Considering a loft conversion? While you may have considered the various permissions and regulations you need, you may not have considered the impact bats might have on your project. Bats are a protected species and carrying out building work that could harm or disturb a roost could result in a £5,000 fine or even a prison sentence. If there is a chance of bats in your home, you need to have a survey which will cost £300-£400. If bats are discovered, a mitigation licence is needed to continue with the planned work.