The floor gave way Monday afternoon inside a home on Margaret Avenue between Lakeview Avenue and Summit Street.
An elderly woman confined to a wheelchair lived in an apartment behind the garage. She was not hurt, but needed help getting out.
The homeowner believes faulty construction caused the floor to collapse and is not sure what he will do now.
Firefighters believe dry rot may be to blame; they say that is a common problem in homes in the city's Oceanview Terrace neighborhood.