duplex apartment, upper berkeley street, westminster

new roof extension above a grade-II listed georgian townhouse
Our client owned the top floor apartment of a townhouse located on Upper Berkeley Street in Westminster. With the addition of a single-storey roof extension they doubled the size of their apartment and added a further two bedrooms, bathroom and terrace. Achieving planning consent required a sensitive design approach to be taken as roof extensions are not usually allowed within the Portman Estate Conservation Area.

After the project was successfully completed in 2013 the client said;

"We went with Stagg Architects after comparing a number of local firms and couldn't be more delighted with our choice. We were very well guided and supported throughout the whole process which greatly reduced our stress and increased our confidence. We also went through a very detailed and thorough contractor selection process for the construction phase which resulted in an excellent schedule of work with fixed pricing, and a contractor that stuck to this as a result of Stagg Architects brilliant project management. I strongly recommend Stagg Architects to anyone looking for an experienced, creative and results-focused architect."

01 The completed mansard roof extension (second building from right)
02 Proposed section showing the mansard form of the new space
03 The new roof extension comprises a high-ceiling open-plan living area at upper level
04 Daylight and sunlight illuminate the space from both sides and through the rooflights above
05 A new shower room and bathroom were created at the lower level
06 Light shelf with concealed fitting built into the arching roof form
07 View from the kitchen towards the sitting area
08 Rear of the roof extension viewed from a new terrace
09 The existing roof terrace prior to construction
10 The steel frame in position
11 The roof extension completed in natural blue-grey Welsh slate