A concrete staircase is formed rather than assembled, which means the design decisions — going, rise, landing position, reinforcement layout — have to be settled before any shuttering goes up. On a Cranbrook job that usually means working around either a narrow village access on Stone Street and the surrounding lanes, or a modern plot on one of the 1990s estates where access is easier but the finished stair still has to sit inside a fixed stairwell opening.
We build the formwork from engineered ply, set the reinforcement to the structural engineer's schedule, and pour in a single continuous lift wherever the flight length allows, because cold joints in a stair flight are one of the most visible defects a client will spot.
Access and delivery in the village core
Stone Street and the lanes running off the High Street are narrow, and pumped concrete deliveries need a wagon position agreed in advance rather than assumed on the day. Where the site sits within the Cranbrook Conservation Area, we also check whether a temporary road closure or banksman is needed for the pour, since concrete lorries cannot simply wait at the kerb here the way they might on a wider estate road.
For properties on the newer estates off Angley Road, access is more straightforward, but we still confirm turning space for a boom pump if the stairwell sits at the rear of the plot, because a line pump with a longer hose run changes the site programme and cost.
Formwork and reinforcement sequence
The soffit shutter goes up first, built to the exact geometry of the flight, followed by the reinforcement cage tied to the engineer's bar schedule and lifted clear of the shutter face on spacers to maintain cover. Riser boards are fixed last, checked for line and level before the pour, because any inaccuracy here shows immediately once the shutter is struck.
Where the stair returns against an existing wall — common in the older weatherboarded cottages where a new opening has been formed for a replacement staircase — the shutter has to be scribed to the wall's actual line rather than assumed straight, since these walls were rarely built dead true.
Curing time and site sequencing
Concrete needs a fixed curing period before formwork is struck and before the stair takes construction traffic, and this cannot be compressed to suit a tight programme. On a renovation where the staircase is the only route between floors, we agree a temporary access route with the client before the pour so the house remains usable during the cure.
Where the project also includes structural alterations to the surrounding stairwell — widening an opening or removing a chimney breast nearby — that work is sequenced either well before or well after the pour, never during the cure window, to avoid vibration reaching the setting concrete.
Finish options for the flight
A polished or ground finish exposes the aggregate and needs a slower, more controlled pour with tighter formwork tolerances, since any blemish on the soffit or riser face is visible in the final surface. A board-marked or shuttered finish, by contrast, deliberately leaves the timber grain of the formwork as a texture, which is more forgiving of minor formwork imperfections and suits a more industrial finish.
Both finishes need a sealer applied once curing is complete, and the sealer choice affects slip resistance on a flight that will be used daily, so this is agreed with the client rather than defaulted to whatever look better in a sample.
Consent and building control
A new concrete staircase replacing an existing timber one, or forming a new stairwell as part of a wider structural alteration, falls under Building Regulations for stair pitch, headroom, going and rise, and building control sign-off is required regardless of planning status. Where the property sits within the Cranbrook Conservation Area but the stair itself is entirely internal, planning permission is not usually needed, though any change to an external opening to accommodate the new stair would be.
We handle the building control notification and inspection stages as part of the project rather than leaving it for the client to coordinate separately.
Common questions
Can a concrete staircase be cast in an existing house, or only in new builds?+
It can be cast in an existing house, but the surrounding structure needs opening up enough to build the formwork and get reinforcement and concrete in, and the floor is generally out of use for the duration of the pour and cure.
How long before the stair can be used after pouring?+
The concrete needs its full curing period before formwork is struck and before regular traffic starts, so a temporary alternative route is agreed for that period rather than trying to shorten the cure.
Does a concrete stair need planning permission in Cranbrook?+
An internal stair replacement is normally Building Regulations matter rather than planning, but if the works alter an external wall or opening — more likely on a listed or conservation-area property — planning should be checked before starting.
Book a free site visit for your Cranbrook concrete staircase
We'll assess access, the stairwell opening and reinforcement needs, then provide a written itemised quote.