Velux & Roof Window Installation Cost UK (2026 Guide)

A Velux window — or more accurately, a roof window — can transform a dark, stuffy loft into a bright, usable space. Whether you're adding natural light to a loft conversion, replacing an ageing skylight, or simply want more ventilation in a room in the roof, roof window installation is a relatively contained job that most roofers can complete within a day.

This guide breaks down the cost of Velux and roof window installation in the UK in 2026.

Velux & Roof Window Installation Cost: At a Glance

Prices include supply of the window unit and installation. Larger sizes, higher specifications and premium finishes (integra, GPU top-hung) add to costs. London and South East typically 20–30% higher.

What Is a Velux Window?

'Velux' is technically a brand name — the Danish company VELUX is the market leader in roof windows globally — but the term is widely used in the UK to describe any centre-pivot or top-hung window installed into a pitched roof slope. Other brands include FAKRO, RoofLITE and Keylite.

Roof windows differ from rooflights or skylights in that they're designed to open for ventilation and egress, whereas a fixed rooflight simply lets in light without opening.

Types of Roof Window

Centre-Pivot Roof Window

The most common type. The sash rotates around a central pivot point, making it easy to clean from inside and allowing good ventilation. Standard sizes start from around 55cm × 78cm. The most popular Velux model (GGL) is a centre-pivot window with an internal timber lining.

Top-Hung Roof Window

The sash opens outward from a top hinge, creating a wide unobstructed opening at the bottom — useful where people need to exit onto a roof terrace or balcony. Top-hung windows are taller and more expensive than equivalent centre-pivot units.

Flat Roof Window / Rooflight

Fixed or opening units designed for flat roofs. Fixed rooflights let in light but do not open; opening versions typically hinge at one edge. Available in sizes from around 60cm × 60cm upwards.

Conservation Roof Windows

For listed buildings or properties in conservation areas where planning authorities require a lower-profile window that doesn't project above the roof line, conservation-style roof windows sit flush with the tiles. They're typically more expensive and installation is more complex.

What's Included in the Price?

A standard supply-and-install quote should include:

• The window unit itself
• Installation collar/flashing kit to weatherproof around the frame
• Any internal lining or reveal finishing (if included — sometimes quoted separately)
• Making good of any disturbed tiles around the opening
• Disposal of any old unit being replaced

Internal plastering or dry-lining around the new window reveal is usually a separate cost if significant work is needed.

Does a Roof Window Need Planning Permission?

In most cases, no — installing roof windows on a pitched roof counts as permitted development provided certain conditions are met:

• The window does not project more than 150mm above the existing roof plane
• It does not increase the height of the roof
• Any window on a side elevation is obscure-glazed and non-opening below 1.7m from floor level

Properties in conservation areas or designated land (National Parks, AONBs) may have restrictions. Listed buildings always require listed building consent before any alterations.

Building Regulations approval is required — the installer should handle this as part of the job, and Competent Person Scheme registration (FENSA or equivalent) covers the installation.

How Long Does Installation Take?

A single roof window installation typically takes a skilled roofer 4–6 hours. Two or three windows in a loft conversion can usually be completed in a single day. Replacement of an existing same-size window can be done in 2–3 hours.

Choosing the Right Size

The rule of thumb recommended by VELUX is that a roof window area should equal at least 10% of the floor area of the room below for adequate natural light, and at least 15% for a good level of light.

For loft conversions, building regulations also set minimum ventilation requirements — your roofer or building control officer can advise on the number and size of windows required.

Maintenance

Modern Velux windows require minimal maintenance. The self-cleaning glass option (available on many VELUX units) uses a titanium dioxide coating that breaks down dirt in UV light and is washed away by rain. Standard glass should be cleaned periodically from outside (centre-pivot windows can be rotated for easier access) and from inside.

Check the weather seal around the frame annually and reseal if any deterioration is visible.

Finding a Velux Installer

Roof window installation requires a competent roofer who is comfortable working at height and familiar with the specific flashing requirements for the tile type on your roof. VELUX and FAKRO both maintain installer networks — choosing a brand-accredited installer offers additional reassurance.

Find a vetted roof window installer near you at Local Roofer Directory.

FAQ

Can any roofer fit a Velux? Most experienced roofers can install roof windows. For guaranteed quality, look for installers registered with VELUX or FAKRO, or ask for references from previous roof window installations.

How long does a Velux window last? A quality roof window installed correctly should last 25–40 years. The flashing kit around the window may need attention sooner if the original installation was not ideal.

Can I add a Velux window without planning permission? In most cases yes — see the planning section above. Always double-check if your property is listed or in a conservation area.

What's the difference between a Velux and a skylight? In common UK usage, 'Velux' and 'roof window' refer to an opening window in a pitched roof slope. A 'skylight' or 'rooflight' typically refers to a fixed or opening glazed panel set into a flat roof.