Installing Raised Heel Trusses

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Harry Whitver

Understand the Probem: Conventional roof trusses have top chords… Read More Understand the Probem: Conventional roof trusses have top chords that rest close to the wall plate, compressing the insulation at the building’s perimeter and creating an underinsulated cold spot.

Harry Whitver

Allow for R-Value: How high a heel? That depends on the insulati… Read More Allow for R-Value: How high a heel? That depends on the insulation needs. In some climates, code-compliant houses may need room for 10 inches of insulation or more. For beyond-code, super-insulated homes, builders may want to pile insulation 2 feet or 3 feet deep.

Harry Whitver

Protect from Wind-Washing: In vented roofs, airflow through the … Read More Protect from Wind-Washing: In vented roofs, airflow through the vents can diminish the heat-trapping effect of insulation. Be sure to install baffles at the eaves to direct the flowing air into the attic, but not through the loose fiber.

Harry Whitver

Brace for Loads and Codes: Tall trusses may topple, so pay atten… Read More Brace for Loads and Codes: Tall trusses may topple, so pay attention to the bracing. In high-wind or seismic areas, raised-heel trusses need special blocking and connectors. And even in a zone with no extra lateral loads, the code’s “braced wall” rules will govern how the truss is attached and braced. Your truss supplier’s engineers should specify the connections; your job is to follow their directions.

When you’re building a high-performance house, you need to shave the heating and cooling loads everywhere you can. Thermal bridging creates hot spots or cold spots in the building envelope, and that makes a difference for heating and cooling costs—as well as for comfort.

One example: the juncture where walls intersect roofs. A house design may call for 16 inches of fiberglass insulation in an attic, but if the top chord of the roof truss only passes 6 inches above the wall plate, there’s no room for that much insulation at that location. Millions of houses that have code-compliant attic insulation over most of the ceiling area have compressed insulation all around the house perimeter—which means the owners haven’t gotten the most out of their insulation.

Fortunately, truss manufacturers know how to build raised heel trusses (also called energy trusses) that leave room for full-height insulation all the way across the joint where the wall plate supports the truss.

Typically, the tall heel of the truss sits flush with the outside of the wall framing, creating a continuous plane that you can sheathe over with plywood or OSB for a strong, well-braced joint. But high-heeled trusses do sometimes require extra bracing (such as in earthquake- or hurricane-prone areas). Your truss maker knows how to engineer the bracing and connection details to meet local codes and national design standards. Give the manufacturer information about the building’s location and any special structural loads, and then follow its details to a T.

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