Roof Truss Bottom Chord

The stability of this shape supported by the bottom chord is the reason for the common usage of the triangle truss.

Roof truss bottom chord.

The roof system is basically a hinge now. For example if the bottom of the truss is buried in insulation while the remainder is in the open attic air this condition can occur. In standard heel applications of roof trusses the bottom chord is cut on each end at an angle consistent with the roof pitch of the truss. The trusses are 42 long with a 2x10 bottom chord 3 12 pitch.

This creates additional surface area for the two members to transfer forces and allows for them to be plated together creating a strong resilient joint. It is utilized in a framed roof comprised of rafters and a ceiling joist. Removal has left them extremely vulnerable to collapse due to spreading especially under snow loads but also under just the load of the roof itself. Those trusses were engineered with a heavy critical dependency on the bottom chords which are in tension.

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