Firefighters spent 20 minutes battling a blaze after a man set his old chicken shed on fire.
Crews from Hyndburn Fire Station were called at 6.40pm on Saturday after smoke was seen coming from allotments on Heron Way in Oswaldtwistle.
The shed was well alight when they arrived and couldn't be saved.
A spokesman for Lancashire Fire and Rescue Service said: "The man had built a new shed and decided to burn the old shed to get rid of a mite infestation.
"This wasn't the best idea. We would advise people not to demolish sheds by setting them on fire. It would be better to contact your local council."