For design and project management of house extensions, refurbishments and new build in Cambridge

House Extensions Around Cambridge

Our architectural service for house extensions in Cambridge is flexible. Sometimes it’s a friendly chat and some contacts. Often we manage the entire project.

If you’d like to brainstorm multiple options, we’ll provider cost-effective pencil sketches. Once we’ve refined an appropriate design, we can obtain planning permission. 

Planning permission typically takes 9 weeks.  Once granted, we create a detailed design plus a full specification for each element.

If desired, we’ll manage the tender process. Once the contractor’s selected, we often supervise the contract. Supervision entails:

  • Regular visits to check the quality of the construction. 
  • Resolving problems: often digging the foundations reveals unexpected problems.
  • Negotating variations, i.e. changes to the orginal specification:
    • We know how much effort the change will require.
  • Agree a snag list for the contractor to fix,
  • Finally, obtain a building certificate.

Approach to Renovations and Extentions

We pride ourselves on our ability to utilize unusual space to create useful areas. These areas improve the efficiency of your home. We also like to create spaces that suit our client’s lifestyle, and enjoy suggesting alternatives that meet your budget.

As Tim Bonavia was born, grew-up and has always worked in Cambridge, we know what sort of  extension increases your home’s value.  With decades of experience, we know what ideas the Cambridge City planners will just about accept, and what schemes they reject.

We have established good relationships with local, reliable structural, mechanical, electrical, air-conditioning and drainage engineers. We know which person in Cambridge has the most appropriate specialist skills for your extension.

Managing Building Contractors

We usually negotiate the cost of changes and variations better than a home-owner. Parlty, we identify identify reliable contractors. These contractors also want to remain on our tender list.

Contactors usually depend on their relationship with architects for future work. Thus, contractors have more incentive to quote fair and reasonable prices for changes and variations.


We know the standards of work expected by the building codes. One client had purchased a new £1 million Cambridge property the previous year. She asked us to persuade the builder to rectify multiple faults, some major, others small annoying quirks. We persuaded the builder the faults resulted from their failure to adequatly supervise their sub-contractors. The builder rectified her home, provided temporary accomodation for her family, and paid for the furniture storage.

We pride ourselves on our ability to utilize unusual space to create useful areas.

House Extension, Quy

Interior Design create feeling of bigger space: AABD architects
Interior Design to create impression of a bigger space

House Extension, Central Cambridge

An interesting house extension arose because of a neighbours extension and balcony. The neighbour to the right had added a balcony, from which they had a good view through our client’s windows. Moreover, being a good neighbour, our client wished to minimise the impact of his extension on the left-hand side neighbour.

As Cambridge Architects, we know that many houses and gardens are relatively small, given the price of the property. Our house extensions can add considerable additional space to our client’s home, yet minimise the impact on a small garden.

In this instance, we built the extension on columns. This created a useful ground floor terrace, and maintained the size of the small garden. We also extended the house to provide an improved kitchen/dining area, a double bedroom/en-suite bathroom on the middle floor, a double bedroom on the top floor, and a balcony. We also designed the roof and balcony to be maintenance free, using the latest flat-roof technology.

We also appreciate that whilst the contractor is on-site, it is a low cost opportunity to fix many nagging problems.However, these problems have to be clearly described in the tender specification, rather than discussed once the contractor is on-site.

So, we added outside lights, light and power for the garden shed, and replastered a kitchen wall. In addition, we recommended moving the boiler, which was due for replacement. We enhanced the plumbing with an efficient boiler and a mains pressure hot-water system. For little additional cost, our client can heat each floor separately, and has gained more usable kitchen space. As the shower is on the top floor, our client now enjoys powerful showers. The design also enabled easy access to the flat roof, which simplified the latter installation and cleaning of solar panels.

  • Outside lights, light and power for the garden shed.
  • Replastered a kitchen wall.
  • Moving the boiler, which was due for replacement, and enhanced the plumbing, with an:
  • Ffficient boiler and a mains pressure hot-water system. So our client can:
    • Heat each floor separately,
    • Gained usable kitchen space,
    • Better showers, since the shower was gravity fed on the top-floor.
  • Gained easy access to the flat roof, which
    • Simplified the later solar panel installation and cleaning.

We provided continous support throughout the project, so the total costs matched our client’s original expectations. Before we finalised the design, we tackled the groundwork, as most problems are below ground. We discovered the foundations were deep, but the house was built on an old bakery, which meant a concrete base on piles was required. Although there were problems building the base, we ensured the contractors accepted that these problems resulted from their negligence.

When construction above ground began, building rates were relatively high. Nevertheless, we found reasonably priced contractors, who delivered high quality work, especially the brick-work. Partly, this was because we drew-up a clear and detailed specification.

House extension central Cambridge: additional bedroom, larger kitchen, enlarged bedroom, and easy access to the flat roof.
Adds a bedroom, extends a bedroom, and provides easy access to flat roof.
Designed by Tim Bonavia of Architecture & Building Design to preserve the small garden, and re-organise the kitchen
Ground floor preserves small garden

House Renovation, Quy

This lovely double fronted cottage, just outside Cambridge,  dates back to before 1810.  Originally, the

  • Ground floor comprised two reception rooms either side of an exceptionally wide staircase, and a small entrance hall.
  • The kitchen was lean-to structure at the rear, accessed from a reception room.
  • Below the reception rooms was a cellar.
  • Above were two bedrooms, partly in the roof.

Sometime in the nineteenth century, the cottage gained a remarkably large outside lavatory with WC, hand basin and foul drainage. This probably replaced a more primitive facility. 

Post-war extensions included an inside bathroom, a first-floor WC, and a kitchen pantry. Unfortunately, the heating, hot-water, damp-proofing and structural repairs were low-cost and ineffective.

Overall, house was damp, had floors at different levels, a leaking roof, with a steeply pitched staircase that sloped sideways. Without increasing the building’s footprint or external surface area, our renovation added:-

  • two more bedrooms,
  • a first floor family bathroom,
  • a ground floor lavatory,
  • a utility room,
  • a central galleried hall,
  • an easy staircase.

We specified a high standard of insulation, which added little cost. Now, the house is mainly heated with a wood-burning stove, backed-up by an oil-fired boiler. This combination provides environmental benefits and automates the heating.

Later, we designed a glazed timber conservatory opening from the drawing room, an enclosed porch, and a part glazed rear porch enabling access to the original building.

Overall, house was damp, had floors at different levels, a leaking roof, with a steeply pitched staircase that sloped sideways.

House Renovation, Quy

Overall, house was damp, had floors at different levels, a leaking roof, with a steeply pitched staircase that sloped sideways.

Glazed Timber Conservatory, Quy