roof

Want a stronger commercial building?

When constructing a new commercial building, enhance its performance against severe weather by following the FORTIFIED standard. FORTIFIED is a construction method developed based on decades of IBHS research to reduce damage from severe weather. It strengthens a building to better withstand high winds, hail, and even tornadoes 


Annual Business Prep

These annual maintenance activities will help to prepare your business before severe weather strikes and reduce the potential for damage 

Building Upgrades

We can’t stop severe thunderstorms, but we can strengthen building components to better prepare for them. Upgrade now and be Thunderstorm Ready! 

Before Severe Event

If severe weather is forecast for your area, follow these last-minute steps before the thunder rolls and the wind blows to help reduce damage to your business.

After Severe Event

Once you are able to safely return to your building, note damage that must be repaired by a professional and tasks that can easily be completed as ado-it-yourself project.