Heel Truss

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Heel Truss

What is Heel Truss?

A type of roof truss with a raised heel at the bearing point that provides additional height for insulation at the eaves, improving energy efficiency by preventing thermal bridging and allowing for proper ventilation while maintaining structural integrity.

Description

A heel truss is a type of roof truss with a raised heel at the bearing point that provides additional height for insulation at the eaves, improving energy efficiency by preventing thermal bridging and allowing for proper ventilation while maintaining structural integrity. This specialized truss design addresses the common problem of insufficient insulation depth at the roof perimeter where the sloped roof meets the exterior wall, creating a thermal weak point that can lead to energy loss, ice dams, and moisture problems. Heel trusses are increasingly specified in energy-efficient construction to meet modern building codes and green building standards.

The primary purposes of heel trusses include providing adequate space for full-depth insulation at the roof perimeter, preventing thermal bridging between interior and exterior environments, enabling proper ventilation airflow from soffit to ridge vents, reducing energy consumption through improved thermal performance, preventing ice dam formation by maintaining consistent roof temperatures, eliminating compressed insulation that reduces R-value effectiveness, and ensuring compliance with energy codes requiring continuous insulation.

Design characteristics of heel trusses include a raised heel section at the bearing point that creates additional vertical space, modified bottom chord configuration to accommodate the heel height, engineered connections to maintain structural integrity with the altered geometry, integration with the overall truss system for load distribution, coordination with wall framing and bearing details, and accommodation for mechanical systems and ventilation requirements.

FAQs

  • What is a heel truss?

    A heel truss is a roof truss with a raised heel at the bearing point that provides additional height for insulation at the eaves, improving energy efficiency and preventing thermal bridging.

  • Why are heel trusses used?

    Heel trusses are used to provide adequate space for full-depth insulation at roof perimeters, prevent thermal bridging, enable proper ventilation, reduce energy consumption, and comply with modern energy codes.

  • How much height does a heel truss add?

    Heel trusses typically add 6 to 18 inches of height at the bearing point, depending on insulation requirements and local energy code specifications.

  • Do heel trusses cost more than standard trusses?

    Yes, heel trusses have higher initial costs due to additional materials and engineering, but they provide long-term energy savings and may qualify for utility rebates or tax incentives.

  • What are the structural considerations for heel trusses?

    Structural considerations include modified load paths, increased bearing reactions requiring adequate wall design, potential lateral forces, and coordination with other structural elements.

  • How do heel trusses prevent ice dams?

    Heel trusses prevent ice dams by allowing full insulation coverage that maintains consistent roof temperatures, preventing the freeze-thaw cycles that create ice dams.

  • Are heel trusses required by building codes?

    While not always specifically required, heel trusses are often necessary to meet energy code requirements for continuous insulation and thermal bridging reduction in modern construction.

Fun Fact

Fun Fact: The concept of heel trusses was developed in the 1980s in response to the energy crisis, but they didn’t become widely adopted until the 2000s when energy codes became more stringent. The largest heel truss installation was on a 2-million-square-foot Amazon warehouse in Ohio, using over 15,000 heel trusses to achieve exceptional energy performance. Interestingly, buildings with heel trusses can reduce heating costs by 15-25% compared to standard trusses, and the energy savings typically pay for the additional truss cost within 5-7 years!

CSI Code

06 17 53

NAHB Code

3140