The Plumber Did It
A friend of mine owns a fairly ancient house in Brandon, VT. It wears a badge-the house, not the owner-proclaiming the year of birth as 1796. One glance at the extraordinary workmanship of the heavy timber, hand-hewn frame shows that it must have been built fairly close to that date. It's a two-story, center-hall Georgian, with a kitchen ell extending beyond the rear wall. Like most kitchen ells of the period, it's framed with a set of girts around the exterior wall to carry the outer ends of the second floor joists, and a summer beam down the second floor center line to carry the inner ends. The summer beam-or sumter beam if you prefer the ancient spelling with the meaning of "burden-carrier," which accurately conveys the fact that such center beams are twice as heavily loaded as the perimeter girts-is a critical part of the framing. Even so, a two-foot chunk was removed at some early time so that a brick chimney could be run through the roof ridge.
I'd bet that the chimney masonry was laid up with pilasters to support the cut ends of the summer-beam-that's the way the old boys did such things. Their work survived for about 130 years, but then, in the 1920s, the chimney was removed. We know this because its stone foundation wasn't. Remarkably, the building didn't collapse immediately. It remained standing because the non-bearing partitions under the joists and the pieces of the summer beam were suddenly forced to become load bearing.
They did their job surprisingly well, but after another 70 years, they were tired out. The building's current owner could clearly see that an unwelcome sag was developing in the ceiling. Besides, it was time for a new kitchen anyway.
A contractor was hired. His troops came in with wrecking bars. Before long, the history described above was laid bare. It took little time to analyze the cut summer beam and conclude that "the mason did it." But that wasn't the only structural mayhem exposed to view. It turned out that a good many of the second floor joists had been victimized as well, to make room for the drainage required by a variety of second floor tubs, water closets and lavatories. About these cuts, we can say, "the plumber did it." As the photo shows, the plumber was remarkably carefree in what he did and remarkably lavish in the amount of joist material he cut away. His handiwork survived, covered for seven decades, and he fears no judgment on this earthly plane.
And, he wasn't the only plumber who "did it." Most wood frame construction jobs will show similar treatment to joists. To those of us who come from the structural side of the industry, it's with some chagrin that we have to admit that it works. Plumbers can, in all but the rarest of incidents, get away with chopping fairly big holes in framing members. Is that because our fraternity teaches us to overdesign? Or is it because their fraternity teaches them exactly where to cut? Maybe it's both.
Actually, when you look a little more slowly and carefully at beams cut by plumbers, something of a pattern begins to emerge. It seems as though there's a preference for cutting pretty much where the stresses are highest-at the center of spans and along the upper and lower edges of framing members. Only in renovation work, you protest, where it's impossible to thread rigid pipes through holes bored at the neutral axis of beams. True enough, particularly with present-day engineered joists where the holes between the flanges are ready and waiting for mechanicals to be laced through.
Those companies that build joists with solid flanges demolish acres of trees building manuals explaining exactly where holes may and may not be cut for plumbing runs. It's not much fun, in fact, for folks like me to stand around observing demolition in a modern structure, camera in hand, breathlessly waiting for the shot revealing a set of joists or a girder ruthlessly cut to ribbons in pursuit of just the right slope-to-drain for a waste line. That's because we're not likely to see what we hope against hope to see.
Renovation, of course, is a different story. It's when the plumbers come in long after the carpenters have gone that we find the sorts of joist cuts captured in the photo. If the plumber responsible for these particular cuts were still around, he'd protest my accusation that he picked the center-of-span to wield his saw. "Not at all," he'd say. "The owner made me do it by dictating fixture locations on the floor above."
I know better. I know that plumbers never listen to owners. I know that plumbers carry little stress meters in their tool-boxes to measure the stress in beams and girders and then to cut exactly where the needle goes farthest off the peg. No, you can't fool me. You can easily check to see whether I'm right. Ask the next plumber you see about the stress meter he was given when he was awarded his license to practice, and see if he doesn't deny that any such meter exists. Now there's proof of guilt which can't be vented away (a little plumber lingo, there).
Meanwhile, back in the 1796 House, we're trying to figure out how to repair the plumber-cut joists and mason-cut summer beam our demolition work exposed. We think we've got the answer: steel.
Steel was a luxury product in 1796, used only for swords and daggers. Welding was still a century in the future. Now, steel is a low-cost commodity, and welding enables us to create any shape needed to reinforce a cut framing member. Wield your stress meters and make your cuts, plumbers. With half-inch plate, 6013 welding rod, and a Lincoln buzz-box, we can fix anything!