Velux Windows: Sizes, Costs and Installation Explained

Velux is the market-leading brand for roof windows, and it has become a generic term for what is technically called a roof light or roof window. Whether you are converting a loft, extending a kitchen, or replacing an existing roof window, this guide covers what you need to know.

What This Guide Covers

• Standard Velux window (GGL range) costs £250–£600 for the unit; installation adds £150–£350
• Centre-pivot windows (most common) vs top-hung (open wider, better for low-pitch roofs)
• Electrically operated and solar-powered options available — popular in hard-to-reach positions
• Triple-glazed Velux units available — worth considering for north-facing or cold-climate roofs
• Building Regulations approval required for new roof openings — we handle this as part of our service

Introduction

London homeowners face unique challenges when it comes to glazing — from period properties with sash windows in conservation areas, to modern developments requiring structural glass installations. Getting the right advice before you commit can save you significant time and money.

At BuilderFix Glazing, we have completed thousands of glazing jobs across Greater London and Surrey — from emergency repairs in Kensington and Chelsea, to bespoke walk-on glass installations in Mayfair and Belgravia. This guide is based on real experience and the questions our customers ask us most often.

What Does This Typically Cost in London?

Costs vary depending on the type and size of work, the glass specification, frame material, and access. As a general guide, always obtain a free written quote before committing — this protects you from unexpected charges.

At BuilderFix Glazing, we provide free, no-obligation written quotes for all work. Our prices are transparent and fixed before we start — no surprises on the invoice.

What to Ask When Getting a Quote

• Is the price fixed, or could it change once work starts?
• What glass specification is included?
• Are all fixings, sealants and finishing included?
• What compliance documentation will I receive?
• What happens if there is an issue after completion?