DCE Ltd carried out an extensive survey of a large barn for bats, which was found to contain roosts of brown long-eared bats and Natterer’s bats. The bats were confined to the upper storey of the building.
The building was proposed for conversion to residential use, and so mitigation measures for bats were drawn up by DCE Ltd which enabled and encouraged the future use of the refurbished buildings by roosting bats. The designs included the incorporation of features which allowed the continued entry of bats into the roof void, as well as the use of purpose-built bat roosting boxes. Mitigation measures in the upper storey included the reservation of a significant portion of the void at one end of the building for exclusive use by roosting bats. Access for bats into the retained void was provided via a converted window frame in which the glazed units were replaced with a solid timber closure with access slots suitable suitable for use by Natterer’s bats. The retained void had vertical interlocking partition walls installed to increase the range of microclimatic roosting conditions available. In addition, battens were fitted to the walls and ceilings in the void to increase the range of crevices and niches available. All retained voids were appropriately sound-proofed, vapour-sealed and insulated from adjacent residential spaces. Natterer’s bats occupied the retained void almost immediately.