Key Takeaway: Winder stairs are generally limited to dwelling units or very small spaces, unless the stair can meet the more restrictive requirements for curved stairways.
Winder stairs, or specifically, winder treads, are a unique architectural feature that an architect or engineer can use when designing a stairway. The International Building Code (IBC) has several limitations on the use of winder treads through, restricting the situations where they can be used. In this post, we are going to explore the code requirements for winder treads to determine how they need to be designed and where they can be used. All references are to the 2021 IBC. If you are working on a one or two family dwelling, a separate set of requirements from the International Residential Code (IRC) likely applies.