House extensions in Kennington, SE11

Describe the missing function

Be specific about the purpose of the additional space. You might want a dining area connected to the kitchen, a place to work or a better relationship with the garden. We compare that objective with the existing plan and test whether rearrangement would answer part of it. Where an addition remains justified, this work helps define its useful size and shape. It avoids treating maximum footprint as the only measure of improvement.

We then draw furniture, door movement and routes through both old and new rooms. The connection should not turn a useful existing space into a narrow passage or leave it difficult to furnish. Consider the daily activities that will overlap, such as cooking while somebody moves between the entrance and garden. These tests give the design a purpose before decisions about roof form, glazing or an external finish begin to dominate.

Understand the rear elevation and garden

The Kennington conservation statement gives importance to rear elevations, building groups, gardens and trees when considering extensions. The rear of a protected terrace is not treated as an unconstrained surface simply because it is less visible from the street.

The survey records the existing return, openings and outside levels, together with the relationships that can be observed at the boundary. We identify what information is required about drainage, structure and access before fixing the footprint. An addition has to leave the retained parts of the property workable too. Refuse storage, maintenance routes and a usable garden deserve space in the proposal instead of being displaced by a design that uses every available corner.

Sources: Kennington conservation area statement

Choose a form that belongs to this proposal

Lambeth's adopted design guidance distinguishes infill, rear and other extension forms and requires a subordinate response to the existing building, with neighbours considered. The correct form follows the property and its design context; a generic extension diagram is not permission for a Kennington site.

We compare the implications of different forms without assuming each is available. A narrow addition, a change in roof shape or a carefully placed opening can have different effects on the existing rooms. Drawings and sections show the relationship clearly enough to assess those effects. The preferred option should be supported by the relevant planning and technical work, with limitations explained while the design can still be adjusted.

Sources: Lambeth Design Guide Part 4: alterations, extensions and retrofit

Resolve the junction with the existing house

The connection is often the most consequential part of an extension. We identify what would be removed, how the retained structure is supported and where new work meets existing floors, walls and roof elements. The engineering assessment and construction details develop alongside the room layout. A broad opening shown on a sketch is not treated as a complete structural proposal, and the finished appearance is reviewed after the required construction depth is understood.

Services also pass through that junction. Heating, lighting, plumbing and ventilation are coordinated with the intended use of the added room and the capacity or condition of existing systems. Routes are shown before ceilings and fitted furniture are finalised. Changes required within the original house are included in the scope, so the proposal does not appear smaller or less disruptive simply because part of its installation happens beyond the new footprint.

Review light, openings and neighbouring relationships

An extension changes how the original rooms receive light and how the garden is reached. We test the proposal as a whole, considering the depth of the retained rooms and the placement of roof and wall openings. More glass is not automatically a better answer. Its position, operation, cleaning access and relationship with furniture need to be considered together, alongside any design assessments required for the project.

Boundary relationships are recorded accurately and passed to the relevant advisers where specialist assessment is needed. We avoid promising that a proposal is acceptable solely because another property has an extension. Differences in levels, openings, orientation and planning history can matter. The information gathered for your design should explain its own circumstances. This also helps keep discussions about privacy, outlook and access grounded in the actual drawings rather than assumptions about a typical terrace.

Carry the agreed design into the build

The construction information identifies materials, junctions and the work required to make good the existing rooms. Samples are reviewed where they help resolve visible decisions, with the approved choice recorded. Access for excavation, deliveries and removal is planned against the real route through or around the property. Any dependence on access outside your control is identified before it becomes a construction requirement. The aim is a design that can be delivered as drawn.

Once complete, assess the addition in use with the original house. Open the doors to the garden, move furniture through the connecting space and test the installed lighting and equipment. Inspect thresholds, weathering details that are accessible for review and the finishes around retained openings. Keep the final drawings and relevant records together. The extension should leave a coherent home and a clear account of the work carried out, not only a new room photographed in isolation.

Official sources

Kennington conservation area statement · Lambeth Design Guide Part 4: alterations, extensions and retrofit · Southwark conservation areas: Kennington Park Road

Checked 4 November 2026. Maps, list entries and directions must be checked for the individual property and proposed work.