Ok, as always in my life, its long and complicated so i will give you the bare facts and can fill in any details you need as we go along.
Loft conversion. Involves removing wall of small bedroom and putting back a little, moving the door from right to left, and stairs to go in space created (half in, half in space already there). bedroom small, approx 8.5ft x 5ft. To lose around 1.5ft.
Architect/structural engineer did drawings. assured us when he suggested moving the wall for the stairs that it would be big enough for a standard sized single bed. He stipulated in writing that the internal structure was to be altered ensuring it would be large enough for single bed - this was stipulated on the plans, in black and white.
Anyway, builder had some issues with the stairs, including width of stairs being questioned by stair company and needing changing. Builder assured me it would have no inpact on the size of the bedroom, so I let him get on with sorting the stairs.
Stud wall just been put in. The room is really small. It is 6ft, and therefore it is now not big enough to put a single bed in at all. I think I can see where the problem is. The stairs are 800mm wide, should have been 600mm from what I recall, although the architect did not specify width. This has added 200mm to the top and the bottom of the stairs, which in total is 400mm, which is about how much the room is reduced too much by. Does not sound a lot, but its made a difference between a usable single room and a cupboard.
So, I do not at this stage know if its the architect, the builder, the stair company.
How do I proceed? The inspector has just signed the stairs off today, and the stud wall was then put in, while I was at work, so I did not know until I got home. I probably should have measured the room but presumed the builder knew what he was doing .