Metal Spiral Stairs
Spiral stairs are a specialized solution to accessing another story or level. Theaters and equipment mezzanines are the main uses for a spiral stair. A residence in need of a little drama is another use.
Benefits
Besides being aesthetically cool, spiral stairs have some key benefits. They have a very small footprint, rivaling a ship's ladder. Spiral stairs are extremely functional. None of their structure is excess, everything works together. For the architect there is no detailing to do, just a layout and selection of parts from the manufacturer's standards. Finally, spiral stairs are fun to use - at least for a while.
Limitations
Code issues - the usual prescriptive requirements apply - only different ones; and, most importantly, where you may use a spiral stair is spelled out. A critical issue is that a spiral stair is not treated as a means of egress, except in certain cases. In all others, spiral stairs are considered an incidental stair.
But the cost at about $2,000-$3,000 per vertical linear foot is a major reason for the few spiral stairs that you come in contact with.
For the designer, the top and bottom orientation is tricky to work out because it is a function of the number of risers, and unlike a typical switchback stair, you might be facing any direction when you arrive at the top. Headroom can be troublesome at landings.
Using a spiral stair makes for a steep climb, almost like a ship's ladder; and descending can give a thrill because straight ahead is open space with a railing that appears to be at ankle level.
COMMENTS:
These plans are needed to specify the size and configuration required for the spiral stair
These plans require further specifications covering materials, construction and finish.
Building Codes have an impact on many aspects of a spiral stair.
A level landing is required at 12' of rise and is equal to three treads.
In a non-functional setting, like a house, be aware of the potential for a modesty issue.
These details should be placed on the Interior Details sheet, the A-400 series of sheets per the National CAD Standards, contrary to the designation shown here.
Download PDF of detail.
See the Terms of Use for disclaimer.