Stair Code by State: Rise, Run, Headroom and Handrails
Applies to stairways within or serving a dwelling, porch or deck under the IRC and the state residential codes that amend it. Stairs not serving a building, stairs to nonhabitable attics and stairs to crawl spaces are outside the section. Your local building department has the final word.
Two numbers decide whether a staircase passes inspection: the maximum riser height and the minimum tread depth. The International Residential Code sets them at 7 3/4 inches and 10 inches, and most of the country builds to that. But six of the states checked here do not. New York, Massachusetts, Pennsylvania and New Jersey all allow an 8 1/4-inch riser over a 9-inch tread, and Oregon allows an 8-inch riser over a 9-inch tread while dropping the handrail minimum to 30 inches. Those amendments change the length of the stairwell, not just the paperwork.
There is a second trap that has nothing to do with your state. The 2024 IRC renumbered the stairway section. Stairways moved from R311.7 to R318.7, and the handrail requirements moved out of the stairway section entirely into R320. In a 2024-based code, R311.7 is now carbon monoxide detection systems. So a plan note or an inspection checklist that cites "IRC R311.7" is pointing at the wrong section in every jurisdiction that has adopted the 2024 code, including California and New York.
Every number below was read from the adopted code text, with the edition and section named — ICC editions for ten states, the Pennsylvania Code for Pennsylvania and the New Jersey Administrative Code for New Jersey. A stair that is one riser short is a demolition job, not a punch-list item, so nothing here is inferred from a neighbouring state.
Riser count and tread depth come straight from your jurisdiction’s maximum riser and minimum tread; an 8 1/4 in state allowance can remove a riser from the flight. Free, no signup.
The IRC Baseline: Every Stair Dimension in One Table
These are the 2021 IRC values, verified unchanged in the 2024 IRC. Dimensions are exclusive of carpets, rugs and runners. The two variance limits matter as much as the maximums: within a single flight, the greatest riser may not exceed the smallest by more than 3/8 inch, and the same 3/8-inch limit applies to tread depth. That tolerance is easy to miss even when every riser is under 7 3/4 inches, because it is set by how level the framing was when the stringers were cut.
| Requirement | IRC value | 2021 section | 2024 section |
|---|---|---|---|
| Maximum riser height | 7 3/4 in | R311.7.5.1 | R318.7.5.1 |
| Riser variance within a flight | 3/8 in (greatest minus smallest) | R311.7.5.1 | R318.7.5.1 |
| Riser slope from vertical | 30 degrees max | R311.7.5.1 | R318.7.5.1 |
| Open riser opening | No 4 in sphere where more than 30 in above the floor or grade | R311.7.5.1 | R318.7.5.1 |
| Minimum tread depth | 10 in | R311.7.5.2 | R318.7.5.2 |
| Tread variance within a flight | 3/8 in | R311.7.5.2 | R318.7.5.2 |
| Clear width above handrail height | 36 in | R311.7.1 | R318.7.1 |
| Clear width at or below handrail height | 31 1/2 in with one handrail; 27 in with two | R311.7.1 | R318.7.1 |
| Headroom | 6 ft 8 in | R311.7.2 | R318.7.2 |
| Maximum vertical rise per flight | 12 ft 7 in between floors or landings | R311.7.3 | R318.7.3 |
| Walkline (winders) | 12 in from the inside of the turn | R311.7.4 | R318.7.4 |
| Nosing projection | 3/4 in to 1 1/4 in; not required where the tread is 11 in or deeper | R311.7.5.3 | R318.7.5.3 |
| Nosing radius or bevel | radius 9/16 in max, or bevel 1/2 in max | R311.7.5.3 | R318.7.5.3 |
| Landing depth, straight run | 36 in in the direction of travel | R311.7.6 | R318.7.6 |
| Walking surface slope | 1:48 (2%); 1:20 where the landing must drain | R311.7.7 | R318.7.7 |
| Handrail required | One side of any flight with 4 or more risers | R311.7.8 | R318.7.8 |
| Handrail height | 34 in to 38 in | R311.7.8.1 | R320.2 |
The 2024 Renumber: R311.7 Is No Longer Stairways
The 2024 IRC moved the stairway section and split the handrail rules out of it. Nothing about the dimensions changed, so a stair built to the 2021 numbers still complies. What changed is where an inspector, a plan reviewer or a permit application will look for them. If your jurisdiction is on a 2024-based code and your drawings cite R311.7, the citation now points at carbon monoxide detectors. Florida is the exception that proves the point: its 2026 residential code is built on the 2024 IRC but kept stairways at R311.7, so the base edition alone does not tell you the number.
