Planning and Dimensional
Information

6 Ft. - 8 In. Diameter, Three Quarter Turn Series, Spiral Stair

Stock Number: USS68-12-3QT
Stair Diameter: 60 - 8" (203.2cm)
Minimum Opening: 84" x 84" (210.82cm x 210.82cm)
Outside Radius: 40" (101.6cm)
Inside Radius: 6" (15.24cm)
Stringer Width, Outer: 11 - 1/4" (28.58cm)
Stringer Width, Inner: 5" (12.7cm)
Stringer Thickness: 1 - 1/2" (38.1 mm)
Tread Width at Outer Stringer: 14 - 3/4" (37.47cm)
Tread Width at Inner Stringer: 4 - 3/4" (12.07cm)
Tread Thickness: 1 -1/2" (38.1 mm)
Tread Passageway: 31" (78.74cm)
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: 2.857 Degrees
Rise per Degree of Turn: 0.35" (8.89mm)
Floor to Floor   Riser Degrees of Turn
74" to 82" (187.96cm to 208-28cm)   9 188 to 208 Degrees
>82" to 90" (208.28cm to 228.60cm) 10 208 to 231 Degrees
>90" to 98" (228.60cm to 248.92cm) 11 231 to 255 Degrees
>98" to 106" (248.92cm to 269.24cm) 12 255 to 278 Degrees
>106" to 114" (269.24cm to 289.56cm) 13 278 to 301 Degrees
>114" to 122" (289.56cm to 309.88cm) 14 301 to 324 Degrees
>122" to 130" (309.88cm to 330.20cm) 15 324 to 347 Degrees
Tread Capacity
lbs. / kgs.
694 /315 Stair Capacity
lbs. / kgs.
@ 114" Ht.
1696 / 769

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