Considerations for Stair Design
In previous posts in this series we looked at stair ideas, stair regulations and terminology. In this post we will look at some of the considerations needed to design stairs.
(please note all images are for inspiration only and do not necessarily comply with local regulations)
Stairs form a primary means of escape to the outside in case of fire or emergency so it is important to ensure the stairs can be used safely. This includes ensuring handrails are fixed at the right height and in accordance with Approved Document Part K, along with keeping rise and tread dimensions consistent.
The building regulations should be consulted for all fire related requirements of a stair. The stairs are a principle means of escape and must be constructed of materials that are able to maintain a fire resistance for a specified period of time. Stair must also be protected from fire and smoke, and they must be constructed to allow for a safe escape from the building. Refer to Building Regulations Approved Documents Part B.
Consider things like integrity of materials during a fire and size of steps for ease of escape.
Materials for the stair treads should be designed to minimise impact sound from foot traffic. A metal or timber stair can be noisy when in use, but a concrete stair absorbs more sound. The materials chosen will depend on many factors including cost, client preferences, location, structural requirements and much more.
Internal stairs can be made out of a multitude of materials, such as timber, concrete, stone, metal and structural glass.
In a standard residential home timber is the most common material for stairs, often prefabricated off site.
Timber stairs can integrate easily into a design, and can be altered on site as needed. Timber has a relatively poor resistance to fire so they tend to be restricted to residential use only. There are many options for a timber stair design, given the versatility of the material. Timber stairs can be traditional in style or contemporary, with cantilever treads from the wall for example. In this case the structural support of the stair is concealed in the wall, from which the stair treads are cantilevered.
A softwood can be used for timber stairs, which is the more economical option, or hardwoods such as oak, walnut or ash can also be used that are more expensive but durable. Timber can also be incorporated with other materials, like metal or glass.
Concrete stairs can be made in situ using specific formwork to create the stair with a screed added afterwards to allow for a smooth finish. The finished stair can be polished, painted or clad in another material. Alternatively concrete stairs can be supplied precast in sections and assembled on site.
Concrete stairs will have a good fire resistance and better impact sound absorption. Stone stairs also have a good fire resistance and impact sound absorption and give a very solid feel to the staircase. For a strong and solid look, but reducing the cost, it is possible to clad stairs with a stone panel finish to get the desired stone appearance.
Glass stairs allow for light to flow easily between rooms or floors in the house. This is a great option to increase the natural light in a space. There are many ways glass can be used in stair design.
Metal stairs can be designed for an industrial heavier feel or be more lightweight and less heavy in appearance than timber. Metal is often used for balustrades in the form of light weight balusters, or even mesh or tension wires.