This wooden porch has been expanding and warping since installed two years ago. It was 2 1/4 KD T&G pine, initially not primed, however when swelling was indicated the bottom was liberally coated with latex paint. The top has had good quality porch paint, oil based. The swelling has become so severe that three boards popped up like a tent. Also several boards are warping across the width even though the boards were milled with a groove on the bottom side. The floor is about 2' above grade. The house is 80 years old and has no vapor barrier. Could the lack of the vapor barrier be the cause? Could there be any other causes? I have always thought that KD lumber had a limit to it's expansion.
