Cantilevered Stairs

Several people have asked me how these stairs are built. The look like they cantilever farther than they actually do. These stairs actually only cantilever 12-18 inches. 

There is a retaining wall underneath the stairs and a portion of the stair is built on-grade. Then outrigger forms are built to hold the cantilevered slab. What is different about these stairs is that the formwork creates the bottom of the stairs and the top is conventional stair forming. 

My typical trick is to paint the vertical wall under the stairs a darker color than the wall beyond to create the illusion of more depth. Color is your friend. 

These white cement stairs were my first attempt at this style of stair. 

The finished stair only has a 12 inch cantilever but the illusion is that the stairs are completely cantilevered.

A canal bank project using the same technique in a more industrial style. 
I typically hold the handrail back from the edge of the steps for increased structural support. 

Stairs at the Ocotillo Road residence which beckon you out into the desert. 

Again, a 12 inch cantilever looks much greater.

Stairs are formed on grade next to the wall and cantilevered out toward the foreground.

Here you can see the two types of formwork. The stairs bottom is formed on the left and the right of the stair is on grade.

The masonry support wall is set in 12 inches from the outside of the stairs. The area to the right of the wall has been filled with soil to support the stairs on-grade. The 12 inches to the left of the support wall is the formwork for the bottom of the cantilevered section of the stairs. The support wall is built to mimic the bottom of the stairs.

The landing is built is built on a wooden platform similar to the way we built concrete countertops. 

The steel posts will support a glass fence.

The bottom formwork stayed in place for three weeks while the concrete cured.

We were working around boulders left over from the previous backyard design. This large boulder visually interrupted the stairs so we ended up buried it in the ground another 12 inches.

I used the same stair detail for the recent Soleri bridge and plaza project. In the photo below, the interior support walls are made out of shot concrete. The steps in the concrete wall mimic the bottom surface of the stairs. 
Outrigger formwork forms the cantilever section of each stair.

This stair cantilevers on both sides.

The stair cantilever continues along the plaza slab using the same outrigger formwork.

Same view with cool toys
Finished stair with handrails. 

Palm Spring, California

During this backyard remodel we designed a new swimming pool that was to be viewed from the entire house. The glass walled bathroom had an existing hedge that provided privacy to the bath but also blocked the view to the new pool. The answer was to create some type of movable screen.

After many sketches I decided that louvers were in keeping with the mid-century architecture style of the house and neighborhood. Once louvers were decided upon, I thought how can I make them cooler looking?

The optimum look would be:
  1. Motorized, switched on/off from the bathroom
  2. Cantilevered off the base
  3. Translucent so sunlight would illuminate them
  4. Internally lit, also switched on/off from the bathroom

I didn’t have any idea of how to actually do this when I started the design.

My first step was to contact Arlon Lewis, a metal fabricator that I had worked with before. He came up with the motor and the steel structure. He suggested using a linear actuator motor, which I had never heard of.

I took the plans to American Fiberglass. I had interior supports for the fiberglass shell and J.B. told me that the fiberglass was so strong it only needed to be bolted to the base.

The light was a challenge also. We had a slot cut in the post as well as the louver base, which has a cover plate over the opening.When the louvers were aligned to a certain point you could reach into change the bulb.

For the light I used a taillight socket from a 1990 Volvo. (from the auto parts store)

Fabricators are a great resource to figure out how to do things. Not only do they know how to make complicated ideas happen, they know about secret tools and gadgets specific to their profession. 

Click on image for larger picture

The steelwork for the louvers were custom made by Lewis Machine & Welding in Mesa, Arizona

The fiberglass fabrication was done by J.B. Donaldson of American Fiberglass.

Glass Bead Concrete Treatment

This is a detail I sometimes use in exposed aggregate to give the concrete more sparkle and interest; these are glass marbles from the hobby store that have a flat side. We push them into the concrete before it sets up and the concrete locks them into the slab. They only work in exposed aggregate finishes.