Unlike standard mattresses, futon mattresses lack an internal frame. This means that rail bunk-bed frames won't work--the mattress will simply sag through. An iron futon bunk bed uses a grille of metal rods to hold the bunks in place. Although each brand and model will have individual differences, for most styles the basic structure is the same. This means the process for assembling your iron futon frame should be similar to others. However, when in doubt, trust the instruction manual printed by the manufacturer.
Clear out the area where you plan to install the bunk-bed frame. Most futon bunk beds are for twin mattresses, meaning you should clear an area approximately 39 inches by 74 inches.
Set the end frames in position where the ends of the bunk bed will be when fully assembled. Most iron futon bunk beds come with the end frames as one piece. If yours doesn't, assemble them according to the instructions in your manual.
Identify the bottom-bunk support platform for your frame. Many models include two identical and interchangeable frames, but it's best to confirm this before beginning.
Set the bottom bunk support platform in position. Often, this involves setting metal tabs into small frames. After the bunk is in position, slide in the bolts and hand-fasten their corresponding nuts.
Install the upper-bunk support platform. In most cases, this will work exactly like installing the bottom bunk.Slide in and hand-fasten the bolts.
Install the safety rails, if any. For most models, this means setting the rail in position and fastening with one or two bolts per side.
Tighten down all nuts and bolts using the screwdriver. You may find this easier if you hold the nut in place using your pliers or vice grips.
You can do this alone, but it's much easier to do this with a partner who can hold the frame steady as you assemble it. These instructions are for assembling the basic frame on an iron bunk bed. Some bunk beds come with additional panels, stairs or other decorations. If your frame includes these, refer to the instructions provided by the manufacturer.