Purpose Of Roof Collar Ties

They supplement the ceiling joists and prevent the rafter couples spreading.

Purpose of roof collar ties.

The purpose of the collar tie roof is to extend first floor rooms into the roof space and so limit the largely unused roof space. The design of collar tie roof provides greater ceiling height if it is required. Contrary to popular belief collar ties are not there to support rafters or to keep walls. Rafter ties prevent spreading.

The collar ties are used to strengthen the roof rafters to prevent them from buckling or sagging under the weight of the roof. However in a conventionally framed peaked roof like the kind you describe collar ties would probably serve little or no function since the attic floor joists serve as ties to prevent the rafters from spreading. 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. Collar ties collar ties must be provided in all coupled roof construction.

Collar ties prevent uplift. By upper third here we mean one third of the length of the rafter from ridge to top plate. The most common reason for installing collar ties is to prevent rafters from spreading apart under load. This is especially important if the home is in the northern climates where snow accumulates on roofs or if there are multiple layers of roofing materials.

Where the rafter span is such that it requires support from underpurlins collar ties are fitted to opposing common rafters at a point immediately above the underpurlins. Collar tie is a colloquial term for collar beam. Collar ties collar ties are connections between opposing rafters at the upper one third of the roof frame area just below the ridge and they are required at a 48 4 maximum spacing which is every other rafter of a 24 on center spacing and every third rafter with 16 on center spacing. Collar tie 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.

Definition of collar tie in roof framing definition. The 2015 international residential code does not require collar ties or collar beams.