Spiral Staircase Kit with Wood Tread Covers and Custom Wood Handrail

Spiral Stair Kit Dimensions and Measurements

Know your local code requirements and measure your floor-to-floor height before purchasing and installing your stair.

FLOOR-TO-FLOOR HEIGHT. The floor-to-floor height should be measured from the top of the floor of the lower level to the top of the floor of the upper level. When selecting a stair kit online, review closely the floor-to-floor height ranges and corresponding number of required risers.

DIAMETER. When you visualize your spiral stair from overhead, its footprint at the lower level is a circle and its diameter is the distance across the center. For spiral stair kits, diameters range from very compact 42” to code-compliant 60" - 72" diameters. (For our custom spiral stairs, much larger diameters are available.) To select the best diameter, consider your requirements for the clear width of the stairway, well opening, and code compliance.

CLEAR WIDTH. This is the amount of walking distance you will have on each step. For example, the clear width for 60” diameter spiral stair kits is 26 1/8".

CENTER LINE OF STAIR. This is the distance from the edge of the upper level to the center of the center pole baseplate and thus depends on the platform size. For example, the center line of a 60” diameter spiral stair kit is 31".

WELL OPENING. This is the opening in your floor at the top of the stair. Spiral stair kits require a well opening greater than the diameter of the stair (for example, a 60” diameter spiral stair kit will go through a well opening minimum of 62” x 62”, if passing through a floor). In addition to installations through a well opening, spiral stair kits can attach to the side of a balcony, deck, loft, or any upper level.

Diameter Tread Width Clear Width Platform Size Center Line Well Opening
17 1/8”
22" x 22"
44" x 44"
20 1/8”
25" x 25"
50" x 50"
23 1/8”
28" x 28"
56" x 56"
26 1/8”
31" x 31"
62" x 62"
29 1/8”
34" x 34"
68" x 68"
32 1/8”
37" x 37"
74" x 74"

Shop our 60" diameter spiral stair kits, or if you need a smaller/larger diameter or help, contact us or ask a question.