Roof valley — water drainage (GS PIR D)

Junction function

Roof valley = the location in a gable roof with an annex / projection where two slopes meet internally (as opposed to a ridge, where they meet externally). Critical for water drainage:

• Both water streams from the two slopes combine → concentration at a single point.
• Gutter profile collects the water and discharges it to the eaves gutter.

Construction:

1. Internal profile (item 03) = bent metal sheet on the inside of the roof, forming a gutter.
2. External profile (item 04) = bent metal sheet on the outside, covering the cladding side.
3. On-site insulation (item 05) fills the space between the profile and the panels.

Critical installation aspects

• 1.5% slope inside the valley towards the eaves gutter.
• Butyl sealant (item 09) seals all joints — critical for watertightness.
• 50 mm gap between panels on both sides of the valley — space for the profile + insulation.
• Maintenance every 2 years — clearing leaves, checking the tightness of the butyl sealant.
• A building without a valley is preferable — valleys are a source of long-term leakage; where possible, design the roof without valleys (treating projections as separate, standalone structures).

Documentation

Technical Catalogue insPIRe S/U + GS PIR D (Gór-Stal 2025), page 87 — Roof valley, water drainage. Scale 1:5.

Components in this junction