The address register comes before the plan. We confirm the local planning authority, current H&F search record, lawful planning unit, earlier additions and conditions, conservation-area result, any Article 4 entry, statutory listing, title and lease. These sources have different legal effects. A house can sit in a conservation area without losing every Class A right; a direction can affect only named properties and operations; and a planning approval does not establish ownership of a side passage or authority to alter retained fabric. The feasibility note records each result, its date and the drawing decision it changes. Unknowns remain visible instead of being filled with assumptions about Hammersmith terraces.
The measured survey captures the original rear walls, back addition, side passage, boundaries, garden depth, floor and external levels, visible drainage, neighbour windows, roof overhangs and any evidence of previous work. We photograph the junctions that will become concealed and mark features that need opening-up or specialist investigation. The kitchen brief is set against that base: appliance runs, island or table, circulation widths, storage, garden access and the relationship to retained rooms. A proposal is not treated as successful because it adds the largest possible footprint; it has to create a usable plan while leaving a coherent house, sufficient outside space and a buildable technical route.
We compare rear-only, side-infill and combined options on the same drawing. A rear addition changes depth and garden relationship; a side-return changes width, boundary construction and roof geometry; a combined scheme must satisfy cumulative planning and technical constraints. The comparison shows gross and usable area, structural spans, daylight routes, likely service positions and the amount of original fabric removed. That makes the planning choice legible and prevents a footprint label such as wraparound from substituting for a measured design. Where a smaller move solves the brief with less structural and consent risk, the option study should show that rather than presume maximum enlargement.
The planning assessment uses two distinct rule sets. National Class A determines whether a qualifying dwellinghouse proposal could be permitted development, while H&F's Local Plan and Planning Guidance SPD guide the assessment of a planning application. The SPD's rear-extension principles consider the original back addition, established building line, rear boundary and retained open area. Those figures are not a substitute for the national limits and do not grant permission. We draw the original building, every existing enlargement and the proposed work together, then state whether the advice is a planning application, a proposed lawful-development certificate or further address research.
Heritage work starts with the mapped designation rather than a neighbourhood label. The Bradmore profile includes relevant Brackenbury streets, while Hammersmith Grove and St Peter's Square have separate records. We identify which record applies and extract only the characteristics that the site and affected elevation engage. The rear roof form, junction to original brickwork, view from public or private spaces, garden setting and surviving plan or fabric can matter differently at each property. If a building is listed, a heritage assessment follows the statutory character test and the affected fabric; conservation-area status alone is not evidence that the home is listed.
Structure is developed from the existing load path and proposed openings. The architect records geometry and coordinates the room, but the appointed structural engineer determines whether the solution uses timber, steel, masonry or a combination; the permanent supports, bearings, connections, foundations and temporary sequence are project-specific. We do not assume a goalpost frame, a chimney removal or a bearing into either party wall. Early structural zones are shown against ceiling heights, kitchen units, rooflights and ducts so a later beam or post does not undermine the layout. Where construction is concealed, the information required before final design is named on the drawings.
A Party Wall screen follows the engineering scheme and adjoining geometry. Work on an existing party wall or party structure, a new wall at the line of junction and qualifying excavation are separate statutory categories. For the three-metre test, proximity is not enough: the excavation must go below the bottom of the neighbour's foundations. For the separate six-metre test, part of the excavation must meet the Act's line drawn downwards at 45 degrees from the bottom of the neighbour's foundations. The minimum notice periods are one month for line-of-junction and excavation notices and two months for party-structure notices. Written consent may conclude a notified process, while a dispute is resolved by surveyor or surveyors and an award. Planning permission does not settle it.
Daylight is tested with the room geometry, orientation, retained openings and likely surface reflectance. Roof glazing can help a deeper plan, but its position is coordinated with structure, waterproofing, maintenance and any heritage assessment. Rear doors can provide light and outlook without proving that the centre of the plan will perform well. We compare sections and views for the proposed kitchen and consider the effect on neighbouring windows and outlook under the relevant local guidance. The drawings state the design assumptions; they do not promise a brightness level or claim that one lantern or rooflight arrangement is universally sufficient.
Ventilation is designed as a system. As checked on 11 August 2026, Approved Document F's 2021 dwelling edition remains the current route; the published 2026 edition does not take effect until 24 March 2027. For a new kitchen, the applicable guidance ordinarily provides extract ventilation to outside; it may be intermittent or continuous and need not be the cooker hood itself. A recirculating hood alone is not extract ventilation where extract is required. The terminal and duct must be coordinated with the elevation, structure, fire separation, noise, access and heritage. Refurbishment-only work follows the alteration provisions and their limited exception for a room with no original system.
Drainage begins with a survey of foul and surface-water assets, levels, ownership and condition. Kitchen wastewater needs an adequate discharge route under Approved Document H, while roof and paved runoff follows the applicable surface-water hierarchy and site constraints. We do not promise that a new sink can use the existing branch or that rainwater must take one fixed route. Where Thames Water is the relevant undertaker, its current guidance says a build-over agreement is likely for work within three metres of a public sewer or one metre of a public lateral drain. The asset must be located and the required agreement obtained before construction.
The extension envelope is coordinated through the applicable Building Regulations. Part A informs structural adequacy; Part L guides the new thermal elements and relevant controlled fittings; Part H covers drainage; and Part F covers ventilation. At this review date the Part L 2021 dwelling edition, incorporating the 2023 amendments, remains current; the published 2026 edition takes effect on 24 March 2027. Other requirements can apply to fire safety, moisture, glazing, electrical work and access. A flush-looking threshold is set from the actual levels, exposure, drainage and door system rather than promised as a standard detail. Planning drawings and a builder's quotation do not replace building-control design and approval.
A flat or maisonette follows a different ownership and planning branch. Part 1 householder rights do not apply, and the title, lease and any superior lease must establish whether the garden, side passage, rear wall and proposed footprint are within the demise and whether written landlord or management consent is required. The lease may prohibit work, allow it or make it conditional. H&F's public-planning decision does not override those covenants, and private consent does not grant planning permission or Building Regulations approval. We record the parties and required documents before detailed design rather than describe a freeholder licence as automatic for every home.
The technical set coordinates architecture, structure and services against one revision. Plans and sections locate retained and removed fabric, openings, levels, roof and threshold build-ups. The engineer's design identifies the load path and temporary stability. Drainage and ventilation drawings establish routes, falls, terminals and access. Schedules identify the decisions still needed from planning, heritage, building control, Thames Water, a landlord or a Party Wall adviser. That coordination gives contractors a defined scope and lets quotations expose exclusions, but it does not certify an unknown existing condition or guarantee that a statutory or private authority will agree.
Programme and cost are reported by stage. Feasibility and survey precede any application; the national eight-week non-major period applies to a valid application unless a longer period is agreed, and it is not the whole project duration. Structural engineering, building-control information, sewer and private-consent work can run only where the design is sufficiently fixed. Our architectural fee is based on the agreed appointment and deliverables. Council charges, engineering, surveys, Party Wall, legal or landlord costs and construction are identified separately unless expressly included, so a homeowner can compare a real scope rather than an area-wide price or approval promise.