| Topic | 2021 IRC | 2024 IRC |
|---|---|---|
| Stairways (whole section) | R311.7 | R318.7 |
| Risers | R311.7.5.1 | R318.7.5.1 |
| Treads | R311.7.5.2 | R318.7.5.2 |
| Handrails, required | R311.7.8 | R318.7.8 |
| Handrail height | R311.7.8.1 | R320.2 |
| Handrail projection | R311.7.8.2 | R320.3 |
| Handrail clearance to wall | R311.7.8.3 | R320.4 |
| Handrail continuity | R311.7.8.4 | R320.5 |
| Handrail grip size | R311.7.8.5 | R320.6 |
| Stairways in existing buildings | no equivalent section | R318.7.9 (new) |
| What R311.7 means now | Stairways | Carbon monoxide detection systems |
The Seven States That Change Rise and Run
These are the amendments that change how a stair gets built rather than how it gets cited. All four allow a steeper stair than the IRC, which means fewer risers and a shorter run for the same floor-to-floor height. Oregon goes further and lets a handrail sit as low as 30 inches. All seven keep the IRC’s 36-inch width, 6 ft 8 in headroom and 3/8-inch variance limits. Watch the winders, though, because the amendments disagree: New Jersey cuts winder treads to 9 inches along with the rest, while Connecticut and Rhode Island leave winders at the IRC’s 10 inches even though their regular treads drop to 9. Pennsylvania also allows a tread projection of up to 1 1/2 inches where solid risers are used, beyond the IRC’s 1 1/4-inch nosing limit.
| State | Adopted edition | Max riser | Min tread | Handrail height | Section |
|---|---|---|---|---|---|
| New York | 2025 Residential Code of New York State | 8 1/4 in | 9 in | 34 to 38 in | R318.7.5 |
| New Jersey | IRC/2024 as the NJ one- and two-family dwelling subcode | 8 1/4 in | 9 in | 34 to 38 in | N.J.A.C. 5:23-3.21 |
| Pennsylvania | 2021 IRC via the PA Uniform Construction Code | 8 1/4 in | 9 in | 34 to 38 in (projection limited to 3 1/2 in) | 34 Pa. Code 403.21 |
| Massachusetts | 2021 IRC with Massachusetts Amendments | 8 1/4 in | 9 in | 34 to 38 in | R311.7.5 |
| Connecticut | 2022 Connecticut State Building Code, 2021 IRC Portion | 8 1/4 in | 9 in | 34 to 38 in | R311.7.5 |
| Rhode Island | 2021 IRC with Rhode Island Amendments | 8 1/4 in | 9 in | 34 to 38 in | R311.7.5 |
| Oregon | 2023 Oregon Residential Specialty Code | 8 in | 9 in | 30 to 38 in | R311.7.5 |
| IRC baseline, for comparison | 2021 and 2024 IRC | 7 3/4 in | 10 in | 34 to 38 in | R311.7.5 / R318.7.5 |
Full State Roster
Thirteen of the sixteen states checked have stair numbers we can point at — ten as their own ICC residential edition, and Pennsylvania, New Jersey and Maine in their state rules instead. Every row here was read from adopted text, including the ones that match the IRC: Maine’s MUBEC Chapter 5 lists every section it revises and stairs are not among them, so the IRC values govern there by verification rather than by assumption. The remaining three leave the numbers to whatever edition your city or county adopts, and are handled below.
