Why heel definitions differ
A roof truss heel is the region where the top chord, bottom chord, web system, and bearing support come together. The term “heel height” is used in several ways. A framer may measure from the top of the wall plate to the top of the top chord. An energy consultant may care about clear insulation depth below the roof deck. A truss manufacturer may report a standardized vertical dimension tied to chord intersection points or bearing geometry. These values can differ even when the physical truss is unchanged.
This calculator therefore reports several related heights. The selected definition becomes the primary answer, while structural and overall dimensions remain visible. The comparison table helps users understand how a different reference point changes the reported number. Drawings should always state both endpoints of the dimension.
Standard heels and raised energy heels
A standard heel is commonly governed by roof slope, bearing width, chord size, seat geometry, and connector-plate requirements. A raised heel adds vertical space above the exterior wall. This added space can allow full-depth attic insulation to continue over the wall plate without being squeezed under the roof deck. Raised heels can also create room for ventilation baffles and improve thermal continuity at the eaves.
The energy calculation in this page is a clearance estimate. It compares entered insulation and ventilation requirements with available geometric space. It does not evaluate local energy-code R-values, insulation products, air-barrier details, wind washing, vapor control, moisture performance, or fire-blocking requirements.
Scissor truss considerations
A scissor truss has an exterior roof slope and a separate interior ceiling slope. The ceiling chord rises toward the center, reducing the vertical distance between chords. The heel must accommodate both chord depths, connector plates, and the difference between exterior and interior slopes. The interior pitch should generally remain lower than the exterior pitch. A small slope difference can create tight geometry and may require a deeper heel or different truss configuration.
Parallel-chord configurations
Parallel-chord roof trusses use chords with the same or nearly the same slope. The clear separation between chords may control the heel depth more strongly than bearing-run geometry. This calculator allows a chord-separation input and compares that requirement with the basic structural heel. Actual web layout and connector plates remain manufacturer-specific.
Bearing width and heel run
Bearing width is the horizontal support available under the truss. Heel run is the horizontal distance used in the slope-rise calculation. They can be equal, but they are not always identical. Seat cuts, offsets, chord intersections, wall geometry, and drafting conventions can shift the effective run. Use a known heel run from the truss detail when available.
Chord depth projection
Top chord lumber depth is normally measured perpendicular to the sloped chord. Its vertical projection grows as the roof becomes steeper. A simple calculation that adds the nominal chord depth without projecting it vertically will understate the height on steep roofs. The calculator includes this projection using the roof angle.
Left and right heel differences
Some trusses have different bearings, overhangs, wall widths, or heel runs at each end. Examples include additions, porch transitions, stepped wall plates, and mono-pitch roofs. The asymmetric option records separate left and right runs and bearings. The main result uses an average run for summary purposes, while separate rises are retained in the calculation engine. Engineered drawings should show each end independently.
Reverse calculations
Reverse mode starts with a target heel height and estimates a required pitch, heel run, bearing width, or wall extension. This can help early coordination when an insulation target or architectural elevation fixes the available height. Reverse results may not correspond to a buildable truss joint. They are geometric starting points only.
Interpreting warnings
Warnings identify inputs that are unusual, incomplete, or likely to cause coordination problems. A warning does not prove the design is unsafe. Similarly, the absence of a warning does not prove the design is acceptable. Structural design depends on span, loads, lumber grades, spacing, duration factors, snow drift, wind uplift, seismic effects, bearing reactions, connector plates, permanent bracing, temporary bracing, and local code rules.
Recommended workflow
Use this tool during preliminary planning. Record the selected measurement definition and all included layers. Send the resulting dimensions to the truss supplier. Compare the supplier’s sealed or approved drawings against wall elevations, fascia lines, soffit depths, roof sheathing, attic ventilation, and insulation details. Resolve differences before fabrication.