Cost of Curvaceous Work

Cost of Curvaceous Work

The popularity of “blobitechture” as practised by Hadid, Gehry etc. has led to a rash of offshore façade and interior finish subcontracting, some successes and some very disappointing results. The atmosphere of panic is often the result of AEC professionals who are shocked to find how much it will cost to build a beloved but curvaceous project. Unless a “perfect fit” supplier is missing from the bidders list, the bids received will closely reflect the productivity of existing technology, the market cost of materials and the current cost of labour. This means that the sticker shock is most often due to a lack of appreciation of the cost of design decisions related to processing labour, not materials.

Innsbruck cable car terminal designed by Zaha Hadid using compound-curved panels
Innsbruck cable car terminal designed by Zaha Hadid using compound-curved panels

In the following article I focus on exterior and interior paneling and cladding and provide a guide for comparing the cost of various categories of curvaceous work, based on the relative difficulty of the detailing, fabrication and installation process. I hope that this information will be useful in making choices during the design phase regarding materials, tolerances, geometry and ease of installation.

Deegies Carma conicaly curved perforated metal on curvaceous tubular steel frames. Designed by Gensler and detailed by Feature Factory
Deegies Carma conicaly curved perforated metal on curvaceous tubular steel frames. Designed by Gensler and detailed by Feature Factory

Because most suitable raw material is supplied in linear or planar form, such as sheets and stock lengths which must be laid out, cut, possibly formed and then assembled, geometric complexity (especially with a lack of repetition) is one of the biggest cost drivers in custom work. Materials like fiberglass and glass, which can be made in to compound curves, but which have no form until processed, are also costly to use. This is because molds are required and they are expensive to design and build. This problem is particularly acute if there is little or no repetition, as with Hadid’s glass-wrapped cable-car terminal in Austria.

Store fixtures designed by Gensler and detailed and fabricated for Deegies Carma by Feature Factory were conceived as single plane curves corld-formed over frames
Store fixtures designed by Gensler and detailed and fabricated for Deegies Carma by Feature Factory were conceived as single plane curves corld-formed over frames

And finally, don’t forget the cost of multiples, which arises in the pricing of mundane but custom components like screen segments, store fixture hooks, lighting shrouds, handrail brackets, machined trims, etc. These might only cost $50 each, but if 2000 are required, they suddenly become a major item. The multiple trap came in to sharp focus on a special effects job years ago, but the problem was with watts and dollars. A production company commissioned a friend of mine to build a full size mock-up of a pocket coil bed to be used in filming a commercial. Each coil had a light bulb in it and the lighting technician thought he needed 3kw to power the bed. Unfortunately he was off by a factor of ten and the bed sucked up 30kw of power, which was a lot more than they had available. My friend called me up in a panic and we spent the next 12 hours re-wiring the prop and running cords out the windows and all over the building; then we stood by with fire extinguishers in case the crew left the bed on for more than 30 seconds at a time.

Following is a list of panelized work organized by varying degrees of geometric complexity with the addition of explanatory notes. 1 is the lowest cost category, while 10 is the highest. Like the Dewey Decimal System, spaces have been left for the addition of intermediate categories. Please note that this system does not take in to account the cost of the material itself, which is relatively easy to determine. If you are in the design phase of a project, the object is to chose the fabrication option furthest up the list that will still provide the impact you want to achieve.

Click on the link below to download the following document:

Matrix comparing degrees of complexity in panels

Annotation of a typical line in the attached matrix (How to read the document!)

Example: Degree of Complexity “Sheet 7”

“Polygonal continuous surface formed in multi-centric conical curves with added edges (edges include multi-centric tapered spirals)”

A multi-centric conical curve could be built from pieces cut from a series of cones, with some parts reversed and joined edge-to-edge with others. The assembled master part would then be cut to an odd outline (as it would if it had to nest against an uneven surface) and these edges require the addition of a formed flange.

“Aluminum, steel, stainless steel, acrylic, curveply with limitations on minimum radius, sheet fiberglass, stone”

All are semi-rigid sheet materials that can be formed in a single curvature, but not a compound curvature without an expensive expert process.

“CNC rolling, continuous adhesive bonding or welding of all edges and corners, welding and flush finishing. Stone milled and polished”.

Processes are all off-the-shelf, except for milling of stone which is relatively expensive.

“Blind studs, edge hangers, adhesives, through fastened with flush fasteners, interlocking. Forms required for assembly”.

Most materials suffer from varying degrees of springiness, meaning that they will spring back towards their original shape when released from a forming machine. For this reason forms are needed to control shapes until they have their edges installed, or they are fastened to a sub-frame. Frms aren’t as expensive as molds, but there is a cost.

“Building cladding, wall panels, screens, column covers, store fixtures etc. with free form geometry”.

The accompanying images of the Deegies carma store fixtures designed by Gensler and fabricated by Feature factory are examples of this category of geometry.

Deegies Carma store fixtures built by Feature Factory. image courtesy ARE
Deegies Carma store fixtures built by Feature Factory. image courtesy ARE