The impact of the staircase on the internal design of a home is huge. Get it wrong and it can ruin the entire flow and feel of a house. Get it right, however, and it can be the making of the home — a design anchor around which all the other elements of the interior scheme are hinged.
Perhaps more than any other staircase design, it is the cantilevered staircase that really stands out as something special, creating the illusion of floating, unsupported and weightless treads. “The main reason a client chooses a cantilevered staircase is because of how it looks,” explains Richard McLane, Design Director at Bisca. “A cantilevered staircase certainly has the wow-factor and also adds an element of intrigue around how and what is holding it up.”
It manages to be minimalist while at the same time creating a massive impact and offers enormous variety in terms of configurations and materials.
How Do They Work?
Although they appear to defy gravity, cantilevered staircases are, of course, supported — albeit in a way that conceals all the fixings.
“A true cantilevered staircase is a design where each tread is fixed only at one end,” explain the experts at Kevala Stairs. “The supporting structure is hidden within each tread and behind the face of the wall. There are no supports between the treads.”
The treads making up the staircase are attached either to a string fixed to or within the wall, or to a metal frame or pockets in the wall. There are several ways in which this is done, depending on the project and the method favoured by the supplier.
One of the most common methods relies on the treads being fixed or pegged into a solid wall. Sometimes a reinforcing metal sheet will also be required. In the case of a steel-reinforced concrete wall, it is common for prefabricated ‘anchoring pockets’ to be installed within the framework of the wall before concrete is poured. When the concrete has cured, the formwork can be taken away and treads fixed into place.
In modern builds, however, stud walls are often employed, with steel strings with foot plates and ‘anchoring pockets’ fitted within the floor and wall to support the treads before the wall is plastered. Finally, it is not uncommon for the weight of the treads to be shared, supported on one side by the frame within the wall and by a structural handrail or glass balustrading on the other side.
“Design elements are usually about what’s happening on site; the state of the walls and the position of the staircase dictates the type of underlying (hidden) supporting structure Bisca will use,” explains Richard McLane.
Can They Be Retrofitted?
It is far more common for cantilevered staircases to be fitted in new builds and substantial renovations than in smaller remodelling projects. The reason for this is that they are easiest to install when planned in at a very early stage in the house design — plus the installation in an existing building can be disruptive given the structural support required.
“In a retrofit situation, a structural engineer would absolutely have to be involved,” says Kevala Stairs. The calculations necessary for this type of work to be successful can in no way be left to chance.
“Structural calculations are important for all staircases, but in the case of a cantilevered staircase, are of paramount importance as the supporting wall effectively becomes an integral part of the staircase,” explains Bisca’s Richard McLane.
What Are They Made Of?
Cantilevered staircases offer huge design possibilities. They are most often seen in
Popular material choices include:
- stone (natural or cast)
- composite materials, such as Corian and concrete
Obviously the material you choose will have an impact on the way in which the staircase is supported, with some materials such as chunky timber and stone being heavier than others. Your material choice will also have an effect on what the staircase will cost — timber tends to be cheaper than those made from glass, although the timber you choose will determine by how much.
What About the Cost?
The cost of a cantilevered staircase will be hugely dependent on individual requirements, materials and size. According to experts, they tend to be more expensive than a standard straight flight, but less than an elaborate helical design.
“If you are looking for a feature staircase but don’t want the cost of a helical, then a cantilevered staircase is the obvious statement staircase,” advises Richard McLane of Bisca.
Prices for bespoke cantilevered staircases are hard to estimate as there are so many material options and the engineering can be very complex. For example, Bisca offers a complete bespoke design, manufacture and installation service, with prices starting from £15,000 (including installation). However, this should only be used as guide and some domestic designs can cost six figures.
A new staircase usually means limited access between the floors while it is being constructed. However, with a cantilevered staircase, temporary treads can be put in place to make access easier, with the rest of the construction carried out at the same time.
“Supported from the wall, the installation of a cantilevered staircase does not impact on any existing underfloor heating — an important consideration if the staircase goes in after the floor and heating elements are finished,” adds Richard McLane.
What About Building Regulations?
While cantilevered staircases are often admired for their apparent ability to float mid-air, many people do express concerns over their safety and how they will conform to Building Regulations.
Providing the treads satisfy the minimum requirements in terms of how far they are apart and that the maximum and minimum pitches for domestic staircases are adhered to (see Approved Document K of the Building Regs), it is the lack of handrail that worries most people.
However, Approved Document K states that: ‘Flights should have a handrail on at least one side if they are less than one metre wide and on both sides if they are wider than one metre. There is no need for handrails beside the bottom two steps of a stairway. Minimum domestic handrail heights should be 900mm for both stairs and landings. It is also a Building Regulations requirement that no openings in any balustrading should allow the passage of a 100mm sphere.’ The installation of a solid glass screen will satisfy this requirement and be true to the minimalist look of the staircase.
Of course, you will still need to consult with your Building Control officer to check your staircase complies with the Building Regs, and consider the safety implications if you have small children.