Planning and Dimensional
Information

6 Ft. - 6 In. Diameter, Half Turn Series, Spiral Stair

Stock Number: USS66-20-HT
Stair Diameter: 6' - 6" (198.12cm)
Minimum Opening: 41" x 80" (104.14cm x 203.2cm)
Outside Radius: 39" (99.06cm)
Inside Radius: 10" (25.4cm) - Optional 6" (15.24cm) or 12" (30.48cm)
Stringer Width, Outer: 10-1/2" (26.04cm)
Stringer Width, Inner: 5 - 3/4" (14.61cm)
Stringer Thickness: 1 -1/2" (38.1mm)
Tread Width at Outer Stringer: 12 - 1/2" (31.75cm)
Tread Width at Inner Stringer: 4 - 3/4" (12.07cm)
Tread Thickness: 1 -1/2" (38.1 mm)
Tread Passageway: 26" (66.04) - Optional 24" (60.96cm) or 30" (76.2cm)
Handrail Width: 3 - 1/2" (8.89cm) - Opt. 4 - 1/2" (11.43) or 5 - 1/2" (13.97cm)
Handrail Thickness: 1- 1/2" (38.1 mm)
Baluster Spacing: Approx. 6" (15.24cm), - Opt. 4" (10.16cm), or alternating 2", 3", 2"
Turn per Inch of Rise: 1.816 Degrees
Rise per Degree of Turn: 0.55" (13.97mm)
Floor to Floor Riser Degrees of Turn
74" to 82" (187.96cm to 208.28cm) 9 119 to 132 Degrees
>82" to 90" (208.28cm to 228.60cm) 10 132 to 147 Degrees
>90" to 98" (228.60cm to 248.92cm) 11 147 to 161 Degrees
>98" to 106" (248.92cm to 2469.24cm) 12 161 to 176 Degrees
>106" to 114" (269.24cm to 289.56cm) 13 176 to 191 Degrees
>114" to 122" (289.56cm to 309.88cm) 14 191 to 206 Degrees
>122" to 130" (309.88cm to 330.20cm) 15 206 to 220 Degrees
Tread Capacity
lbs. / kgs.
768 / 348 Stair Capacity
lbs. / kgs.
@ 114" Ht.
3006 / 1364

Specifications for heights up to 190" (4.83m) are available upon request.