January 13, 2021

Types of House Extensions - From Glass Boxes to Basements

Written by Rebecca Clayton

From glass boxes to basement renovations: a guide to house extension design ideas

The ‘don’t move, improve!’ trend has seen homeowners increasingly turn to renovating and extending their homes, rather than looking to buy elsewhere. And for good reason - there is a huge range of different options when it comes to extending a home, which can be adapted to fit the bespoke character and requirements of any existing house design, aesthetic and available space.

From elegant glass box extensions and side returns, to basement renovations and garden rooms, we’ll be showcasing different extension types to kickstart the planning process for renovating cramped or outdated living spaces.

Glass box extensions

The contemporary older sibling to the conservatory trend, glass box extensions capture the true meaning of light-filled living spaces. These frameless glass units use structural glazing with minimal silicone joints to create a modern extension space, while the fully glazed elevations allow natural light to flood the space throughout the day.

Advanced glass technology ensures that the extension maintains a comfortable temperature during the changing seasons. Our Invisio structural glazing system is fully thermally broken and can be specified as double or triple glazed for exceptional thermal performance.

Specifying solar control glass is strongly recommended for any South-facing installations, to reduce solar gain, as it deflects the sun’s infrared rays back out into the atmosphere, rather than trapping them inside the glass box. Hawthorns house is a great example of the modern simplicity of a glass box extension, designed using cutting edge technical glass that doesn’t impact the transparency of the glazing.

Integrating minimal glass door systems into a glazed box is an easy way to create a seamless indoor-outdoor living transition with the garden and patio space. This listed manor house extension opted for elegantly minimal sliding glass doors that link the rustic dining room with the outdoor terrace and grounds.

Additional structural glazing can also be built into the roof above the doors to create an elevated sense of space and depth, as was done to great effect for this small rear renovation in Twickenham and this larger countryside property in rural Dartmoor.

For more advice, check out our beginners’ guide to glass box extensions.

Rear extensions and renovations

One of the go-to methods to add valuable space to any home, rear extensions are a particularly great choice for terraced houses that lack the space for other extension options.

Single-story rear extensions often use sliding or bifolding doors to create large, light-filled openings that seamlessly link the kitchen and dining space with the external living areas. When opened, they allow uninterrupted views of the garden and add to the sense of space and open plan design that rear extensions are ideal for creating.

Elms Road is a perfect example of this, using ultra-slim framed sliding systems from panoramah! to create a minimal glazed opening. Alternatively, integrate a hidden pocket door design for a completely open aperture, as demonstrated by the contemporary Malbrook Road project.

Adding a frameless rooflight is another great way to dramatically increase the amount of natural light flooding the extended space, as was done to great effect to this modern extension project. Choose between a minimal fixed rooflight like the Invisio system, or venting rooflights to introduce adjustable ventilation with the new ARES.

Rear extensions don’t have to be a regular box shape either. Bespoke-shaped structural glazing can be integrated above the rear patio doors to create a truly unique renovation, as was done for this unique property in the Netherlands that chose to combine minimal steel doors with overhead architectural glazing.

Basement renovations

For an extension that doesn’t take up additional land, consider building downwards. Basements don’t have to be dark and dingy, with options to create bright, airy living spaces using structural glass roofs, walk-on rooflights, and sliding doors.

Basement extensions vary in complexity and cost, depending on whether the house already has an existing cellar space or if excavation is required. The latter will often require planning permission, so it’s worth getting some advice on the feasibility of your property at the early stages of the renovation plan.

The basement extension at Gloucester Place saw the installation of a large frameless structural glass roof designed and installed by IQ. Frameless supporting glass beams were integrated into the design for a truly minimal look that maximises the natural light in the space. Walk-on toughened glazing with a non-slip ceramic coating was specified for the roof panels, creating a glazed courtyard above.

