This is the first in a series of instructional videos explaining A to Z how to use each of the tables on the Chappell Universal Square. This and upcoming videos will cover how to apply the factors expressed in the various tables, to the square, and to the timbers.

This video specifically explains how to use the first line of the Equal Pitch Rafter Tables. The first line covers three elements of roof framing concerning common and jack rafters:
1) Determining the length of the common rafter per inch of common run (or any unit of of 1) from the information in the tables,
2) Determining the difference in length of jack rafters based on the spacing per inch (or any unit of 1) along the plate, from the data imprinted on the square, and
3) Determining the top cut of Jack Rafters per unit of 1.

The first two concern length ratios, and the third is an angular ratio. All of these are determined by the factors imprinted on the Chappell Square.

We hope you enjoy, and stay tuned for more videos to be published in this series.

To learn more visit chappellsquare.com