TR-15 – Eaves Detail: Pitched Warm Roof

This pitched warm roof eaves detail shows a junction with a rendered masonry cavity wall, with rigid insulation installed between and below the rafters or truss top chords.

The drawing demonstrates how the roof insulation should extend over the wall plate to meet the cavity-wall insulation and form a continuous thermal envelope. It also shows the relationship between the rafters, under-rafter insulated plasterboard, ventilated void, roofing underlay, counter-battens, wall plate and external-wall construction.

A brick-faced version of this warm-roof eaves detail is also available. For broader guidance on moisture and condensation, consult Approved Document C.

Supporting notes cover:

• Structural design of rafters or prefabricated roof trusses.
• Wall plates, restraint straps and framing anchors.
• Rigid insulation between the rafters or trusses.
• Continuous insulation beneath the roof members.
• Sealing insulation joints and perimeter gaps.
• Insulation continuity over the wall plate.
• Roof-level cavity closers and cavity barriers.
• Ventilated and unventilated warm-roof options.
• Eaves and ridge ventilation.
• Condensation-risk assessment.
• Vapour-control and airtightness layers.
• Connection of the roof airtightness layer to the external wall.
• Junction SAP reference E11 and the calculated PSI value shown on the drawing.

The customer receives one downloadable PDF construction drawing, prepared at a scale of 1:10 and formatted to fit an A3 sheet.

Insulation thicknesses, structural members, ventilation and vapour-control arrangements must be selected using the project-specific U-value calculation, SAP assessment, condensation-risk assessment and structural design.