Laying out winder stairs
Here’s an easy, accurate way to lay out stairs that have wedge-shaped treads where the stair makes a 90° turn. This type of stair is called a winder, and it can bail you out of a situation where there isn’t enough headroom for a standard landing.
As shown in the drawing, use a compass to strike a radius from point E. The length of the radius isn’t critical — it just needs to come down in the approximate point shown on the drawing. This arc determines points A and B. Now, using the same radius, swing an arc from point A to find point C, and from point B to find point D. Next, extend lines from point E through C and D to find the position of the risers for the treads.
By the way, local codes have different interpretations of how wide the treads need to be at a given distance from point E. Be sure to check with your inspector to find out what the requirements are.
Kelly Johnston, Overland Park, KS