Thanks for you reply BigWallop. I forgot to put a link in to show the
typr of stairs. Here it is:
http://www.stairs-direct.co.uk/Asset...ns_kompakt.pdf

you can see - the steps fit together like vertebrae of a spine.

I also need the stairs to wind round through 180 deg like a spiral.
does this not have an impact on the loading? I wondered if anyone has
a weight for the staris or even a knowledge of a reasonable assumption
for loading ON a stair (i.e. reasonable from the point of view of the
building control inspectors.

I think I understand there are those that consider what practically
works to be what one does. But then there are those that consider it
important to abide by regulations, for future piece of mind.

Although I lean to the former on an optomistic day, my pessimistic
half has won and I'm getting out the chequebook and stumping up the
building control fee for the full plans. So I can afford this - I've
drawn the plans myself and I hope to do the sturctural calculations
myself with some free software (fastrak simple beam design)

..What I need is the loading on the beams. I can't get these figures
easily and I was wondering if anyone has put these stairs in before or
has done this type of calculation before. As I said - what do the
stars weigh? and what loading is standard to assume on a stair? I
think I read 0.25 kN/m2 is loading for the actual floor (if only a
single habitable room used as a bedroom)

Hope someone can help.

Maybe Hugo has some idea, I've based my entire loft plans on his FAQ
and the Swansea guide. I'm really grateful for these wonderful
resources.

I really hope the plans go through, I would advise anyone to pay for
plans to be drawn after the time I have spent researching and drawing.
(Why am I willing to work for 10p per hour in my own time on this? Is
it because I'm committed now the roof windows are in and I have male
pride?)

Regards

Philip