Always use 2x12 lumber for cut stair stringers. A 2x10 does not leave enough structural "meat" (the uncut throat) to safely support the stairs over time.
2x12 to be safe. If your step rise is closer to 8” than 7” you will not have the proper width left where the riser and tread cut meet. Causing weak steps not to mention the inspector smack down. Always 12.
Yes, you can use 2x10 lumber for stair stringers, but it is not recommended and often fails building codes for most standard staircases.
The 7-11 stair rule is a widely used architectural and carpentry guideline stating that the ideal stair riser (the vertical height) should be 7 inches and the tread (the horizontal depth) should be 11 inches. This ratio mimics the natural human stride, providing maximum comfort and safety.
Always use 2-by-12 lumber for stringers, regardless of the wood type, as smaller dimensions don't provide adequate strength after notching. In the video below, Tom Silva shares tips for installing an interior staircase.
For a standard set of 7 steps, you will generally need 2x12 lumber that is 8 to 10 feet long. A common rule of thumb is to allow at least 14 inches of board length for each step to account for both the rise and run, plus excess for cutting, making a 7-step stringer roughly 84 to 98 inches (7 to 8+ feet) long before final cuts.
▪️ Uneven Risers: The height of each step varies, making it difficult and potentially dangerous to climb. ▪️ Narrow Treads: The treads are too narrow, leaving insufficient space for comfortable foot placement. ▪️ Correct (✓): This shows a staircase with consistent riser and tread dimensions.
For standard staircases, you should use 2x12 lumber. Anything narrower will not leave enough "throat" (the solid wood left beneath the notched triangles) to safely support the weight of the stairs and foot traffic.
The "Stair Rule" (or "Staircase Etiquette") is a classic chivalric tradition based on the simple premise of protecting a lady. The guideline shifts depending on the direction of travel to ensure the man is always positioned to catch her if she loses her footing.
The "27-inch rule for stairs" typically refers to two important safety and comfort design guidelines.
For standard 2-stringer staircases, the maximum safe and code-compliant width is 36 inches.
Cutting stair stringers
The stringers are commonly cut of 2x10-inch or 2x12-inch boards made of spruce-pine-fir (SPF) or LVL. This configuration results in an effective throat depth on a 2x12-inch cut stringer of approximately 5 inches, and a total horizontal stringer span of 12 feet and 3 inches.
A 2x10 can span anywhere from 12 to 24 feet without support. However, this exact distance depends entirely on how it is being used, the species of wood, and the spacing between the boards.
Overly grand staircases and ornate rail details are both considered outdated by designers. LED strip lights and floating steps may feel modern and futuristic, but are actually out of style. Carpeted stairs aren't always seen as stylish, but they can be elevated and modernized.
Yes, you can use 2x10 lumber for stair stringers, but it is not recommended and often fails building codes for most standard staircases.
The 7-11 stair rule is a widely used architectural and carpentry guideline stating that the ideal stair riser (the vertical height) should be 7 inches and the tread (the horizontal depth) should be 11 inches. This ratio mimics the natural human stride, providing maximum comfort and safety.
Here are some key considerations for stair dimensions and connections: Stringers: Use solid 2×12 wood members or similarly sized preservative-treated lumber. The maximum horizontal span for a cut stringer is 6 feet, while a solid stringer can span a maximum distance of 13'-3”.
An 8-inch step is generally considered at the upper limit of comfort and often exceeds the maximum riser height allowed by standard building codes for standard indoor staircases.
The Most Common Staircase Design Mistakes
The ADA states that all stairs and stairway must have uniform riser heights and tread widths. One section also states that stair treads cannot project past the stair riser by more than 1/2″ and should be curved or beveled to help prevent falls from a step.
Baluster Spacing (Sphere Rule): The general rule is to install balusters and newel posts between the handrail and flooring materials so that a 4” sphere (the head of an infant) cannot pass through.
Always use 2x12 lumber for cut stair stringers. A 2x10 does not leave enough structural "meat" (the uncut throat) to safely support the stairs over time.
Building a staircase can seem overwhelming, but with the right steps, it's completely doable—even for DIY homeowners. To understand how to make your own stair stringers, you'll need to calculate your rise and run, mark precise cuts on the stringer board, and install them securely.
For a 36-inch deck, you will need 5 steps (risers).