The stairs, now installed, look like this, but this page shows how they got that way...
A full-scale drawing was made in preparation for the intricate work.
This required a drawing board twenty feet long.
Beginning pre-installation under the Big Top. We built a mockup of the stairwell on top of the big drawing. Pre-install will be in 2 stages: Upper & lower levels.
Here you can see the edge of the main floor, sitting up high enough that we can install everything down to the underside of the Garage floor. For stage 2, we will move the Garage floor up high & install the lower 2 flights.
The posts are lying on a table waiting to be bolted to their locations. You can see the finish work on the upper part of the posts, while the lower part still looks skinny, because it is only at the core stage.
Here, you can see the garage level, currently near the ground. It will be up in the air when we get to stage 2. Flight 2 is resting in near-final position, between the steel support and the garage floor frame.
Peter is checking out an adjustment that is needed to allow the flight 2 to assume its final position. The back of the stringer needs to be relieved for the bolts and mounting plate of the steel support. No big deal, but it has to happen!
Closeup of the woodwork: White oak treads & risers are let in 3/8" to solid poplar stringers. Everything is glued & screwed.
Flights 1 and 3, the longer ones, are standing by on a cart, awaiting their turn to be located, drilled & bolted in. Their undersides are ready for sheetrock.
Gary, for scale, standing on the steel support for the main landing, holding onto the rolling hoist which helps us move these heavy pieces into place.
Closeup of the rolling hoist, which will also be used onsite at Washington St. We need this to lower the massive sub-assemblies into the stairwell with only 1/8" clearance to the shear walls.
Beefy 5/8" lag screws, 4 on each 3/8" thick mounting plate, make sure the steel support can never move.
The underside of flight 2 clearly shows the sheetrock supports. Stringers are exposed at the center, hidden at the shear walls.
A view of the whole stairwell mockup, showing the steel support installed.
Peter poses with the 2 models, 1/4 scale & full-scale.
Work is progressing on the main landing. This intersection drives the entire design. The stringer at the west wall will become part of the baseboards, while the plywood/poplar lamination gripping the east side of the step will become an integral part of the base cladding of post #2.
Peter is intent on accuracy as he checks the alignment of the stairs. Incredible as it may seem, you are looking at a week's hard work in the landing alone. Step & stringers for the other landing at the lower level were also made this week.
The underside of the landing is visible here, showing the joists bolted to the steel support, as Peter grinds the weld beads to allow our stairs to fit over the frame.
The step awaits fitting as Peter finishes grinding. Tolerances are tight. There isn't any extra room in the stairwell in either width or length, so our work must fit tightly.
A perfect fit. In this detail, we see the mitered return at tread #8, where it will overhang post #2.
A plywood gusset, laminated to the back of the poplar stringer, bonds the step section to the two levels of the landing at the west wall. It makes sure that the present alignment will remain unchanged during transportation and installation.
A view from above, on the main floor, looking down at the landing. This is what you would see if you were leaning against the railing at the bathroom door.
Post #3 is in place, and the cosmetic stringers have been added, visually doubling the thickness of the stringers and providing a broad base for the balusters and handrails.
By Friday evening, June 24, the solid oak plank flooring has been installed at the 2 levels of the main landing.
Post #2 is seen installed in its place at the main structural junction.
Peter is preparing the slot which will receive Post #1.
Post #1 is now clamped in place and ready to be plumbed and drilled for bolts.
Here we see a good view of flight number one, which descends from the main floor above to the main landing below.
Post number two is through bolted in both directions, through the stringers as well as into the steel support of the landing. These massive joints, in combination with the steel support of the landing, have suspended the staircase in the shaft and eliminated the need for a solid two-story post to support the cuts in the floors and the staircase itself. This is truly structural furniture.
This is the main junction seen from above. From this angle, you can see part of the drawing on the floor.
At the bottom of flight number one, the stringer is bolted to the post, where the staircase turns the corner onto the landing.
