Spiral staircases are space-efficient.
They are not, however, suitable for everyone; and moving bulky items up and down can be challenging.
What is needed is the new BorgCo Spiral Stairwell.
Ths consists of three tubes, one inside the other, the outer and inner tubes being fixed, and the inner
diameter being 1200 mm.
There are two vertical slots in the inner tube, running from the lower floor level to the upper.
The user steps onto the platform at ground level, and closes the curved sliding door.
The middle cylinder, which has a double spiral slot cut in it, rotates, causing the platform - which has lugs passing through the vertical slots in the fixed inner cylinder, and engaging in the spiral slots - to gently rise; the angle of the spiral is shallower at the top and bottom, giving a gentle acceleration and deceleration.
When the platform reaches the top, the door can be opened and the user steps out.
Mechanical interlocks driven by the spiral prevent the doors being opened when the platform is not present.
In an emergency the spiral can be cranked by hand, internally or externally.