I've cut hundreds of irregular hip and valley roofs during my 35-year carpentry career. Although I use a framing square for drawing and layout, I rarely use the rafter table imprinted on it because it only applies to regular plans and pitches and a calculator is faster. So when veteran timber-framer Steve Chappell recently introduced the Chappell Master Framer square, I was pleased to try one out to see if its unique decimal scales and patented rafter tables might change my approach.
The Chappell square ($118 at chappellsquare.com) is made in the U.S. of 304 stainless steel, with deeply etched and blackened markings. It has the usual 2-inch by 24-inch blade, but the tongue is 1 1/2 inches by 18 inches, which is two inches longer than normal. The extra length helps on extra-steep rafters, forms a 3-4-5 triangle, and holds more information. So far I've found the longer tongue to be useful in stick framing for bringing up layout lines between floors, but overall a standard 16-inch tongue works fine for me.
The tool is guaranteed to be square to within .003 inches, and the one I tried was perfect.
Scales and Tables
Unlike traditional framing squares, whose edge scales are broken into 8ths, 10ths, 12ths, or 16ths of an inch, the Chappell square is laid out in 20ths of an inch and in 1/4-inch increments. The decimal scales make it easier to do mental math, are compatible with common calculators, and mesh with the decimal rafter tables on the square. They also allow you to use your choice of imperial or metric units without conversions. The distinct 1/4-inch graduations help you measure fractions (there's a decimal/fraction conversion chart on the square if you need it).
The rafter table has enough information in it to build a timber-frame roof complete with purlins and other components. It also gives the miter and bevel angles to use when applying fascias to square-cut rafter tails on hip and valley roofs. Plus, this is the first square to add tables for irregular-pitch hip and valley roofs, and a table for octagonal and hexagonal roofs.
The square comes with a manual that thoroughly explains the tables, has clear illustrations, and gives a nice history of framing squares. But the fact is, I can solve a complex roof much faster using geometry, drawings, a calculator with trig functions, and Hawkindale Angles. I've talked with several other timber and stick framers who feel the same way. Even so, some of them are buying the square because it's a precise, American-made, stainless-steel layout instrument that will probably last for generations. Also, the information is there if you need it in a pinch or want to use it as a teaching tool, as one California framing contractor I know is doing. The square comes with a 90-day guarantee; you can send it back for a complete refund, no questions asked.
William Dillon is a job supervisor, co-owner, and member of the Management Committee with South Mountain Co., an employee-owned design-build firm on Martha's Vineyard, Mass.