A Velux roof window is one of the quickest ways to transform a dark loft or landing, but prices quoted online vary wildly. As roofers working across Hampshire, Wiltshire and Dorset, we are asked about this almost weekly. Here is what actually drives the cost, with realistic figures rather than best-case guesses.
For a standard Velux centre-pivot window fitted into an existing pitched roof, most homeowners in our area pay somewhere between £1,200 and £2,500 all in. That covers the window itself, the flashing kit, timber trimming, internal lining and making good, plus labour and scaffolding or tower access where needed. The window alone typically accounts for £400 to £900 of that, depending on size and glazing spec.
Prices climb if you choose a larger unit, an electric or solar-powered opening model, or top-hung windows designed for fire escape use in loft conversions. An electric Velux with rain sensor can add £300 to £500 to the window cost before installation. Conservation-style windows, often required in older properties or sensitive areas, also carry a premium of roughly 15 to 25 per cent.
No two roofs are the same, which is why a fixed price over the phone should make you cautious. Access is the biggest variable. A bungalow with easy ladder access is a different job to a three-storey townhouse needing scaffolding, which alone can add £400 to £800. Roof covering matters too: slate takes longer to dress around a window than concrete tiles, and older slates are more prone to breakage, so allow for some replacement.
The structure inside the roof also plays a part. If a rafter needs cutting and trimming to fit the window width, that is standard work, but trussed roofs built after the 1960s sometimes need an engineer's input before any timber is cut. Internally, the finish affects cost as well. A simple plasterboard reveal is quick, whereas matching an existing lath and plaster ceiling in a period cottage takes more care and time.
If you already have an ageing Velux, replacement is usually cheaper than a first-time installation because the structural opening exists. A like-for-like swap generally runs from £700 to £1,200 including new flashings, which we would always recommend renewing at the same time. Velux windows made since the 1990s follow standard sizing codes, found on the data plate behind the top-hinged flap, so matching a replacement is normally straightforward.
One thing to check before replacing rather than repairing: misted glazing units can sometimes be swapped on their own for a few hundred pounds if the frame and mechanism are sound. A decent roofer should tell you when the cheaper fix is the right one.
Ask any installer to break the quote down into the window unit, flashing kit, labour, access equipment and internal finishing. That makes quotes comparable and flags anyone who has skipped the flashing kit, which is essential and specific to your roof covering. Check whether making good the plaster and decoration inside is included, as this is the item most often left out.
Also worth knowing: fitting a roof window into an existing roof slope does not normally need planning permission under permitted development, though flats, listed buildings and conservation areas are exceptions. Building regulations still apply to the structural alterations and glazing, so keep the paperwork your installer provides. In coastal spots around the Solent and exposed downland sites, it is worth specifying the correct wind and exposure fixings, which a local roofer will do as a matter of course.
A straightforward installation into an existing pitched roof usually takes one to two days, including the internal lining. Replacements of an existing window are often done in half a day to a day.
Yes, usually. Access equipment, travel and setup are shared across both windows, so the second unit typically costs 20 to 30 per cent less to install than if done separately.
In most cases no, as roof windows fall under permitted development provided they do not project more than 150mm from the roof plane. Listed buildings, flats and homes in conservation areas need checking with your local authority first.
Free quotes and free roof inspections across Hampshire, Wiltshire & Dorset.
Tell us about the job and we’ll come back with a free, no-obligation quote.