Top landings in spiral stair layout
Access to the top and bottom floors will dictate the spiral stair layout. Most spiral stairs will require a top landing. The top landing provides access to the upper floor. The bottom tread provides access to the lower floor.
The number of treads governs how much you turn when you go up or down the spiral. This turn fixes the bottom tread location relative to the top landing.
Figure 3 shows how the landing fits a typical spiral staircase. We also show which landing edges may be attached to the top floor.
Figure 4 demonstrates the turn of all the treads. You measure this angle from the bottom tread nosing up to the leading edge of the landing. Dashed lines represent the treads under the landing.
Figure 5 shows how different numbers of treads will change the bottom tread position. Also we show the treads under the landing. Arrows represent the path of access on the lower floor.
Other spiral stair layout considerations
A spiral stair can be either Left Hand (LH) or Right Hand (RH). Often only one or the other will fit your floor plans. As you can see in Figure 6, a Left Hand spiral has the handrail on the left as you go up. The Right Hand spiral has the handrail on the Right.
You can change the desired path of access without changing the layout. The left side of Figure 7 gives two examples. Arrows indicate each desired access. You can follow a desired path and then turn as you enter or exit the stair.
You can also rotate the spiral slightly to change access on both floors. The right side of Figure 7 shows two examples. This changes the landing shape, but manufacturers will provide whatever shape is needed.
First step in the design of a spiral stair layout
Spiral stair design begins by planning the top landing’s position. The landing must provide the desired top floor access as closely as possible.
Figure 8 depicts a group of spiral stair layouts with landings in various positions. Begin your design by selecting layouts with landings in the best positions. Then sketch the directions to the bottom treads, just as we demonstrated in Figure 5.