My uncle swore by a 3-4-5 triangle for every layout, but it cost me a day on a big deck job.

He said, 'Kid, if you can't trust a 3-4-5, you can't trust anything.' So I used it to square a 24-foot deck frame last month. The long run was fine, but over that distance, the small error in the triangle stacked up. The far corner was off by over an inch. I had to pull all the rim joists and start again with a laser. When do you guys switch from the basic triangle to a different method for bigger projects?

4 comments

4 Comments

gray8752mo ago

Feel your pain... that inch of error is a real gut punch on a big frame.

reesej272mo ago

My contractor buddy swears by the diagonal measure method past ten feet.

emeryj662mo ago

Wait, does your buddy actually think that's more accurate than a laser? @reesej27, I've seen guys mess up the diagonal math on site all the time. A cheap laser measure gives you a straight number instantly, no squinting at a tape or doing geometry in your head. For long runs, any little bend in the tape or a bad angle on the diagonal throws everything off. I trust a digital readout over someone's tired brain at the end of the day.

drew_jones311d ago

emeryj66, you're spot on, I've watched guys burn half a day trying to fudge a diagonal that a laser could have nailed in two seconds.