Staircase science – all the numbers you need to know

If you’ve settled on a style and picked out all the parts you’ll need to breathe new life into your staircase, all that’s left is to install it. If you’re taking on parts of the installation yourself, you’ll no doubt have a number of questions. For example, how big should it be? Do I need a handrail?

Don’t worry. To help you plan ahead for 2020, we’ve trawled the official regulations and guidelines to compile all the details you need to be aware of when installing a staircase. 

Do my stairs need to be at a particular angle?

The overall staircase should have a maximum pitch of 42 degrees and there must be headroom of at least two metres (2000mm) to allow people to pass down the stairs normally. 

How wide do my stairs need to be?

There’s no minimum or maximum width when it comes to stairs, but most fall between 800mm and 900mm. The average is around 860mm. 

How deep does each step need to be?

You’ll obviously need enough room to step on to each individual step. This is called ‘the going’. Each step will need to have a minimum going of 220mm. Under UK regulations, each step also should have a ‘nosing’ – essentially an overhanging lip. This should be at least 16mm and is incorporated into the overall ‘going’ of each step. 

Do I need a handrail?

Put simply, yes. But how many depends on how wide your staircase is. If your stairs are more than one metre (1000mm) wide, you’ll have to have a handrail on both sides. If your stairs are under one metre wide, you’ll just need to install a handrail on one side.  Any handrail also needs to be placed at a minimum height of 900mm. 

You can read more about handrails in our useful guide.

How many spindles or balustrades do I need?

It’s important that you have enough spindles or balustrades spaced out equally so no opening would allow a 100mm ball to pass through it. 

This is also the same for the space between any open risers between steps.

Do I need a landing?

Yes, it’s a regulatory requirement to have a flat surface at the top and bottom of each flight of stairs. This space must also be wider than the stairs themselves. And if you are installing new doors, these must not swing open any close than 400mm from a step. 

Remember to check

We do recommend that you do your own checks as regulations may change over time.

For more information, you can view all building regulations on the Government website.