| State | Adopted edition | Base model code | Stair section | Riser / tread |
|---|---|---|---|---|
| California | 2025 California Residential Code, Title 24 Part 2.5 | 2024 IRC | R318.7 | 7 3/4 in / 10 in (IRC baseline) |
| New York | 2025 Residential Code of New York State | 2024 IRC | R318.7 | 8 1/4 in / 9 in (amended) |
| Massachusetts | 2021 IRC with Massachusetts Amendments | 2021 IRC | R311.7 | 8 1/4 in / 9 in (amended) |
| Oregon | 2023 Oregon Residential Specialty Code | 2021 IRC | R311.7 | 8 in / 9 in (amended) |
| Washington | 2021 Washington State Residential Code | 2021 IRC | R311.7 | 7 3/4 in / 10 in (IRC baseline) |
| Minnesota | 2020 Minnesota Residential Code | 2018 IRC | R311.7 | 7 3/4 in / 10 in (IRC baseline) |
| Florida | 2026 Florida Building Code, Residential, 9th ed. | 2024 IRC | R311.7 (kept old numbering) | 7 3/4 in / 10 in (IRC baseline) |
| New Jersey | IRC/2024 adopted as the one- and two-family dwelling subcode (N.J.A.C. 5:23-3.21) | 2024 IRC | R318.7 | 8 1/4 in / 9 in (amended) |
| Pennsylvania | 2021 IRC adopted through the Uniform Construction Code (34 Pa. Code 403.21) | 2021 IRC | R311.7 | 8 1/4 in / 9 in (amended) |
| Connecticut | 2022 Connecticut State Building Code, 2021 IRC Portion (eff. 2022-10-01) | 2021 IRC | R311.7 | 8 1/4 in / 9 in (amended) |
| Rhode Island | 2021 IRC with Rhode Island Amendments | 2021 IRC | R311.7 | 8 1/4 in / 9 in (amended) |
| New Hampshire | 2024 IRC with New Hampshire Amendments | 2024 IRC | R318.7 | 7 3/4 in / 10 in (IRC baseline) |
| Maine | Maine Uniform Building and Energy Code (MUBEC) Chapter 5, adopting the 2021 IRC | 2021 IRC | R311.7 | 7 3/4 in / 10 in (IRC baseline, unamended) |
Where Your City or County Sets the Numbers
In three of the states checked there is no state-published residential edition with its own stair numbers, so the edition your city or county adopted decides them. The three are not alike. Texas does set a floor: state law adopts a minimum residential code for all cities and some unincorporated areas, and lets local officials adopt a more recent edition, but it publishes no Texas stair amendment. Vermont regulates commercial buildings statewide and leaves dwellings alone. Illinois has historically left codes to local government. Call your building department and ask which IRC edition is in force before you cut stringers, and remember that the edition decides the section number as well as the dimensions.
| State | Situation | Where your number comes from |
|---|---|---|
| Texas | State law adopts a minimum residential code for all cities and some unincorporated areas; local officials may adopt a more recent edition. No Texas-specific stair amendment is published | The IRC edition your city adopted, at or above the state minimum |
| Illinois | No statewide building code historically, with local governments adopting codes of their choice; the Capital Development Board Act (20 ILCS 3105) calls for a statewide building code effective 2025-01-01. Whether it reaches your dwelling project is a question for your building department | Your municipality |
| Vermont | Since 1972 Vermont has adopted national codes for commercial building safety only; dwellings have a Residential Building Energy Standard but no statewide stair rule | Your municipality |
Existing Stairs: The 2024 Code Added Relief for Remodels
This is the provision most likely to matter on a renovation, and it is new. The 2024 IRC added R318.7.9, which has no equivalent in the 2021 IRC. It says, verbatim: "Alterations to existing stairs shall not be required to comply with the requirements of this code where the existing space and construction does not allow a reduction in pitch or slope." In plain terms, if you are refinishing or rebuilding a staircase inside an existing stairwell that physically cannot be lengthened, you are not required to flatten the stair to current rise and run. It appears in California and New York, both of which are on the 2024 IRC. New Jersey is the warning: it also adopts the 2024 IRC, but N.J.A.C. 5:23-3.21 deletes R318.7.9 in its entirety, so the relief does not exist there. Under a 2021-based code there is no such section at all, and relief for an existing stair is a judgment call by the building official, which may be handled through the existing-building code. Confirm before you assume it applies.
