Not wishing to be a 'Job's comforter' but a mate of mine is in the same situation. About 3 weeks ago he discovered what he thought was a minor leak behind his kitchen cabinets. When he got a plumber in to investigate it became apparent that the leak had been running for some considerable time and because of the very unusual layout of his house the ceiling of a bedroom that was situated below the kitchen was about to collapse. All of the kitchen cabinets (which had not been fitted very long) had to come out and he has had 2 dehumidifiers running for over a fortnight to dry out the walls and ceiling. The builders were due in yesterday to start rebuilding the damaged areas. Basically, what I am trying to say is that, yes, I reckon that you will need a dehumidifier. Hope the damage is not too bad but water is insidious and gets into places that you never even knew existed. I would say that expert advice was required.