This very small house in East Dulwich was to be substantially extended. Edwards Covell Architecture and Planning were asked to provide proposals for a rear extension and loft conversion as well as remodelling the interior. All had to be done to an extremely tight budget.
There were no precedents for other loft conversions (dormer windows) on this street and most adjoining ground floor extensions were much smaller than was required here. Obtaining planning permission would have been difficult and slow and possibly result in the project being aborted. A two-storey extension was originally considered but given the impact this was likely to have on neighbours a loft conversion was preferred.
In the end the project was built under permitted development (PD) rights and avoided the need to go through a long and potentially contentious planning application process. The overall floor space of the property was to be increased significantly but because the dormer effectively added only a small amount of overall volume to the property, it was possible to do the work under PD (adding just under 10% to the original cubic content of the building). The three-dimensional volume is the way the percentage rights are calculated, so this helped immensely. Furthermore the ground floor proposed extension was to replace an existing one. This existing volume could also be subtracted from the total additional volume.
The aim of the extension was to provide one large living space within the house that would also spill into the garden room. The difficulty with providing such rooms is that the central space in the house can often become very dark, especially as the garden was east facing. This was dealt with by employing two large roof lights. The absolute maximum ceiling height was also achieved as well as providing four retractable glazed doors to the garden.
The loft conversion presented several construction challenges. These houses were built with masonry walls between every other house. This meant one of the walls we were building over was timber stud, and non-structural. Furthermore the rear of this wall had a chimney where there had once been a back boiler. This meant no steelwork could bear from front to back above this non-structural wall. We dealt with the problem by reducing the dormer width to inside the staircase. The load of the floor and dormer was borne by the central “spine” wall of the house and using flitch beams and minimal steelwork the self-weight was kept to a minimum. Another restriction to the proposal concerned the party wall(s). In order to maximise the extension, we proposed to straddle the party wall to both sides. After much negotiation the width of the overall wall was reduced by a very small amount on both sides, and the neighbours were appeased.
For a project of this scope (a loft conversion and rear extension) the budget would usually be 15-20k for the rear extension and 20-30k for the loft conversion. The original budget for the job had been 45k but in the end the project was completed for a total of 36k. This was achieved by managing each of the works contractors individually. The work was also done over a long period of time.