Tread overlap for open-riser stairs

16 mm

For stairs with open risers, each tread must overlap the one below by a minimum of 16mm, or 15mm in Scotland, to meet safety requirements and prevent foot entrapment.

Every figure for this topic is on one page: Stair dimensions and handrail heights in UK homes

Read the full answer

For stairs with open risers, each tread must overlap the one below by a minimum of 16mm, or 15mm in Scotland, to meet safety requirements and prevent foot entrapment.

Basis in regulation

Part K
Approved Document K
Read the source

How to check it on site

Visually check and measure the overlap of treads in open-riser stairs to confirm it meets the minimum specified distance.

Common failure

Insufficient tread overlap can lead to a safety hazard, particularly for children, by allowing small feet to slip through the gap.

Last updated 23 August 2026. This is our editorial summary of publicly available regulation, not building control approval or a warranty determination.

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