The vertical part of the step. Risers and treads. The depth of a riser is critical to a comfortable walk and is regulated by Building Control, both for safety and ease of walk, limited to a fairly narrow band of possibility. One thing that is important for all risers, on any staircase, is that they are made equal- once the climber gets into a stride pattern it is quite dangerous to be knocked suddenly off kilter as the risers change pace.
The tread and the riser combined add up to the ‘step’ six when it comes to ordering materials – and for the purposes of carpeting is usually around 50 cm per step.
The depth of the riser governs the amount of steps needed in any given flight. The distance between the top and the bottom of the flight – in a house this is between one floor and the next – is divided by the riser depth to find the number of steps. The tread width determines the amount of floor space that any one flight of steps or stairs will take up.
Steps for outside need shallow risers – they should be both less steep and and wider – deep enough and shallow enough to provide good spaces for casual and impromptu seating and for conversation.
Risers are often decoratively ignored, but can look particularly good with their own form of finish – perhaps tiled or painted with a different colour or pattern to anything else around- such as half diamonds in black and white, or terracotta, or a floral trial, between wooden floors. Or clad with timber that runs in a different direction to the tread timber. By this the step risers stand out, albeit in combination, as an element in their own right, and show a strong character.
Step lights are let into the stair sides, the walls or the timber stair string to either side of the riser, and arranged to wash out across the riser, to show the depth and height of the step, and by this, the safe way forewords.