Moving into a new apartment that has drywall returns already installed around the windows, but does not have any window framing or sills (I understand they’re called stools when on the interior).
I’d like to add in sills / framing, but I am not sure if I need to remove or reduce the drywall returns first, or if I can add framing and a sill on top of what is already there. There is concern that sills that are too thick will impede the ability to open the windows themselves (double-hung, grab bar at the bottom to open / close).
What is good to know when approaching this kind of project?
If it was me doing this to my own house, I would put the face trim around the existing returns, use a 1x2 or similar to add a lip on the outside with the top flush with the bottom return to look like a sill, then paint the returns to match the framing. Or if I wanted to go with wood trim, apply matching veneer or very thin plywood to the returns. Either way, the opening is only reduced by the thickness of the paint/veneer.