- Project plans
- Project activities
- Legislation and standards
- Industry context
- Specialist wikis
Last edited 06 Oct 2020
Alternating tread stair
Approved document K, Protection from falling, collision and impact, defines an alternating tread stair as:
In dwellings, alternating tread stairs may only be used in loft conversions where there is not enough space for conventional stairs and where the stair is for access to only one habitable room and, if desired, a bathroom and/or a WC (although this must not be the only WC in the dwelling).
Alternating tread stairs should:
- Make alternating steps uniform with parallel nosings.
- Have slip-resistant surfaces on treads.
- Should be constructed so that a 100mm diameter sphere cannot pass through the open risers.
- Provide a minimum clear headroom of 2m.
- Have tread sizes over the wider part of the step in line with the table below, and should comply with the diagram below.
 Find out more
 Related articles on Designing Buildings Wiki
Featured articles and news
Take just two minutes to provide your feedback.
An update of standards and regulations are under consideration.
Exploring the key to the adoption of this abundant energy source.
His clients have ranged from Liberace to St Nick to world-class athletes.
These tactical structures can be permanent or temporary.
Organisation recognises milestones of the project's next phase.
Welding and metalworking businesses must manage respiratory risks.
New report explores how regulations are being put into action.
The golden thread and BS 8644-1.
Bitumen binder may delay road surface deterioration.
A varied portfolio of internationally recognised buildings.
Threatened by housing and expanding universities.
Getting "boots on the ground" to make things happen.
Building systems may begin to learn.