Caddis Close HA7

rear extension and loft conversion
Brookbank Road SE13
planning permission for building new houses
Thayers Farm Road BR3


Who can get planning permission to build a triple storey rear extension?

Lucky for you, we documented each step that we took to renovate this detached property and add triple storey extension. Use this proven process to produce the same results for your new extension project.



This project, like any project, came with a number of interrelated challenges. First of all, a review of precedent cases revealed that a number of rear and side extension proposals had been rejected by the Local Planning Authority (LPA) in north-west London. Thus, we knew we would have to overcome the LPA’s resistance to developments that interfere with the style and design of the local area. In this case, the neighbouring properties in the cul-de-sac were all nearly identical to one another, making our job even more challenging. Moreover, it is generally the case that planning authorities frown upon excavation projects, as they have been known to affect the integrity of the neighbouring foundations.

In addition to the council’s resistance, we also faced push-back from one of our client’s neighbours, who contested the development on the basis of overshadowing. They claimed that the double storey rear extension would block sunlight to the rear of their property. With the LPA’s history of resisting development in the area and the general distaste for excavation projects, we had our work cut out for us.


We took each challenge as an opportunity to help our client find creative design solutions that would increase the property’s quality and value, but also noticed a number of opportunities. For instance, we observed that the property was located on a hill, with the front-end being higher than the rear. This, we found, would allow us to generate far more space for future occupants. And with the property’s garden being very large, we had plenty of room to extend the house. We were also blessed with a detached property, which would offer us greater flexibility in terms of the design.

First, we needed to come up with a design that would provide future occupiers with more space and a smart layout, and we needed to do this without upsetting the council’s expectation of consistent and sympathetic design. We knew we wanted to create a new level via the excavation of the existing footprint and more space with the double storey rear extension, but we needed to determine an ideal layout to take full advantage of these additions.

To provide the best arrangement for future occupiers, we decided to move the living-dining area – which was originally located on the ground floor with the kitchen – to the new lower level, where occupants would have direct access to the garden. With this new level in place and a double-storey rear extension, we would then have plenty of room on the ground floor for a very large kitchen, and we could increase the number of bedrooms from two to four – with two double and two single bedrooms, each having plenty of space. In addition, we were able to create two large bathrooms and one large utility space. On the whole, our designs provided plenty of extra space for future occupants and a more direct access point from the house to the garden.

Of course, when making our designs, we also had to consider the various planning challenges mentioned above. For starters, we were more or less in the clear in terms of the general distaste for excavation projects because, luckily, we were dealing with a detached property, so the foundation-related issue was a non-starter. With regard to the neighbour’s objections, we soon found that here there was also nothing to worry about. As mentioned, the neighbour asserted that the rear extension would prevent sunlight from reaching their property, but upon further evaluation, we found that no such blockage would occur – in fact it wasn’t even close. We thus discovered that the objections were not relevant to any ‘material planning considerations’, and since only objections that pertain to such considerations are considered valid by the council, the neighbour had no grounds for rejecting the proposed development.

We also had to make sure that the exterior of our designs matched the look and feel of the surrounding area because, as mentioned, the council wished to maintain a consistent style across the various properties. Additionally, we had to ensure that any alteration to the property was subordinated to the main dwelling, so that the extensions didn’t dominate the property in terms of design and the overall character of the building. To do this, we selected materials and roof typologies that would not interfere with the local context, and that would thereby satisfy the LPA’s requirements. In the end, we only submitted one application, which was indeed successful. This was a major victory, considering the fact that so many other applications had been rejected by the same authority.

By thoroughly examining the challenges and opportunities of the property, we were able to arrive at a design proposal that would satisfy our client’s financial needs. In the end, we helped our client obtain planning permission for a well-thought-out development, which in turn, would allow him to sell the property at a higher value. If you’re interested in investing in your property in this way, come to us at Urbanist Architecture - with planning permission in hand, the value of your property can go way up.

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

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  • Increase space

  • Increase comfort

  • Increase value

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