Charity Dorothy House has been left counting the cost after thieves stripped lead roof tiles from its shop in Trowbridge.
Volunteers at the shop, in Silver Street, only discovered the roofing, spanning around 30ft, was missing when they noticed a water leak at the rear of the store on Monday.
It is thought the theft happened between last Monday and this Monday.
Kate Stenner, the charity’s retail administrator, said: “This is very frustrating.
“We are getting a contractor out as the job to replace them, is too big of a job for our maintenance team and I’m sure it’ll cost quite a lot of money.”
This incident follows two break-ins, on March 19, at charity shops in Trowbridge.
The British Heart Foundation store, in Fore Street, lost petty cash and suffered £1,000 worth of damage when thieves used an angle grinder to break into a third-storey window.
The neighbouring Age UK store was also broken into on the same day.
Nothing was taken but the thieves caused substantial damage to the shop’s roof.
Wiltshire Police are investigating the incidents and are appealing for any witnesses who saw the roofing being taken from the Dorothy House store.
Inspector Chris Chammings, based at Trowbridge Police Station, said: “It is distressing to think that someone would target a charity.
“We will be contacting scrapyards and dealers while we would also appeal for anyone with information to get in touch with us.”
Witnesses can call the police on 101.