To reduce the visible impact at ground level, opt for fixed walk-on floorlights to create large ‘windows’ of frameless structural glass that brighten the basement space. Victoria Road integrated several Invisio thermally broken floorlights above a modern, broken plan basement to ensure the whole area was permeated with natural light throughout the day. Frameless internal glazed doors and screens were then installed to enhance the functionality of the basement, create dedicated zones within the space, without interrupting the paths of natural light.

Basements can also be combined with sunken external courtyards as a way to both introduce plenty of light and create a linked outdoor living space. Integrate slim framed sliding or casement doors such as the aluminium pivot doors used for this London home project, to allow seamless access to a secluded garden courtyard. Choosing frameless glass balustrades to line the courtyard at ground level ensures the space stays bright and airy throughout the day.

Side infill / side return extensions

Side returns refer to the narrow strip of land running down the side of many townhouses and semi-detached homes. Usually dark and unused, these side passages provide an easy opportunity to expand useable space and bring light into the house to forge an improved connection with the garden.

A key element of many side infill extensions is the use of fixed roof glazing to brighten up dark internal spaces. Frameless strip rooflights are a great option, as their narrow width means that no additional support is needed, allowing the homeowner to create long vertical seams of glass running the length of the extension.

For an even bigger influx of light, entire frameless structural glass roofs can be used to create the infill extension, as can be seen in this listed Georgian terrace extension. Two panes of toughened structural glass make up the roof of the Claremont Square project, with a slim steel T-section for support and a structural gutter on one side to allow water drainage from the glass roof.

Side infills are often combined with replacement glazing to the rear of the home to achieve a more coherent design. Victoria Park Road opted for Mondrian steel patio doors for a bespoke, industrial style, while a steel glazed window box creates a cosy seat overlooking the garden. Slim framed pivoting doors can also be used to mimic full-length picture windows when closed while providing step-free access outside, this was done to great success for the Ravendson Street project.

Garden rooms

All the extensions thus far have been integrated as part of the original house. However, there is another option for those with large or unused outdoor space, in the form of building a self-contained garden room. Garden rooms can be used for all kinds of functions, from simple recreational spaces to secluded home offices or personal gyms.

Slim sliding doors and Invisio thermally broken fixed structural glazing are great options for creating bright, open-plan external rooms that maintain a comfortable living temperature throughout the year. Opting for large elevations of glazing is also beneficial for smaller properties or where planning permission is required, as it reduces the visual impact and obstruction of views and light for any neighbouring properties.

IQ Glass installed several sets of minimal windows sliding doors to create multiple adjacent glazed elevations for this cosy garden living room project. The flush thresholds and minimal 21mm sightlines allowed the homeowners to enjoy their peaceful garden surroundings with easy access from the main house.

Roof extensions

Loft conversions are a longstanding popular home renovation technique, often accompanied by the installation of dormer windows to add additional full-height space to otherwise restrictive sloping roofs.

You can take this type of extension one step further with projects such as this family home renovation, that extended their loft space using sliding doors that lead out onto a small balcony space lined with frameless glass balustrades, overlooking the garden. Next to the extension, a large frameless picture window in a dormer design puts a contemporary, minimal spin on the classic attic window design, while creating a well-lit master bedroom space.

Loft extensions are not the only thing you can do when considering a roof extension project. You could also opt for adding a glass box to your property, an option that works particularly well for penthouse apartments.

This Southwest London flat installed a glass box within a large existing balcony, creating an additional living space while still retaining a strong connection to the outside. A similar bespoke design was created for the Hallam street penthouse, this time adding a new floor above the main living spaces to house a comfortable seating space, linked to a balcony with city views via slim framed sliding glass doors.

Closing Thoughts

There is a huge range of extension options that can be tailored for any home improvement project. However, the key to creating a truly modern and light-filled living space lies in the careful choice of architectural glazing, with high-performance values to ensure a comfortable environment throughout the year and minimal sightlines so as not to impede the flow of natural light.

IQ Glass have enjoyed years of experience in adapting and engineering modern glazing solutions for a range of bespoke and adventurous extension projects. Get in touch with the team today for expert advice on your project.

For more information on planning permission and building requirements, you can read our technical article here.