Total material cost for this project, including hardware, bed base sabotaged from an old iron bedstead, and mattress from the same old bed was only about 175 quids, with about 110 quid on the wood itself.
All in all it took 2 days to build. I done the cutting and part assemblys myself on the first day, and on the second I had a friend help with the major assembly.
This bed is sturdy, thats for sure! Being an Engineer/Architect for a living makes you acutely aware of structures and strength, and I was paranoid that my girlfriend and I might plummet to our doom so I over engineered the thing somewhat... it is reasuringly solid though, and it is also wedged and packed off of the walls, thus it dosent move in the slightest, and no creaking either!
Step 1: Design
The main load bearing side beams are therefore 200mm x 25mm and span 2.75m, with a 50mm x 50mm rail glued and through bolted along the bottom edge for the bed base to sit on. The main uprights are 100mm x 100mm. I could have got away with 75mm x 75mm here, but opted for the chunkier material instead. Under bed clearance is 1.8m, and me being 1.85m tall I can generally get under it if I slouch a bit! My girlfriend is shorter at 1.65m and has loads of headroom. Clearance above the mattress was 700mm. I deemed this to be the best compromise between useable space beneath the bed and sleeping room above it. I would say 700mm is at the lower end of the comfortable above bed clearance for sleeping.
I wanted the bed to span a whole wall so that the legs would not intrude into the room. This requirement drove up the need for beefier structure as it spans more than a normal bed. It was also necessary for my nice big desk from Ikea to sit under the far end, as this would be the only available space for it - I was still storing it in my bathroom!!! What is also cool about having it next to my little hallway is that I will be able to put a 24" cheapo Ebay CRT telly up at the far end of the bed for bed time viewing.
So, with these requirements, I started drawing in Rhino. As the design evolved the calcs were influenced and I kept to the factor of 3 safety with 2 people rule as closely as possible. the final design looked like this... I'm pleased to say that this is almost exactly what was built.