Standing seam

Steel or aluminium sheet cold roll-formed into trapezoidal, sinusoidal or other profiles to provide spanning stiffness, used as roof and wall cladding and as structural decking. Sheets are typically metallic-coated steel with a factory-applied organic coating, fixed through to purlins or rails, or used as the skins of built-up and composite panel systems.

A horizontal secondary structural member spanning between principal rafters, portal frames or walls, supporting the roof cladding or decking. In modern industrial buildings purlins are commonly cold roll-formed galvanised steel sections such as zed and cee profiles; in traditional construction they are timber.

The horizontal line at the apex of a pitched roof where two slopes meet, closed with ridge tiles, a formed metal capping or a ventilated ridge system. The detail must weather the junction of the meeting coverings and often provides high-level ventilation to the roof space.

The lower horizontal edge of a roof slope, usually projecting beyond the wall face, where rainwater is discharged into the gutter. Eaves details typically include the fascia, soffit, ventilation openings and underlay support to prevent water being trapped behind the gutter.