Rafter purlin anchors
A rafter purlin anchor or rafter purlin connector is an angle connector in the roof structure that connects two support elements (a rafter and a purlin ) that are perpendicular to each other. Typically, it is made of metal and designed as an angled perforated plate , which is attached on one side to the rafters and purlins with anchor nails . But there are also wooden rafter purlin anchors.
The metal variants basically consist of two congruent , interconnected surfaces that are shifted lengthways and positioned at 90 ° to one another. The anchor is attached to the side of both girders in one of the four angles formed by the rafter and purlin. The middle part of the connector does not lie against the girders, but runs freely "in the air" and is therefore protruding. With the variants available on the market, attempts are often made to minimize the protruding part by adapting the design.
There are various other designs for special purposes; z. B. those that are attached on both sides, or those that largely correspond to the classic 90 ° angle connector for bookcases. The 90 ° angle of the anchor also does not necessarily mean that all angles between the beams must be 90 °. There are still two degrees of freedom of rotation left and in fact girders are regularly connected by rafter anchors in such a way that one girder rests diagonally on the edge of the other.