Over-rafter pitched roof — corner with gable wall

Junction function

The over-rafter roof corner with a gable wall is a three-dimensional building corner — the edge of the pitched roof meets the vertical gable wall (most often triangular). The detail must:

• Close the side edge of termPIR® boards at the gable wall — without this the PIR core would be exposed.
• Ensure continuity of insulation in the 3D corner — without interrupting the insulation of the gable wall and the roof, to avoid a thermal bridge.
• Aesthetic finish of the roof gable edge — OB-31 flashing masks the transition from roof to wall.

The over-rafter system facilitates this junction (vs the between-rafter system) — the insulation is continuous above the rafters, and the counter-batten ends at the gable wall without interrupting the PIR.

Critical installation aspects

• termPIR® AL boards (item 02) cut at the roof angle end at the gable wall line. The edge is sealed with PIR installation foam (item 09) — fills microgaps.
• OB-31 gable flashing (item 07) — finishing of the roof gable edge from the façade side. A 50 mm overlap with the roof covering (tile/sheet metal) is required.
• Aluminium tape (item 08) seals the joints between boards in the gable strip — vapour tightness.
• Gable counter-batten (item 04) — the last counter-batten before the gable wall, fixed with higher screw density (roof edge zone = +50% density).
• Windproof membrane (item 03) overlaps 200 mm onto the gable wall façade finish (item 12) — eliminates wind leakage at the corner.
• Roof-to-wall insulation connection — ideally termPIR® AL (roof) meets termPIR® ETX (ETICS wall) or termPIR® AL (3-layer wall) without a gap — requires careful design and workmanship.

Choice of gable wall finish

Variant	Wall finish	Connecting flashing
ETICS wall + termPIR® ETX	silicone render	OB-31
3-layer wall	clinker / facing brick	OB-31 + brick plinth flashing
Façade timber wall	wood / composite	OB-31 + timber drip edge

Occurs in systems: over-rafter pitched roof, ETICS, 3-layer wall.

Documentation

termPIR® Catalogue — Residential Buildings (Gór-Stal, 2022), p. 20 — over-rafter roof corner.

Components in this junction