What do stair treads sit on?
What do stair treads sit on?
In the structural framework of a staircase, stair treads primarily rest on stringers. Stringers are the inclined support boards that run along each side of the staircase, providing the main structural backbone. The treads, which are the horizontal surfaces we step on, are attached to notches cut into the stringers.
The Role of Stringers in Supporting Stair Treads
- Primary Support: Stringers are the primary load-bearing elements of a staircase. They transfer the weight of the treads, risers (the vertical boards between treads), and people using the stairs to the floor structure below.
- Notched Design: Stringers are typically notched or routed to create a series of horizontal and vertical recesses. The horizontal recesses are where the treads sit, while the vertical recesses accommodate the risers.
- Material and Construction: Stringers are usually made of solid lumber, engineered wood, or steel. The choice of material depends on the design of the staircase, the load it needs to carry, and local building codes.
Other Supporting Elements for Stair Treads
While stringers are the primary support for treads, other elements may also play a role depending on the staircase design:
- Carriages: In some staircases, particularly open-riser or floating staircases, carriages may be used instead of stringers. Carriages are similar to stringers but are often concealed within the wall or under the treads, offering a more minimalist aesthetic.
- Center Stringer: In wider staircases, a center stringer may be added for additional support. This central beam runs down the middle of the staircase, helping to distribute the load and prevent sagging.
- Tread Brackets: In certain designs, metal brackets may be used to reinforce the connection between the treads and stringers, especially in cases where the treads overhang the stringers.
Building Codes and Stair Tread Support
Building codes in the USA have specific requirements for stair tread support to ensure safety and structural integrity:
- Minimum Stringer Size: Codes specify the minimum dimensions for stringers based on the span of the staircase, the type of wood used, and the anticipated load.
- Notch Depth: The depth of the notches in the stringers is also regulated to ensure adequate support for the treads.
- Fasteners: Codes dictate the type and size of fasteners used to attach treads to stringers, ensuring a secure connection.
Trends in Stair Tread Support and Design
- Open-Riser Staircases: The trend toward open-riser staircases, which have no risers, has led to increased use of carriages or concealed stringers for a cleaner look.
- Floating Staircases: Floating staircases, where the treads appear to cantilever from the wall, often rely on hidden steel supports or wall-mounted brackets.
- Minimalist Design: The minimalist design trend has influenced stair construction, with a focus on sleek lines and concealed support elements.
Conclusion
Understanding how stair treads are supported is crucial for anyone involved in building or remodeling a staircase. Whether you’re a homeowner, contractor, or designer, knowing the role of stringers, carriages, and other supporting elements will help you ensure a safe, sturdy, and aesthetically pleasing staircase that meets all building code requirements.