You need to consider spiral stair location and access together
People often have a good idea of the best spiral stair location in their homes. They may choose an area where the spiral staircase will look good. Or, they may have to make a practical decision based on the only location available.
But one thing they often determine wrongly: how they will get on the stairs at the upper and lower floors. We call this access. Both where you get onto the stair and the direction you go define the access on each floor.
Obstructions near the spiral stair location can restrict access. These include walls, doors, windows, furniture, fireplaces, and so on. Low headroom under a slanted upstairs ceiling could also cause a problem.
The height between floors will dictate the number of treads in the spiral. The number of treads determines how far the stairs turn. The total turn fixes the positions of the top and bottom treads. An effective spiral stair layout will allow comfortable access to the top and bottom treads despite nearby obstructions.
All the spiral stairs considered in this post have 11 treads that turn 30 degrees each, for a total turn of 330 degrees.
Examples of spiral stair location
Imagine your spiral staircase as a full cylinder. Place this cylinder on your lower floor at the proposed spiral stair location. The cylinder should have the same diameter as the spiral stair. Be sure that the cylinder can go all the way up to the top floor unimpeded by obstacles. In stairwells you should include 1-1/2″ for finger room outside the cylinder.
Figure 1 shows three common spiral stair locations. We do not show most walls for the sake of clarity. (We will put in some walls in Figures 4 and 5.) Figure 1 also displays possible locations for top landings.
Figure 2 depicts incorrect positions for a spiral stair. Do not place the cylinders under any part of the top floor.
Effective layouts to fit each spiral stair location
Figure 3 illustrates the spiral stair against the loft floor, as if you were looking down from above. Here we give a clear view of the top landing, top tread and spiral handrail. You can’t see the bottom tread because if is out of sight below the landing.
Figure 4 contains three examples of a spiral going to a loft edge. This figure also introduces the concepts of Right Hand and Left Hand spiral stairs. See as well the location and direction of access to the top landings and bottom treads. Here dashed lines represent the bottom tread under the landing.
In the second example low tread rises may constrict access on the bottom floor. In other words low rises might mean that the upper treads are too low. You would have to keep close to the bookcase to avoid bumping your head.
Figure 5 has three layouts where the spiral stair location is in a stairwell. To simplify the drawings we show a separate view at each floor. Solid arrows indicate position and direction of access in each view. All three layouts are LEFT HAND spiral stairs.
Spiral stair layouts that do not work
Sometimes a spiral stair layout will not provide the access you would prefer. Figure 6 has two such examples.
In the first, a RIGHT HAND spiral accesses the top floor going away from the exterior wall. To make this work you would have to enter below by sliding your back against the lower wall.
The second example depicts a LEFT HAND spiral stair that exits on the top floor parallel with the exterior wall. This forces you to squeeze past the doorway
and along the wall to get on below.
Sometimes you have to accept an access other than your first choice.
Use the information in this post to see if your spiral stair location will allow a layout with acceptable access. Consider changing from RIGHT HAND to LEFT HAND and/or rotating the spiral 90 degrees at a time. Can you come up with a layout that has good access?
If so, you are beginning to understand spiral stair design. And there should be fewer surprises when you contact your spiral stair manufacturer to order.