Stringer Cutting Comes After the Stair Geometry Is Finished

A framing square does not design the stair. Before marking a 2×12, establish the finished total rise, exact riser count, tread depth, landing elevation, stair width, tread product, and top-attachment detail. This page turns those finished decisions into a physical stringer.

To cut stair stringers correctly, first measure the finished total rise, calculate the exact riser height and tread depth, lay out each step on a pressure-treated 2×12 using a framing square and stair gauges, adjust the top and bottom cuts for the finished deck and landing conditions, cut the notches without overcutting, and test-fit the first stringer before using it as a template.

A stair stringer is the sloped structural member that supports the stair treads and transfers loads down to the landing or ground support.

On a typical deck stair, the stringer is cut from dimensional lumber with a repeating series of notches. These notches create the rise and run pattern for each step.

This matters because every notch removes wood. The more wood removed, the less material remains to resist bending. A correctly laid out stringer is not just about step dimensions — it is also about preserving enough intact wood for strength.

Good stringer layout depends on:

• using adequate lumber size
• placing notches accurately
• avoiding major knots and weak grain
• minimizing overcuts
• keeping every riser consistent
• matching stringer spacing to the tread material

• pressure-treated 2×12 lumber for stringers
• framing square
• stair gauges
• tape measure
• pencil
• circular saw
• jigsaw or handsaw
• level
• structural fasteners
• approved stair attachment hardware

The framing square and stair gauges matter because they allow you to repeat the same rise and run accurately across the entire stringer.

The stringer layout has to satisfy three different rule sets at the same time:

1. Locally adopted residential code — stair geometry, width, landings, headroom, handrails and guards.
2. Structural design or a valid prescriptive detail — stringer size, remaining throat, span, attachment and bearing.
3. Manufacturer instructions — especially composite/PVC tread support, fasteners, railing posts and connectors.

Common residential geometry baseline

• Maximum riser height: 7 3/4 inches
• Minimum rectangular tread depth: 10 inches
• Maximum rise/tread dimensional variation within a flight: generally 3/8 inch

Those dimensions do not tell you whether a particular cut stringer is structurally adequate. Notching removes a large portion of the original 2×12, so stringer span, remaining wood, grade/species, attachment and tread support must be checked separately.

Related: Deck Stairs Guide, Deck Stair Dimensions, and Deck Stair Calculator.

Measure from the finished deck surface to the finished landing surface.

Do not measure to raw soil if the landing will later receive:

• concrete
• pavers
• compacted gravel plus surface material
• any other finished walking surface

This is one of the most common starting errors. If the finished landing ends up higher or lower than the surface you measured to, every riser changes.

Once total rise is known, divide it by a target riser height to determine the number of risers. Then divide the total rise by that whole-number riser count to get the exact riser height.

Example:

• Total rise: 42 inches
• Target riser height: 7 inches
• Number of risers: 42 ÷ 7 = 6
• Exact riser height: 42 ÷ 6 = 7 inches

Then establish a compliant tread depth and check the resulting total run. A deeper tread increases the stair footprint; it should be treated as a design choice within the complete geometry, not as a universal “better” dimension.

This stage determines whether the stair will fit the available footprint before you touch a saw.

To simplify this step, use the Deck Stair Calculator to calculate riser height, tread count, total run, and layout dimensions.

Every Stringer Step Uses Two Measurements

Repeat the same exact rise and run for each step.

This is the part of stair-stringer layout that generic diagrams often oversimplify. There is not one magic “top adjustment” that works for every deck. The top cut depends on how the stringer is actually attached to the deck framing. The bottom correction is more predictable: it compensates for the thickness of the finished tread so the first finished rise matches the others.

Bottom correction: subtract the tread thickness

After the repeated rise/run pattern is laid out, shorten the bottom rise by the thickness of the finished tread assembly. If the treads are 1 inch thick, for example, the bottom of the stringer is typically moved up 1 inch. Once the treads are installed, the first finished rise can then match the remaining finished rises.

Top condition: design the connection before finalizing the cut

The upper end can terminate against a stair header, rim/header assembly, support block, or another engineered/prescriptive attachment detail. The top cut must leave enough wood for the intended bearing and connector while preserving the finished top-riser geometry.

In other words, do not cut the stringer first and invent the attachment later. Confirm the header depth, connector, fasteners, stringer position and top-riser relationship before duplicating the master stringer.

Shorten the Bottom by the Tread Thickness

The tread adds that thickness back, keeping the first finished rise consistent.

Use the circular saw for the straight cuts, but stop short of the inside corners. Finish the corners with a jigsaw or handsaw.

Do not run the circular saw past the notch intersections.

Why overcutting is a problem:

• the inside corner is a stress concentration point
• overcutting removes extra structural material
• the remaining stringer section becomes weaker
• cracking and flexing become more likely over time

The remaining wood below the notch is the stringer’s structural throat. As a useful scoped reference, AWC DCA6’s prescriptive cut-stringer detail shows a 5-inch minimum throat. That is not permission to apply DCA6 blindly to every stair, but it demonstrates why preserving material at the notch is structurally important.

Never cut all stringers before testing the first one in place.

