An open string stair is a stair whose steps rest on top of cut-out notches in the string (Dutch “keepboom”), so the treads sit on the string rather than being housed in routed mortises within it. It is also called a cut string stair.
Characteristics
The string is the sloping board that runs up the side of a stair and carries the steps. What sets the open string apart is how those steps are supported.
- The top edge of the string is cut, or notched, into a staircase profile.
- The treads sit down on top of these notches, following the steps of the cut.
- The stepped profile of the string is visible from the side.
This differs from a closed string, where the treads and risers are set into routed slots inside a string with a straight top edge, hiding the ends of the steps. On an open string, the ends of the treads are exposed, which gives a lighter, more open appearance and allows for decorative finishing of the step ends.
Application
Open string stairs are chosen where an open, attractive look is wanted, since the staircase profile and the ends of the treads are on show. They are common in homes and in more decorative settings. The exposed step ends also make the construction easy to read, which can help when fitting balusters and finishing the sides of the flight.
Related terms
- String
- Tread
- Stair
- Landing
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