Project type
A vertical sliced view of the proposal for extensions on a Victorian building in a conservation area to convert into flats and maisonettes while still keeping the store front leading out onto the high street
Vertical sliced render of the current layout of the property which currently held a lof of unused space in the back and very small rooms on the top floor
Measured building drawing of the exisiting floor plan for the basement
Proposal of the basement to be extended into a triangular shape to maximise the development possible on the land
Architectural drawings of the current ground floor which is in a triangular shape
Proposed alterations to the ground floor plan to include toilets and amenities to maximise the space despite the triangular space
Floor plans of the exisiting first floor of the Victorian property in South East London
Proposal of extension on the first floor to accomodate for a one-bedroom flat unit with a large bathroom, living room and kitchen
Basic floor plans for the current exisiting layout of the second storey
Architectural drawings of the second floor proposal for an extension to allow a two-bedroom flat unit
Third floor proposal layout to have the storey converted into a living room, formal dining area and kitchen to create a maisonette in London
Drawings of the exisiting roof plan of the property in Southwark
Proposal of the alteration to be made to the roof plan to accomodate for higher ceilings and create a spacious top floor flat unit

Ambitious expansion and coversion of a small high street building in a conservation area


Denmark Hill SE5

Local Authority

Southwark Council

Plot Type

Conservation Area

Project Type

Flat Conversion


A maisonette and a one-bedroom flat plus expanded commercial space

Services by Urbanist Architecture

Project Architect, Delivery Architect, Planning Consultant


When a bustling high street is not just part of a conservation area but also in an archaeological zone, that can lead to clashes between a council’s own policies. On the one hand, the excellent access to shops and services makes this an ideal place to be adding new homes. On the other hand, the council is meant to be safeguarding the heritage of the area.

Helping the council feel they were getting that balance right was at the heart of this project. Our client owned a four-storey Victorian building with a shopfront on the ground floor and storage in the basement. Above, there was space for offices, although they had been vacant for a while. The conservation area rules were clear that the shopfront had to stay as a business.

The idea was to turn the upper floors into flats, but in order to create livable spaces, we would need to extend on all floors, including the basement and the roof. Would the council allow such a sizeable addition to the building, especially with heritage conservation and (in relation to the basement) archaeology in mind?

Knowing this was going to be tricky, we began doing intense research into the local planning history.

Before & After

Grey and black scale floor plan drawings of the existing traingular ground floor commercial unit with a two door access from the street


The neighbouring buildings provided the crucial context. They had full mansard roofs, which made it seem likely that the council would allow us to match them. The large extensions to one of the neighbours not only provided a precedent, but they also created a situation where the problems of overshadowing and overlooking between the properties would actually be reduced if we were able to match what they had done.

Armed with this knowledge, we were able to start working on an ambitious design that would increase the size of the building on every floor while stepping back at each level it went up. The basement would be expanded to add crucial space for the ground-floor business. Then there would be the large double-storey rear extension covering the entirety of the backyard. Because this was an infill extension, we were sure to include windows all along the rear wall and a skylight on the ground floor.

On the first floor, we placed a one-bedroom apartment with an open-plan kitchen-living-dining area flowing seamlessly into the double bedroom. On the second and third floors, we took advantage of the triple-storey rear extension and the new mansard roof to design a spacious maisonette. The two bedrooms and the bathroom are on the second floor, with the open-plan kitchen-living-dining area up in the mansard.

And so, despite the archaeology area and the limitations that could have meant for the basement, and the conservation area and what that could mean for the rest of the building, we were confident that what we had designed would be a clear improvement on what was there before both in practical and heritage terms. We backed that up with a carefully written heritage statement we prepared in-house. The council were convinced by both our design and the case we had presented, and granted planning permission.

Extensions on four floors to accomodate for larger flat units and maisonettes to be added to a buzzy high street Victorian property

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