Antonia Harding of British Spirals and Castings discusses the various factors architects and specifiers need to bear in mind when selecting a bespoke staircase
A staircase provides a key focal point in a property and its design can have a significant bearing not only on how easy it is for occupants to get from floor-to-floor, but also on the arrangement and overall feel of the property. To get the best results, it’s worth considering the advantages of a bespoke staircase. While these are more costly than mass produced ‘kit’ alternatives, they also give specifiers much greater control over the overall dimensions and style of the staircase.
When specifying bespoke staircases, there are a number of aspects to consider.
Style
A standard straight staircase has a long, linear footprint which requires a good amount of available floor space on the lower level. If space is limited, a spiral staircase or kited staircase (a straight staircase with a 90° turn) may be more appropriate, due to their reduced footprint. On the other hand, if you have a larger volume such as a foyer, where space is less of a concern, then a helical staircase (a curved staircase with no central pillar) can help to make a statement.
‘Clear width’
The staircase width should also be determined by its end use. A main staircase within a home or a public building will need to be wide enough to allow two or more users to pass each other (typically a 900 mm clear width or more). In contrast, a staircase to a utility space can be much narrower (as little as 600 mm).
The key measure for the width of a staircase is the ‘clear width’ (also known as the effective width), this is the unobstructed width of the tread. For example, if a staircase has handrails which overhang the treads on both sides, the clear width is measured from the inner face of one handrail to the inner face of the other.
Minimum clear widths are set for different types of staircase within Approved Document K and BS5395 Part II to the Building Regulations (England and Wales) and Technical Handbook 4 (Scotland).
If you are looking for escape staircases, additional guidance can also be found in Approved Document B and Technical Handbook 2 if in Scotland.
‘Rise’ & ‘going’
Setting the pitch of the staircase is a balancing act. Staircases with steeper pitches have a more compact footprint but are also more challenging to climb, making them less suitable for families with young children or for older users.
The angle is set primarily using the ‘rise’ (the height from the top of one tread to the top of the next) and the ‘going’ (depth of the tread minus any overlap with the nosing of the next tread). Again, minimum requirements are set within the guidance to the Building Regulations and Standards.
In general, it is recommended that to achieve a comfortable step size, the total measurement of twice the rise plus the going (2R + G) should be between 550 mm and 700 mm and maintain a pitch of below 42°. Once set, the rise and going measurements must be the same along the full length of the staircase.
Railing height & gaps
The baluster/railing needs to be sufficiently high to provide owners with the right level of safety. It is generally recommended a height of at least 900 mm to ensure compliance with the Building Regulations, although 1000 mm may be preferred for taller homeowners or public spaces.
In addition, there can be no gaps large enough to allow a 100 mm sphere to pass through on any part of the staircase including the baluster. This means riser bars need to be fitted across open risers and may also prevent recreation of some period designs, for example, where only one spindle may have been used per tread.
A step ahead
Bespoke staircase manufacturers can work with you to refine these key characteristics of the staircase along with the choice of materials, finishes and finer design points.
In practice, virtually every element of a staircase can be adapted to achieve your desired look and feel, from the profile of the tread noses, to the design of spindles. Experienced manufacturers should be able to walk you through the options, for example, discussing the use of open risers or perforated treads to improve light transmission, or how materials such as cast aluminium can provide a lighter alternative to traditional materials such as cast iron – reducing structural requirements.
In addition to traditional drawings, some manufacturers can now provide bespoke 3D CAD services, allowing you to visualise the staircase and make any final adjustments before it is manufactured. The result should be a staircase which fits accurately within the space, and delivers on your design vision.
Antonia Harding is commercial director at British Spirals & Castings