Read the profile before pricing finishes

The ratio 1:N states how many horizontal units are provided for one vertical unit. A 1:14 concept therefore needs 14 metres of horizontal run for every metre of rise. Percentage grade is rise divided by horizontal run multiplied by 100. The angle is the arctangent of rise divided by run. These are equivalent descriptions, but construction documents should identify which dimension is horizontal and which is the sloping surface.

The calculated ramp surface length follows the hypotenuse, so it is slightly longer than the horizontal run. The tool divides the run by your entered maximum run per flight and rounds upward. It then schedules a landing at each end and between flights. Real layouts may turn through 90 or 180 degrees, share an existing porch, or need larger circulation landings; edit the resulting scope rather than treating the rectangular allowance as a site plan.

Identify the regulatory pathway before choosing a ratio

Australian ramp requirements depend on building class, location, purpose and the people using the path. An accessway in a building required to be accessible can lead to NCC Volume One provisions and AS 1428.1 details. A step-free access path for applicable housing can involve the Livable Housing Design Standard and jurisdictional adoption. A private ramp serving an external doorway may follow a different Housing Provisions pathway. Landscaping slopes that do not provide access to a building can sit outside some NCC provisions, while planning, workplace and duty-of-care obligations may still matter.

That is why the calculator does not select a national “legal gradient”. Record the building class, edition and jurisdiction, the exact clause or project specification, and the date checked. Enter the approved gradient and maximum flight run only after that review. Where the path must serve a specific person, an access consultant, occupational therapist or designer may set requirements beyond the minimum compliance pathway.

Test the whole circulation footprint

Measure the actual finished levels. A nominal step height from an old drawing can be wrong after paving, resurfacing or settlement. Survey both sides of a threshold and note whether the ramp connects to the internal floor, an external landing or a drainage grate. Include construction tolerances: a shallow design can be made steeper by a small level error over a short flight.

Design structure, edges and water together

A concrete ramp needs subgrade preparation, reinforcement or joints appropriate to its design, durable edges and controlled curing. A timber or metal ramp needs footings, bracing, corrosion protection, fixings and a load path. Do not price only the visible deck. Retaining edges may also hold fill, while posts near services or footings can need revised locations.

External ramps must shed water without creating unsafe crossfall or discharging across a doorway. Detail surface falls, grated drains, downpipe interfaces and overflow. Select a finish whose tested slip resistance suits the application and expected wet or dry condition. Paint, sealer, wear, leaves and algae can change performance after handover, so maintenance belongs in the plan.

Handrails and barriers solve different risks. A handrail supports a user; a barrier controls a fall from an edge. Their triggers, geometry, extensions, clearances, openings and loading must be checked through the applicable requirements. Adding them late can reduce the clear width or obstruct a landing.

Build quotations from measurable packages

The default dollar figures only demonstrate the arithmetic. Replace them with quotations that share the same inclusions and GST basis. The area rate combines ramp and scheduled landing surface, but unusual structures should be priced as their own packages. The handrail allowance uses the sloping length plus every scheduled landing length for each selected side; a real rail layout may differ at turns, walls and doors.

Check set-out and handover in stages

Before excavation, mark the start level, finish level, horizontal run, flight breaks and landing rectangles. Confirm boundaries, easements and underground services. Check that doors, gates, vehicles and existing paths still function. Review headroom and any fall from the ramp edge along the entire route.

During work, verify compacted support, footing positions, reinforcement, connections and drainage before they are concealed. Measure each completed flight rather than relying only on total rise and total run: one steep local segment can be hidden inside an acceptable overall average. Check crossfall, changes in level, gaps and transitions with the method required by the project.

At handover, obtain approvals, inspection records, product information, coating or slip-resistance evidence, warranties and maintenance instructions. Demonstrate drainage under a controlled test where appropriate. Keep the final measured profile because future resurfacing can alter thresholds and gradients.

Create a measurement record another person can reproduce

Write the datum, instrument, benchmark and measurement date beside the calculation. Use horizontal run rather than ground distance, identify the exact finished surfaces at both endpoints, and record every flight separately. Where a laser or level is used, state whether readings were taken to the structural substrate or completed finish. A short table of chainage, design level and measured level is more useful than a single overall ratio because it exposes local high points and sags.

Draw the landing direction and door swing, then mark clear width between finished obstructions. Photograph drainage outlets, rail supports and concealed reinforcement at agreed inspection stages. If the concept changes, issue a revised profile instead of annotating several conflicting dimensions on site. These records help the designer assess tolerances and give the contractor an auditable set-out basis.

For a temporary ramp, also document restraint, edge protection, weather exposure, inspection frequency and the user load. Portable equipment still needs a stable support and safe transition; a quick installation does not remove the need to manage foreseeable risks.

Ramp calculator questions

References

Official sources checked 14 July 2026. Apply the edition and jurisdiction adopted for the project.

• National Construction Code — Part D4 Access for people with a disability
• ABCB — Livable Housing Design handbook
• ABCB — Stairways, barriers and handrails FAQs