Leaking Valley After a Re-Tile on a Low-Pitch Roof
You have completed a re-tile of a 17.5 degree roof with a main valley where two planes meet. Three weeks after handover the client reports water staining on the ceiling directly below the valley during heavy rain. You inspect and find the valley tiles are slightly proud, the valley iron is sound, and there is no visible sarking damage from above. The original roof had the same pitch and did not leak. Heavy rain has been driven by strong wind from an unusual direction. The client wants the roof fixed at no cost and is threatening to complain to the regulator.
1. How do you diagnose the cause before deciding on a repair?
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Diagnose systematically rather than guessing:
- Confirm the leak path. Staining below the valley does not prove the valley is the source; water can travel along sarking or battens. Check the ceiling stain location against the roof above and look for tracking on the sarking from below or through a lifted tile.
- Check the valley geometry. At 17.5 degrees, the valley is a low-pitch detail where water volume and wind-driven rain are significant. Verify the valley boards and iron are correctly set, the tiles overhang the valley correctly, and the valley is not holding water or debris.
- Check for wind-driven rain entry. Strong wind from an unusual direction can drive rain under tiles and laps. Confirm the tile lap and side lap meet the manufacturer's requirements for 17.5 degrees, and that sarking is continuous and correctly lapped and turned up at the valley.
- Check flashings and penetrations near the valley, and confirm no fixings pierce the valley iron.
- Consider a water test with a hose on a dry day, applied from low to high, to reproduce the entry point.
Only after identifying the actual entry point should you specify a repair.
2. Assuming the cause is wind-driven rain entering under the tiles at the valley, what is a fair and defensible response to the client?
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A fair response separates defect from weather event, but still protects the client:
- Explain findings in writing: the valley iron is sound, the leak occurred under unusually directed wind-driven rain, and the entry point is under the tiles at the valley. Be honest about whether the installation met the specified lap and sarking requirements for 17.5 degrees.
- If your work met the specification, the leak may be a performance limitation of the tile and valley detail under extreme wind-driven rain rather than a workmanship defect. However, the client still has a leaking roof, so offer a practical remedy.
- Propose an upgrade that improves performance: for example, additional sarking turning up at the valley, a valley seal or a proprietary valley flashing suited to low pitch, or improved tile fixing and lap in the valley zone. Quote the cost transparently.
- If inspection shows your laps or sarking were non-compliant, rectify at no cost - that is a defect, and the client is entitled to it fixed.
- Document everything and respond promptly to the complaint. Offer to attend with the client and, if needed, an independent inspector. A prompt, evidence-based response reduces the risk of a regulator complaint and preserves your reputation.