Fire investigators are trying to find the cause of two separate weekend blazes in the Geelong region.

The first broke out in a shed in Thomson at around seven Saturday night. CFA crews say it began in one shed and quickly spread to another one in the same back yard.

And a unit in North Geelong has been badly damaged after catching alight in the early hours of yesterday morning.

It’s taken four fire trucks two hours to control and at the moment is being treated as suspicious.