Stair dimensions

Every New Zealand regulation's sizes for a stairway, side by side. Millimetres unless marked.

D1/AS1Second Edition Amendment 61 Jan 2017
NZS 4121:2001
C/AS1Second Edition Amendment 128 Jul 2025
C/AS2Second Edition28 Jul 2025
F4/AS1Third Edition Amendment 21 Jan 2017
Kāinga Ora v2.1
Lifemark v2

		Building Code and standards					Client and rating
		D1/AS1	NZS 4121	C/AS1	C/AS2	F4/AS1	Kāinga Ora	Lifemark
Steps
A	Riser		≤180				≤190	≤180
	accessible	≤180
	common or main private	≤190
	secondary private	≤200
	service or minor private	≤220
	steps to the main entry						150–180
	other steps outside						≤190
B	Going		≥310				≥280	≥310
	accessible	≥310
	common or main private	≥280
	secondary private	≥250
	service or minor private	≥220
	steps to the main entry						≥300
	other steps outside						≥280
	Pitch						≤37°
	accessible	≤32°
	common or main private	≤37°
	secondary private	≤41°
	service or minor private	≤47°
	Variation in one flight	≤5
	Nosing, past a closed riser	≤25	≤25
	overlap, open risers	15–25
Width and handrails
C	Clear width	≥900	≥900	≥850	≥1000		≥1050	≥900
	hospital exitway				≥1500
	single escape route				≥850
	Escape width, per person				≥9
	hospital				≥10
D	Handrail height	900–1000	900–1000				900
	steps to the main entry						900
	from the wall		50–60
	clear above it		≥100
	its size		32–45
	into the width	≤100		≤100	≤100
E	Handrail past the top	≥300	≥300
	past the bottom	≥300	≥300 + going
	One handrail, width up to	≤2000			≤1500
	no centre rail, up to	≤4000			≤2000
	each part, up to				≤1500
Flights and landings
F	Rise of a flight		≤2500
	accessible or common	≤2500
	private or service	≤4000
G	Landing length	≥900	≥1200					≥1200
	door swing, clear beyond	≥400	≥400
	wall return, from the top		≥300
	from the bottom riser		≥300 + tread
H	Headroom	≥2100	≥2100
	shorter than 2000 long	≥2000	≥2000
Barrier
I	Barrier, over a 1 m fall					≥900	≥1100
	gap, homes or under-6s					<100
	gap under the bottom rail					<150
	no under-6s, between rails					≤460