How Wide Do Loft Stairs Need to Be?

When converting a loft into a usable room, one of the most important — and often overlooked — aspects is the staircase. It’s not just about style and material; getting the dimensions right is critical for both safety and building regulations. One of the most common questions we get is: how wide do loft stairs need to be? Here’s a straightforward guide to help you plan properly.

Minimum Width Requirements (UK Building Regulations)

In the UK, there are no explicit minimum width requirements for loft stairs in Building Regulations (Approved Document K), but most loft conversions follow the general guideline that the staircase should be at least 600mm wide. This is considered the bare minimum for a space-saving staircase.

However, the recommended width — for comfort, safety, and future resale value — is between 700mm and 850mm. If space allows, a standard staircase width of 860mm to 900mm (around 34-36 inches) is ideal. This provides enough room for comfortable use, carrying furniture up and down, and meeting the expectations of building inspectors and potential buyers.

Why Width Matters

Comfort & Usability: Narrow stairs can feel cramped and awkward, especially if you’re carrying laundry baskets, luggage, or furniture.
Safety: Wider stairs reduce the risk of falls and make handrail installation easier and more effective.
Compliance: While narrow space-saving stairs are sometimes accepted, building inspectors will expect clear justification if your design falls below typical widths.
Fire Escape Routes: In loft conversions, stairs often form part of the emergency escape route. A narrower stair might not provide safe and rapid egress in an emergency.

Space-Saving Stair Designs

If you’re short on space, you might be considering alternate staircase designs such as:

Alternating tread stairs: Compact and steep, typically used for occasional access. These need careful justification and are often only approved for storage or hobby spaces.
Spiral staircases: These can be beautiful and save floor space, but must meet specific requirements — such as having a minimum clear tread width and rise between steps.
Fixed ladders: Generally not permitted for habitable rooms, but might be accepted for access to a non-habitable loft.

Always check with your local authority or a qualified building control officer before deciding.

Practical Tips for Planning Loft Stair Width

Measure the available space carefully: Loft stairs often need to turn, so account for headroom, pitch (maximum 42 degrees), and landing space.
Involve your staircase manufacturer early: A specialist will help design a staircase that’s safe, stylish, and compliant with regulations.
Don’t skimp on usability: A slightly wider stair may mean trimming down a cupboard or moving a partition, but it’s almost always worth it in the long term.

Final Thoughts

In summary, the minimum width for loft stairs is around 600mm, but a width of 700–900mm is far more practical and future-proof. Always balance the constraints of your space with the needs of safety and comfort — and get expert advice before making any final decisions.

Need help designing the perfect loft staircase? Get in touch — we specialise in custom timber staircases that maximise space without compromising on quality or style.

How Wide Do Loft Stairs Need to Be?