The parts and how they connect.
Cut string staircase without tread brackets.
The cut string staircase has the stringers cut to sit under the treads and behind the risers, this is more involved than routing out a housing for the treads and risers into the closed string.
This is further complicated when the staircase is to have a natural finish rather than painted; as no fixings can be used through the riser faces.
The stringers although made from the same width stock as closed strings, will have large sections cut out. To overcome this, either thicker material or carriages are used, in many cases, both are used for strength and longevity. I have worked on many flights that are over a hundred years old and are still solid without any bounce, cracks or creeks.
The stringer is cut to sit under the tread and flush with the face of the riser. The tread sits on the stringers while the riser sits between the visible stringer faces.
The riser faces are mitred to allow the riser to come through to the stringer face.
The stringer riser face.
The vertical face for the riser is cut with a 45º leading edge, the ends of the riser will have a similar angle cut onto them, allowing for the stringer and riser faces to meet
On a cut string staircase, the tread will sit on top of the stringer, the end of the tread finishing flush with the visible face of the stringer.
Allowing for the return nosing.
The tread will initially be cut with additional length to allow for the projection of the return nosing, this will then be mitred back to run flush with the stringer.
The return nosing.
The return nosing is mitred onto the end of the tread overhanging the stringer.
On straight flights, the mitres are at 45º.
The grain is at 90º to that of the tread.
Both ends of the return nosing are mitred, with a small return – return nosing to return the back end of the return nosing to the side of the stringer.
The underside of the tread will be rebated to let the top of the riser in, there are a number of ways this can be done.
- On the high end stairs from the 19th century, the full thickness of the riser and the thickness of the scotia would be rebated in.
- The tread is rebated just for the width of the riser.
- The tread is rebated to half the width of the riser, this allows a shoulder line that the tread can sit onto or that the riser may be pushed home up to.
Riser to cut string mitre.
The end of the riser where it meets the cut string may be formed in 2 basic ways.
The first is that the riser end is mitred the full way through the thickness of the riser.
This will require a bit more effort to alighn the mitres correctly during assembly.
The riser will be cut at 45º for straight treads, this will also work for many of the winders.
Should the riser angle be too acute for a 45º mitre to work, then the angle between the riser face and stringer face may be bisected.
The riser face of the stringers will be mitred back in to match that of the riser, to the thickness of the riser.
The rest of the stringer thickness will be cut at the same angle as the face of the riser.