How to Design Circular Stairs
- 1). Measure the space available for the staircase. The standard allowance is 5 feet square. This means the tread width – the part of the stair that you walk on – is a minimum of 26 inches wide. The tread should be at least 7½ inches deep as measured at a foot out from the center post. The stair does not have to be a tight spiral all the way up; depending on your space, it could consist of a half turn to a landing and then straight stairs the rest of the way.
- 2). Decide whether you want the stair to spiral up from the left-hand side or the right-hand side. This will depend in part on its location in the structure and whether people will usually approach from right or left. In the Middle Ages, circular stairs in turrets were deliberately built clockwise to slow down attackers and give the advantage to defenders.
- 3). Decide on the material for your stair; choose wood, metal or a combination. A common treatment in contemporary homes is wood treads over a metal framework. Common wood choices include cherry, teak and hickory. If you purchase a circular stair kit, the wood may be unfinished so you can choose your own stain. Cast concrete stairs are also an option, though you will see these more often in outdoor hardscapes, where the stair width will often be greater than for an indoor application.
- 4). Calculate the number of risers for the height of your stair. Code regulations dictate a 30-degree tread and a certain limit on riser height – usually 4 to 7 inches -- and all risers must be the same height. Use an online calculator such as that provided by the website Stairways Inc. to make it easy on yourself. Medieval castle stair builders deliberately built uneven risers to keep attackers off balance.
- 5). Choose a stair style to go with your décor. If you have a traditional look, for example, you might choose a Victorian-style circular stair, which includes treads, balusters and other details in ornate styling reminiscent of wrought iron, though modern structures are more likely to be made from high-strength cast aluminum. A house in the woods might look good with an all-wood stair; these models are often constructed with metal rods within for greater strength.
- 6). Decide whether you need or desire a landing. There must be landings at the top and bottom of the stair, but you may add additional landings if you wish to highlight a particular view, for example, or if the stair is accessing more than one area.
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