Graphical Construction Glossary >> Roofs and roofing. >> valley rafter

valley rafter

The main support timber directly under the valley intersection of two roof surfaces. It corresponds to the hip rafter in terms of the same slope and roofing angles. It supports the valley jack rafters and any valley creepers.

Plan showing parts of a hip roof.

The sketch above shows two valleys in a typical hip roof. They are the ones leading of at 45 Deg. from the internal corners of the building. They follow the same rules as hips in that a valley in (a regular)plan dissects the angle of the walls that it rises from.

In this normal case, the angle of the walls is 270 Deg. so the valleys are set at 135 Deg. from each wall.

A close up sketch of a valley timber and the rafters it supports.

Shown in the sketch above is one of the valley timbers running up to the ridge. It is essential that the valley section is connected firmly to the main roof.

Roofs have been built like this for centuries, but they rely for a certain extent on good workmanship by the carpenters. Today the use of timber connectors has improved things strength wise, but this type of construction in my opinion is inherently weak. Scotch valleys are far stronger and simpler to frame.

A section through a valley showing the gutter and roof battens for a steel corrugated iron roof.

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"When we build, let us think that we build for ever."John Ruskin 1819-1900