Ridge — pitched roof in the over-rafter system (termPIR® AL)

Junction function

In the over-rafter system without sheathing, the ridge is the simplest detail of a pitched roof: termPIR® AL boards run continuously across the entire slope up to the ridge line, where boards from both slopes meet. No gaps, no thermal bridges, no additional insulation flashings.

This is a fundamental difference vs sandwich panel systems (insPIRe® D), where the ridge requires separate OB-22/OB-23 flashings and precise panel cutting. In the over-rafter system, it is enough to provide:

1. Boards cut at the pitch angle — edges of both slopes meet along the ridge line.
2. Aluminium tape at the joint — preserves the vapour tightness of the insulation layer.
3. Windproofing through the ridge — vapour-permeable membrane laid with a min. 200 mm overlap.
4. Broken counter-battens + vented ridge cap — ventilation of the space beneath the covering.

Critical installation aspects

• Counter-batten fixing (item 03) — fastened to the rafter through the insulation board with self-drilling screws (item 04) every 40 cm, with every second screw at a 67° angle (transfer of shear forces from the covering to the rafter, prevents sliding).
• Cutting boards at the ridge — at an angle matching the roof pitch (e.g. 30° → cut at 60° relative to the board surface). Joint geometry depends on the pitch angle.
• Aluminium tape (item 06) — width min. 75 mm, applied symmetrically on both slopes with an overlap ≥ 30 mm; prevents migration of vapour and air through the joint.
• Windproofing (item 05) — the vapour-permeable membrane must be continuous through the ridge, with a minimum 200 mm overlap on each side, sealed with butyl tape.
• Ridge ventilation — counter-battens are broken ~5 cm on both sides of the ridge; the covering gap is closed with a vented ridge cap or a dedicated ventilation tape. No ventilation = condensation under the covering and dampening of the windproofing.
• High-humidity rooms beneath the roof (sauna, bathroom, kitchen without extractor hood) — per note b of the catalogue: additional PE vapour barrier on the interior side, beneath the termPIR® boards.

System comparison — where does the ridge require flashings?

Feature	Over-rafter termPIR® AL	Sandwich panel insPIRe® D
Dedicated ridge flashing	none (insulation continuity)	OB-22/OB-23 (separate)
Thermal bridge at ridge	none	minimal (between panels)
Number of metalwork elements	only vented ridge cap	ridge cap + ridge flashing
Installation tolerance	wide (board cut in-situ)	narrow (factory-made panel)
Detail installation time	~30 min per linear metre	~15 min (panel + ridge cap)
Roofer skills required	system knowledge + windproofing	typical sheet-metal roofer

Occurs in the system pitched roof — termPIR® over-rafter.

Documentation

Technical Catalogue termPIR® — Residential Buildings (Gór-Stal 2022), page 15 — Pitched roof, over-rafter system (without sheathing), roof cross-section. Scale 1:10. Technical notes per notes a-b of the original.

Components in this junction