Thieves stole nine radiators and copper piping worth £2,000 from a terrace house in Accrington.
Sgt Simon Holderness, of Accrington Police, said the incident occured between February 12 and February 26 at an empty property on Avenue Parade.
He said: "The house subject to the burglary was under renovation. Thieves used a screwdriver to force open the back door. Once inside they stole copper piping worth £1,000 and nine radiators worth £1,000."
An unoccupied mid-terrace property on Heywood Street, Great Harwood has also been targeted by burglars.
They stole copper piping, value unknown, some time between February 1 and February 25 after entering the rear yard and climbing into the house through a window.
Sgt Holderness said: "If anyone has any information regarding any of these incidents you can contact police on 0845 125 35 45."