Tenants just moved out of an apartment I bought 3 years ago. During the 3 years, I never had reason to visit the property as the tenants paid rent on time. Upon departure, I was shocked to see rising damp in all the rooms. It is a ground floor (over basement carpark) unit. There is what I believe to be rising damp on all the walls (except the wall which is joined to another apartment). The apartment was built in 2005. Where do I go from here? Is the builder responsible ? How is rising damp permanently eradicated?