Herne Hill is unusual in being shared between two planning authorities. The London Borough of Lambeth administers the western side and the London Borough of Southwark the eastern side, with the boundary threading through the middle of the area rather than skirting its edge. As a broad pattern, streets to the west report to Lambeth and those to the east to Southwark, yet the split can flip from one road to the next, so we verify the responsible council against your precise address rather than the neighbourhood name. This matters in practical, not academic, terms: the two boroughs publish different validation checklists, apply their own local policies and weigh householder schemes in their own way. Settle the wrong authority at the outset and the drawings, the supporting documents and even the design emphasis can end up pointed at the wrong council. That address check is the first line of any Herne Hill kitchen brief we take on.
The house type then sets the rest of the puzzle. Herne Hill's bay-fronted Victorian terraces near the station and Brockwell Park, and the roomier Edwardian and semi-detached villas climbing towards Dulwich, nearly all carry a rear closet wing with a slim return running beside it. The standard remedy is to fill that return and push a little further across the back, folding the poky rear kitchen and the room behind it into one open kitchen-diner. What owners underestimate is how far that combined footprint reaches away from natural light. A galley plus a projection can leave the working heart of the kitchen — the run of units, the island, the spot you actually stand at — marooned in the darkest band of the room. So our drawings begin not with the maximum footprint the garden could swallow, but with where the light will land and how a family will move through the space.
Getting light to that core is an engineering task in its own right. The party boundary hemming in the old return usually rules out windows down one long flank, which leaves two directions to exploit: the sky and the garden wall. We treat the new roof as the main lantern, placing rooflights or a glazed roof panel precisely over the deepest, dimmest stretch — the cooking zone — rather than scattering them where daylight already arrives. At the garden end, wide sliding or bi-fold glazing pulls a second wash of light back into the plan. Because this is as much a question of cross-section as of layout, we model how sun angles drop through the roof at different hours, and, where the property lies within a conservation area, how that roof form reads against the run of rear elevations behind the terrace.
Joining the old house to the new room is where the build gets serious. A continuous kitchen-diner means taking out the rear wall and the flank of the back addition, both of which hold up the storeys above, so a structural engineer sizes beams — usually steel — to bridge the gap and carry that load. On a Herne Hill terrace those beams commonly land on the walls shared with the houses either side, and it is that bearing detail, more than anything on the plan, that pulls the Party Wall etc. Act 1996 into the job. The depth of the beam also fixes the ceiling: get it wrong and a fat downstand drops across the join, so the old and new halves never quite read as a single room. We therefore lock the beam scheme down with the engineer before the layout is signed off, not after it is drawn.
A kitchen is the busiest service point in any home, and a deep extension has to absorb all of it. Waste from the sink, dishwasher and any utility run needs a clear path to the existing drains — and on these period houses the soil and rainwater stacks frequently descend the very side return being built over, so the pipework must be diverted or bridged and any inspection chamber left reachable under the regulations. Overhead, the hob wants an extract duct out to a wall or the roof, and mechanical ventilation is a regulatory requirement in a kitchen. All of this competes for the same ceiling void as the new steel and the rooflights, which is why we set the appliance, socket and lighting plan alongside the structure and glazing, not once the shell is already standing.
The last few centimetres — where the kitchen floor meets the garden — carry a surprising share of the finished quality. A flush or near-flush sill to the patio has to reconcile the floor build-up, the door detail and a channel drain that stops water gathering at the low edge, all while meeting the insulation and weathering rules. On the sloping ground towards Dulwich, where gardens sit at shifting levels, those falls and the damp-proofing demand even closer attention on the construction set. Layered over everything is Herne Hill's conservation grain — both Lambeth and Southwark run conservation areas here, taking in streets near Half Moon Lane, Poet's Corner and the fringes of Brockwell Park — which can restrict permitted development and sharpen the scrutiny of roof and glazing. From measured survey through to the technical package, we keep the correct borough, the conservation position and the daylight test moving together, so the room that gets built is bright, serviceable and consented under the right council.
