Is there a lot of maintenance to owning a large bat house?

Our bat houses have been designed to be virtually maintenance free.  The bat houses have an open bottom so guano simply falls to the ground.  We do not permit bats access to the attic area of our houses as experience has shown these fill with guano rapidly causing structural failure of the house.   The exterior of the house is covered in cement composite siding and the roof has galvalume metal, our mounting brackets all are finished with the highest quality powder coat paint application process and all mounting bolts are stainless steel. Every partition is secured with ring shank galvanized nails and construction adhesive.  We recommend pouring a small concrete slab under the house for the easy harvesting of guano.  Some parks actually sell the guano to organic gardeners to help fund the addition of another bat house.