Connecticut Puts a Number on the Existing-Stair Problem
Every other jurisdiction handles an existing stair qualitatively, if at all: the 2024 IRC says an alteration need not comply "where the existing space and construction does not allow a reduction in pitch or slope," which leaves the building official to judge it. Connecticut instead publishes hard numbers, and they are the steepest stair found in any state checked. Under the 2022 Connecticut State Building Code, an existing stair serving an unfinished attic or unfinished basement being converted to habitable space, or a replacement stair where the pitch cannot be reduced because of existing construction, may use a 9-inch riser over an 8-inch tread. For anyone finishing a Connecticut basement or attic, that is the difference between reusing the stair that is already there and rebuilding the stairwell.
| Situation | Max riser | Min tread | Section |
|---|---|---|---|
| New Connecticut stair | 8 1/4 in | 9 in | R311.7.5.1 / R311.7.5.2 |
| Existing stair to an unfinished attic being converted | 9 in | 8 in | R311.7.5.1 Exc. 1 / R311.7.5.2 Exc. |
| Existing stair to an unfinished basement being converted | 9 in | 8 in | R311.7.5.1 Exc. 1 / R311.7.5.2 Exc. |
| Replacement stair where pitch cannot be reduced | 9 in | 8 in | R311.7.5.1 Exc. 1 / R311.7.5.2 Exc. |
| IRC baseline, for comparison | 7 3/4 in | 10 in | R311.7.5.1 / R311.7.5.2 |
Handrails, Graspability and Guards
A handrail is required on at least one side of any flight with four or more risers, at 34 to 38 inches measured vertically from the sloped plane adjoining the tread nosings. It must be continuous for the full flight, with each end returned to itself or toward a wall, guard or walking surface, or terminated at a post, and held at least 1 1/2 inches off the wall. Graspability is the requirement a site-built rail is most likely to overlook: the code gives two ways to comply and a plain 2x4 meets neither, whichever way it is turned, because its 10-inch perimeter is well over the 6 1/4-inch Type I limit and it has no finger recess. Remember that in a 2024-based code these rules are in R320, not in the stairway section.
| Requirement | Value | 2021 section |
|---|---|---|
| Handrail required | Flights with 4 or more risers, at least one side | R311.7.8 |
| Height above nosing line | 34 in to 38 in | R311.7.8.1 |
| Projection into required width | 4 1/2 in max each side | R311.7.8.2 |
| Clearance from wall | 1 1/2 in minimum | R311.7.8.3 |
| Type I, circular | Outside diameter 1 1/4 in to 2 in | R311.7.8.5 |
| Type I, non-circular | Perimeter 4 in to 6 1/4 in, cross section 2 1/4 in max | R311.7.8.5 |
| Type II | Perimeter over 6 1/4 in, with a finger recess on both sides | R311.7.8.5 |
Winders, Spirals and Special Stairways
Winder treads are measured at the walkline, 12 inches in from the inside of the turn. A winder needs the full tread depth at that line and at least 6 inches at any point in the clear width, so a true pie-shaped tread that pinches to a point at the newel does not comply. Spiral stairs get their own relaxed set of numbers, including a 9 1/2-inch riser, the same limit the code sets for alternating tread devices and ship’s ladders. Alternating tread devices and ship’s ladders may not serve as required egress except from lofts and mezzanines of 200 sq ft or less that do not provide the only access to a kitchen or bathroom.
| Stair type | Riser | Tread | Clear width | Headroom |
|---|---|---|---|---|
| Standard (IRC) | 7 3/4 in max | 10 in min | 36 in | 6 ft 8 in |
| Winder | same as standard | 10 in at the walkline, 6 in min at any point | 36 in | 6 ft 8 in |
| Spiral | 9 1/2 in max, treads identical | 6 3/4 in at the walkline, walkline radius 24 1/2 in max | 26 in | 6 ft 6 in |
| Alternating tread device | 9 1/2 in max | 5 in, projected 8 1/2 in, width 7 in | 20 in | n/a |
| Ship’s ladder | 9 1/2 in max | 5 in, tread plus nosing 8 1/2 in | 20 in | n/a |
Standards & Citations
| Standard | Code / Section | Requirement |
|---|---|---|
| IRC Stairways | 2021 IRC R311.7 | 7 3/4 in maximum riser, 10 in minimum tread, 36 in clear width, 6 ft 8 in headroom, 12 ft 7 in maximum vertical rise per flight. |
