NZ Ramp Gradients (NZBC D1)

The requirement

The steepest slope for an accessible ramp is 1:12. A common ramp that can get wet: 1:10. A common ramp that stays dry: 1:8. A service ramp can go to 1:3. Those numbers come from D1/AS1, the Acceptable Solution for Clause D1 Access Routes. It sets the slope by the ramp’s job.

New Zealand does not set one ramp slope for a house and another for a shop. Pick the type that matches your ramp. Then read the slope off the table.

Ramp type	Where it’s used	Max slope
Accessible ramp	step-free access routes	1:12
Common ramp, can get wet	outside, or anywhere it can be rained on	1:10
Common ramp, stays dry	indoors, kept dry	1:8
Service ramp	plant / service access only	1:3 (footholds needed if steeper than 1:8)

There is no “house ramp” number. The D1/AS1 table has no private, residential or household category. It sorts ramps by accessible, common and service use. A ramp into a home fits none of them cleanly. So do not quote a single “NZ residential ramp gradient”. There isn’t one.

Want a step-free entry? Build to the accessible 1:12. A plain dry ramp can go to 1:8 at the steepest. If the ramp can get wet, do not go past 1:10.

Landings

The landing is the flat bit at each end and along a ramp. Every ramp needs a level landing at the top and bottom. A ramp steeper than 1 in 33 also needs intermediate landings along the run. Space them at the vertical intervals in Table 5.

How much a ramp can climb before a landing depends on the type.

Accessible ramp: rise up to 750 mm between landings. Each landing is 1200 mm long.
Other ramps: rise up to 1500 mm between landings. The landing is as long as the ramp is wide, up to 900 mm.

NZBC D1/AS1 · Table 3 (accessible ramp 1:12)

Work it out on site

You are building a step-free entry ramp into a home. So you aim for the accessible 1:12. The door sits 450 mm above the path. How long does the ramp need to be?

Pick the type and slope. A step-free entry means an accessible ramp. That is 1:12 at the steepest. 1:12 means 1 unit up for every 12 along.
Do the sum. 450 mm up × 12 = 5400 mm. That is 5.4 m of ramp run. The 5.4 m is just the maths of this example, not a code figure.
Check the rise between landings. An accessible ramp can rise up to 750 mm between landings. Your 450 mm is under that. One run is fine, and no mid-ramp landing is needed.
Add the landings. A level landing 1200 mm long goes at the top and the bottom.

So: about 5.4 m of ramp at 1:12, with a 1200 mm landing at each end. The slope calculator does this rise-over-run sum for you.

Do it in 5 seconds

Part of the NZ Building Code rules for chippies — the hub, with the D1/AS1 access-route articles.
Building the stairs that ramp might replace? See NZ stair & barrier rules.

Sources

NZ Building Code Clause D1 Access Routes — Acceptable Solution D1/AS1 (2nd edition, Amendment 6) — ramp slopes by type at Table 3 (para 3.1.1) and landings at Table 5 (para 3.3.1): accessible 1:12, common wet 1:10, common dry 1:8, service 1:3; level landings top and bottom of every ramp; intermediate landings when steeper than 1 in 33; 750 mm rise / 1200 mm landing for accessible ramps, 1500 mm rise / up-to-900 mm landing for others. Read it at building.govt.nz. (D1/AS1 is one Acceptable Solution — a voluntary deemed-to-comply route to the mandatory Clause D1. You can instead use Verification Method D1/VM1 or an Alternative Solution. The 2nd edition, Amendment 6 has been current nationwide since 1 January 2017; confirm it is still the current amendment before you build.)
Slip resistance is set by a separate standard — check AS/NZS 4586 and D1/AS1 Table 2 for the ramp surface, not the gradient rules above.

Frequently asked questions

What ramp slope does the NZ Building Code allow?

D1/AS1 sets the slope by the ramp's job, not by the building. An accessible ramp is 1:12 at the steepest. A common ramp that can get wet is 1:10. A common ramp that stays dry is 1:8. A service ramp can go to 1:3, but anything steeper than 1:8 needs footholds.

Is there a slope just for a ramp in a house?

No. D1/AS1's ramp table has no private, residential or household category. It sorts ramps into accessible, common and service. A home ramp fits none of those, so there is no code-set house number. Most people build a step-free entry to the accessible 1:12. A dry ramp can go to 1:8.

When do I need a landing on a ramp?

You need a level landing at the top and bottom of every ramp. If the ramp is steeper than 1 in 33 you also need intermediate landings along the run, spaced at the vertical intervals in D1/AS1 Table 5.

How much can a ramp rise before a landing?

An accessible ramp can rise up to 750 mm between landings, and each landing is 1200 mm long. Other ramps can rise up to 1500 mm between landings, and the landing is as long as the ramp is wide, up to 900 mm.

Is D1/AS1 the only way to comply?

No. D1/AS1 is one Acceptable Solution — a safe deemed-to-comply route to Clause D1. You can also use Verification Method D1/VM1 or design your own Alternative Solution. Slip resistance is handled by a separate standard, so check AS/NZS 4586 and D1/AS1 Table 2 for the surface.