Staircase Code Quick-Reference Card

BuildCalc Pro

buildcalcpro.org

Every critical stair dimension on one printable page — based on the International Residential Code (IRC)

Tape this card inside your toolbox or stick it to the garage wall before you cut a single stringer. It distills the IRC stair rules most building inspectors check first — riser height, tread depth, headroom, handrails, guards, and landings — into a single sheet. Always confirm against your local amendments, but these are the figures that fail inspections most often.

Core Stair Dimensions

Requirement	Code Value	Notes
Max riser height	7 3/4 in	Measured vertically, nose to nose
Min tread depth	10 in	Nosing to nosing, excluding overhang
Min stair width	36 in	Clear width above the handrail
Min headroom	6 ft 8 in (80 in)	Vertical, measured from nosing line
Max riser variation	3/8 in	Largest minus smallest riser in a flight
Max tread variation	3/8 in	Largest minus smallest tread in a flight
Nosing projection	3/4 in - 1 1/4 in	Required when tread depth is under 11 in
Max vertical rise	12 ft 7 in (151 in)	Between floor levels or landings

Handrails & Guards

Requirement	Code Value	Notes
Handrail height	34 in - 38 in	Above the stair nosing line
Handrail required	4+ risers	At least one side of the flight
Handrail grip (round)	1 1/4 in - 2 in	Cross-section diameter
Guard height (residential)	36 in	Open sides over 30 in above floor
Baluster spacing	Under 4 in	A 4 in sphere must not pass through
Handrail wall clearance	1 1/2 in min	Between handrail and wall

Landings

Requirement	Code Value	Notes
Landing width	Equal to stair width	Minimum, perpendicular to travel
Landing length	36 in min	In the direction of travel
Top/bottom landing	Required	At each end of a flight

The Comfort Formula (2R + T)

A flight feels comfortable when twice the riser height plus the tread depth lands between 24 and 25 inches. The most comfortable real-world combination is a 7 in riser with an 11 in tread. Use this to sanity-check your layout before cutting:

Total Rise (floor to floor)

No. of Risers (rise / 7.5)

Actual Riser Height

Tread Depth

2R + T (target 24-25)

Total Run (treads x depth)

No. of Treads (risers - 1)

Stringer Length

Pre-Cut Inspection Checklist

☐Total rise measured floor-to-finished-floor (not subfloor)

☐Riser count chosen so each riser is 7 3/4 in or less

☐All risers equal within 3/8 in

☐Tread depth at least 10 in (11 in for comfort)

☐Headroom 6 ft 8 in clear at every point on the flight

☐Stair width 36 in clear above handrail

☐Handrail planned at 34-38 in for flights of 4+ risers

☐Guard planned at 36 in where open side exceeds 30 in drop

☐Landings sized at least 36 in in direction of travel

☐Local code amendments confirmed with building department

Project Notes & Local Amendments

Plan it before you cut it. Use the free Staircase Calculator at buildcalcpro.org to turn your total rise into exact riser height, tread depth, and stringer length — then check the result against this card. Code figures are based on the IRC; always verify local amendments with your building department.