| IRC Stairways (renumbered) | 2024 IRC R318.7 | Same dimensions as the 2021 IRC; stairways moved from R311.7 to R318.7 and handrail provisions moved to R320. |
| IRC Stairways in Existing Buildings | 2024 IRC R318.7.9 | Alterations to existing stairs need not comply where the existing space and construction does not allow a reduction in pitch or slope. |
| Residential Code of New York State | 2025 RCNYS R318.7.5 | Maximum riser height 8 1/4 in; minimum tread depth 9 in. |
| Pennsylvania Uniform Construction Code | 34 Pa. Code 403.21(a)(7)(ii) | Adopts the 2021 IRC with maximum riser 8 1/4 in, minimum tread 9 in, 3 ft clear width, 6 ft 8 in headroom, handrail projection limited to 3 1/2 in per side; 2021 R311.7.4 (walkline) excluded, with the 2018 IRC R311.7.4 walkline kept in effect as modified by an added figure for winder tread and landing detail (403.21(a)(7)(iii)(A) and (viii)(A)). |
| New Jersey One- and Two-Family Dwelling Subcode | N.J.A.C. 5:23-3.21 | Adopts the IRC/2024 with R318.7.5.1 riser changed to 8 1/4 in and R318.7.5.2 / R318.7.5.2.1 treads changed to 9 in; R318.7.9 (stairways in existing buildings) deleted in its entirety. |
| Massachusetts Residential Amendments | 2021 IRC with MA Amendments R311.7.5 | Maximum riser height 8 1/4 in; minimum tread depth 9 in. |
| Connecticut State Building Code, IRC Portion | 2022 CT State Building Code R311.7.5.1, R311.7.5.2 | Maximum riser 8 1/4 in, minimum tread 9 in; existing attic/basement conversions and replacement stairs that cannot be reduced in pitch may use a 9 in riser over an 8 in tread. |
| Rhode Island Residential Amendments | 2021 IRC with RI Amendments R311.7.5.1, R311.7.5.2 | Maximum riser height 8 1/4 in; minimum tread depth 9 in; winder treads remain 10 in at the walkline. |
| Maine Uniform Building and Energy Code, Residential | MUBEC Chapter 5 (16-642) Sections 4 and 5, adopting the 2021 IRC | Adopts IRC Chapters 1 through 11 by reference, so R311.7 applies as written; Maine’s list of revisions covers R101 through R113, R301, R302, R310, R313, R502, R602 and R802 and does not touch the stair provisions. |
| New Hampshire Residential Amendments | 2024 IRC with NH Amendments R318.7.5 | IRC baseline 7 3/4 in riser and 10 in tread; retains R318.7.9 relief for altering existing stairs. |
| Oregon Residential Specialty Code | 2023 ORSC R311.7.5, R311.7.8.1 | Maximum riser height 8 in; minimum tread depth 9 in; handrail height 30 to 38 in. |
| California Residential Code | 2025 CRC, Title 24 Part 2.5 R318.7 | IRC baseline rise and run; follows the 2024 IRC renumbering to R318.7. |
| Washington State Residential Code | 2021 WA Residential Code R311.7 | IRC baseline: 7 3/4 in riser, 10 in tread, 34 to 38 in handrail height. |
| Minnesota Residential Code | 2020 MN Residential Code R311.7 | IRC baseline rise and run; headroom worded as the minimum in all parts of the stairway, 6 ft 8 in. |
| Florida Building Code, Residential | 2026 FBC Residential, 9th ed. R311.7 | IRC baseline rise and run; built on the 2024 IRC but retains R311.7 numbering for stairways. |
Apply These Requirements
Open a calculator to run this guide’s requirements against your own project.
Stairs Calculator
Riser count and tread depth come straight from your jurisdiction’s maximum riser and minimum tread; an 8 1/4 in state allowance can remove a riser from the flight.
Deck Calculator
Deck stairs follow the same rise and run limits, and the stair run sets how far the landing lands from the deck.
Deck Railing Calculator
Stair handrail height, graspability and continuity are code-driven and differ from the guard rules on the deck surface.
Attic Conversion Calculator
Headroom and maximum vertical rise per flight can decide whether an attic stair can be built in the available space.
Basement Remodel Calculator
An existing basement stair built to an older code may not meet current rise and run; the 2024 existing-stairs provision decides whether they must be rebuilt.
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Frequently Asked Questions
What is the maximum stair riser height?
