"I've watched carpenters for years struggle with the mathematics and calculations of constructing a hip roof. This product eliminates all of the complicated procedures. Anyone can use it."

# Calculating Hip & Valley Rafters, Hip Roof Calculator, Hip Roof Framing

In the construction industry, more specifically the residential construction industry, builders, tradesmen and carpenters are reluctant to change methods and materials that work. Everyone wants to find a better way, but we often want someone else to stumble through new materials, tools, or techniques to avoid lost time or wasted money. We have all experienced use of the “latest and greatest” only to find out our old way was better.

Starting as a laborer and carpenters helper in 1979 and creating my own business in 1984, I have experienced these same pitfalls (many times) of new products in the construction industry over the past 30 years. Having stated this, by occasionally trying something new I have found better methods and products. Recognizing the difference is the difficult part.

 For decades now, construction manuals and online sites have told people to layout a hip roof starting with the common rafters and the level ridge members first. Then fill in the hip and valley rafters by measuring from the wall plates to the ridge. THIS IS WRONG!

While working in the field on a very difficult hip roof system back in 1992, I researched different methods, past and present, to approach hip roof construction. I had constructed hip roofs in the past, but none like this. This roof had multiple hips and valleys, with differing exterior wall heights, and many small interconnecting roof planes. None of the carpenters I employed at the time had the expertise to construct something like this, and I had to find a way to put this together correctly and efficiently, without spending months to do it.

Though I discovered a wide range of solutions, I wanted the method that did not involve complicated calculations. I had already found through experience that most carpenters could not or chose not to grasp the higher math of trigonometry. I have tried in vain to have my carpenters memorize the Pythagorean Theorem, for a variety of applications, for years without much success. So when I stumbled across the “rule of 17” that is shown on some framing squares and is explained in some how-to guides, this looked like something anyone could master.

The “rule of 17” refers to the length of the hypotenuse of and isosceles triangle when the sides A and B each measure 12” or one foot. This allowed me to transfer measurements of the walls to the hip or valley rafters. I took a framing square and attached a clamp on one side at 16.97” and the other edge to match the desired roof pitch of 6”. Now with this modified square, I could simply “step” off the number of feet the rafter spanned. For example, if the building end was 20’, each hip rafter was 10 steps, or equivalent 10 feet.

It worked beautifully. My employees were shocked when I completed all the hip, valley and ridge members in one day. I stood in one spot in the front yard with the plans, by myself, dragging large lumber around, creating some members over 30’ long, and had it all laid out, cut and labeled for assembly. The next day, we assembled the roof skeleton in about 6 hours without problem. This very large, complex roof was dried in completely in one week.

 I knew that I was onto something, but there was a lot of room for improvement of my method. When a rafter that was not an even increment, I had to go back to the calculator to determine the last few inches. I quickly discovered that I could extrapolate from the information I already had to create a more detailed scale to represent any dimension, an inch, half inch, etc. I took masking tape and put on my framing square and divided 16.97” into 12 equal segments and subdivided those into eights. Now I could “step” any dimension of a wall onto hip rafters. Although the framing square along with clamps was successful, it was easy to place the clamps slightly off number or bump them out of place while working. I began cutting triangle shapes from scraps of plywood to mimic where the clamps would be placed on the square. The bottom edge was cut to 16.97” and the leading edge was cut to the dimension of the pitch of the roof for the project on which we were working. I put the new Hip Scale across the bottom and a small strip of wood at the top to hook the edge of the board in creating a rafter. Each minor new development was an improvement and saved time. I began to let my carpenters in on the secret. They had no problem at all with use of the device.
 With the Adjustable Hip Square all the layout work of all the members is done on the ground, including the layout of the common or "jack" rafters as they fall on the hip and valley members. The scale on the bottom of the square lets you forget about the fact that the hip and valley members are at a 45 degree angle to the walls of the structure. Just read the scale as if it were a rule on the wall plates. It really is that easy.

When I realized that I could also use the scale to transfer the layout of the common rafters from the wall plates to the side of the hip and valley rafters while still on the ground, there was and obvious need to have openings in the tool to see the rafter below to mark these placements. I was also growing tired of recreating a new tool for every project and every pitch we encountered. This is when I moved toward developing a tool for all these applications. After several prototypes, the Adjustable Hip Square was born.

I created a short video to demonstrate how effective and just how simple this tool is to operate. There are no gimmicks. This really is that easy to master. I also have developed a table of ratios to determine length of common rafters based on how far the rafter is from the hip. If you are constructing a hip roof, these tools can cut your construction time in half. We all know that a hip roof requires less material to construct. With these new tools, it requires less time to construct as well. Give it a try, you won't be disappointed.

Watch the short video on how this works. Everyone that has seen the tool in action has been amazed, and mastered it in no time at all, saving many man hours.

"The greatest time saving device since the nail gun replaced the hammer."