The message

from sm_jamieson contains these words:

Planning loft conversion (loft plus bathroom - prob not quite an
"ensuite" !) As usual, space restrictions for stairs. What width of
stairs would be practical ?
Surely much narrower than a standard narrow doorway (e.g. 28", 700mm)
and you would be squeezing up sideways, but loft companies seem to
produce stairs not much more than 600mm wide !

I don't think there is a statutory minimum width these days but 2 feet
is about as narrow as practical and at that width you really need an
alternative route for furniture if you don't have a straight flight, and
even them some furniture won't fit.

That's what we did in the loft conversion in the ancestral chalet
bungalow. A 2 foot wide staircase with a right angle turn near the
bottom. The original loft entry (which was a generous size opening) was
retained as a coffin hatch.

--
Roger Chapman