A single-pitched roof truss with a claw-purlin structure with one gable purlin.
In buildings, which are located at the border with the neighboring plot, the most common are single-pitched roofs, enabling drainage of rainwater in one direction – to the inside of the plot, on which they stand.
The structure of single-pitched roofs is analogous to the structure of gable roofs, of which they seem to be half – With this difference, that the lack of opposite rafters causes pressure towards the wall closing the roof. This pressure must be balanced by resting the rafters on purlins supported by poles and swords, and by bracing the poles and rafters with clamps.. For single-pitched roofs with a span of up to 5 m, one pole at the rear wall and a purlin are sufficient. In span roofs 5 – 6 m, two columns are used in each truss, of which the wall pole must be vertical. The center column may be horizontal (i.e.. leaning towards the back wall), vertical or trestle (leaning towards the roof slope)