The first design decision is what evidence to collect. A measured survey records the existing house, rear additions, boundary relationships, levels, adjoining windows, drainage points, trees and the direction of the garden. Title and lease documents identify ownership and alteration controls. Council mapping and the planning history establish designations, conditions and previous work. This baseline prevents a neighbouring extension or an estate-agent plan from becoming a false precedent. It also shows whether the useful comparison is an internal remodel, a rear projection, a side-return infill, a combined option or no extension at all.
A kitchen brief should be tested against the retained ground floor rather than measured only by the new footprint. We plot cooking, preparation, dining, storage, utility and circulation zones, then examine what happens to the room between the front of the house and the proposed garden doors. Removing more wall can create apparent openness while leaving an overlong route, weak storage or a dark central zone. Alternative plans let the client compare net usable space, furniture clearances and the value of keeping a separate room before structure or planning assumptions harden into the scheme.
Daylight is assessed from the actual section and orientation. Rooflights, a lantern, a clerestory and glazed doors admit light from different directions and at different depths; none is an automatic answer. We model the retained rear wall, ceiling heights and opening positions so that light to the existing plan is considered alongside light inside the addition. The study can compare clear sky exposure and the distribution of glazing without promising a particular daylight result. Final specification also has to address privacy, safety, structure, cleaning, solar gain and the thermal performance of the complete envelope.
More glass can introduce summer overheating, glare and winter heat loss as well as daylight. Garden orientation, external shading, opening area, internal blinds, thermal mass and ventilation strategy change that balance. A west-facing elevation and a shaded north-facing return present different conditions, but orientation alone does not dictate a product or glazing ratio. We coordinate the roof and elevation with the energy and ventilation design, then use the applicable Approved Documents and product data at technical stage. This keeps an attractive planning image from becoming an uncomfortable or non-compliant kitchen.
A rear extension and a side-return infill solve different plan problems. Rearward depth can enlarge dining or living space and move the garden threshold; side infill can add width beside an existing rear addition. Combining them may be useful on a particular survey, but it also changes the boundary condition, roof geometry, drainage and permitted-development analysis. We draw the options separately before combining them. The comparison records retained garden, internal width, daylight path, neighbour relationship and cost-bearing structural moves, so the chosen footprint follows the brief rather than a claim about what Kew kitchens are supposed to be.
Neighbour amenity needs evidence rather than a standard roof recipe. Richmond's house-extension SPD uses the BRE 25-degree and 45-degree methods as screening guidance and asks proposals to avoid significant loss of daylight and sunlight. That BRE screening guidance does not guarantee a pass, approval or outcome. We show adjoining habitable-room windows, levels, boundary structures and the proposed massing in plan and section. A low eaves line or a lantern set away from a boundary can be tested as an option, but neither guarantees compliance, officer support or protection from private rights. Orientation, existing obstruction and the affected window's position remain material to the assessment.
A private right to light is distinct from planning daylight and sunlight assessment. The Law Commission describes rights to light as easements, and a planning permission does not extinguish them. Not every window has such a right, and proximity alone does not establish infringement. Where the proposal could materially affect an adjoining opening, specialist legal or survey advice may be appropriate after the relevant ownership history and geometry are understood. That review should not be presented as part of the council's decision or as an outcome that an architectural section can guarantee.
Structure begins with the retained building and ground conditions. A wide opening in the rear elevation, removal of an internal wall, a new roof and a glazed corner create connected load paths; their supports may reach existing walls, new columns or new foundations. The structural engineer determines sizes and bearings after survey and investigation. We coordinate those zones with cupboards, ceiling lines, rooflights and doors so a beam or column does not appear after the kitchen layout is fixed. Foundation design also responds to nearby trees, drains, soil and the adjoining structure rather than using a standard detail.
Drainage and services can alter the viable layout. The survey locates soil and rainwater pipes, manholes, gullies, meters, boilers and available extract routes. A proposed sink or utility may need a workable fall to an existing connection, and building over or close to a drain can introduce access and third-party requirements. We develop drainage, ventilation, heating, hot water, electrical and lighting strategies with the plan. Existing routes can sometimes be retained and sometimes need diversion; the drawings should identify which conclusion remains subject to opening-up, survey or utility approval.
Technical design translates the planning envelope into buildable performance. The package can cover structure under Approved Document A, relevant fire precautions under B (Approved Document B), ventilation under F (Approved Document F), drainage under H (Approved Document H), glazing and impact safety under K (Approved Document K), and thermal performance under L (Approved Document L), together with other requirements engaged by the work. Approved Documents give guidance on ways to meet the Building Regulations; they are not product specifications or a substitute for the building-control body's assessment. The applicable editions and transitional provisions should be checked when the application is made and work starts.
For a listed or leasehold property, internal reconfiguration may be as important as the external addition. Opening an old wall, removing joinery, relocating services or cutting through historic fabric can affect special interest even when the garden elevation changes little. A lease can reserve structural walls, foundations, garden or external fabric to the landlord and require prior written consent. We therefore align the architectural option with heritage significance and ownership before detailed coordination. Planning permission and building-control acceptance cannot grant rights over fabric or land the applicant does not control.
A credible programme has decision gates. Feasibility establishes the property, policy and design constraints; planning or lawful-development evidence settles the public planning route; technical design and engineering resolve compliance and construction; any listed-building, landlord, tree, sewer, Party Wall or other third-party process runs on its own facts. Procurement and site dates follow those decisions rather than an assumed eight-week approval. At each gate we record what is verified, what depends on a consultant or authority and what remains a client choice, giving the kitchen project a traceable route without promising consent, cost or completion.
