Roof Lantern Sizes: A Complete Guide to Dimensions and Proportions

The right roof lantern size depends on your extension, the position of the opening and the product you choose. Start with the effect you want in the room, then confirm the exact dimensions and installation requirements before ordering.

Standard sizes or made to measure?

Available sizes vary by roof lantern system. Do not assume every manufacturer uses the same dimensions or that a familiar size is available in every configuration. Explore the SmartaView aluminium roof lantern range and check the sizes offered for your chosen product.

Choose a size that suits the room

Consider where daylight is needed, how the lantern sits above the kitchen or living area, and how it will look alongside the rest of the extension. Furniture layout, neighbouring glazing and the roof design all affect that decision. There is no single ceiling-area percentage that should be treated as an ordering rule.

Do not confuse the opening with the order size

The structural opening, upstand and finished product dimensions may be different. Confirm which dimension the selected manufacturer requires and follow its current fitting guidance. Ask the person responsible for installation to check the measurements before you approve the order. Do not apply a generic deduction or allowance.

Check product limits and the roof design

Confirm the permitted width and length, overall height, glazing specification and installation requirements for the exact model. Your builder or designer should check whether the proposed opening and supporting roof design are suitable. A product configurator does not replace those checks.

One lantern or more than one?

For a larger extension, compare a single feature lantern with separate openings positioned over different zones. The best layout depends on the roof structure and room design rather than room area alone. Discuss the options with your project designer before finalising the openings.

Compare roof lanterns with flat rooflights

If you are still choosing the style, compare our aluminium roof lanterns with aluminium rooflights. Check the available dimensions, appearance and product-specific guidance for each option rather than assuming they are interchangeable.

Before you order

• Choose the exact product and configuration.
• Confirm what the order dimensions refer to.
• Have your fitter verify the final measurements and suitability.
• Check the chosen glass, colour and current delivery information.
• Review the full specification before approving manufacture.

SmartaView is supply only, so arrange installation with your own competent fitter. Contact the SmartaView team with your planned opening and product choice if you need help finding the available configuration.