What space is required to fit a curved stair?

A curved stair takes far more floor space than other types of stairs. Ideally you want a large square space to allow for the most gracious and elegant curved stair. You can narrow and tighten up the space, which will require your radius to get tighter. As your radius gets tighter your stair will not look as grand and elegant. Additionally a tight radius will likely require hand carved railings and therefore become more costly.

You will first need to know how many treads or steps needed. To figure the quantity of treads:

Take your overall rise floor to floor — including finished flooring — and divide it by the ideal riser height, say 7.6"
You will need to round up or down (high riser, or lower rise) to select your total number of rise

For example: Overall rise is 133" / 7.6 = 17.5. I can make the risers lower: 133/18 = 7.39, so 17 treads, or taller 133/17 = 7.82, so 16 treads. Less treads will take less floor space, which typically ends up being needed. Subtract 1 from your tread count and that is the number of risers. Now that we know the # of risers and treads, we can look up a curved stair layout and see how that fits to our space.

curved stair layouts