Roosting bats can get fatally entangled in the fibers, which degrades the roofing membranes, invalidating their guarantees.

CNN: Architects building dream homes for bats

Clayton actually contains only two roosting bats, but they are an unusually gregarious couple, inviting over scores of friends to fly among the rafters, and defecate with abandon.

ECONOMIST: Bat raves

"If you have bats roosting in your building, you can't disturb them in any way without getting a special license, " says Kelly Gunnell, Built Environment Officer with the Bat Conservation Trust, a charitable organization in London, England.

CNN: Architects building dream homes for bats