7 3/4 inches under the IRC, measured vertically between the leading edges of adjacent treads. Seven states checked here allow more: New York, New Jersey, Pennsylvania, Massachusetts, Connecticut and Rhode Island all permit 8 1/4 inches, and Oregon permits 8 inches. Connecticut goes further for conversions, allowing a 9-inch riser on an existing attic or basement stair. Just as important as the maximum is the variance limit — within one flight the tallest riser may not exceed the shortest by more than 3/8 inch, a limit that is easy to break with framing that is out of level even when every riser is under the maximum.
What is the minimum tread depth?
10 inches under the IRC, measured horizontally between the vertical planes of the foremost projection of adjacent treads. New York, New Jersey, Pennsylvania, Massachusetts, Connecticut, Rhode Island and Oregon all reduce it to 9 inches, and Connecticut allows 8 inches on a qualifying existing stair. The same 3/8-inch variance limit applies across a flight. A nosing of 3/4 to 1 1/4 inches is required unless the tread is 11 inches or deeper, in which case no nosing is needed.
Why does my code book say R311.7 is carbon monoxide detectors?
You are reading a 2024-based code. The 2024 IRC renumbered stairways from R311.7 to R318.7 and moved handrails out to R320, and R311.7 now covers carbon monoxide detection systems. The stair dimensions did not change, only the section numbers. California and New York are both on 2024-based codes. Florida’s 2026 code is also 2024-based but kept stairways at R311.7, so check your state rather than assuming.
Do I have to bring an old staircase up to current code when I remodel?
Under a 2024-based code, possibly not. The 2024 IRC added R318.7.9: alterations to existing stairs are not required to comply where the existing space and construction does not allow a reduction in pitch or slope. That covers the common case of a steep stair in a stairwell that cannot be lengthened. Watch New Jersey: it adopts the 2024 IRC but deletes R318.7.9 in its entirety, so the relief is not available there. Connecticut goes the other way and publishes hard numbers instead of a judgment call — a 9-inch riser over an 8-inch tread for attic and basement conversions and for replacement stairs. There is no equivalent section in the 2021 IRC either, so under an older adopted code it is a judgment call by the building official, which may be handled through the existing-building code.
How many risers can one flight of stairs have?
A flight may not exceed 12 feet 7 inches of vertical rise between floor levels or landings. At the 7 3/4-inch IRC maximum that works out to 19 risers before a landing is required. Going past that height means breaking the run with an intermediate landing at least 36 inches deep in the direction of travel.
How much floor space does a staircase need?
It depends on your jurisdiction’s tread minimum. For a 112-inch floor-to-floor height, the IRC requires 15 risers at 7.47 inches, and the 14 treads at 10 inches consume 140 inches of floor. In New York, New Jersey, Pennsylvania or Massachusetts the same height takes 14 risers at 8.00 inches, and 13 treads at 9 inches consume 117 inches — nearly two feet less. That difference is why the state amendment matters on a tight remodel.
Does a 2x4 handrail meet code?
No. A handrail must be graspable in one of two specified ways. Type I circular rails need an outside diameter of 1 1/4 to 2 inches; non-circular Type I rails need a perimeter of 4 to 6 1/4 inches with a cross section no greater than 2 1/4 inches. Anything with a perimeter over 6 1/4 inches is Type II and needs a finger recess on both sides. A nominal 2x4 laid flat fails the perimeter and cross-section limits and has no recess.
Why do Northeast stairs feel steeper than the code allows?
Because in much of the Northeast they legally are. New York, New Jersey, Pennsylvania, Massachusetts, Connecticut and Rhode Island all amend the IRC to allow an 8 1/4-inch riser over a 9-inch tread, a full half-inch taller and an inch shallower than the 7 3/4 by 10 the rest of the country builds to. The block runs unbroken from Pennsylvania through New England, with two exceptions worth knowing: New Hampshire holds the IRC baseline, and Vermont has no statewide residential stair rule at all. Oregon does something similar at 8 by 9. A stair built to those numbers is code-compliant at home and would fail inspection in a baseline state, which is worth knowing if you are working from plans drawn somewhere else.
Do stairs to a deck or porch follow the same rules?
Yes. The section applies to stairways within or serving a building, porch or deck, so deck stairs get the same riser, tread, width, headroom and handrail requirements. The exceptions are stairs not serving a building at all, stairs to nonhabitable attics, and stairs to crawl spaces, which fall outside the section entirely.
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