Dyfed-Powys Police is investigating the theft of copper piping from a property that is being renovated in the Crew Green area.
The incident happened between 5.45pm on October 4 and 7.45am the following day.
Police believe the offenders parked in an adjacent field, climbed a hedge and entered the unfinished building and removed the copper piping, causing significant damage that – along with the stolen materials – could top £10,000.
A spokesperson said: “If you saw any suspicious activity in the area at the time, please call Dyfed-Powys Police.”
To contact Dyfed-Powys Police, call 101. Alternatively, you can call Crimestoppers, anonymously, on 0800 555 111.