Wood

This Is Ungood

by Don Friedman on October 18, 2017


From a few years ago, some rotting wood beams and a failing brick pier.

In 1989, I performed a long and difficult site visit to check on a structure I won’t name (confidentiality is still in place, even after all these years) that had to be reviewed once per year. The fellow who had been teaching me site work had performed the inspection every year prior to that and gave me his old reports to review before I went. The inspection required the use of a scissors lift some forty feet in the air. One of the old reports described, in the driest possible language, a problem that developed with the lift that had caused it to buck sideways several feet in an unpredictable manner. The sentence I remember word for word is “I then asked the operator to lower the platform until such time as the lift could be repaired.”

My point is that engineering reports are deliberately written in completely dispassionate language. People expect it. It helps reinforce the profession’s image. It’s easier to write for people who are often badly trained in writing. But most importantly, it’s often more convincing. In terms of professional dynamics (or professional psychology), someone whose opinion changes with different circumstances is more convincing than someone whose opinion is always the same: an engineer who says everything he sees is terrible and needs to be fixed seems no more credible than one who says everything is good; both seem less credible than one who says some things are good and some are bad. Similarly, someone who uses calm language is seen as calm and therefore more convincing. If the old inspection report had included “Then I yelled ‘Are you trying to kill me? GET ME DOWN!'” it would not have been more convincing even though that reaction is a natural one.

When I took the picture above, I was thinking that I wanted to minimize my time in that building. And I did. But my report was written in dispassionate language, describing cracks in the pier and percentage of wood loss due to rot. And, eventually, the pier and floor beams were both repaired.

Steel Trusses and Wood Purlins

May 19, 2017

No deep thoughts today, just appreciation for a well-designed roof. It’s an industrial building so finishes were kept to a minimum, and there was no requirement for fire-rating. The trusses are steel because they span about 50 feet; the purlins span 18. The end bays have diagonal rod bracing in the plane of the truss upper […]

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Worse Than Termites

January 26, 2017

That’s a nice early-twentieth-century partition: plaster on expanded metal lath (on the far side of the studs) full 2×4 studs, diagonal fire-blocking between the studs. And, yeah, a big chunk is missing from a stud where an electrician or plumber needed some room to work. We see more damage from guys with saws than we […]

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A Subtle Hint

January 24, 2017

That picture was taken in a mid-to-late-nineteenth-century industrial building, on the top floor with only the attic above. The exposed wood beam is about 8 inches wide and 12 inches deep but appears to span some fifty feet, which is obviously ridiculous. The building has a gable roof so the most likely bet is that […]

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Failure Portrait: Dramatic

October 6, 2016

No, that photo isn’t rotated 90 degrees. The floor above has failed and the bathtub has fallen through. You can’t see it from this angle, but the only thing holding the tub in place is the drain pipe. One of the difficult judgement calls that we face during field investigation is when a building is […]

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Non-Structure

September 28, 2016

The white stripes show the gaps between the now-removed lath: Structural engineering is about structure, right? A while ago, while looking at a historic house upstate, we ran into a problem. The building had wood-stud bearing walls sheathed with clapboard and we ran into an obvious problem: the bearing walls were not performing properly. The studs were buckling, […]

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Failure Portrait: A Little Off The Top

September 21, 2016

There’s a lot going on in this picture, and much of it is not good. The center of the picture is a girder* with joists on both sides framing in. (The joists on the left are mostly hidden below the plywood.) The fact that we see the tops of the joists inset past the edge […]

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Historic Structural Detail: The Edge

August 23, 2016

I’ve mentioned heavy-timber construction before. Here’s an interesting detail from an old warehouse: The planks above are four inches thick and splined to one another, which is typical in heavy-timber construction to prevent hot gas from a fire burning through to the next floor. (The thick wood in this kind of construction will char but […]

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Historic Structural Detail: Tree

August 16, 2016

The cellar of an 1890s tenement: That’s a girder running right to left with its original support (a barely-trimmed tree trunk) and a 1990s supplement (a steel pipe column). I’m not sure that there’s anything else to say. Cheap construction was cheap, maybe. And “they don’t build ’em like they used to.”

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Students and Wood

August 10, 2016

The Seward Park Urban Renewal Area (SPURA) has been sitting empty for almost fifty years since the old buildings were demolished. The latest scheme is the kind of large-scale development that we’ve seen a lot of in the city in recent years. The Timber in the City Competition had students competing to do something more […]

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