Design Intent Versus Common Sense

by Don Friedman on May 12, 2011

An engineering or architectural design has many components, one of which is intent. The designer has a goal in mind – which may not be obvious to someone looking at the design drawings or the completed construction – and that goal influences design decisions from beginning to end. There are occasions when the intent is far enough from average that the intent is not clear without explicit explanation. This is the source of much discussion during construction.

To use a simple example, if modern high-strength bolts are used with materials other than steel, they cannot be torqued down as they are in ordinary use, in steel framing. The reason is simple: the tightening of these bolts is specifically meant to induce high levels of tension in them and therefore equally high levels of compression, through clamping, in the base material being bolted. This is fine when the base material is steel, it is problematic if the base material is wood, it is dangerous if the base material is cast iron. In other words, a note on a structural drawing telling the contractor to not tighten the bolts is based on a design intent to use the bolts only for shear, not for clamping.

The conflict between common sense – the ordinary way of seeing and doing – and design intent was beautifully illustrated when we moved into our current office in 2009. 111 Broadway was constructed in the early 1900s with ornate plaster ceilings and operable windows. In modern use, HVAC units have been installed on every floor and, typically dropped ceilings put in to hide the ducts. When we first saw the space that would become our office, the previous build-out had been demolished, exposing the still ornate but damagedĀ plaster. We asked for our build out to include simple repairs of the plaster (flat repairs where there were missing dentils, for example) and an exposed duct. This would give us a higher ceiling, some of the architectural feeling of the original design, and an illustration of very practical, very simple conservation. We had to explain our idea repeatedly to the building management and plasterer, because it was so far removed from the position of the majority of the tenants that it was, from their perspective, nonsense. Our intent and their common sense view of the world completely missed each other.

Our ceiling isn’t beautiful but it is what we wanted and, in the context of a discussion of design and construction, what we intended.

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