What is Stringer?
A stringer is a sloped wood or steel support that holds stair treads and risers, or a horizontal timber supporting floor system.
Definition
Purpose
Stringers transfer the weight of people and materials from the treads down to the structure below. Accurate measurement and installation are more important here than most people realize. A stringer cut to the wrong rise-and-run, or fixed out of plumb, will create stairs that feel uneven and don’t meet code.
Examples of Use
- Residential Staircases: Wooden stringers are properly shaped and also notched. They are important for supporting traditional wooden staircases.
- Commercial Buildings: Steel stringers are used for heavier stair structures where extra strength and long-term durability are required compared to timber.
- Decks and Exterior Stairs: Pressure-treated stringers support outdoor stair treads and help withstand changing weather conditions, making material choice important.
- Flooring Systems: Horizontal stringers tie into floor framing and help carry loads between primary beams in open-plan spaces.
Related Terms
Notes
- Most residential stairs have three stringers, two on the outside and one in the middle for additional support.
- Open stringers have the profile cut to expose tread ends; closed stringers are straight-edged with treads fitted into routed grooves.
- The stringer depth and material must correspond to the span and load, especially where deflection limits are involved in flooring systems.
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