Velux Roof Windows

Velux roof windows are known for their excellent quality, but this doesn't mean they cost a fortune. On the contrary, they're some of the most affordable roof windows out there. You make sure to list all the prices of the products we offer, so take a look and decide for yourself.

A well-maintained Velux roof window lasts 20 to 30 years, and every Velux window we sell carries the manufacturer's 10-year guarantee.

The part that usually fails first is the sealed glazing unit. Misting or condensation between the panes is the classic sign, and it normally appears after 20 years or more rather than before. In practice the fitting matters as much as the window: water getting past a badly fitted or corroded flashing will rot the timber around the frame long before the window itself wears out, which is why the flashing is worth checking every few years.

Both the GZL 1051 and the GLU 0051 have maintenance-free aluminium exterior covers and a sash that rotates 180°, so you can clean and inspect the outside of the glass from inside the room without going on the roof.

Fitting into an existing opening takes a competent roofer about half a day: fix the frame to the rafters, fit the flashing, then refit the sash.

The sequence for a like-for-like replacement is:

1. Check the roof pitch. Both Velux ranges we stock fit roofs from 15° to 90°.
2. Strip the tiles or slates back around the opening to expose the rafters and battens.
3. Lift the sash out of the frame so you are only carrying the frame up to the roof.
4. Screw the mounting brackets to the rafters and set the frame square and level.
5. Fit the flashing kit that matches your roof covering - a tile flashing for profiled tiles, a slate flashing for flat coverings such as slate.
6. Re-lay the roof covering up to the flashing, refit the sash and line the internal reveal.

Cutting a brand-new opening is a different job. The rafters have to be trimmed and reinforced, which is structural work under Building Regulations, and it usually runs to one and a half or two days. That one is for a roofer or builder, not a DIY afternoon.

Expect £250 to £1,000 in labour to fit a Velux into an existing opening, based on roofer day rates of £200 to £350 per tradesperson.

A straight like-for-like swap is normally a one-day job for one or two people, so most quotes land near the bottom of that range. Cutting a new opening pushes it up: rafters to trim and reinforce, a reveal to line and plaster, and one and a half to two days on site, which typically puts the whole job including the window somewhere between £900 and £2,500.

Scaffolding, a steep or awkward roof and a slate covering all add to the figure, and labour in London and the South East runs roughly 10-20% higher than the rest of the country. Buying the window direct rather than through the installer takes the merchant's margin out of the total - our Velux range runs from £235 to £405.

The main alternatives are Optilight, Fakro, Keylite and Dakea. We stock Optilight and Fakro, both centre-pivot windows built to the same standard sizes as Velux.

Roof windows are made to a common set of size codes - 55x78, 55x98, 78x98, 78x118, 78x140 and 114x118cm are all stocked across the brands here - so a same-size Optilight or Fakro window will go into an opening built for a Velux with only minor adjustment, as long as you buy the flashing that matches your roof covering and the brand of window.

Optilight is made in Poland and shares its flashings, restrictors, locks and control rods with Fakro, so spares stay easy to source years down the line. You can compare all three brands side by side in our full roof windows range.

Optilight is the cheapest alternative we stock: a 78x98 Optilight is £190 against £280 for the same-size Velux GZL 1051, a saving of £90.

That gap holds at roughly 30% across every size we carry in both brands:

The specification is closer than the price gap suggests. Optilight centre-pivot windows carry the same 1.3 W/m²K window U-value as the Velux GZL, the same 15° to 90° pitch range, the same 180° rotating sash for cleaning from indoors, and a laminated pinewood frame under an aluminium exterior.

The honest trade-off is operation and choice of extras. The Velux GZL and GLU are top-operated, so the control bar sits above the glass and you can put furniture under the window - Optilight's centre-pivot models are not available with a top handle. Velux also has the wider range of blinds and accessories. If neither of those decides it for you, Optilight does the same job for less: see the full roof windows range.

Velux windows are thankfully easy to mount and install. If you're only going to replace an existing window, you only need to mount them from the inside. There's no need to get on the roof or go outside even. This ease of installation is one of the main reasons Velux windows are popular.

Sadly, however, if you're retrofitting your home with an entirely new window, the task is far more complex, and you might not be able to do it yourself. Doing changes to the roof can be complicated, and you shouldn't be afraid of hiring construction workers to help you get the work done.

You can definitely be sure that adding Velux roof windows will add great value to your home. It not only makes the interior of your home look better with improved natural lighting and ventilation, but it will also increase the curb appeal of your home. You can expect the house's value to increase by half to almost twice the cost of the windows, so you might end up making money off of your purchase.

Even though windows with the Top Handle are less common, in our offer, you can find a wide range of Velux windows that open on the top. We will help you find a model that will suit the needs of your home perfectly.

GZL windows offered on our website are produced specifically for the European market and meet the highest requirements. Those particular windows are installed both on the north and south of the old continent, where they have to measure up to extreme weather conditions of temperature and humidity. We recommend the Velux GZL windows to clients that prefer the Top Handle, which is unfortunately not an option when it comes to Optilight windows. This type of opening is also offered by Fakro windows, available on our website.