Littlecombe SE7

garage to residential development
Alexandra Close HA2
Architects London example residential project
Denmark Hill SE5


How to add Side Extension to Semi Detached House without Breaking the Bank

Lucky for you, we documented each step that we took to add side extension to this semi detached house. Use this proven process to produce the same results for your home extension project.



The client came to us in 2015 with a lofty ambition to increase the size of their home with a variety of large extensions on the rear, side and top of the house – extensions that broke with the surrounding roof typology. Prior to development, the property itself was a small corner end-terrace house, standing two storeys tall with a large garden that is approximately 300sqm.

We knew right away that, with regard to local and national policy, the proposed extensions would be out of character with the neighbouring parade and would produce a terracing effect – meaning the original property would be overtaken by the extensions. Succinctly put, the biggest challenge with this project was the size of the property: it was simply too small to handle the desired extensions. Local, regional and national planning policies would not allow such a massive development. We also had to be sure our designs were carefully put together, taking into consideration all the limitations pertaining to permitted development rights.


But at Urbanist Architecture, we’re always looking for creative design and planning solutions that will help our clients maximise the potential of their home. First thing’s first: we went through the pre-planning process (which was free in those days!) with the local planning authority, and they confirmed our suspicion: The proposed development would be out of character with the parade and would lead to overdevelopment of the property. They, therefore, advised that we reduce the size of the extensions. In developing our plan, we took stock of the inherent opportunities. We saw that the property had lots of potential: the garden was massive, providing plenty of space to extend; the owner had already dug out the garden around the perimeter of the house, which allowed us to design taller rear extensions without too much impact on the neighbouring property; and, finally, the house was a corner property, providing us with more flexibility in terms of design.

Seeing clearly the opportunities and challenges ahead, we suggested pursuing the project in a series of stages. Instead of submitting one large application for three extensions and two dormers – which would lead to an almost-certain rejection – we decided to submit a separate application for each extension. Only then, could we get the number of extensions our client was asking for. We also had to make sure the our designs conformed to the local context, with roof typologies that matched the surrounding parades. With our plan in place, we started with a permitted development application for the 6-meter, single-storey rear extension, and we were successful! We then submitted a permitted development application for the 3-meter double-storey rear extension, together with the two dormer windows, and once again, we prevailed! Finally, we submitted a full application for a large double-storey side extension, and this time, the planning authority rejected the application.

Our client didn’t want to take no for an answer, so we appealed to the planning inspectorate. Again, they refused. According to the planning authority, a two-storey extension was simply out of character with the surrounding properties, and from the point of view of the street, the large extension would overwhelm the view of the original house – this is that terracing effect mentioned earlier. The struggle would not end there. We continued our fight by reducing the double-storey side extension to a single-storey side extension under permitted development. This time, we prevailed. It wasn’t easy, but with enough elbow grease and determination, we were able to help our clients realise their dreams. Not only were we successful during the planning stages; we were also able to produce smart internal layouts that fulfilled our client’s needs. For instance, our client had a very particular vision for the staircase. They wanted to move it from its original position toward the side of the house. We were able to accommodate this vision, using a sloped roof and the side dormer window. In the end, they had plenty of space to lounge, eat and entertain guests.

Of course, the benefits of using our services extend far beyond the results above.

We surveyed our clients and asked them to name the three benefits of our services that they found most useful. Here are the top benefits as cited by more than 100 survey respondents.

  • Get access to proven strategies

  • Have a dedicated architect

  • Minimise risk and feel safe

  • Make the project stand out

  • Save time

  • Save money

  • Save effort

  • Get photorealistic 3D visuals

  • Increase space

  • Increase comfort

  • Increase value

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