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Home Extensions

Updated: Feb 1, 2022

Home extensions are great fun to design. Every house has its constraints; and to GreenTrace Architect these constraints make the project more interesting. We very much enjoy finding solutions; turning these constraints into opportunities. Below are a selection of the extensions we have been working on over the past year or so. Each design is different in its response to the site, planning context, brief and budget.

Chester Park Road

Site: End of terrace house in Speedwell, Bristol.

Planning context: Not permitted development due to proposed alterations on the principal elevation. Householder application required.

Brief: Provide a more open plan living arrangement at ground floor that relates to the landscape and existing house. Determine the most cost effective location for a new bedroom. High performance materials and unique design.

Budget: £80,000

Design response: After undertaking a measured survey and building a 3D CAD model of the house and grounds, we began investigating various strategies to gain the extra living space and 4th bedroom. An extension at the rear provided the opportunity to create an interesting relationship with the raised garden. A curved green roof could glide over the new construction, responding to the seating area cut into the garden. This enabled a new covered area for seating and storage, and provides a sense of enclosure and privacy.

For the extra bedroom, it became clear that a loft conversion would have been a very costly approach and would have impeded on the lovely sense of space that the existing hallway afforded. Instead, we proposed a first floor extension at the front of the property that enabled a porch area at the front, helping also to improve the somewhat awkward entrance to the home.

Lower Hanham Road

Site: Victorian mid-terrace house in Hanham, Bristol.

Planning context: Householder application. Proximity of public sewer required declarations to Wessex Water. Party Wall Agreements.

Brief: Loft conversion to provide space for an extra bedroom with en-suite. Provide a more open plan living arrangement at ground floor with visible structure and lots of light.

Budget: £70,000

Design response: This project aimed to make the most of small spaces (both in the roof and garden) with a tight budget. To do this we considered the structural options from the outset; gaining an understanding of the building fabric of both the house and neighbouring properties in order to propose a light-touch solution. Building against existing houses brings forth structural and architectural conundrums. Building against neighboung houses adds further complexities, and there are various approaches. In tight spaces (and tight budgets), an effective approach can be to utilise existing buildings as the structure for new-build elements subject to structural investigation. This approach will reduce costs associated with foundations, structure and weathering, but will require party wall discussions and careful consideration of how moisture and heat will be affected; taking care not to encourage interstitial condensation or cold bridging.

The vaulted ceiling also aims to grab as much space as possible, and this feature will make a big difference to the feel of the new open plan living area. The project has passed Building Control approval and is currently being priced by a contractor to be delivered under a fixed price building contract.


Site: Detached 1960s house in Felton, North Somerset. Sloped site with hillside views.

Planning context: New permitted development rights allow roof extensions up to two storeys directly above an existing house. To benefit, the building has to have been constructed between July 1948 and October 2018. However, other considerations regarding principal elevations pointed towards a householder application.

Brief: New open plan living extension at lower level to link existing disjointed house with garden. Loft conversion to provide space for 2 extra bedrooms and bathroom. Retain as much garden space as possible. Scandinavian aesthetic with lots of timber.

Budget: £50,000 (to first fix).

Response: The difference in levels from the house to the garden presented an interesting challenge, and the clients were keen to see how a new extension could link the two successfully. The trick was to stagger the extension, dividing it into two forms that navigate the slope. This not only reduced the visual impact of the extension from the road and neighbouring properties, but also enabled a view through the house upon entry via the clerestory windows that also provide light and ventilation for the new kitchen below.

Another trick was to rotate the patio and decking to sweep the focus onto the garden, aided by the corner glazing of the extension. Upstairs, a loft conversion could allow for 2 extra bedrooms. Cladding the entire rear façade at ground floor helps to further break up the mass and achieve a Scandinavian-style oasis in the garden.

Anstey Street

Site: Victorian mid-terrace house in Easton, Bristol.

Planning context: Householder application.

Brief: Eco-friendly loft conversion and new single/two storey extensions. Fabric to be low carbon, high performance (hempcrete and timber frame). Energy saving services such as air source heat pump and MVHR.

Budget: Flexible.

Response: The clients unwavering intentions to build with low carbon, renewable natural materials chimed well with GreenTrace Architect, and we were delighted to be approached by them for this project, having been recommended via the Green Register. The clients had begun renovations on the house prior to meeting and were seeking help with both concept and technical design. They also had made their own 3D CAD model of their own design but wanted me to resolve a few aspects, make it prettier and provide advice on Building Regulations and buildability with their chosen construction systems.

The process revealed constraints with the hemp roof construction system if acceptable ceiling levels were to be achievable. Alternative low-impact materials were put forward to get around this, such as wood fibre sarking boards with blown cellulose insulation. Planning permission has been granted and the build is underway!

Hempcrete construction. Source:

If you have an eco-friendly extension project in mind, please do get in touch. We can help in many ways.

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