Bats in the building
Bats roost in attics, wall cavities, soffits, chimneys, barns, steeples and older commercial buildings. A colony can live in a structure for years, leaving piles of guano on attic floors and insulation, urine staining on wood and drywall, and a strong musky odor.
Bats are beneficial animals, and several species are protected. That shapes how and when they can be removed, and it is why the first call should go to a wildlife professional rather than to us.
Churches, schools and owners of historic buildings often face the largest colonies, because older structures have more gaps and quiet spaces. Homeowners and landlords usually notice droppings below an attic vent or hear movement in the walls at dusk.
Guano can be surprisingly heavy when it accumulates for years. Before crews walk on ceiling joists, we check for sagging drywall or weakened areas below the roost.
Exclusion has to happen first
We do not remove, trap or exclude bats. A wildlife professional determines the species, the right timing and the exclusion method, which often involves one-way devices that let bats leave but not return. Timing can matter, because flightless young may be present during part of the year.
Once the wildlife professional confirms the bats are out and entry points are sealed, we can begin. Cleaning before exclusion risks harming bats and having to repeat the work.
How we remove guano
- Confirm exclusion We check with you or your wildlife professional that the colony is gone and openings are sealed.
- Contain and protect The attic or cavity is isolated from living areas, and the crew wears respirators, hooded coveralls, gloves, eye protection and shoe covers.
- Dampen and collect Guano is misted to limit dust, then removed with hand tools and HEPA-filtered vacuums designed for hazardous dust.
- Remove soiled materials Insulation and other porous materials saturated with guano or urine are bagged and removed.
- Clean and disinfect Framing, sheathing and surfaces are cleaned, often with enzyme products for urine staining, and then disinfected per label.
- Odor treatment Remaining odor in wood may be treated or sealed once surfaces are dry.
Histoplasmosis precautions
NIOSH notes that Histoplasma, the fungus behind histoplasmosis, grows in soil and material enriched with bird or bat droppings, and that infection happens when spores are inhaled. Its guidance emphasizes reducing dust and using a NIOSH-approved respirator with protective clothing. We do not test for the fungus; we use those precautions every time we handle guano.
Anyone who has been in a heavily affected attic and later develops respiratory symptoms should mention the exposure to a healthcare provider.
Places guano collects
- Attic floors and insulation
- Wall cavities and soffits
- Chimney chases
- Church steeples and bell towers
- Barn lofts and outbuildings
- Porch ceilings and eaves
What not to do
- Do not seal openings while bats may still be inside.
- Never handle a bat with bare hands; call a wildlife professional if one is inside your living space.
- Avoid entering the attic or stirring up guano without respiratory protection.
- Do not use a household vacuum on guano.
Related trades
Wildlife professionals handle exclusion and any follow-up checks. Replacement insulation, drywall and roof or soffit repairs go to contractors, unless we agree in the scope that we will reinstall insulation. For bird roosts, see bird droppings cleanup, and for broader context see our animal waste cleanup overview.