A futon bunk bed frame must include support for the futon mattresses, which lack the internal support of a traditional mattress. You can also use them for just the top mattress of a regular bed, eliminating the need for box springs. Where many bunk beds assemble using only rails, futon bunk beds have a grid or set of bars that provide the extra support. Metal frames come from many different manufacturers, but most work on the same basic framework.
Clear the area in the room where you want the futon bunk beds. You should have room for the entire footprint of the bed, plus clear space to walk around.
Identify the end pieces of the bunk bed frame, using the instruction manual if necessary. Set them in place, approximately where they will be once the frame is built and installed.
Check the installation hardware for the bottom mattress frame. This usually consists of several hex nuts with corresponding washers and bolts. Gather enough for the installation and put them in a pocket.
Line up the holes in the bottom mattress frame with the mounting holes in the end pieces. Slide the hex bolts into position along with the washers. Hand-tighten the nuts in place.
Repeat Steps 3 and 4 to install the top mattress. This will be much easier with the bolts for the bottom bunk a little bit looser -- it gives you some wiggle room.
Use the hex wrench and pliers to tighten down the hex nuts for all connections. Test the bunk bed by shaking it with your weak hand. If it wobbles easily, double-check for loose nuts.
Side the bunk bed into position, then add the mattresses.
Many futon bunk beds come with extra components. Because of the variety of available components, it would be impossible to give comprehensive instructions for these optional parts. Consult your assembly instructions if installation isn't intuitive.