The truss heel is typically at the end of the truss, usually over the outer bearing. It consists of a minimum ¼” butt cut and the height of the top chord measured vertically or plumb. This is known as a “standard heel” application whose measurement varies based on the top chord material and the pitch of the truss. The greater the pitch and wider the material used, the higher the standard heel.
Raised heel applications increase the roof plane over the outer bearing walls to increase capacity for ventilation and insulation. This condition is often referred to as an “energy heel” and, while no standard measurement exists for an energy heel, anything over 9” is commonly considered applicable. Often, raised heel trusses will require blocking between each other for shear purposes. While solid wood blocking can be used, this is an opportunity for flat top truss blocking, furthering the use of components.
Multiple methods exist to increase the height of a heel. The butt cut can be increased from ¼” up to the full width of the bottom chord member. Additionally, a “slider” adjacent to the top chord or bottom chord can further increase the heel height and ultimately a “vertical web” of any length reinforced with a web member can meet any height necessary as required by design specifications. Alternatively to a slider, a reinforcing web can be used along the top or bottom chords that extend the entire length of the first panel.
Architecturally, the heel is quite significant to the overall building design, but is often not specifically defined in construction documents and can create confusion between various design professionals, including the truss technician. If the heel is not specified on the construction documents, the truss technician is required to scale the heel height from a section view, which can be less than desirable for accuracy. The heel dictates the plane on which the roof is established, and if it is designed incorrectly, can carry significant implications to the roof and how it interacts with the rest of the structure. An example of this is the heel of a truss that sits on the first floor that planes with a second floor roof.