Theo Markettos wrote:

I'm looking at designing a spiral staircase (for a new-build). For various
reasons it needs to be possible to separate the floors the staircase links,
so I'm thinking of having a trapdoor that fits into the gap in the ceiling
formed by the staircase. The door would be hinged and counterweighted, on a
pulley controlled by a handle somewhere, tight fitting and fairly heavy (for
sound and thermal insulation), with a bolt to lock it. It wouldn't be moved
very often (once a week maybe), otherwise staying fixed open or fixed closed.

As more than one other poster has hinted, there are big implications for
building regs here.... what are the "various reasons" the floors need to
be separated - can you give more information about the project as a
whole? What accomodation is on these two floors, what access
arrangements and means of escapes etc are there, etc etc?

David