How many stringers do I need?

Three stringers for stairs up to 36" wide. Add a stringer for every additional 16-18 inches of width.

Can I use 2x10 instead of 2x12?

No, stair stringers should always be cut from 2x12 lumber to maintain adequate structural depth after notching.

Stair StringersGenerating image…

Stairs & Railings

Structural

Budget: $15-$25 each (pre-cut 3-5 step) | Mid-range: $25-$40 each (pre-cut 6-8 step or custom) | Premium: $35-$60 each (pressure-treated custom)

Stair Stringers: Pre-Cut & Custom Stair Framing for Decks & Interiors (2026)

Prepared by Lumberama's Building Materials Team

|Last updated May 25, 2026|Sources & methodology

Stair stringers are the diagonal structural members that support stair treads and risers. They can be purchased pre-cut at standard heights or custom-cut from 2x12 lumber to match your specific rise and run requirements. Pressure-treated stringers are required for exterior and deck stair applications.

Key Features

Pre-cut standard sizes available; Custom-cut from 2x12 lumber; Pressure-treated for exterior use; Supports treads and risers structurally; 3 stringers standard for 36" wide stairs

Specifications

Material: 2x12 #1 or better lumber | Pre-cut heights: 3-step to 8-step (standard rise) | Rise: 7-7/3/4" per step | Run: 10-11" per step | Treatment: untreated interior

pressure-treated exterior

Applications

Deck stair construction; Interior stair framing; Basement stair building; Garage step construction; Porch stair replacement

Installation Overview

Calculate total rise and divide by desired step height for number of steps. Lay out rise and run on 2x12 using framing square with stair gauges. Cut notches with circular saw, finishing corners with handsaw. Attach top to deck or floor frame with joist hangers. Anchor bottom to concrete pad or landing.

Pros & Cons

Pros

✓ Pre-cut options simplify construction; Structural foundation of any staircase; Pressure-treated for outdoor durability; Can be custom-cut for any height

Cons

✗ Accurate layout requires skill; Pre-cut may not match your exact rise; Heavy and awkward to handle; Custom cutting requires careful math

Top Brands

Available at all major lumber retailers (commodity item)

Code Requirements

IRC R311.7 governs stair geometry: max 7-3/4" rise, min 10" run, min 36" width. Three stringers required for stairs wider than 36". Must be attached top and bottom per code. Exterior stringers must be pressure-treated.

Buying Tips

Pre-cut stringers save significant time if your total rise matches a standard height; Always use #1 grade lumber for stringers - knots in the throat can cause failure; Invest in a set of stair gauges for your framing square to speed up custom layout