Loft Conversion Stairs: Design Advice, Building Regs and More

Loft Conversion Stairs - Simply Lofts
Simply Loft maximized space in this mansard loft conversion by fitting the new staircase to sit above the existing flight. The same materials were used to create a seamless transition between old and new (Image credit: Simply Loft)

Loft conversion stairs are tricky to get right. Not only will their location play a part in how you use your newly converted space, but also affect how the existing house flows. 

Also, did you know that badly designed and commission loft conversion stairs are one of the more common reasons that loft conversions are failed by building inspectors? 

While any reputable loft conversion company will have expertise in loft conversion stairs, if you're working with a general contractor or even DIYing your loft conversion, the design and how it meets regulations is important to get right from the get go. If issues aren't discovered until later, your loft stairs may need major structural alterations, which will also come with a large cost implication.   

Where Should Loft Conversion Stairs be Located?

In an ideal situation, your loft conversion stairs would be above the existing stairs as this is the most space efficient solution. "This is the best way to try and make the new stairs look like they have always been there too," says Emma Tucker from Simply Loft. "In short we want the loft stairs to just feel part of the original home."

Do You Have Sufficient Headroom for Your Loft Conversion Stairs?

Ensuring that there’s the right amount of headroom above your loft conversion stairs is of fundamental importance, as it can be virtually impossible to rectify matters retrospectively. 

It obviously helps a great deal if accurate dimensions are clearly marked on the working drawings so that problems can be spotted early on. This should go a long way to avoiding the nightmare scenario where lack of headroom only gets flagged up at the 11th hour — when a disgruntled homeowner complains they have to duck to get into their new accommodation! 

stairs up to a loft conversion in a terraced house

Creating a turn in loft conversion stairs ensures the staircase emerges at a point of the room with the most headroom.  (Image credit: Simply Loft)

In most cases, Building Regulations stipulate a minimum of 2m clear headroom along the entire length. Because of the associated risks of falling and injury, the Building Regulations are pretty rigorous with stairs, stipulating minimum dimensions for handrails, balusters, steps (goings, risers and winders), and the maximum pitch.

However, when it comes to loft stairs, the rules are more relaxed, allowing for the fact that awkward sloping ceilings often need to be accommodated. Here the minimum headroom on the low-ceiling side can be as shallow as 1.8m rising to 1.9m in the centre of the staircase width and 2m on the inner side. 

Whilst this is a real help, it can still sometimes be a tall order to make it all fit where space is tight.

What Can I Do if I Have Insufficient Headroom for my Loft Conversion Stairs?

The main challenge when designing loft conversion stairs is that there always seems to be an inconvenient roof slope just at the point where you want them to enter the loft. 

Where restricted headroom is an insurmountable problem, such as when looking at loft conversions for difficult roof constructions, it may necessitate switching to ‘Plan B’  — moving the stairs to a more central location under the roof’s highest point.  

The trouble is, if the staircase now pops up just where the double bed was meant to go, it could easily wreck your carefully devised plans for the new living space. 

It may also complicate matters on the floor below if an existing bedroom needs to be partitioned to make space for the new stairs rather than placing them directly above the main staircase. 

Loft Conversion Stairs by The Gentleman Architect

Designed by The Gentleman Architect, this geometric loft staircase features a bespoke oak handrail with soft backlighting for extra wow factor  (Image credit: The Gentleman Architect)

Experienced designers know that the optimum solution is often a modified ‘Plan A’ — where additional headroom over the stairs is created by:  

  • Extending the roof with a new dormer window
  • In marginal cases, installing a small roof window that adds an extra 100mm or so of headroom might just do the trick 
  • At the other extreme, hipped roofs sometimes require drastic surgery to break free from their low roof slopes on all sides by creating a hip to gable loft conversion

It’s important to note however, that any alterations to the external profile of the roof must be factored in at the design stage, otherwise construction work may need to stop on-site while a new planning permission application is made, with no guarantee of success.

Loft Conversion Stairs by Amos Goldreich Architecture

Amos Goldreich Architecture designed this bespoke winding staircase to maximise space within the tight footprint of the house. Solid oak treads match the property’s existing staircase, with timber slats spanning the full height of the stairs providing a safe enclosure  (Image credit: Olly Hammick - Stairs)

Designing Your Loft Conversion Stairs

New loft conversion stairs generally work best where they’re designed to match the existing main stairs, ideally appearing indistinguishable from those in the original house. This doesn’t mean they have to be configured as a straight flight, however. 

Loft conversion stairs by Inglis Badrashi Loddo

Designed by Inglis Badrashi Loddo Architects, this loft conversion was hidden behind the existing brick gable end of the house. The new flight is an extension of the existing staircase up from the ground floor, and features a curved stringer to echo an existing arch on the landing  (Image credit: Brotherton Lock)

To circumvent awkward obstacles like chimney breasts and low roofs, loft stairs are often designed to change direction with one or more L-shaped quarter turns, either with landings or tapered steps (known as winders). 

What Fire Regulations Apply to Loft Conversion Stairs?

Whatever style your new loft stairs ultimately take, they will need to comply with fire safety regulations.

In most loft conversions, the stairs form part of the ‘escape corridor’ and need to have a minimum of 30 minutes protection from fire. This can normally be achieved if they are located within a fire-protected zone or by lining with fire-rated plasterboard with a skim plaster finish.

A fire-rated lobby is also usually required, with a suitable fire-door located either at the top or bottom of the new loft stairs. Also, where an existing bedroom is partitioned to accommodate the new stairwell, the walls also need to provide a minimum of 30 minutes fire resistance.

Space-Saving Loft Conversion Stair Ideas

Where space is very tight, and conventional stairs simply can’t be made to work, the Building Regulations provide a certain amount of flexibility. Building Control has discretion in these matters, so it’s important to hammer out the details at the design stage. 

a compact loft conversion stair idea

Patalab Architecture are the brains behind this striking black stained timber staircase. The flight is positioned within a triple-height space that runs through almost the entirety of the building’s depth. Rooflights have been positioned above to bounce natural light around   (Image credit: Lyndon Douglas)

There are a number of potential options where it may be possible to use special compact loft conversion stairs, such as:

  • Alternating tread stairs are designed with each paddle-shaped tread projecting in turn – similar to nautical stairs in small yachts
  • Fixed ladder stairs combine the flexibility of a ladder with the stability of conventional stairs, with a typical incline of 60%. Retractable ladders are not acceptable
  • Spiral stairs can add a sense of style, saving space and volume with a vertical ‘tunnel’ stairwell

How Much do Loft Conversion Stairs Cost?

When it comes to stairs, the cost will depend on the type of staircase you choose and the quality specified. You can expect to pay the following, depending on your choice. 

  • Simple staircase: £1,000-£2,000
  • Bespoke staircase: £5,000-£8,000+
  • Alternating tread staircases: £250-£400
  • Fixed loft ladder: £200-£300
Ian Rock

Chartered surveyor Ian Rock MRICS is a director is and the author of eight popular Haynes House Manuals, including the Home Extension Manual, the Self Build Manual and Period Property Manual.

Ian is also the founder of Zennor Consultants. In addition to providing house surveys, Zennor Consultants provide professional guidance on property refurbishment and maintenance as well as advising on the design and construction of home extensions and loft conversions, including planning and Building Regulations compliance.

Ian has recently added a 100m2 extension to his home; he designed and project managed the build and completed much of the interior fit-out on a DIY basis.