Why Do Roof Windows Leak, and How Is It Fixed?

A leaking roof window is a common enough call-out, and it's easy to assume the window itself has failed. In our experience, that's rarely the actual cause. Here's what Back to Back Roofing Worcester usually finds, and how we fix it properly.

The Real Cause, Most of the Time

Roof windows are genuinely well-engineered products, and the glazing unit itself rarely fails. The far more common cause of a leak is a poorly fitted, damaged, or ageing flashing kit — the component that seals the junction between the window frame and the surrounding roof covering.

Common Reasons Flashing Kits Fail

• Poor original installation, particularly inadequate overlap with surrounding tiles
• Physical damage from storms or nearby roof work
• General ageing of the flashing material over years of exposure
• Incorrect flashing kit specified for the roof covering type

Other Less Common Causes

• Failed seals around the glazing unit itself, though this is less frequent
• Condensation being mistaken for a leak, particularly in poorly ventilated spaces
• Blocked drainage channels within the window frame
• Damage to surrounding tiles or slates rather than the window installation itself

How We Diagnose and Fix It

1. Inspect the flashing kit first. Since it's the most likely source, we check this thoroughly before assuming anything else.
2. Check the window seals and drainage. Ruling out the less common causes systematically.
3. Confirm the actual source before repairing. So the fix addresses what's actually wrong, not just where the leak shows.
4. Repair or replace the flashing kit as needed. Using the correct kit specified for your roof covering.

Why Getting the Diagnosis Right Matters

• Avoids paying to replace a window that wasn't actually the problem
• Fixes the genuine cause rather than a temporary patch
• Prevents the same leak recurring after a misdiagnosed repair
• Gives you confidence the issue is properly resolved

Why Choose Back to Back Roofing Worcester

We're a domestic and commercial roofing team based right here in Worcester, on Rose Avenue in WR4, so we know the area and can get to you quickly. Every job comes with clear pricing before work starts and workmanship you can rely on.