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Roof Lantern Design: The Goldilocks Principle

Roof Lantern Design: The Goldilocks Principle

You may have heard of the Goldilocks principle, a reference to the children’s story ‘The Three Bears’. It highlights the importance of getting something ‘just right’ and can be applied across a variety of disciplines and situations. Designing an orangery is no exception, especially when it comes to the roof lantern.

A roof lantern is one of the most distinguishing features of an orangery, often the main talking point of the room. Specifying the roof lantern with the correct proportions is hugely transformational to the build. An orangery with a roof lantern of incorrect scale or composition may no longer be fit for its intended purpose, so a bespoke lantern is often the best way to ensure neither form nor function is compromised.

Below, Mervyn Montgomery of Hampton Conservatories, a leading designer and manufacturer of bespoke hardwood glass buildings, details why getting the roof lantern ‘just right’ is so crucial in orangery design.

Roof lantern design

The roof of an orangery is the main point of differentiation from a conservatory. A traditional orangery roof comprises two key elements, a flat roof area around the perimeter and a multi-faceted roof lantern that creates an elevated ceiling.

A roof lantern allows for light to be channelled from all angles, not only making the room look bigger but also creating a stunning architectural showpiece in your home. The lantern itself may be square, rectangular or octagonal and can extend upwards, incorporating a clerestory or cupola. 

A clerestory is an angular raised area of glazing that sits atop the main roof lantern, allowing for ample light whilst maintaining privacy. This design can be dated back to Egyptian times, often used in ancient temples. A Cupola is a similar concept but commonly a more intricate domed shape. Cupolas were first used in 8th Century Islamic architecture, placed atop minarets (the buildings adjacent to mosques). Daily prayers would be announced from the cupola.

Both cupolas and clerestories are designed to enhance the space and light in the room below whilst giving greater stature to the structure. These styles of roof lanterns may also aid the energy efficiency and temperature control of your orangery: when used in conjunction with high-mass materials, such as stone or brick, both clerestories and cupolas can store solar heat during the warmer parts of the day, allowing the walls and floor of the build to maintain heat during the colder times.

Architectural considerations

To be in-keeping with the existing architecture of your home, there are some rules that your orangery designer will apply when designing the roof lantern. The main source of inspiration for this front will be the current roof angles as well as important sight lines from the upper windows.

Another key consideration is how the room will be used and where the sun falls throughout the day, as the balance of light and shade is of high importance in a glazed structure like an orangery. The room may lend itself to a larger or smaller roof lantern, and bigger builds may benefit from multiple roof lanterns in order to effectively zone the space. The ultimate goal is for the orangery to be flooded with light in designated areas whilst also optimised for areas of shade and the projection of dramatic shadows as the sun shifts throughout the day.

Although the shape and size of the roof lantern are important, the dimensions and spacing of the ‘jack’ rafters and hip rafters are equally as crucial to achieving the ideal light balance, as well as the desired aesthetics. ‘Jack’ rafters are the individual roof lantern beams and the hip rafters are the key structural beams that span from the corner of the lantern to the central middle ridge. Most commonly, roof lanterns are designed with straight rafters to produce beautifully clean lines, but a more curved shape can be incorporated, raising the height and allowing more light to penetrate, creating a striking end result.

Depending on your preference, the glass that the roof lantern is composed of can be standard double-glazed, solar or low maintenance. Additional extras can also be incorporated if you so wish, such as automatic thermostatic ventilation and rain sensors, which can both aid the build to maintain a comfortable indoor environment.

Whatever your needs, wants and preferences for your new orangery, a design expert can help make your dreams a reality. Don’t cut corners or compromise on design, be sure to get your roof lantern ‘just right’.


Images: Hampton Conservatories