Roof Lanterns: Are They Worth It for Your London Extension?

Roof lanterns have become a signature feature of London's rear and side-return extensions, bringing dramatically more natural light into kitchen-diners and open-plan spaces. Here's what to know before adding one to your project.

What Is a Roof Lantern?

A roof lantern is a raised, multi-sided glazed structure fitted into a flat roof, typically finished in aluminium for strength and slim sightlines. Unlike a flat rooflight, a lantern's pitched design allows light to enter from multiple angles throughout the day, rather than only directly overhead.

Why Lanterns Suit London Extensions

Many London extensions — particularly rear and side-return projects on terraced properties — rely heavily on roof glazing for natural light, since neighbouring buildings often limit light from side windows. A well-proportioned lantern can transform a potentially dark kitchen-diner into a bright, open space throughout the day.

Roof Lantern vs Flat Rooflight

Roof lanterns offer a more traditional, architectural aesthetic and typically let in more light due to their multi-angled glazing, but sit at a higher price point and require more structural consideration.

Flat rooflights offer a minimal, contemporary look with a lower profile, often at a more accessible price point, and suit a more understated design aesthetic.

Which is right for you often comes down to the style of your extension and personal preference as much as performance.

Sizing a Lantern Correctly

Getting proportions right matters enormously — a lantern that's too small won't deliver noticeable light improvement, while one that's oversized for the roof area can look disproportionate and may raise thermal performance concerns in summer. A good installer will size this based on your room dimensions and roof area, not a generic template.

Managing Heat Gain and Loss

Because lanterns introduce a large glazed area directly overhead, glazing specification matters more here than almost anywhere else in the home. Solar control glass helps manage summer heat gain, while a well-insulated aluminium frame with a thermal break reduces winter heat loss — both worth discussing directly with your installer.

Planning Considerations

For most extensions, roof lanterns fall under the same planning permission or permitted development rules as the extension itself, but it's worth confirming this at the design stage, particularly for larger or more prominent lanterns.

Get Expert Advice for Your Extension

Sizing, positioning, and glazing specification all affect how well a lantern performs — both for light and comfort. We work with homeowners and builders across London on lantern specification from the design stage onward.

Talk to us about your extension's roof glazing — call 020 8550 2929 or [book a consultation here].