Rafters And Roof Ridges Are Normally Under Tension

This style of roof construction is often called stick framing.

Rafters and roof ridges are normally under tension.

The 2015 international residential code does not require collar ties or collar beams. That s true for horizontal ties in the lower third of the roof. Collar tie is a colloquial term for collar beam. Homes with vaulted ceilings usually don t have rafter ties to keep the walls from spreading and the ridge from sagging so they use a structural ridge.

In a home with a structural ridge the ridge consists of a beam strong enough to support the roof load without sagging. Rafter framed roofs consist of individual rafters sawn lumber members usually spaced from 12 to 24 inches on center which span from the exterior walls or roof eaves up to the roof top or ridge or into the sides of the main hip rafters. Rafter tie a tension tie in the lower third of opposing gable rafters that is intended to resist the outward thrust of the rafter under. A collar tie is a tension tie in the upper third of opposing gable rafters that is intended to resist rafter separation from the ridge beam during periods of unbalanced loads such as that caused by wind uplift or unbalanced roof loads from snow.

A ridge board was not always required and the photo above of the attic in a 1920s era house shows a roof framed without one. A tension tie in the upper third of opposing gable rafters that is intended to resist rafter separation from the ridge because of wind or unbalanced roof loads.