Check the first stringer for:

• top attachment alignment
• bottom bearing on the landing
• riser consistency
• tread depth consistency
• total run
• fit within the available space

If the first stringer fits correctly, use it as a template for the remaining stringers.

If it does not fit, fix the layout before cutting more boards.

Stringer spacing is a separate design decision from cutting the stringer. It depends heavily on the actual tread product. This is especially important with composite and PVC decking, where stair-span ratings can be much shorter than the same board’s permitted span on the main deck.

Use our Deck Stair Stringer Spacing Guide to turn the permitted support spacing into an actual stringer count for the stair width.

Use pressure-treated wood treads if:

• lower upfront cost matters most
• you want easier field cutting
• higher tread stiffness is important
• you do not mind periodic maintenance

Use composite treads if:

• lower maintenance matters more
• color consistency is important
• you are willing to frame for tighter spacing
• you want the stairs to match a composite deck surface

A correctly cut stringer still needs a complete load path. Stair loads travel through the treads into the stringers, then into the deck framing at the top and the landing/support condition at the bottom. A weak connection at either end can defeat otherwise accurate layout work.

Top connection

The stringer should attach to framing that is deep and strong enough for the selected connection detail. Purpose-made adjustable stair-stringer connectors are one option; Simpson Strong-Tie, for example, publishes the LSC adjustable stringer connector for solid and notched stringers. Use only the fastener schedule and installation conditions published for the connector.

Avoid treating toe-screwing into a thin rim board as a generic structural detail. The header/rim assembly, connector, fasteners and supporting framing need to work together.

Bottom support

The lower end needs stable bearing and a landing/support condition that will not settle enough to change the first riser. Coordinate the landing elevation before cutting the master stringer.

Related: Deck Framing Layout, Stair Railing Code, and Deck Footing Size Chart.

The highest-value mistake prevention happens before the first cut. Confirm every item below on the master stringer before duplicating it.

Uneven deck stairs usually come from a mistake made before the stairs are ever used.

Common causes include:

• measuring total rise to unfinished grade
• rounding riser height incorrectly
• skipping top cut adjustment
• skipping bottom cut adjustment
• using a bad first stringer as a template
• allowing the landing to settle after construction

Uneven risers are especially problematic because people subconsciously expect each stair step to be identical.

Choose custom-cut stringers if:

• your deck height is not standard
• you want exact control over rise and run
• the stair must fit a specific landing condition
• you are comfortable with accurate layout work

Choose pre-cut stringers if:

• the stair geometry is standard
• you want speed and simplicity
• you accept less flexibility in the final layout

Avoid cutting your own stringers if:

• you do not have a reliable rise/run calculation yet
• the stair footprint is tight and mistakes will be expensive
• a low, wide stair would be better built as box steps

Before cutting stair stringers, calculate the entire stair layout.

Confirm:

• total rise
• number of risers
• exact riser height
• number of treads
• tread depth
• total stair run
• stair angle
• stringer spacing

The Deck Stair Calculator can help verify these values before cutting the first board.

What size board should be used for stair stringers?

Pressure-treated 2×12 is generally preferred because it leaves more intact wood after the stair notches are cut.

How do you cut stair stringers without overcutting?

Use a circular saw for the straight sections, stop before the inside corners, and finish the corners with a jigsaw or handsaw.

Do you need to adjust the top and bottom of a stair stringer?

Yes. The top and bottom must be corrected for finished tread and landing conditions so the final riser heights remain consistent.

How far apart should deck stair stringers be?

There is no single universal spacing for every deck stair. Wood-tread spacing depends on the structural/tread detail being used, while composite and PVC products must follow the exact manufacturer stair-span requirement. Current published examples include 9 inches O.C. for Trex Enhance and TimberTech Composite, while other collections permit different spacing.

Can you use pre-cut stringers for a deck?

Yes, but only when the stair geometry matches the pre-cut dimensions and the finished deck height and landing conditions work with that layout.

Why do stair treads slope forward over time?

Causes can include lumber movement, poor support at the base, settling, inconsistent layout, or inadequate stringer support.

Should I cut all stair stringers at once?

No. Cut and test-fit the first stringer before using it as a template for the remaining stringers.

Cutting stair stringers correctly is not just about copying a notch pattern onto a board. It requires accurate rise and run calculation, correct top and bottom adjustments, clean cutting, tread spacing matched to the actual material, and stable support at both ends.

The reliable sequence is: finish the stair geometry, resolve the top and bottom support conditions, verify the structural/stringer detail, lay out one master stringer, cut without overcutting, test-fit it with the actual finished-surface assumptions, and only then duplicate the remaining stringers.

Last reviewed: September 2026

Model Code

• International Code Council — 2024 International Residential Code, Chapter 3

Prescriptive Wood-Deck Reference

• American Wood Council — DCA6 Prescriptive Residential Wood Deck Construction Guide — based on the 2015 IRC; use only within its stated scope.
• American Wood Council — Residential Deck Resources

Stair-Tread Manufacturer Instructions

• Trex — How to Build Deck Stairs
• TimberTech — Decking Installation FAQs
• TimberTech — Composite Decking Installation Guide

Structural Connections

• Simpson Strong-Tie — Wood Construction Connectors
• Simpson Strong-Tie — 2026–2027 Wood Construction Connectors Catalog