Building & structure
Deck Stair Stringers: Rise and Run in Canada
A stair take-off begins with the finished floor-to-floor rise and the horizontal run available between landings. The Canadian calculator shows equal risers, goings and theoretical stringer length, but it does not certify compliance with the code adopted in your province or territory. This guide separates geometry from local building requirements.
In this guide
Rise, run, going and stringer length
Total rise is the vertical distance between the finished lower and upper floors. A riser is the vertical height between adjacent treads. Total run is the horizontal distance from the first riser face to the last, and a going is the horizontal distance for one step. A stringer is the sloped structural member that supports treads and risers. Its finished length and cuts depend on the stair arrangement, stock size, tread thickness and how it connects to the landings.
For a simple equal stair layout, divide the total rise by the number of risers to get one riser height. The number of goings is usually one fewer than the number of risers when the upper floor is the final landing, then divide the measured run by the going count. The calculator uses that geometry to estimate a line length. It does not include landing projections, end cuts, nosings, stringer strength or the full cut layout.
The National Building Code is a model code
The National Building Code of Canada is developed as a model code that provincial and territorial governments may adopt with changes. The federal publication record explains that the jurisdiction concerned determines which code is applicable. A table in the 2020 model code gives private-stair risers from 125 to 200 mm and rectangular runs from 255 to 355 mm. Those values describe that published edition and stair scope; they should not be treated as a current rule for every Canadian project.
Check the code and amendments in force where the stair will be built, including the building type and stair use. Ontario’s current code materials and provincial amendments can differ from an earlier NBC table. The Canadian stair calculator now offers the named British Columbia 2024 private-stair rise and going reference, excluding Vancouver. It compares only those two dimensional ranges. Ontario, other provinces, federal lands and other editions remain geometry-only. Confirm the applicable permit edition and all other stair requirements locally.
| NBC 2020 model-code item | Minimum | Maximum |
|---|---|---|
| Riser | 125 mm | 200 mm |
| Rectangular run | 255 mm | 355 mm |
Work through a calculator geometry example
The Canadian calculator example enters a total rise of 2,700 mm, a total run of 3,600 mm, 15 proposed risers and a 25 mm tread thickness. It calculates 180 mm per riser and 14 goings at about 257.1 mm each. The theoretical line from the bottom to the top is √(2,700² + 3,600²), or 4,500 mm. The estimated bottom seat rise is 155 mm after subtracting the entered tread thickness.
These are mathematical outputs, not a current Ontario code check. The example demonstrates how the calculator divides dimensions and why the number of risers affects each going. A different floor finish can alter the finished rise, and a change in run may alter the landing or stair arrangement. Remeasure from finished surfaces, then have the stair checked against the current code and actual framing before cutting any stringers.
Choose stringer stock and make a cut plan
The calculator’s sloped line length is a geometric baseline. Choose stock long enough for the cut pattern and any waste, and verify that its width, thickness, grade and condition are suitable for the span and loads. The first and last cuts, tread seat depth, tread overhang, riser thickness, landing connection, handrail and stringer spacing are all outside that simple line calculation. The material count is not a structural sizing instruction.
Draw one stringer at full scale or make a controlled template after the design is confirmed. Include the tread thickness and bottom seat adjustment and check that all repeated cuts leave adequate material at the narrowest section. Do not cut every stringer from a rough measurement; verify the first against both floors and correct levels before duplicating the pattern. Follow safe saw setup, support the stock and wear the protective equipment required by the tool maker.
When permits and inspections may matter
Permits, inspections and code enforcement are handled by the local authority having jurisdiction. Requirements can depend on whether the stair is part of a dwelling, deck, secondary suite, public access or another building. Ask the municipality which edition and amendments apply, whether a permit is required, and what drawings or inspections are expected before construction. This article cannot resolve that question for an address.
Use a qualified designer or builder for stairs that form part of a regulated building, have unusual geometry, support significant loads or connect to a raised deck. A stringer calculator does not check guard height, handrail continuity, headroom, landings, fire egress, structural support or slip resistance. Keep the approved drawing with the cut list and make sure any field changes are reviewed.
Before you finalize the estimate
Use the geometry output to check arithmetic only after a local designer or authority confirms the applicable stair requirements. Keep the finished rise, run, floor build-up, tread thickness and landing details with the drawing. If those dimensions change during construction, recalculate and have the resulting stair checked before cutting additional stringers.
The NBC 2020 table is a model-code reference, not a statement of the current requirements in every province or territory. Ask the local authority about code adoption, amendments, permit and inspection steps. The calculator does not provide an approval decision.
Make it your project.
Use the supporting calculator with your measured dimensions and the product you plan to buy. Read its worked example, sources and assumptions before ordering.
Frequently asked questions
How many risers are in the Canadian stair example?
The example enters 15 risers over a 2,700 mm total rise, giving 180 mm per riser.
What is the difference between total run and going?
Total run is the horizontal distance across the stair flight. Going is the horizontal distance for one step; the calculator divides run across the entered number of goings.
Are the NBC 2020 riser and run values current law across Canada?
No. NBC is a model code that provinces and territories adopt or amend. Confirm the current local code for the project.
Does the tool confirm that my stair complies?
No. It can compare rise and going with the named BC 2024 private-stair ranges, excluding Vancouver. Other jurisdictions remain geometry-only. Neither mode certifies full compliance.
Should I cut the stringers from the calculated line length?
Not from that value alone. Confirm the complete stair drawing, stock dimensions, end connections and cut layout first.
For general information only, not professional advice. Rules and prices change, so check the official sources below. Use your own judgement and speak to a solicitor or lawyer before you act.