TR-24 – Pitched-Roof Valley Detail

This pitched roof valley detail illustrates a typical junction formed using either a proprietary GRP valley trough or a Code 5 lead lining.

The drawing is intended for architectural designers, building professionals, roofing contractors, developers and self-builders who require a clear valley construction detail for incorporation into a Building Regulations drawing package or project specification.

For the corresponding facing-brick drawing, see our TB/24 pitched roof valley detail. Approved Document C provides official guidance on resistance to moisture and roof ventilation.

The detail shows:

• Proprietary GRP valley trough
• Alternative Code 5 lead valley lining
• Treated valley boards
• Valley rafters or roof trusses
• Plywood sheathing and tilting fillets
• Lead upstands and mortar bedding
• Roofing underlay dressed into the valley
• Concrete tiles cut to the valley rake
• Mechanical fixing of cut tiles
• Required laps and lining support
• Continuity of warm-roof insulation around the valley
• Maintenance of roof ventilation where required
• Vapour-control, airtightness and fire-stopping principles

The accompanying notes cover valley selection, structural support, underlay, tile cutting, mechanical fixing, drainage-channel width, leadwork lengths and laps, thermal continuity and weather protection.

What You Will Receive

• One downloadable PDF construction drawing
• A3 landscape sheet
• Drawn at 1:10 when printed at 100% on A3 paper
• Drawing reference: TB/24
• Detail title: Valley Detail

Important Information

This is a standard construction detail intended to provide general guidance. The selected valley system must be suitable for the roof pitch, covering, catchment area and exposure conditions.

Valley rafters, trimmers, boards and connections must be confirmed through the structural roof design. Proprietary GRP valleys must be installed in accordance with the manufacturer’s instructions, while lead valleys must follow the relevant Lead Sheet Association recommendations.

The drawing does not include structural calculations, roof-drainage calculations, a condensation-risk assessment or Building Regulations approval.

The PDF is supplied for use by the purchaser on their own projects. It may not be resold, redistributed or reproduced for commercial resale without written permission.