🏗 Stair Stringer Calculator
Turn total rise and run into code-aware riser counts, tread depth, stringer angle, blank length, and lumber needs before you cut.
| Rise | Tread | 2R+T | Status |
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| Type | Total rise | Steps | Angle |
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| Item | Formula | Use | Check |
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A stair stringer is the structural member that runs along the sides or center of a staircase. It bears the treads and risers of the stairs. You install stringers at the sides of a stair flight to give that support Without them the staircases would lack rigidity.
Most stair stringers you cut from 2×12 lumber. Douglas fir is strong wood for such a task. The uncut part of the stringer must not be less than 5 inches.
What Is a Stair Stringer and How to Make One
After cutting the run and rise, the joist indeed taprs. For outside use, pressure treated wood is the best choice. Southern yellow pine works for outdoor staircases.
Some builders choose KD spruce for dimensional stringers.
When you cut triangular tread blocks according to the rise and run of the stairs and screw them to 2×6, you have 5.5 inches of uncut wood. That often results in a stronger build than traditional cutting of 2×12 in stringer form. Using multiple stringers, a pair of side plus center…
Help to reduce the span of every element. For wider staircases you commonly add a third stringer.
Steel stair stringers form another option. Fast-Stairs offer modular adjustable steel stair stringers. Simply screw treads and railings to the ready steel stringers to build firm, square and plumb free-standing staircases inside or outside.
Some steel stringers use C-channels like MC10 or MC8. For long spans or heavy loads, steel plates or rolled sections work well. Built-up or glued wooden elements also serve for rough jobs.
LVL or glulam can act as thick structures if required.
A framing square with stair buttons help to determine the rise and run. Drawing the lines, you clamp the framing square on the stringer as a guide for the circular saw. A stair jig for cutting stringers simplifies the work.
For exact cuts, a vertical blade like a hand saw or jig saw works. The brass stair gauges with thumb screws give better control for layout work.
Proper hardware is important. Simpson LSCZ stringer connectors bind stringers to rim joists. Only rim joists from 2×12 or bigger give enough surface for mounting stringer brackets.
Stairway connectors have a long metal part at the bottom of the stringer and must connect fully on the uncut section. The staircases must support dead and live loads at all ties. Use proper structural screws instead of average deck screws is key for safety.
At the bottom, bind the stringers to the floor and the kickboard to the upper platform set the weighttransfer of the staircases.
