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Getting the size of staircase you want 

04 September 2020

Timber Spiral Staircase and Balustrade

A staircase is a fairly unusual purchase so when our customers first get in touch with us, they have usually done some looking around. One thing we hear all too often is that they’ve been advised that they can only order their spiral staircase in specific diameters. Nothing could be further from the truth! 

The myth of limited sizes 

In most cases, the reason that suppliers only offer a limited number of sizes is because they are mass produced ‘kit staircases’. The obvious advantage of this approach is that the staircase itself can be sold at a lower price. If you are working on a particularly tight budget then this might be the best option, just make sure you read some reviews of the company and ensure their products are correctly CE marked the last thing you need is to end up with a staircase which is potentially unsafe! 

Whilst we offer a number of standard sized items in our cast iron store, including grates and railing components, our staircases are all manufactured bespoke for each project. There is a simple reason for this. In our experience, every project we work on has its own unique requirements. 

The most obvious factor is the design and dimensions of the space where the staircase is going to be installed. Here in the UK, buildings come in all shapes and sizes and when you’re dealing with older properties you have to account for wonky or sloping walls and uneven floors.  

However, bespoke design is about much more than simply adapting the staircase to the space, it also needs to be shaped around the needs and tastes of the people who live within the property. If you walk down a suburban street, you can see people decorate identical spaces in all types of different ways and a staircase should be just as adaptable.  

For example, homeowners with a young family may want a wider spiral staircase to allow their children to safely pass each other going up and down. On the other hand, a single person might prefer a more compact diameter which has a smaller footprint in the room below.  

What are the actual limitations? 

In practice, the only limitations on staircase size come as a result of safety requirements or practicalities. Most countries set limitations on the width of staircases to ensure you can evacuate safely in the event of an emergency. Here in the UK, for example, this is measured as the clear width of the staircase. The minimum requirements within the Building regulations and standards here in the UK are shown below: 

Stair category Clear width (mm) Minimum Staircase Diameter (mm) 
Small private spiral staircase — used by a limited number of people e.g. a staircase in a home which doesn’t go to a communal room like a kitchen or an access stair to a small room not used by the public for a commercial property. 600 1448 
Private spiral staircase — a main staircase within a home 800 (900 in Scotland) 1830 (2083 in Scotland) 
Small semi-public* spiral staircase — used by a limited number of people such as a communal staircase leading to more than one flat. 800 (900 in Scotland) 2100 (2300 in Scotland) 
Semi-public* spiral staircase — used by a larger number of people such as a stair serving a large area in a factory, office or shop. 900 2300 
Public spiral staircase — intended to be used by large numbers of people at the same time (meaning room is needed for passing). 1000 2500 

* defined as a space serving up to 50 people and serving a limited floor area 

If space is particularly limited, then the English and Welsh regulations actually allow some additional wiggle room, but this is down to the discretion of the building inspector. Also if the staircase is secondary access to an area then there is no width requirement imposed although we would always encourage you to think not just about the size but the size that will be fit for purpose. 

In addition to these limitations, there is also often a set requirement for headroom above the treads on a staircase. Here in the UK this is typically 2000 mm (it can be reduced to 1900 mm with permission from the building inspectors). If the space you are installing the staircase in has a sloped ceiling, this may mean you have to limit the overall diameter to ensure the space above the treads is sufficiently high. 

From a practical perspective, installing extremely wide treads may also be undesirable simply because of the size of support these would require.  

What sizes can British Spirals & Castings offer? 

Our spiral staircases begin at a diameter of just 970 mm. In our experience, this is the slimmest you can design a spiral staircase and still ensure it is useable. At the other end of the scale we have produced staircases of 2500 mm and beyond. These extremely wide staircases are typically only used within commercial or public buildings where there is likely to be high volumes of foot traffic going up and down the staircase at the same time. 

Between these two, we can produce staircases in virtually any dimension to suit your particular project or needs. For our cast metal staircases, we will generally try to find an existing pattern sizing which will suit your project as this will help to keep overall costs lower. If you have specific requirements, however, we are more than happy to meet them. In the past we have created whole patterns simply based on the particular needs of a homeowner. 

Of course, we can also adapt the height of the staircase and incline of the treads to meet your needs along with tailoring virtually every other element of the staircase from the design and number of spindles per tread, to the choice of riser bar and handrail material. 

Bespoke means just that. We expect our staircases to fit your home and life as perfectly as a custom-made suit from Savile Row and will happily meet your specific requirements. Take a look at our gallery and submit a quote and we’ll help you to achieve your dream design. 

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