[mikeg]

I found that 1:72 was a good gradient to use in O and did not have any problems with approx 30 yards at that slope in the garden. A 1/2in bit of wood under a 3ft level and you have the right gradient. I don't think you will have enough space in a loft to get a run in at that slope and you might be best making all new boards to run at say 30in above the floor, I have found this to be OK when sitting on a chair and you can just about work under it.

regards

mike g