I would like to build a floating L-shaped banquette bench (no legs). It would be constructed out of a 2x4 frame and topped with 3/4 birch plywood. It would be 70 long on one side, 48' on the other and 18 deep (see attached pic). Would the brackets be enough to support the weight of people sitting on it? On a regular basis, it would only be 2 adults (~350 lbs), but I think the size could fit up to 5 adults (which could mean up to 900 lbs or so!). If this could work, any advice on the number/placement of brackets and any bracket features would be appreciated. I'm not completely opposed to having legs in the front, but I'd rather not because of finding the right legs and I think attaching legs at the bend could be a PITA.
if it was me + you should buy one of those brackets and go find a welder that can make you some stronger better brackets your plan is good and I think it will look nice when finished . who knows -- maybe the welder says that 6 or 8 of those store bought brackets will work !!!
If you used five of those brackets, each rated at 1000lb working load, it would be more than capable of holding five adults. The issue would lie in what you are attaching the bench to. The wall needs to be strong enough to hold the bench. Those brackets will create a pivot point at the bottom and if the wall isn't sturdy enough or the wrong anchors are used, the bench could rip out of the wall when under load.
