What Are The Different Types Of Roof Truss And Which Is Right For You?

Pros, cons and features of different types of roof trusses. Decide which is right for your project with these tips and reviews.

There are many types of roof trusses: Raised Heel, Dropped Chord, Scissor, Belgian, Howe, Hip Stepdown, Gambrell, Semi Howe, Bowstring, Custom, Pratt Bottom Chord, Pratt Top Chord, Warren, Arch Frame, Slope Frame, and Parallel Chord trusses. Each has it pros and cons for use, and each is intended to fulfill a different structural and aesthetic quality. When you are designing your dream home, or working on a remodel of your current home, knowing the differences between the types of roof trusses will help you create a look and function that fits with your dreams and the design of your home. Below is a discussion of the benefits and drawbacks of four truss types: the Raised Heel Truss, the Dropped Chord Truss, the Scissor Truss, and the Parallel Chord Truss.

Raised Heel Trusses are designed so that they span an area and provide space for a full depth of insulation in the attic. In addition to this energy saving characteristic, this type of truss also provides an air-vapor barrier that reduces mold, condensation, and rot. The drawbacks to this type of truss are mostly financial. Because of its design it will require more soffit siding, an increase in manufacturing cost, and because it allows for maximum insulation space, it will take more insulation to fill the attic.

There are two segments in a Dropped Chord Truss. First there is a convention truss with a second chord truss suspended below it. This configuration helps to reduce truss uplift, a condition that occurs where the interior ceiling is lifted upward causing damage to the ceiling and the walls. Like the Raised Heel Truss, the Dropped Chord Truss provides a clear span and allows for a full depth of insulation to be inserted, and also creates an air-vapor barrier. The drawbacks to this type are mostly due to structure modification. Taller studs will be needed, and more siding and blocking will need to be installed at the intersection of the ceilings and walls to provide a foundation for the air-vapor barrier.



Scissor Trusses also have lower chords, however, instead of being horizontal the lower chords slope in creating a shape that looks similar to a hang-glider. This type of truss is used in the construction of cathedral ceilings. Scissor trusses eliminate the need for a bearing beam and for a bearing wall. The drawbacks to this type of truss formation are that it is more expensive to manufacture and sometimes it is more difficult to install insulation around.

The final type of truss in this discussion is the Parallel Chord Truss. This is another type of truss that is often used in the construction of cathedral ceilings, however unlike the Scissor Truss, it allows more insulation to be installed with greater ease. In addition to allowing for more insulation to be installed, it also allows for a continuous air-vapor barrier to be installed. The drawbacks to this type of truss are mostly economical. Because of the use of steel braces and various wood products there is a higher cost associated with its construction, and also thermal bridging due to the steel braces, may increase energy cost in the winter months.

If you are designing your dream home look for the truss type that will fit not only your esthetical design, but also your budget. If you are working within the constraints of a tight budget, you may want to consider using pre-fabricated trusses, or at least reducing the amount of customized trusses you use in your design. Another consideration is which trusses will be best suited for your climate. If you live in an area that experiences cold weather during the winter, you will want to select a truss design that allows for both maximum insulation and an air-vapor barrier, and if you live in an area with high humidity, you will want to select a design that at least allows for the installation of the air-vapor barrier.

© High Speed Ventures 2011