A staircase in solid oak

Six weeks from the first cut to the final coat is a realistic schedule for a staircase in solid oak, and most of that time goes into work nobody sees once it is fitted. The part that decides the job is usually the curved string — the one component that has to be right first time.

Measuring before anything is cut

A staircase is built to a room, not to a drawing. The joiner measures the total rise from finished floor to finished floor, the opening above, and every wall the stair will touch. From those numbers come the rise and going of each step, and they have to be equal from top to bottom — a single step that is a few millimetres out is the one people trip on.

The oak needs time as well. Boards are chosen for straight grain and left in the workshop to settle before they are machined. Timber cut too early keeps moving after it is fitted.

The curved string

A straight string can be cut from one wide board. A curved one cannot — cut from solid, the short grain across the curve would split under load. The usual answer is to laminate it: thin strips of oak, glued and clamped over a full-size form that carries the exact curve, with a little spring-back allowed for. Once the glue has cured, the strips act as one piece.

Everything depends on the form, which is set out from the site measurements and checked first. The glue-up is one continuous job: every strip coated, every clamp tightened before the glue starts to set. A mistake found the next morning cannot be undone, which is why the dry run without glue is never skipped.

Treads, housings and assembly

• Housings by template. On the curve, each housing for a tread is set out individually and routed against a template, because no two sit at quite the same angle.
• Dry assembly first. The stair goes together in the workshop without glue, so a rocking step is found on the bench, not on site.
• Extraction on every cut. Routing and sanding oak produces fine dust, so the router and sanders run coupled to a dust extractor throughout.

The final coat

A stair takes more wear than almost any other joinery. The surface is sanded through the grits without skipping, and the finish — usually a hard-wax oil or a hard-wearing lacquer — goes on in thin coats, each allowed to cure. It has to resist wear without becoming slippery. Then the stair is fitted, and six weeks of work is judged by the first person who walks up it without looking down.