Velux Window Repair: Leaks, Problems & Costs

Velux and other roof windows are exposed to weather on all four sides, making them one of the more demanding components in a house to keep watertight and operational. When problems develop, a drip during rain, a handle that will not move, or fog between the panes, it helps to understand what is actually failing before calling a contractor, as the diagnosis dramatically affects both the cost and who you need to call.

Many reported “Velux leaks” turn out not to be faults in the window itself but flashing or roof problems that would affect any roof window. Knowing the difference saves wasted call-outs.

Common Velux Problems and Their Causes

1. Water Leaking In During Rain

Water entry during rain is the most alarming and most misdiagnosed Velux problem. There are four distinct failure points, each with different repair approaches:

Flashing failure, a common cause. The flashing kit that directs rainwater away from the frame-to-roof joint can lift, be damaged, or be blocked by leaves and debris, and the surrounding tiles or slates can slip. Water tracks under the flashing and appears at the ceiling. VELUX advises clearing leaves and debris from the flashing once a year so that rainwater can flow freely.¹ This is usually a roofing job; a roofer (not a glazier) should attend.

Compression seal failure, the rubber seal where the sash meets the frame degrades and no longer compresses watertight when the window is closed. Water enters around the frame perimeter rather than from the roof. The window may also feel slightly easier to open than it used to.

Draught seal (brush pile) collapse, less likely to cause active ingress on its own but can allow windblown rain to enter around the sash in stormy conditions.

Poorly sealed cable entries (on mains-powered electric models), a minor but easily overlooked source of localised drips.

Diagnosis: In dry weather, run a garden hose along each edge of the window in turn, sealing one edge at a time with a towel to localise where water enters. This simple test distinguishes flashing from frame seal failure in minutes.

2. Condensation Between the Glass Panes

Fog or droplets trapped between the two glass panes means the hermetic seal of the double-glazed unit has failed, allowing moist air to enter the cavity. Once the seal has gone, it cannot be repaired: the entire glazing unit must be replaced. Condensation on the room side of the glass is different: VELUX treats it as a warning sign that the room needs more ventilation, not as a failed unit.¹

This is a supply-and-fit job requiring the unit to be ordered to the exact Velux model and glass specification, which are shown on the window’s type sign in the right corner of the top sash, behind the ventilation flap.¹ Replacement units are usually available in several glazing variants, such as energy-saving or noise-reducing glass.

3. Stiff or Broken Handle / Locking Mechanism

Centre-pivot Velux windows are opened with a control bar along the top of the sash, so they can be operated even with furniture under the window.² The control bar (a handle on some older models) and the lock are among the more commonly replaced parts. Causes include:

• Dirt and dried-out lubricant in the lock and hinges, often resolved by cleaning and lubricating (VELUX sells maintenance kits for this) without part replacement.¹
• Broken control bar or handle, typically cracked by force against a warped frame or by a sharp impact.
• A stiff or seized lock or barrel bolt, which can stop the window locking properly or being secured in the cleaning position.²

Most parts are model-specific but are sold through the VELUX spare parts shop and by independent suppliers. Some discontinued models have been superseded by updated handle designs that are cross-compatible.

4. Broken or Bent Hinge/Pivot

The pivot hinges on a centre-pivot Velux sit at the sides of the sash and are heavy-duty components that rarely fail in themselves, but they and their friction mechanism can be strained or bent if the window is forced open against an obstruction or while it is frozen shut.

5. Electric Model Not Responding

For electric and solar-powered Velux (INTEGRA range), common failures include:²

• Drained solar battery (after extended cloudy periods)
• Faulty rain sensor (electric models have a built-in rain sensor that closes the window automatically when it rains)³
• Lost pairing between remote and actuator
• Actuator motor failure

Most of these are resolvable without hardware replacement by resetting the control unit per the installation manual. Actuator replacement (if the motor has failed) costs £120–£250 in parts alone. VELUX recommends replacing the motors on electric roof windows within 10 years of installation to prevent malfunction.¹

Repair Costs (UK, 2026)

When to Repair vs Replace

Check the guarantee before paying for a repair. VELUX roof windows carry a 10-year guarantee.⁴ Registering the window extends that cover by a further five years.⁴

A Velux window installed in the 1990s that presents simultaneously with a failed glazing unit, a broken handle, and compromised flashing is almost certainly cheaper to replace than to repair piece by piece, particularly when scaffold or roof access costs are factored in.

Finding a Velux Repairer

Velux has a network of certified installers, searchable on its UK website under “Find a VELUX Certified Installer”.¹ However, independent roofers who are familiar with Velux products are generally equally competent for flashing repairs and often charge less. For internal mechanical or glazing repairs, specialist roof window contractors (search “roof window specialist” or “Velux repair [your town]”) are the most efficient option.

Get at least two quotes for any repair over £200. A competent contractor should be able to diagnose the problem visually before quoting, and should specify which parts are needed rather than giving a vague estimate.

Always ask whether the repair comes with a written guarantee against recurrence, particularly for flashing work.