Humberside Police are appealing for witnesses following a suspected arson at the Immingham Resource Centre.
Fire crews were called to the centre on Margaret Street at around 10pm on Thursday, December 7.
The fire was quickly put out but the building sustained substantial structural damage.
No-one was hurt.
Anyone with information or saw anyone acting suspiciously in the area should call police on 101, quoting log 551 of December 7.