I received a call from someone who looks after a big old property in the south Lake District that is rented out for holiday lets. Some guests had been very upset about bats getting in down the chimney and flying around a bedroom. So upset that they cut their holiday short. A voluntary batworker investigated and soon worked out that there was a colony of brown long-eared bats in the loft, with their access point right next to the chimney.
He had a look up the chimney – the gap was 16 inches square! (That’s 400mm to you young ‘uns). The young bats just thought the chimney was the way home – imagine their confusion when they thought they were going back to a lovely dark attic and found their way into someone’s bedroom.
Normally there is a throat brick or similar that narrows the chimney above the fireplace. This helps to retain heat in the room and draw the waste gases out more efficiently. In this property there was just the 16 inch square gap. I don’t know how any heat stayed in the room.
We made a hand one to size that fitted the gap snugly. Now not only will it stop bats from frightening guests but there should be a noticeable difference in the room temperature with the draught excluder doing a double job.