Not sure how relevant but thought I would post in case. I build 2 tables for outside out of scaffold boards. 170 X 90. I made a frame out if 2" X 1" timber (2" vertical) which was a few inches in from all the edges and put a brace across the middle. I then glued then screwed though the 2 X 1 up into the boards from underneath. 4 legs out of scaffold board too. Had them outside now for a few years and no issues rock solid.