Construction services

Flat roofs with a claw-purlin structure

tmpe1a2-1Truss of a flat roof with a claw-purlin structure with one gable purlin.

In flat roofs, with a slope of from 1:3 (18,5 %) do 1:10 (5,7 %), the most commonly used are claw-purlin structures. Tongue structures are not suitable for use in flat roofs, because the smaller the slope of the roof, the greater the force spreading the side walls.

A typical flat roof truss above a building with a span of approx 8 m consists of a ridge purlin supported by poles and swords, and a pair of clamps bracing the pole with two rafters.

With a larger span, the only modification is to add more purlins. In a roof with a span of approx 12 m, the truss consists of two intermediate purlins, with a span of approx 16 m, the truss has two intermediate purlins and a ridge purlin.

With very flat roofs (about the slope of the roof 1:10) The forceps may not cover the rafters, but the poles themselves.