With wind speeds up to 300 miles per hour, tornadoes can chew up anything in their path — including a construction site.

Spring and summer are the peak seasons for these swirling funnel clouds. A loud roar, a sudden calm after a thunderstorm or a dark, greenish sky can mean trouble is imminent.

A job site may not offer much in the way of shelter, but smart tornado prep can help keep everyone safe. These tips do double-duty if you’re in a hurricane zone. The Atlantic hurricane season runs June 1 through November 30.

Put an emergency-response plan in place

Having a plan can help protect workers and avoid confusion in the event of a major weather event such as a tornado or hurricane. A few guidelines:

• Make sure the project office has a battery-operated weather radio and extra batteries.
• Create a system to know who’s on site.
• Determine how you will warn workers of an emergency.
• Designate a safe zone. Ideally, this is a basement. If your site doesn’t have one, the next best space is a small, interior, windowless room on the lowest floor possible. Instruct workers that if a safe zone is not available within walking distance, they can try to drive in a vehicle, wearing a seat belt, to the nearest shelter. Never take shelter in a vehicle or trailer.
• Use a roster to account for workers as they take refuge.
• Designate which crew member(s) will survey the site for damage post-tornado and who will determine what repairs should be done before the crew resumes work (usually the site superintendent).
• Make sure crew knows that when returning to work stations, they should proceed with caution and inform supervisors of downed power lines and other damage.
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If there’s time, take these steps

If the National Weather Service issues a tornado warning, workers should head for safety ASAP. (A tornado watch is issued when a twister has been sighted or indicated on radar.) A tornado watch, on the other hand, gives you more time to prepare. (It means conditions may be ripe to produce a tornado.)

Ed Collins, founder of Construction Pros, an insurance agency serving contractors in Florida, offered this advice in the event a watch is issued: “Empty the dumpsters and get anything secured possible.”

Louisiana Associated General Contractors (LAGC), as part of its construction site hurricane preparedness plan, outlined similar advice: “Be prepared to anchor or restrain everything that could blow away with netting for dumpsters, banding and banding tools for lumber, formwork, scaffold planks, port-a-potties, etc. Look and see what will fly, then restrain it.”

It also recommends laying down booms if there’s time or hooking the load line to the structure at a low point.

If you need to evacuate the construction site, this Project Uptime article explains how to do it quickly.

Make sure the project is properly insured

Builder’s risk insurance is important for large-scale construction projects. It covers the property as well as materials intended to be used for the project. 

“Usually it’s up to the owner of the building, but most well-meaning GCs will offer to buy it for the building owner,” said Collins. He added that contractors shopping for a builder’s risk policy should:

• Use an agent with knowledge of commercial construction, such as one with a CRIS (construction risk and insurance specialist) designation.
• Ask about exclusions. For example, flood loss is rarely covered by builder’s risk policies. “The big thing to know is if something’s excluded from your [builder’s risk] policy, make sure it’s covered under another policy,” Collins said.

Prep for hurricanes, too

If your construction project is in an area that could be affected by hurricanes, you’ll likely get ample notice of a hurricane threat. Some tips to secure the site:

• Tie down or store lumber and loose tools.
• Dismantle, bundle and band scaffold planking.
• Anchor portable toilets or have them picked up.
• Empty dumpsters or cover them with netting.