Friday, March 2, 2007

Detail of the Week: When Good Drawings Go Bad

Well, not so much the drawings, perhaps, as the contractors reading the drawings incorrectly with big-time consequences. Generally, when a contractor reads a drawing and isn't sure what's being represented or think he or she is reading it incorrectly, the contractor will call the architect or ask the question in a Request For Information, or an RFI. My present contractor on Wheatlands is really good about this. Mark calls and asks me the question, then we work through it, then he issues an RFI to confirm our decision. Interestingly, this saves us time overall because we both worked through the solution instead of me issuing him a solution that might still not work or might cause more problems than it solves.

However...sometimes it doesn't occur to the contractor to ask. They assume their reading is correct and do something totally unintended. Sometiems these errors are huge, and sometimes, they're silly, like our first detail. This was on a project of a former colleague of Sarge's. We often note details in a plan by putting a dashed circle or rectangle around the detail and note the sheet and detail number off to the side and connect the detail and sheet number to the dashed circle with a line called a leader line. This sort of detail is shown on the right. However, the contractor interpreted this as the edge of the top step and built it as shown on the left. As the architect commented to Sarge, "They built the fucking leader line."Guy passed this around his office, and one of his colleagues noted that the stair as built violates code. Because of this, as well as because they didn't build it as the architect drew it, the architect would be completely in his right to tell the contractor to tear this out and build it correctly. Building codes require that the height of any step (called a riser) be of a minimum height, and this stair likely doesn't meet that. Look at the plan; only three stairs (four risers) are shown, but the contractor had to do the math to change the height of each riser in order to make what he thought was the extra riser but was actually the leader line between the detail and sheet number and the rectangle around the detail.

Below is another detail on a project a friend of mine worked on several years ago. This is a drywall soffit in a hallway. You can see the lines that go from the wall to the edge of the curved soffit; those are control joints, which allow large expanses of drywall to expand and contract with heat. But see the line running longways down the soffit?

That line is actually a grid line. A grid line is an imaginary line that runs through the center of the structural columns and is used not only to locate the columns and beams but is also used to help dimension other things in the floor plans and ceiling plans. So, the outer edge of the curve of this soffit was dimensioned off this gridline. However, the contractor read this in reverse--he thought that the architect was trying to show an architectural reveal in the underside of the soffit dimensioned off the edge of the soffit. While this doesn't violate any codes, it just looks doofy. it's the only soffit in the hall with this line in it. "They built the grid line in, Pixie!" my friend sighed. "It looks different from everything else on the plan, but they read it like it was a reveal! What the hell?"

I'll have something more amusing tomorrow, but believe me, when we passed these details around our office, we howled with laughter.

I know, I know...we're total archinerds....


BaxterWatch said...


Aren't autonomous contractors a Pain In The Ass. They seem to forget they are working for SOMEONE ELSE.

I had one argue with me on a project last year because he thought what he was doing was "good enough." I'm sorry, did I miss the years of experience you have working on this type of equipment? OH wait, that's ME. How silly.

funny. very good post, chica. The spa must have inspired you!

faded said...

The step detail is priceless. When they rebuilt the step did they entomb the contractor inside it? I can't stop laughing. it's just so "out there," it needs to be in a Monty Python skit.

The Wandering Author said...

I saw a step like that once. (I think it was in the building the Connecticut Vital Records are in.) It made no sense to me, so I figured the contractor must have been drunk. Now I know the truth - the contractor must have been drunk while reading the architectural drawings! LOL! That was great. I find these posts interesting.