Do wooden stairs need to be fire rated in a house?

This is one of the questions the trade answers vaguely and often gets wrong, so it is worth being plain about. In a normal two-storey house, your wooden staircase does not need to be fire rated, and the timber does not need a fire class. What the fire regulations actually care about is escape, and that only brings the staircase into scope once the house gets tall enough. Here is where the line sits.

The ordinary house: no fire rating on the stair

Fire safety in homes is covered by Approved Document B, Volume 1. The part that sets reaction-to-fire ratings, the resistance to flame spread, applies to the surface linings of walls and ceilings. A staircase is neither a wall nor a ceiling, and the document specifically excludes narrow members like skirtings and mouldings from the "wall" it is talking about. So in a standard two-storey home there is no fire class the treads, strings or handrail have to meet. You choose the timber on looks, wear and budget, not on a fire rating.

What actually triggers a protected stairway: the 4.5m rule

The staircase comes into scope when a house has a floor, a habitable storey, more than 4.5m above ground level. In practice that means a third storey, and the most common way an ordinary house gets there is a loft conversion. Once you cross that line, the stair has to become a protected stairway: an escape route enclosed in fire-resisting construction, rated REI 30 (thirty minutes), leading to a final exit, with fire doors protecting it. For a loft conversion the document is explicit that fire-resisting doors (E20) and partitions (REI 30) should be provided, including upgrading existing doors where needed. Higher again, above 7.5m, you need an alternative escape route or a sprinkler system to BS 9251.

So the fire question is not "is my staircase fire rated", it is "does my house need a protected stairway", and the answer turns on height, not on the wood.

The fire-door confusion: FD20 or FD30

One point that trips people up. The code figure for the doors on a protected stairway is E20, the European expression of the old FD20, a 20-minute fire door. But FD20 doorsets are effectively obsolete and hard to certify on the market now, so in practice building control accepts FD30 (E30) as the nearest available door. If a quote or a builder says FD30, that is normal: the regulation says 20 minutes, the real-world doorset is 30.

Class 0, 1 and 3 are the old language

You may still see timber or finishes described with British fire-spread classes: Class 0, or Class 1 and Class 3 surface spread of flame under BS 476. These are the legacy national terms. Approved Document B now uses the European reaction-to-fire system to BS EN 13501-1, where classes run A1, A2, B, C, D, E, F with smoke (s) and flaming-droplet (d) sub-ratings, for example B-s3,d2. The old classes only survive for products already tested and lawfully on the market, and they do not automatically convert to the European ones. If you are being sold a "Class 1" tread as if it is a current requirement for a house stair, it is neither current language nor, in a normal home, a requirement at all.

The bottom line for a timber stair

In an ordinary two-storey home, pick your staircase timber for how it looks and wears, not for a fire class, because there is not one to meet. If your project adds a third storey or converts the loft, the fire requirement is about enclosing the stairway to REI 30 with fire doors, not about the species of the treads. It is worth getting this straight early, because it is a Building Control matter that is far cheaper to design in than to retrofit. See the building regulations overview and Building Control approval.