I live in a triple-decker which has back porches off the second and third-floor units. The third floor has a tongue-and-groove deck (we’re told it was replaced 10 years ago) that leaks badly. Of course, both porches get wet but the rain also is clearly leaking through the boards. Also, all that damp is peeling the paint on the bottom of the third-floor deck. A contractor tells us the problem is that the third-floor porch is laid flat and needs to be rebuild on a slight incline. Do you think that will fix the problem?
Yes, if the third floor deck was sloped a little, it would make a big difference. I would have to guess the third-floor deck is covered by a roof, as in all triple-deckers I know. All three decks should be primed and painted with an exterior primer and exterior deck paint.