Although the team at Istueta Roofing, in Miami, knew there would be bats under the roof tiles of the suburban Pine Crest, Fla., home on which they were working, they had no idea how many. The bats — Mexican free-tail bats, which feed on flying insects — had been living under the concrete tiles of the home for years. “This was a surprise and a first,” marketing director Ariel Istueta says, as thousands of bats flew out of the roof.

The roofing company doesn’t do bat mitigation but learned quickly about the possible health hazards of finding so many bats. Once they realized what they were in for, crew members donned protective gear.

In Upper Michigan, on the southern shore of Lake Superior, Mike Carey, owner of Carey Contracting also has run into bat infestations — at commercial and residential properties in the siding and rafters and in attics — more than a dozen times. For 100 years, bats have been roosting in the abandoned mine shafts in and around his city of Iron Mountain. “It’s one of the major migration points for the brown bat,” Carey notes.

A Better Understanding of Bats & Bat Mitigation

After the first bat incident, Carey decided to learn more about the health risks to homeowners and his employees as well as finding out more about bat habits:

  • Use a HEPA filter respirator and wear a Tyvek suit and booties so as not to have contact with histoplasma, which often exists in bat droppings. It will make people ill if they breathe in the fungal spores.

  • Make sure employees remove their booties and clean their gear before going home.

  • Roosting bats are pretty docile. If they don’t fly away once you start working, pick them up gently and put them in a cage to release them later. Carey has built bat houses elsewhere, smearing the bat guano on the structures to attract the bats to their new home.

  • Vacuum the bat guano and spray to keep dust particles out of the air. You can bring guano to a landfill in trash bags but call ahead if there is a lot of it.

  • Disinfect and encapsulate the area using a coat of clear or pigmented shellac to seal in any remaining odors. “You have to make the scent go away so the house becomes ‘invisible’ to the bats”; otherwise, they’ll be back, Carey says.

  • If the bats roosted in siding, that siding needs to be washed, disinfected, and re-stained or painted to get rid of the scent.

Check the Center for Disease Control’s National Institute for Occupational Safety and Health (NIOSH) website for more information on health risks, employee protection, and mitigation. —Stacey Freed, senior editor, REMODELING.