Executing the 3-4-5 Method

What happens here

To execute the 3-4-5 method, measure 3 feet along one string line from the corner intersection and mark it. Then, measure 4 feet along the perpendicular string line from the same corner intersection and mark it. Finally, measure the diagonal distance between these two marks. If the corner is perfectly square, this diagonal measurement will be exactly 5 feet. For increased accuracy, especially on larger projects, the creator suggests holding the measuring tape at a 1-inch or 1-foot mark from the starting point and adding that amount to the final reading, which helps eliminate any inaccuracy from the tape's end hook.

Goal: Perform the 3-4-5 measurement to check corner squareness