I'm building a lofted structure that includes a queen bed, storage stairs, and some storage space over my door. Here is a rudimentary mock-up I made in PS.
All the vertical support beams are 4x4s and the outside frame of the bed will be 2x6s. Like this: I will be replacing the wooden grooved pieces with metal L beams and adding a support rail down the middle of the frame. Also I'd turn the 2x4s onto the broadside.
The brown colored pieces in the mockup are for support. Using this design what would be the best way to secure the joints from shear force (add metal brackets, mortise and tendon the joints etc..)? I want this thing to be solid.
Best Answer
The design you have looks quite solid. If you really wanted to add a touch more, you could mortise and tenon the joints. That would give it a nice look and add a lot of strength (meaning that you wouldn't see fasteners). I would certainly glue the joints as well. I like the notched 2x4 boards. Keeps you from using metal hardware or trying to toe-nail them in.
If you can fasten this to the walls of your room, that would add a significant amount of strength to the structure. Obviously, make sure to fasten it to the studs in the wall and not just drywall.