My daughter has always had her own room, but envies her brothers' bunk bed. So I built her a loft bed that look likes a floating cloud, which made her happy and created a little more space in her room. It uses some of the design principles of the one-legged bunk bed I posted previously - namely using the walls as part of the frame. However, this one has a heavy duty combination ladder/bookshelf for support, rather than a single leg. It's built using simple joinery out of construction lumber (2x4 and 2x6) and plywood, it's incredibly solid, and it only cost about $150 to build.
And pretty much as soon as I'd built that one, my eldest son moved into a room of his own... and wanted a loft bed, too. His incorporates a second bookshelf, a desk, and a secret compartment, and is designed for someone with longer legs, more books, and who isn't fussed about sleeping on a cloud...
One end of the cloud loft bed (from here on in, #1) is a combination ladder/bookshelf. It's angled at a 4:1 ratio, which equals 14º away from vertical. It has six steps and six shelves, and can hold nearly three linear meters (10') of books. The bed is about as high off the ground as it can be and still retain head room above, with 8' ceilings (important so the occupant can sit up in bed).
The side of one of the beds is a stylized cloud. It's pretty cute for an eight-year old, but I have no illusions that a teenager will necessarily think it's just as cool, so I anticipate removing it and replacing it at some stage with some other design. The ladder and bookcase are pretty future-proof, I hope - it's quite comfortable for an adult to climb, and we all need storage for books.
Click on the icon below to download the SketchUp 3D design file for this loft bed, and use it as a starting point to design your own.