In Transit We Trust
The laser don’t lie.
In construction, as in life, you’ve gotta learn who and what you can rely on. Put your faith in the wrong one, and everything may crumble around you. Literally. You know what happens when you assume—you’re utterly screwed. As complex as a house build is, it’s basically a series of if/then statements. If this is actually where it’s supposed to be, then this thing goes here. If this goes here, then this goes here…rinse and repeat. If one thing in that chain is off, then you might end up with an Escher drawing, if you’re lucky.
This is part of why keeping things level and plumb (the vertical version of level) is so important. It eliminates a whole dimension of variables from that equation. Level and plumb provide a reference point, a replicable state that ensures that things stay exactly parallel or perpendicular to each other as well as helping to keep entropy where it belongs, which is to say, everywhere but in my goddamn house.
Our finished, first floor will be at exactly 980’ above sea level. I’m currently working over 12’ below that in a pit that will become our basement. All the components that we’re using to build the basement are of a fixed height. So how the hell do we know where to start so that we finish where we need to be?
This guy right here.
The top of the orange stake is set at the top of the finished basement floor. The brown dog is set where ever he damn well feels.
This is what makes it possible, the rotary laser, or transit level. While water levels are elegantly simple and builder’s levels are cool and complex, both are two person tools. This guy makes it an easy and accurate solo mission. Set ‘em up, turn ‘em on, they automatically level themselves and start a-spinnin’. This spinning laser provides a dead level, horizontal plane that a receiver on a measuring stick can pick up. This provides a reference point that I can trust. If I set the stick on that orange stake and line the receiver up with the transit, I can mark that spot on the stick and as long as the transit doesn’t move I can find that height anytime, anywhere. From there I can move the receiver up 28” (which moves the bottom of the stick down) and find the exact bottom of my footing.
There’s now a compacted layer of gravel, at exactly that height. Let’s form some footings.