Help! We had a handyman replace the rotting porch boards on our back porch which lie above a lower entrance to our basement (it's a small unfinished vestibule that leads to the finished basement). The deck boards lie above plywood (the latter being the ceiling of the vestibule).
We had been in the house for 12 years and never had a problem with water leakage but since replacing the porch boards we have had a deluge of water coming in every time it rains. Our best guess is that he removed something that sat atop of the plywood. Any ideas what it might have been and/or what can be done at this point to rectify the problem short of ripping apart the whole very expensive porch (which we just spent 3 days sanding and staining)?