Purpose Of Roof Collar Ties

A collar tie is a horizontal roof rafter compression connector that is located in the uppermost third of the span of a pair of opposed sloped or gable roof rafters.

Purpose of roof collar ties.

Contrary to popular belief collar ties are not there to support rafters or to keep walls below from spreading under the weight of the roof. They supplement the ceiling joists and prevent the rafter couples spreading. The most common reason for installing collar ties is to prevent rafters from spreading apart under load. This collar tie roof is suitable for the span varying from the 4 to 5 5 this roof is used for a maximum span of 4 8 m.

Contrary to popular belief collar ties are not there to support rafters or to keep walls. Collar ties collar ties must be provided in all coupled roof construction. 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. 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.

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

By upper third here we mean one third of the length of the rafter from ridge to top plate. 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. 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. The design of collar tie roof provides greater ceiling height if it is required.

The collar ties are used to strengthen the roof rafters to prevent them from buckling or sagging under the weight of the roof. 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.