A housing is the recess in a stair string into which a tread is fitted. It is a routed trench in the inner face of the string, taking the end of the tread and, on a closed staircase, the riser as well. Depending on the thickness of the string, a housing is typically around 15 to 20 mm deep.
What it does
The housing performs three jobs at once:
- Bearing — the tread sits on its full end grain in solid timber, not merely on screws or glue
- Setting out — all housings are routed in one operation from a template, which keeps rise and going identical over the whole flight
- Closing — a tight housing prevents the gap where a staircase begins to creak
A staircase built this way is a closed string stair. On an open or cut string, by contrast, the treads sit on top of the sawn profile and there are no housings.
How it is made
Stair joiners work with a template and a router. The template gives the housing a slight taper towards the back, leaving room for the wedges. Once tread and riser have been slid in, timber wedges are driven in from the back in glue. Those wedges press the components against the front of the housing and lock the joint solid.
Points to watch
- Wedges are not a detail. Loose or missing wedges are the most common cause of a creaking staircase. They can be re-driven from underneath with a little glue
- Always rout to a template, even when repairing a single tread; freehand housings never close cleanly
- Allow for movement. A tread that is tight in summer may shrink in winter, so glue inside the housing rather than on the end grain alone
- Replacing one tread means removing the wedges, drawing the tread back out of the housing, and fitting a new tread with new wedges. If the old tread is jammed, saw it through in the middle
- Do not rout too deep. In a 40 mm string, a 20 mm housing leaves only half the material at the thinnest point
Related terms
- Open string stair
- Stair tread
- Tread depth
- Stair run
- Overhanging stair tread
- Nosing
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