Why is my VELUX window leaking?

If you have noticed water around your VELUX window, damp marks on the surrounding plaster or dripping during heavy rain, it is natural to assume the window itself has failed. Sometimes that is true, but not always.

A leaking roof window can be caused by several different issues. The window, flashing, seals, surrounding roof tiles, blocked channels, condensation and the age of the installation can all play a part. This guide explains the common causes and what to do next before arranging a VELUX repair.

First, is it definitely a leak?

Before assuming rainwater is coming in, it is worth thinking about whether the issue could be condensation. Roof windows are often installed in rooms where warm air rises, such as bedrooms, bathrooms, kitchens, loft rooms and stairwells. If warm moist air meets cold glass or cold surfaces, condensation can appear and may look like a leak.

Condensation may be more likely if:

• water appears on the inside of the glass rather than around the frame
• the problem is worse in cold weather
• the room has poor ventilation
• the issue happens after showers, cooking or drying clothes indoors
• there are no obvious signs of water entering during rainfall

Condensation still needs managing, but it is different from an external water leak. If you are unsure, photos and a clear description can help AR Windows understand what may be happening.

Common causes of a leaking VELUX window

Water can find its way into a roof window area for several reasons. Some problems are relatively simple to inspect and repair. Others may be linked to the wider roof, the age of the window or the original installation.

Possible causes include:

• worn or damaged seals around the window
• blocked drainage channels
• faulty or damaged flashing
• slipped, cracked or poorly fitted roof tiles
• debris building up around the window externally
• age-related wear to the frame or glazing
• incorrect installation details
• condensation being mistaken for a roof leak

Because there are several possible causes, it is important not to guess. Replacing a window may not solve the problem if the issue is actually with the surrounding roof, and a simple repair may not be enough if the window itself is badly worn.

Could the flashing be the problem?

Flashing is the weatherproofing system around the roof window that helps direct water away from the opening. If flashing is damaged, incorrectly fitted, blocked or no longer working properly with the surrounding roof covering, water may enter around the window.

Flashing issues can sometimes look like a failed window because the water appears near the frame or plasterboard. However, the source may be outside the visible internal area.

This is one reason why professional inspection can be useful. AR Windows can advise whether the issue appears to be with the window itself, the flashing or the surrounding roof detail.

Could blocked drainage or debris cause a leak?

Leaves, moss, dirt and general roof debris can collect around roof windows over time. If drainage paths become blocked, water may not run away as intended. This can increase the chance of water finding its way into vulnerable areas.

You should not climb onto the roof or lean out of the window to clear debris unless you are properly equipped and it is safe to do so. If the window is high, awkward or difficult to access, it is better to arrange professional help.

When seals and glazing start to fail

As a roof window ages, seals and glazing can deteriorate. You may notice draughts, moisture, misting between panes, visible wear, movement around the frame or repeated issues during bad weather.

If the window is otherwise in good condition, a repair may be possible. If the window is old, inefficient or showing several problems at once, replacement may offer better long-term value.

What should you do when you notice a leak?

If water is coming in, try to limit further damage while keeping yourself safe. Do not attempt roof work unless you are trained and equipped to do so.

Helpful first steps include:

• move furniture, flooring or valuables away from the affected area
• use a towel or container if water is dripping inside
• take photos of the window, frame and surrounding plaster
• note whether the issue happens during rain, after rain or in cold weather
• check whether the problem appears to be internal condensation
• contact AR Windows for practical advice

It can also help to note whether the leak happens only during heavy rain, wind-driven rain, certain wind directions or all weather conditions.

What information should you send to AR Windows?

The more detail you send, the easier it is to advise on the likely next step. Before contacting AR Windows, try to provide:

• clear photos of the whole VELUX window from inside the room
• close-up photos of damp, staining, dripping or visible damage
• photos of any product code or VELUX plate if safe to access
• a short description of when the leak happens
• the approximate age of the window if known
• whether the issue is new or recurring
• details of access, especially if the window is high or awkward to reach

This helps the team understand whether the issue may need repair, maintenance, replacement parts or a full replacement roof window.

Can maintenance help prevent leaks?

Regular maintenance can help reduce avoidable roof window problems. Cleaning, checking seals, keeping drainage areas clear and dealing with small issues early may help prevent some problems from developing.

Maintenance cannot prevent every leak, especially where the window is old, badly worn or affected by wider roof issues, but it can support better long-term performance.

For planned support, AR Windows offers VELUX maintenance and an Annual Service Contract for eligible roof windows.

Does a leaking VELUX window always need replacing?

No. Some leaks can be repaired, particularly if the cause is isolated and the roof window is generally in good condition. However, replacement may be more sensible if the window is old, repeatedly leaking, badly worn, inefficient or difficult to operate.

The right answer depends on the window, the surrounding roof and the cause of the leak. AR Windows can help you decide whether repair or replacement is the better long-term option.

Final thoughts

A leaking VELUX window should not be ignored, but it also should not automatically be assumed that the whole window has failed. The problem may be linked to condensation, seals, flashing, drainage, roof coverings, installation details or age-related wear.

If you are unsure what is causing the problem, send AR Windows photos and details. The team can provide practical advice and help you understand whether a repair, service or replacement is likely to be the right next step.