Sunday, 3 July 2011

The impossible staircase by Div De Villiers

I have lifted this from Divs own web site,many thanks Div.


The impossible staircase

Sun, 02/07/2010 - 22:37
by Div

Sometime last year I was approached by a client who wanted a very unusual staircase. It had to consist of a single beam with the treads straddling the beam. To make matters interesting, the beam had to have the shape of a bow when seen in plan view. To make matters even more interesting the beam also had to have concave sides when seen in section, wide at the top, narrow at the bottom.

No structural plans were available and the architect had only provided a conceptual plan view and elevation with no details or dimensions. I don’t think his computer could cope with all the compound curves! The architect felt it was impossible to build the staircase in timber.

Gluing up the laminates

Now if you want my attention, tell me it is impossible to build something in timber! I immediately accepted the challenge and told my client in not so many words that it is not about whether it is possible or not but rather whether his cheque book was big enough!

And so with my big mouth I quoted a price, accepted a deposit and tied myself to a delivery date. The agreement even included a penalty clause! Thinking back, I must have sounded very confident to the client. Or something. No drawings, a hefty deposit, me telling him to trust me with the design of form and structure, construction and installation, all in the face of a respected architect that said it was not possible.

The time came where I had to put my money where my mouth is. I laid out the plan view shape as I saw it on some hardboard, then mocked it up in the house to get a feel for where I was going. The client approved of the shape. I took the hardboard pattern back to the shop and built a laminating form out of shutter ply. The total span or length of the beam was to be around 4,5m. Using my very scientific thumb suck approach, I figured a beam of 250mm x around 140mm would do. That meant 15 laminations of 9mm exterior Pine plywood. I decided to use resorcinol glue for the job. It is widely used in industry for structural bonding i.e. lam beams, plywood etc and is very good for laminating.

Also I’ve had much experience with it building masts when I was boat builder.

Read Divs full story at

Well done mate,thats a fine piece of work!


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