The short answer: There is no fixed date on which a VELUX window stops working. The frame and sash often outlast the parts around them, and the sealed glass unit, the flashing and the seals at the edges tend to give out first. How long yours lasts depends on the model, the pitch of the roof, how exposed the house is and how the window has been used. A survey of the actual window tells you far more than an average would.
Anyone asking how long VELUX windows last is usually standing under one that has started to misbehave, or planning a loft room and wondering what the glass will look like in twenty years. Both questions deserve a straight answer. This page belongs to our wider guidance on VELUX windows in Brighton & Hove, and it sticks to what we see on roofs rather than quoting a number we cannot stand behind.
Why one number does not exist
A roof window is not one component. It is a frame, a sash, a sealed double or triple glazed unit, a set of seals and a flashing that ties the whole thing into the roof covering. Each part ages at its own pace. A timber or polyurethane frame that is kept dry can look fine long after the glass has clouded. A flashing that was fitted badly can let water in within a couple of winters, while a well-fitted one never troubles the lining at all.
So when someone says a VELUX window lasts a set number of years, they are describing the better end of what can happen. The honest version is that a well-fitted window, on a sound roof, in sensible conditions, can serve for a very long time, and that a window with a weak point can fail well before that.
What wears out first
The parts tend to wear in a rough order.
- The sealed unit. The two panes are bonded around a spacer and filled with dry air or gas. Over time the edge seal lets damp air in. You see a milky haze or droplets between the panes that you cannot wipe away.
- The flashing and the roof covering around it. Slates, tiles and lead move, crack and lift. The flashing is only as good as the roof it sits in.
- The seals and the hardware. Rubber gaskets harden and the hinges, handle or control bar loosen. The window starts to rattle, or the sash will not close firm.
- The frame itself. A frame usually goes last, and mostly when water has been getting at it for years.
A failed sealed unit cannot be repaired. Once the seal has gone, the glass has to be replaced, and whether that means the glass alone or the whole window is covered on our page about replacing just the glass in a VELUX.
Things that shorten a window's life
Conditions matter as much as age. These are the ones that matter most on a house near the Sussex coast.
| Condition | What it does | What you notice |
|---|---|---|
| Salt-laden wind near the coast | Attacks metal parts, finishes and seals | Pitting, stiff hardware, dull trim |
| South-facing roof slope | Heat and UV tire rubber and coatings | Cracked gaskets, faded finish |
| Low roof pitch | Water sits at the head and sill | Staining, damp lining |
| Condensation in the room | Wets the lower frame and lining | Black spotting, peeling paint |
| Poor original fitting | Gaps in flashing or insulation | Drips, draughts, cold patches |
Signs it is time to plan a replacement
You do not need to wait for water on the floor. A window is usually ready for replacing when one or more of these is true:
- moisture or a haze sits between the panes and returns after wiping
- the sash will not shut tight, or the opening mechanism is stiff or loose
- there is a stain or soft plaster on the lining below the frame
- you can feel a draught around the edges on a windy night
- the window predates the current energy standard and the room is hard to heat
An old window can still be worth keeping if the frame is sound and only the glass has failed. That is a call we make at the survey, with the sash open and a torch on the seals, not from a photograph.
What replacing one involves
When an ageing VELUX is swapped for an equivalent, that is building work, so Part L of the Building Regulations applies. A new roof window in an existing dwelling must achieve 1.4 W/m²K or Window Energy Rating band B. The Building Control notice is something we file, and the details are in Building Regulations for skylights and rooflights.
The bigger question on many Brighton and Hove houses is getting to the window. A tall terrace, a mansard or a roof behind a parapet may need a scaffold or a tower from the street. We set the route, the licence and any bay suspension out in the access plan, which is a written page in every quote. For the full replacement process, see replacing an old VELUX window.
When we lift a tired window out, the timber around the opening tells the real story. A dry, pale batten means the old flashing did its job. A dark, soft one means water has been getting in for a long time, and the surrounding timber needs attention before anything new goes in.
Getting a firm answer on your own window
If yours is showing its age, the quickest route is a look at the real thing. The survey costs nothing and is followed by a fixed written quote, and a 10-year workmanship guarantee applies to the work, as described on our guarantee page. If you are comparing models first, our guide to VELUX window types explains the differences.
Back to the main page on VELUX windows, or request a no-charge survey and we will report on the condition of your window.
