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VELUX roof windows are the UK’s benchmark for quality, performance and reliability in pitched and flat roof glazing. Designed to maximise natural light and ventilation, they are a first-choice solution for loft conversions, extensions, refurbishments and new-build projects alike.
At Condell Ltd, we supply the full range of VELUX roof windows and accessories to trade professionals and informed homeowners across London and the Home Counties. With strong stock availability, experienced technical support and the ability to source specialist or legacy products, we help you specify the right window first time and keep projects moving without delay.
VELUX WINDOW SIZES & SIZE CHARTS
VELUX roof windows are manufactured in standardised sizes, each identified by a clear size code such as MK04 or GGU SK06. These codes relate directly to the window’s width and height, making specification, replacement and ordering far more accurate than relying on measurements alone.
When selecting from the full range of VELUX window sizes, it’s important to:
Confirm the existing size code from the data plate on the window
Use a VELUX size chart to match width and height correctly
Allow for installation tolerances, linings and flashing requirements
Whether you’re replacing a single roof window or specifying multiple units for a loft conversion, using the correct size code ensures compatibility with flashing kits, blinds and glazing options. Our team can guide you through size charts and help confirm the correct product for your roof structure.
Over time, roof windows may require replacement due to wear, changes in regulations or improvements in glazing performance. In many cases, homeowners and contractors can choose between:
Full window replacement – ideal when frames, seals or operating mechanisms are tired
Glass-only replacement – suitable where frames are sound but glazing has failed or needs upgrading
Extra care is needed with older or pre-1991 VELUX windows, where size codes and compatibility can differ from current ranges. Condell regularly assists customers with identifying legacy models and sourcing suitable replacement windows or glazing units to maintain weather performance and thermal efficiency.
Not all roofs meet the same pitch requirements, and incorrect specification can lead to poor drainage or installation issues. VELUX offers dedicated solutions for low pitch applications, typically from around 10° upwards, depending on the system used.
Low pitch installations rely heavily on the correct flashing kit, including:
BFX insulation and underfelt collars
EDW and EDL flashing systems for profiled and plain tiles
For trade customers, correct pitch assessment and flashing selection are critical to achieving a compliant, long-lasting installation. Our team provides practical, trade-focused guidance to help you choose the right combination for your roof covering and pitch.
Beyond standard centre-pivot roof windows, VELUX offers a wide range of specialist solutions designed for architectural impact and specific planning requirements, including:
Black VELUX windows for contemporary designs and modern extensions
Conservation rooflights suited to heritage properties and sensitive planning areas
Dormer and balcony windows that transform roof spaces into usable living areas
Flat roof and terrace windows for rooms where pitched glazing isn’t suitable
These options allow greater design flexibility while maintaining VELUX performance standards for light, ventilation and weather protection.
WHY BUY VELUX WINDOWS FROM CONDELL LTD
Choosing the right supplier is as important as choosing the right window. Condell Ltd is trusted by contractors, developers and homeowners because we offer:
Strong local and regional stock availability
Knowledgeable technical support for sizing, pitch and flashing
Access to hard-to-find sizes, glazing units and specialist kits
Reliable delivery across London and the Home Counties
We understand how roof windows are specified, ordered and installed on real projects, and we support you at every stage.
NEED HELP FINDING THE RIGHT VELUX PRODUCT?
If you can’t see the size, glazing option or flashing kit you need, speak to our team. We’ll help you source the correct VELUX solution and keep your project on track.
