Collaboration

A wood-frame house during construction, by Jaksmata.

There’s a pretty good article from a house-building contractor: here. I have mixed feelings about his conclusions.

The case study he presents, about the construction of a complex open-tread stair for a house, is great. I agree with the changes he suggested (and ended up making) in the original design. I think the final result is a beautiful stair. He doesn’t overtly say this, but open-tread stairs are among the hardest to do well because everything is exposed to view. Hidden spaces are the designers’ and builders’ friends, since they allow us to make things work behind the scenes.

I don’t agree with his overall conclusion, as stated in the second paragraph: “To be honest, my view on [design drawings] is that they are a suggestion as to how we should build any given addition, renovation, or new home.” Actually, “I don’t agree” is far too mild. I violently disagree. Drawings represent exactly what the designer has asked for and exactly what should be delivered by the contractor barring further discussion. There’s nothing wrong with a contractor asking or suggesting that something be changed. In the article’s case study, the contractor suggested changing the geometry so that the stair risers would be the same height above and below a central landing. That’s not only logical, it’s safer and therefore furthers the design goals. If a designer objected to that type of change, I’d violently disagree with them.

Sometimes the answer to a question from a contractor is “no.” We had a steel shop drawing in the office today where a stair fabricator was suggesting a change that would have made the stair more expensive and less stiff. The change would have increased the downward deflection of the stair under its own weight and under the dynamic loading of use. People are very, very sensitive to deflections and vibrations when they are going up or down stairs, so even if the price wasn’t gong to increase, we wold have said no to the change. In other words, we told the contractor that he had to follow the drawings as designed.

Architects and engineers have to work collaboratively with contractors. I’ve situations where the designers allow no discussion; I’ve seen contractors who ignore the instructions from the designers; and I’ve seen plenty of middle-ground relationships where both sides get their say. In short: asking questions is good, making assumptions is bad. Just like in the rest of life.