Hi,
I am intending to build a mezzanine, using ltreated umber (not steel).
The main beams (legs and frame) would be so-called 4x4 beams (in reality 3.5x3.5), and the beams inside the frame that carries the deck would be 68 inch long, 3.75 inch tall, and 1.75 inch wide ( = 2x4x68). The...