Reverse Engineering for the Builder

By Matt Cantor
Thursday January 14, 2010 - 09:39:00 AM

I hate code books. Not code as in dot-dash-dot or SLWBT means I love you. I mean the building codes. Codes have loads of exceptions and don’t address each case with real clarity. They vary by year; by city, county, state and region; by building department and ultimately by the site inspector who enforced or ignored the edict. Yes, I’m very much aware of the need for codes, but the frustrating contradictions that a person faces when the code is invoked make me want to pull my hair out.  

That said, I’m slowly getting used to them. 

Given this relationship, how did I learn about buildings? How did I learn how wiring was supposed to be done, how joists were selected, how many nails were needed in a particular connection? Well, I’ve learned from other builders and specialists, from city inspectors and really good lumber clerks. I’ve learned from how-to books, architectural books, and trade manuals. I’ve actually learned a lot from installation manuals for furnaces, vent fans and disposers. Once a guy has seen enough of this stuff and cross-referenced it all in his head, he has a fair idea of what’s in the code book. Sort of.  

However, there is one very important source of data at the source of my own personal education that is not codified, published or preached by those on the city dole, and that is the knowledge I’ve gained from dead contractors. In the years during which I did remodeling, I developed a series of relationships with a host of dead (or at least long-absent) builders. Every time I crawled under a building or looked through an attic or took apart a wall, there they were, showing me how they nailed things together.  

I feel a strong sense of the men (in those days, they were all men) who soldered knob-and-tube wiring connections together. Each wire was bent just so, torched white-hot, drenched in molten metal and then taped ever so carefully to make sure that the little girl who lived in the house two generations beyond would be able to sleep safely at night within those plastered walls. 

The carpenter called out to the man on the handsaw to cut the next one “5-foot-6 and five-sixteenths, just a hair fat and angle one end just a smidge.” You can see the way they fitted the hidden roof supports just right and compensated for a slope here or a knot there. The longer you look, the more you can see the great expertise in a simple thing like a roof framing. 

Some would sheath a wall with one-inch-thick lumber on a 45-degree angle, just to make things a little stronger. Today, it turns out that this has tremendous “shear value” (the capacity of a surface to resist tearing) and may substantially decrease the need for additional “shear-wall sheathing” (to prevent said tearing or collapse). 

The shimming (nailing of spacers) of a window was also a real art. Quick, to-the-point, strong and virtually permanent. But you’d never get this one from a book. You have to open a wall and look. Now, materials and architecture change, so that you may not be able to apply the very same methods today. You cannot solder knob-and-tube any longer. But knowing how this was done helps enormously in working with the stuff and making upgrades. It also helps in evaluating the safety of the existing work. 

While I may have had books to reference, there’s never been any better teacher for me than the well-nailed floor framing that I had to kill myself pulling apart. These men drove 20d (we say 20-penny) nails though framing members with but a few blows, clearly having learned over the course of many years just where to place the nail and how to drive it. An amateur might easily split the same stud, bend the nail or fail to make a firm connection. 

I learned from the plumber who clearly took enormous pains to support the pipes at the best possible incline and installed those deadly liquid-lead joints with the intention of making the system run smoothly for as long as the material might survive. Taking apart those lead joints (which I have done), carving through the lath and plaster (yes, that too) and drilling through the concrete has shown me precisely how these workmen did what they did. Now, if you look at 30 or 40 examples of a particular detail, you’ll see something interesting: you’ll see aberrations for better and for worse. You’ll be able to tell how most careful workers did things, and in this way you’ll come to recognize the common protocol. You’ll then be able to discern, through a simple comparison of each case and by thinking through the advantages and disadvantages of each maneuver how certain builders would do things a little better and how some had failed to learn from their peers. 

So, doing this for a while, it’s not too hard to see how and why each thing was done. If you cross-check with old code books or old how-to books you can take it a bit farther. 

The same is true of living builders. Everyone has a technique, and if you look at enough electrical panels you can see how the really clever (and magnificently obsessive-compulsive) electrician wires a panel. Some mistakes may not be apparent without a trip to the code or instruction book, but as a general rule and given the way my mind works, I’ll learn more from looking at the work.  

I also learn from the idiot who leaves me scratching my head at the stupid or lazy thing. This gives me the chance to run the worst-case scenario ending in a death by fire or collapse. Even the worst builder makes a contribution, I guess, when you look at it this way. 

I was describing this way of looking at houses to my friend Gillian, and she said that what I was doing was a sort of reverse-engineered inspecting. Hmmm. I like that.