We picked up a free mattress and box spring from Kijiji the other day as we are having relatives over to our new house in a couple of weeks. On it's own, that was ok except the mattress would be to close to the ground and would be very uncomfortable to get into or out of. So I built a bed frame for the box spring to sit on. Here's how I did it.
Step 1: Materials and measurements
Firstly measure your box spring. This isn't particularly important at this stage, but it does make sure you aren't making a mistake when buying materials. The box spring was 53" by 74". I also measured our existing bed to see how far off the ground the top surface of the mattress was, to see what's reasonable. Turns out that's 25". Deduct the height of box spring and mattress means the top of the frame needs to be 10" off the floor.
Next buy your materials. I'm using construction grade 2 by 4s. They look ugly, but that doesn't matter as my wife will tack a skirt round the box spring and frame to make the whole thing look pretty. They are strong enough to build houses from, so they should be able to withstand building made into a bed. You will need:
7 x 2 by 4s
1 box of 3 inch screws (and if you want to, a drill bit to drill pilot holes. I didn't but I'm lazy that way)
1 piece of plyboard big enough to cover the headboard.
Also, you will need
1 1/2 inch drill bit
1 screwdriver. You will probably find a power screwdriver/drill is the way to go.