Loft Staircase Cost Calculator
The staircase is usually included in a loft conversion quote, but it is worth pricing on its own — it is the item most often value-engineered, and Part K sets hard limits on what a builder can do in the space available.
Open the calculator →Price your loft staircase in 30 seconds
4 steps. Stair type, material, fitting and region.
How this calculator works
A loft stair is a geometry problem before it is a price. Part K fixes the rise, the going and the pitch, so the length of landing you have available decides which shapes are legal — and that, far more than the timber, decides the cost.
The third question is the one that moves quotes most. A stair that lands over the existing stairwell changes nothing below it. One that takes space from a bedroom brings a stud wall, a new doorway and redecoration with it.
On space-savers: alternating-tread stairs are allowed only where a conventional stair will not fit, and only to a single room that is not a principal habitable room. Building control will ask. Do not design around one without checking first.
Loft staircase cost by type (2026)
| Staircase type | Typical 2026 cost | Notes |
|---|---|---|
| Straight flight, softwood | £1,500–£2,500 | Needs a long landing |
| Quarter-turn / winder | £2,000–£4,000 | The usual loft answer |
| Spiral | £2,200–£4,500 | Compact, awkward for furniture |
| Space-saver (alternating tread) | £1,200–£2,200 | One non-principal room only |
| Bespoke hardwood, glass or steel | £4,000–£8,000+ | Priced as joinery |
| New opening in the landing | +£500–£1,000 | Trimmers and making good |
| Fire door onto the enclosure | £150–£400 each | Part B, per door |
Figures match our loft staircase guide. Part K and Part B rules are set out in loft conversion stairs.
What changes a loft staircase quote the most
Where the new stair lands is the whole cost story. Rising straight up over the existing stairwell is cheapest because nothing on the floor below has to move; taking space from a bedroom below adds a new doorway, making-good and often a lost or reconfigured room, and that knock-on work is usually worth more than the stair itself.
Building Regulations set the shape and they are not negotiable: a minimum going and pitch, at least 2m of headroom over most of the flight (1.9m at the edge), and — because a loft is a third storey — the stair must sit in a protected enclosure with fire doors onto it and mains-linked alarms on every floor. Those Part B requirements, not the timber, are what turn a simple flight into a bigger job.
Materials come last: a softwood flight is the baseline, while oak, a glass balustrade or a steel spine is priced as joinery and can multiply the cost. If you are pricing the stair as part of a wider conversion, use the loft conversion cost guide to see where it sits in the total.
Loft staircase calculator FAQs
Normally yes, at a standard painted softwood specification. It is also the most common thing to be quietly downgraded, so ask what stair the price assumes and what an upgrade costs before you sign.
Only where a conventional stair genuinely will not fit, and only serving one room that is not a principal habitable room. Building control will ask the question. Designing around one and then being refused is an expensive way to find out.
Two metres normally. In a loft conversion that is relaxed to 1.9m at the centre of the stair width, which is what makes conversions possible under a sloping roof at all.
Because the loft adds a storey, and Part B wants a protected route from the new room to the front door. In practice that means fire doors onto the stair enclosure and mains-linked alarms on every floor.
Related cost guides
- Loft staircase guide — Part K, step by step
- Stair regs explained — rise, going and fire doors
- Loft conversion costs — every type priced
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