Alternating tread stair
Approved document K, Protection from falling, collision and impact, defines an alternating tread stair as:
A stair with paddle-shaped treads where the wide portion is on alternate sides on consecutive treads.
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.
|
| Victorian timber alternating tread stair. This is sometimes referred to as a 'witches stair' because of the belief that witches are unable to climb them. |
[edit] Related articles on Designing Buildings
Featured articles and news
Gregor Harvie argues that AI is state-sanctioned theft of IP.
Heat pumps, vehicle chargers and heating appliances must be sold with smart functionality.
Experimental AI housing target help for councils
Experimental AI could help councils meet housing targets by digitising records.
New-style degrees set for reformed ARB accreditation
Following the ARB Tomorrow's Architects competency outcomes for Architects.
BSRIA Occupant Wellbeing survey BOW
Occupant satisfaction and wellbeing tool inc. physical environment, indoor facilities, functionality and accessibility.
Preserving, waterproofing and decorating buildings.
Many resources for visitors aswell as new features for members.
Using technology to empower communities
The Community data platform; capturing the DNA of a place and fostering participation, for better design.
Heat pump and wind turbine sound calculations for PDRs
MCS publish updated sound calculation standards for permitted development installations.
Homes England creates largest housing-led site in the North
Successful, 34 hectare land acquisition with the residential allocation now completed.
Scottish apprenticeship training proposals
General support although better accountability and transparency is sought.
The history of building regulations
A story of belated action in response to crisis.
Moisture, fire safety and emerging trends in living walls
How wet is your wall?
Current policy explained and newly published consultation by the UK and Welsh Governments.
British architecture 1919–39. Book review.
Conservation of listed prefabs in Moseley.
Energy industry calls for urgent reform.