Building components · Paving & Decks
External Step
Explains the external step as a ground-works position, distinct from the stair elements that belong to a building's structure and are carried by it.
Educational reference entry. What this element has to do, and whether any particular arrangement of it is adequate, depends on the whole assembly, the loading, the exposure, local requirements, the manufacturer's instructions and qualified professional design.
Overview
What a external step is
An external step is a change of level in ground-level works: in a path, a terrace, a driveway or a garden. It is formed as part of the paving construction — a riser built off a foundation, with a walked surface above it and another below — rather than as part of a building's structure.
Because it is ground construction, what governs it is ground behaviour. External steps settle when what is beneath them settles, and uneven settlement is what turns a consistent flight into an inconsistent one, so that the level change a person has learned is no longer the level change they meet.
Boundaries
How it differs from nearby elements
The distinctions that keep this entry from being a restatement of its neighbours.
- It is not a stair tread or a stair riser. Those are the two positions within a flight, set out from the flight and carried by its structure; an external step is a single unit of level change in ground construction, set out from the ground at one end and a finished level at the other, and it is not part of a flight that anything carries.
- It is not a door threshold. The threshold is the junction at an opening where the building's weather line is resolved; a step is a change of level in the ground outside, and the two are most often confused exactly where one leads to the other.
- It is not an edge restraint. A restraint holds a paved surface laterally at its perimeter; a step raises one surface above another, and although a step can act as an edge to the paving beside it, that is a consequence rather than its purpose.
Terminology
Common names and aliases
These names describe the same element. The library keeps one entry per component so that a trade term or a regional name never becomes a second, thinner page.
- garden step
- entrance step
- paving step
Dependencies
What it depends on
What has to be right elsewhere for this element to do its job.
- What is beneath it, since a step built on made ground or over backfill moves with that ground.
- Drainage around and beneath it, because water arriving at a level change has to be taken away rather than left standing against the riser.
- Consistency between one step and the next, since a change in a repeated level is what a person negotiating a flight is least prepared for.
- Its surface in wet and cold conditions, because an external walked surface is used in weather an internal one is not.
Considerations
Topics that genuinely apply here
Subjects worth discussing about this element. These are discussion topics, never measured values, ratings or performance claims.
Settlement is the usual failure, and because it acts on some steps and not others it produces an inconsistency that matters more than the settlement itself.
Water running down or across a flight arrives at each riser, and where it has nowhere to go it stands on the surface in front of it.
External walked surfaces are wetted, frozen and grown on, so the surface characteristics that matter are those in those conditions rather than when dry.
Steps are commonly set out from a finished level at one end and a ground level at the other, and reconciling the two is where inconsistent risers come from.
Materials
Commonly formed from
Material families this element is commonly realised in. This states common practice only — it is not a statement that any of these materials suits this component in a particular building, which depends on the whole assembly and on qualified review.
Assemblies
Building systems this element is met in
The role this component fills inside each assembly. A role describes what the element does there — it is not a statement that this component suits that system in any particular building.
Clarifications
Commonly misunderstood
- That an external step is a paving detail. It is a level change people negotiate, and the consistency of that change is the property that matters most.
- That steps outside a building are outside the reach of requirements. Level changes on access routes are regulated, and what applies depends on where the step is and what it serves.
Conversations
Questions for qualified professionals
Questions worth asking someone with the project in front of them. This page cannot answer them.
- What is the step built off, and has that ground been made up or backfilled?
- Are the risers consistent across the whole flight, and has anything settled since construction?
- Where does water go when it reaches the step, and can it stand on the surface in front of the riser?
- What requirements apply to this level change, given where it is and what it serves?
Go deeper
Related Build Design Hub guides
Planning guidance behind the decisions this element involves.
Preparation
Related planning checklists
Owner-side preparation before the conversation where this element comes up.
What this entry does not do
- This entry describes a position. It states no rise, going, number of steps, gradient, surface rating or handrail provision, and none can be inferred from it.
- Level changes on access routes are regulated, and whether a particular arrangement is acceptable is a matter for qualified professionals and the relevant authority.
External Works & Paving Elements
The laying course, wearing course, edge restraint, deck framing, guarding posts and the enclosing and surfacing elements that make up the ground outside the building.
Browse all paving & decks entries →