Lead has been stolen twice from Holy Trinity Church, Darlington, County Durham, forcing the vicar, Ven Nick Barker, to take drastic action and start sleeping in the building.
He hopes it will deter the thieves as work totalling £420,000, which was raised in grants and donations, takes place.
"We have an excellent roof burglar alarm system, on which we are putting extra sensors, and a very good security patrol company working for us," he said.
"However, I have been sleeping in the church over the past fortnight to provide added peace of mind in case they try again.
"This has left me feeling cross and frustrated. There is only a minimal amount of lead on the roof but thieves can soon do a very costly amount of damage for little reward.
"We are an active church trying to do something positive for the community yet we find ourselves targeted by thieves.
"It means that some of the money that people kindly donated to the project has had to go on improved security.
"I am also concerned that the people trying to steal the lead are putting themselves at risk. It is dangerous to climb on the roof at night, in the dark."
The work currently being undertaken is to tackle dry rot and repair the roof of the Grade II listed building.