At the garage level, we get a view under the main intersection, from the top of a now imaginary flight number three. The gray primer of the steel support is visible.
We get a view over the lower level of the main landing as Peter descends the ladder.
On Friday, July 1st, we completed in-shop work on the upper flights.
The view from the west side.
The view from the east side, garage level, as we prepare to climb the stairs.
Stepping on to the stairs, we see that the posts now have their base cladding, and the handrail and balusters are finished. Post caps and molding details, now missing, will be added at installation. Similarly, the dummy molding along the bottom of the balustrades will be replaced by finish molding.
Beginning our climb, we can see the solid, secure oak handrail and the stringer of Flight #1, above. Visible in this view are the temporary blocks attached to the underside of the stringer, where the ropes will be anchored during installation.
From this position, a glance upward shows the base of Post #1, with its beveled detail, as well as the diagonal line of the massive plywood triangle which simulates the actual cantilever of the main floor in our mockup. Wide poplar stock has already been milled to cover the exposed floor frame, forming a clean fascia.
At the corner, the steps of the landing wrap around Post #2. Here, we see the joint in the post cladding where the landing step joins the post. Carlos's paint work will make this disappear, but it forms a very solid joint between the 2 structures.
Here is a wider view of the corner.
Pausing here, a glance upward shows the upper railings as they intersect Post#1.
Continuing around the corner, we prepare to ascend the next flight.
Looking up Flight #1 from the landing, we can see the horizontal railing at the main floor as it connects Post #1 to the (imaginary) casing of the bathroom door.
Approaching the top, we see a detail of the handrails.
Standing near the bathroom door, this is the view over the railing.
As we turn to descend, the railing of Flight #1 gives a secure feeling.
Here is the same railing seen from the other side, as if we were standing at the bathroom door looking into the stairwell.
The view from overhead.
Our first task of the week was to disassemble everything we had built so far, and reconfigure the mockup to reflect the situation at the lower levels. This was all pretty simple, except for dismounting the enormously heavy landing structure with its steel beam, hardwood floors, and extra bracing. First, we attached the pulley track to a large beam, so it wouldn't fail under the weight.
We added a massive brace of 1 1/8" plywood to the underside of the landing, after deciding that we could take no chances on the our smaller brace at the step being able to keep the landing from flexing under handling and transportation.
A specially fitted cart was built to contain & transport the landing. We lowered the landing onto the cart using our pulley hoist and rolled it off the assembly floor using a temporary ramp. Gary sits happily on the successfully dismounted landing. The ramp can be seen at the bottom.
Our next step was to mockup the existing concrete footing at the basement level, to make sure our stairs would fit perfectly around it.
The garage floor, which was near the ground in our previous mockup, is moved up to its new position.
Here, Peter holds the support post in position as we prepare to fasten it in place. This post, unnecessary in the final installation, is needed here to keep our slender garage floor mockup from twisting under the weight of flight number three with its heavy post. It is the only way we can be certain of true alignment.
Stepping back, we see the support post is now installed.
From this angle, it is easy to see why the the support is needed. Without the triangular brace, the floor could twist or sag.
The landings at this level are much simpler than the ones above. They are basically two framed boxes. The upper one sits on the concrete form, while the lower one is suspended between the concrete and the north shear wall.
We then install flight number four, the lowest flight.
This is followed by flight number three, which descends from the garage level.
We next assemble and fit the landing step, shown here after installation. Again, the complexity of the intersection is is apparent.
Peter studies the intersection as we prepare to install post number four.
Looking over his shoulder, we can see he has plenty on his mind.
Post number four has been prepared for installation. The diagonal block of the base core will sit atop the stringer of flight number three, while its lower core is notched to fit over the concrete footing.
Post number 4 is now clamped in its final position.
A closer look reveals how post number four fits over the concrete footing and drops down behind the stringer of the lowest flight.
At quitting time on Friday, we take another look at a good week's work.