Custom Spiral Stair designs



	Custom spiral stairs:

	All spiral stairs are custom designed to fit your floor height as shown here. This includes standard spiral styles and diameters as well as custom spirals.

	Beyond these standard styles, however, there are other ways of customizing a spiral, such as using smaller or larger diameters, and different tread angles and tread shapes.

	Smaller diameter spirals: Small custom spirals offer limited options. Small wood spirals are particularly tight to climb because their center column is larger than a steel spiral's center column, as shown below.



	The smallest practical wood spiral stair is usually four feet in diameter. This is used to access a small loft, or where there will be infrequent use. Note, to meet building codes "A" (or "B") must be at least 26". Be sure you will be allowed to install a smaller spiral...some building inspectors may not approve it. Precision Pine has supplied smaller custom wood spirals when there was absolutely no room for an adequate stairwell. For a 3'-6" diameter wood spiral the clearance "A" would be about 14-1/2".

Large diameter spirals: With large spirals much can be done with custom designs. An important feature would be more narrow treads (say treads that turn 20 degrees, instead of a standard 30 degrees). Because of the large diameter the portion of the treads near the handrail, out where you would walk up the stair, is just as large as with a smaller spiral with wider treads. It means that you can fit more treads in the spiral, which decreases the rise between each tread to more comfortable heights. Each step up could be much lower than the maximum 9-½" rise allowed by building codes.

Figure 1 shows a 9'-0" diameter spiral with treads that rotate just over 16 degrees each. It has 16 treads and therefore 17 rises. This means that this spiral can climb 9'-6" with rises of less than 7" each...much

more comfortable than a standard spiral that would have 9-1/2" rises.

The hatched area is where you would step to climb the stairs. Note the size of this area shown at the right.

Figure 1

9'-0" diameter custom spiral with 16 treads

Figure 2 shows a typical 30 degree spiral that meets national building codes. Note the size of its stepping area. The larger spiral has about the same width area, but much longer. So even though the tread angle is smaller, the larger diameter allows plenty of room to climb the stairs.

Figure 2

Standard spiral that meets codes

Precision Pine, Inc.,
7322 Hodges Ferry Road,
Knoxville,Tennessee 37920

Phone (865) 573-5322
Toll free (877) 885-8902
Fax (865) 573-0143
email:
spiralstairs@earthlink.net