What should I do if I think I have bats in my roof?

Bats in a roof alarm people more than they should. UK bats do not build nests, do not gnaw wires or timber, cause no structural damage and are usually present for only part of the year. The protection is strict because populations declined severely, and it is written around the roost rather than around the animal, which is what catches householders out.

Safety

What you'll need

• A torch, used from a distance
• A phone camera, for a photograph of droppings (optional)
• A chair outside at dusk, for the emergence count (optional)

Step by step

1. Identify from the evidence, not by going up to look.Bat droppings look similar to mouse droppings but crumble to a glittery powder between finger and thumb, because they are made of insect fragments. Mouse droppings are hard and smear. That single test resolves most cases.
2. Watch at dusk.Sit outside and watch the roofline from about twenty minutes before sunset on a warm evening. Bats emerge in a stream from a specific point — often a gap under a tile, at a soffit, or at a lead flashing. It is the definitive identification and it disturbs nothing.
3. Note what is not happening.No nesting material, no gnawing, no smell of urine soaked into insulation, no chewed cable, and no daytime noise beyond faint chittering in hot weather. Those absences distinguish bats from rodents and birds immediately.
4. Do not block, seal, spray or disturb anything.Blocking a roost access point is an offence even if no bats are inside at the time, because the roost itself is protected. This includes sealing a gap you found while doing something else.
5. Ring the national bat helpline.The Bat Conservation Trust runs a helpline for exactly this situation, and advice is free. They can identify the species from a description or a photograph and tell you what, if anything, you need to do.
6. Understand what a roost usually means in practice.Most house roosts are a summer maternity roost or a small number of individuals, present for part of the year, in a space you never use. In the great majority of cases the correct action is to do nothing at all.
7. Plan any roof work around them.Reroofing, insulating, converting a loft or replacing soffits near a roost needs advice first, and often a licence and a survey by an ecologist. This is normal, well-trodden ground for builders in most areas.
8. Get the survey early if you are planning work.Bat surveys can generally only be done in the active season, so discovering the requirement in November can delay a project by months. Ask at the design stage.
9. Keep cats in at dusk during the emergence period.Cats catch bats at the roost exit and are a significant cause of bat casualties. Keeping a cat in for an hour around dusk in summer makes a real difference.
10. Know what to do with a grounded bat.Do not handle it with bare hands. Cover it with a box, slide card underneath, keep it somewhere dark and quiet, and ring the helpline for a local volunteer to collect it. If you are bitten or scratched, wash the wound and seek medical advice promptly.

Tips

• Bat droppings under a gap in the eaves, with no other sign of an animal, is the most common way a householder discovers a roost. It genuinely requires nothing but a phone call.
• Roosts are often used for decades. A house with bats has usually had them long before you arrived.
• If a builder proposes to just seal it up quietly, do not accept it. The legal liability falls on whoever does the work and on the owner who instructed it.

Common mistakes

• Sealing the gap while the loft is empty — The roost is protected whether or not bats are present, so sealing it out of season is still an offence. It also traps returning bats outside their roost.
• Treating loft timbers without checking — Standard timber treatment chemicals are lethal to bats. Any timber treatment in a roof with a roost needs specific products and appropriate advice or licensing.

If it doesn't work

Questions people ask