Technical Booklet R Access to and Use of Buildings·Page 28·4.6
Floor surface requirements for corridors and passageways
Corridor and passageway floors must have suitable slip resistance and be level or have a gradient less steep than 1 in 20; steeper gradients require ramps and landings.
The floor of a corridor or passageway should –
(a) have a surface that has a suitable slip resistance; and
(b) be level, or contain a gradient in the direction of travel less steep than 1 in 20. However, where the floor has a gradient of 1 in 20 or steeper, a ramp or ramps and landings, should be provided.
Source — /Users/richardhill/Documents/planning-arch-project/data/documents/regional/Technical Booklet R - Access to and Use of Buildings.pdf