How to Install a DIY Timber Frame Pergola Kit; Square Up Posts 3of12

Continued from: How to Install a Timber Frame Pergola Kit; Getting Started 2/12.

Right now we are going to square up this concrete patio, measure the pad. It’s just over ten feet. From our post to post it is going to be 9’ 10“ outside to outside. So it’s going to come in about and 1 3/4” from each side. Make our marks here and then square up our patio there. Once we get a couple of little marks we use a little PLS laser that will shoot a 90 degree or you can just do the math with the three, four, five method; A square plus B square equals C squared.

The 3, 4, 5 method means to measure three inched from the corner and make a mark. Then on the opposite side from the corner, measure four inches and then make another mark. Next, measure between the two marks and if the distance equals five inches then your corner is square. Then there is one of the oldest tricks in the woodworking world. It is a very simple way to determine when something is square based upon Pythagorean’s Theorem which says that "the sum of the squares of two sides of a right triangle is equal to the square of the third side, or hypotenuse." If you measure the diagonals with a measuring tape, checking to see if both distances match. If they do match then it is square. If they are not equal in length, then this rule cannot be applied.

Measure from this edge (not from the dovetail) ...

...to this edge down to the other edge here.

The laser is going to be the most accurate and the quickest especially if you are going to go around a hot tub and you can’t get a corner to corner dimension. If you are ever in doubt in exactly where to place the posts you can measure from the edge of the load beam, not the dovetail, but this edge down to the other one here. That’s going to tell you exactly what your dimension is between the posts.