Velux Cost Guide: Roof Window Pricing, Sizing, and Alternatives
A standard Velux center-pivot roof window typically starts at £400 for the unit itself, but once you add professional installation, flashing, and internal finishing, the total cost for a single window usually lands between £600 and £1,200.
Velux vs. Fakro vs. Keylite: Price Comparison
| Brand | Base Unit Price | Typical Install Total | Market Position |
|---|---|---|---|
| Velux | £400+ | £600 – £1,200 | Market Leader / Premium |
| Fakro | £350+ | £550 – £1,100 | High Spec / Technical |
| Keylite | £300+ | £500 – £1,000 | Budget-Friendly / Reliable |
Critical Sizing and Model Selection
The cost of a roof window is driven primarily by the “glass area” and the operation mechanism.
- Center Pivot: The most common and cost-effective option. It rotates around a central axis, allowing for easy cleaning from the inside.
- Top Hung: Generally more expensive due to the hinge mechanism, but offers a larger open area and better views.
- Fixed/Non-Opening: The cheapest option, used primarily for light introduction where ventilation isn’t required.
As the size increases from a “standard” (e.g., 56cm x 118cm) to a “large” (e.g., 106cm x 118cm), the price typically jumps by 20-30%.
The “Installation Gap”: Why Your Quote is Double the Price
Many homeowners are surprised to find that a £400 Velux window costs £900 to install. This is because roof windows are not “drop-in” products; they require structural modification of the roof rafters.
The Installation Process includes:
- Rafter Cutting: Precision cutting of the roof timbers.
- Flashing: The installation of weatherproof seals (lead or aluminium) to prevent leaks.
- Internal Finishing: Plasterboarding and painting around the window reveal.
- Scaffolding: Depending on the height of the property, a £200-£500 scaffolding charge may appear on your quote.
What most guides miss: Thermal Bridging in Roofs
Most roof window guides focus on the glass, but the real energy loss happens at the “reveal”—the gap between the window frame and the roof insulation.
If your installer doesn’t use specific insulation collars (such as Velux’s insulation collars), you create a thermal bridge where heat escapes directly through the rafters. This can lead to condensation and mould growth in the ceiling corners during winter. We recommend specifying a “warm-edge” spacer bar to further reduce this effect.
For those aiming for a Passivhaus standard, consider the Passivhaus windows spec to understand the impact of U-values on roof glazing. In an energy-efficient retrofit, strategically placing roof windows can eliminate the need for artificial lighting during the day, significantly lowering the operational cost of the home.
If you are dealing with a property that is Unmortgageable because of roof leaks or structural issues, installing certified roof windows with a 20-year seal warranty (like those from Roof Maker) can provide the necessary structural assurance for lenders.
Summary: Choosing Your Skylight
- Pure Budget: Keylite.
- Balance of Trust and Performance: Velux.
- Technical Precision: Fakro.
- Modern Aluminium/Flat Roof: Roof Maker.