If you have spent your truss career in one region, and even more so with just one company, you will have seen that, generally speaking, your competitors and co-workers tend to frame houses essentially the same way. Only when you are exposed to a different company or region do you start to see the myriad ways that seemingly similar truss roofs are put together. I know that until Thom and I started Component Systems Institute/Component Design Center back in the late 1990s, I certainly had little idea about all of the different approaches that could be taken for solving what seemed to be the same basic roof geometry.
Of course, chances are that you can find many alternate solutions to roof framing in your truss design software. It is also very likely that your design manager, your production manager, and your clients don’t want you trying out some unique solution that looks cool in the software. Having said that, here are some of the things I’ve seen that tend to be specific to a company or region.
When it comes to pre-fabricated ladders for gable end framing, I worked for one company where it was virtually impossible to sell a truss roof without including gable ladders (outlookers) in part of our sales region. At the same time, we had other market areas where you couldn’t give them away.
Of course, the biggest variation I’ve seen is in the way that hip ends are framed. My personal “favorite” is the Atlantic hip, with everything but the corner jack meeting at 90 degree angles. Even then, there are a number of ways to approach the framing.
Do you use a fixed setback for your Atlantic or other hip framing solution? I’ve heard many very experienced truss people give me detailed and impassioned arguments as to why 5-11-04, 5-10-08, 6-0-0, or some other fixed increment is the only way to determine the setback for the hip girder. For example, I’ve been told many times that a 5-11-04 (or 7-11-04) setback puts the center of a truss exactly 8 feet from the end wall. But the roof sheathing doesn’t start at the end wall, it starts at the overhang, so why not base your setback at some fixed distance from the fascia?
When talking to designers in Florida, I was told that they use 7 feet – period. When I asked why, it was like I had asked why the Sun rises in the east and sets in the west. Of course, I’ve never gotten an answer that really satisfied me for any of the other fixed setback values either, other than “because that’s how we do it around here.” I do believe that using a fixed setback may make it a little easier for the framer on site to know how to start setting the trusses, but it’s still seems to come from an arbitrary decision made at some point.
Some companies will use an “Apex down” approach which will give an even spacing from a common truss at the hip apex and work down to some acceptable range for the hip girder setback. This has the advantage of placing a common at the apex, and possibly saving a truss or two, but it means that different span hips on the same house might have different end jack spans. And the framer better be paying attention before they start laying out trusses.
California hips are common in some areas, and at first glance I see some merit in the end jacks flying over the hip trusses. But when I start to see the jack top chord extending more than 8 feet or so, I wonder about how well that stands up in production/shipping/installation. To my mind, the same benefit can be obtained by using an Atlantic-type step down system and supplying a pre-fabricated lay-in gable to create a uniform surface for the roof sheathing.
It may be that what works best in the higher snow load areas (where I’ve spent most of my career working) is not right for high wind load areas in the southeast. If you want to give me an explanation of why the hip framing approach in your area is the best, I’d be happy to hear from you. Maybe you have an explanation as to why your setback value makes the most sense. Maybe (probably) there are still a few tricks I can learn.