Sunday, July 7, 2013

A Staircase Saga, Part 3. The big flight.

The staircase I am building completes it's ascent with a big straight flight, with Tread Nos 11 - 20. The whole staircase will be a very functional and beautiful feature in an 1930's Art Deco home which is being renovated. Lucky me ...  I am blessed with the task of providing a significant amount of the carpentry, joinery, and cabinetwork within the building. It's such a privilege!

The planning process is outlined in an earlier post: A Staircase Saga, Part 2. Getting Started. Having done the planning, then bought and dimensioned the stringers, it was time to get stuck into building the big flight. This would be the first part of the staircase build, as it would determine the position of the opening on the top floor. It would need to be in place before the plasterers and gyprockers could do their thing and would become part of the structure of the building once everything had been built around it. It would be in place for some months before the rest of the staircase could be completed.  It was also going to be very heavy!

I started setting out the treads and riser-board positions on the stringers. With these drawn in place, I then made up a couple of jigs for the router to enable accurate housings to be consistently cut.
The tread housings were cut by the router using a purpose made jig.
The pair of stringers with tread housings completed.
A different purpose made jig was used for cutting the riser board  housings.
With all the housings cut, it was time to fit the treads and riser boards. 
Making the treads. The intention was always to recycle the old jarrah rafters from the original roof into the treads. The rafters were docked oversize, scrubbed with a wire brush, scanned with a metal detector and de-nailed as required. I then machined the material, flattened and dimensioned the sticks to 47mm thick and as wide as possible for each individual stick. Suitable wider boards from the roof timbers would be machined to create the riser boards, finishing at 18mm thick.
Rafter sections (right) cleaned up ready to be machined, and potential riser boards (left). 
Three treads simultaneously glued and cramped.
A 1/4" plywood spline, 25mm (1") wide, was inserted full length in each join in the treads, and epoxy glue was used for the joints. It worked out mostly at 3 rafter pieces per tread. When the glue was dry, these treads were machined to the required 45mm thickness.A finished tread depth (width) of 282mm was required for each tread. The riser board face sits 16mm (5/8") behind the  nosing of the tread, so I machined the required groove on the underside of the treads, ready to take the tongue (a barefaced tenon) on the top of the riser boards. The noses of  the treads were rounded over with a 1/4" radius rounding-over router bit.
With the treads, risers and stringers prepared, it was time to put it all together. Well, it was going to be too heavy to put together in my workshop and deliver to the site - so it was going to have to be assembled on site. Each of the joints was individually test fitted at my workshop, then all the components taken to the building site ready for assembly.
The test fitting of the treads and risers in full swing.
View of some tread ends, showing construction with plywood tongues in the joints.
Lookin' good... from the back of the stairs.
The big flight was glued and assembled on site, on a pair of sawhorses right below the opening in the floor above, and then two chain blocks I had rigged were used to lift the big beastie into place.
Much careful planning by way of a scale drawing of the wall.and floor joist structure at the top end, and the preparation of the top of the stringers had been undertaken during the construction of the stringers, which enabled the stringers to be parked on the top of the wall plate when the top flight was lifted into position. While getting it all up there was a challenge, it finally went beautifully into place. It was a winner! Props were placed and secured, to hold the lower end in position, and several fixings put into the wall through the underside of the stringer against the wall. A couple of bolts through the top of the stringers into the floor joists, and the big flight was in place.

The next step was to build the wall on the kitchen side of the big flight, joining the outer stringer to the floor joists and ceiling above. Below this stringer and the big flight will in be the mini-laundry behind doors. The big Blackbutt posts framing the laundry area would also serve as the props for the outer stringer.
The upper wall frame being built around the top flight.
The big flight was in place. Nothing else would happen on the stairs for a few months, until the other trades had completed all their work around the big flight and the openings top and bottom and through the wall.

Great to see once again how careful planning and preparation has once again paid off.
While I had plenty of other tasks to get on with around the building site, I would be looking forward to getting back onto the stairs again downs the track...