Old drafter taught me a layout trick that saved me 2 hours on a commercial job last week

I was working on a big store remodel in Austin and kept fighting with our CAD to match the existing steel beams. An old timer walked by, saw me cursing, and told me to use a pythagorean check on my grid lines instead of just trusting the snap tools. Turns out the building was 3/8 inch off square from the original 1970s construction. Once I manually plotted my reference points using his method, my whole framing layout fell into place. Has anyone else run into buildings that are way out of square and had to ditch the computer for old school math?

3 comments

3 Comments

the_anthony2mo ago

Yeah that 3/8 inch off square thing is way more common than people think. I've seen plenty of 60s and 70s buildings where the grid lines are basically suggestions. The problem is most CAD snap tools assume the building is perfect, and they'll fight you on it. Your pythagorean method makes sense, you're basically establishing your own coordinate system based on what's actually there instead of what the computer thinks should be there.

nathanbennett1mo ago

I've definitely been there too - had a job in an old warehouse from the 70s where every single wall was off by at least half an inch and the CAD just kept snapping to the wrong thing until I gave up and drew everything manually from measurements. Your pythagorean approach is exactly what I ended up doing, just trusting the tape measure over the grid.

jessicamiller2mo ago

i dunno man, i've run into that 3/8 inch thing a couple times and honestly it never caused me that much trouble... like yeah it's annoying but i just nudge things over in cad and move on. feels like sometimes people make a bigger deal out of it than it really is, you know? half the time i bet the framers or drywall guys cover it up anyway, so who's even gonna notice.