Hampstead Architecture and Planning

Barnet

Kitchen Extension Architects in Hendon

The interwar semi puts the kitchen in a small room at the back, separated from the reception rooms by a wall and usually by a door. That layout is what a Hendon kitchen extension is really addressing, and the biggest gains come from working in two directions at once — rearwards into the garden and sideways into the gap or the garage — rather than simply pushing the back wall out.

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The short answer

What is the best kitchen extension for a Hendon semi?

Width first, then depth. The original plan puts a narrow kitchen at the back behind a wall, so taking the side gap or an attached garage to bring the room to the full width of the house fixes more than pushing the rear wall out does. Two or three metres of added depth on top is usually enough, leaves more garden and produces a brighter plan. On an undesignated address that combination is often achievable without a full application.

Planning at a glance

Hendon

Planning at a glance in Hendon
Local planning authorityBarnet
Likely approval routeHouseholder planning application or permitted development, depending on conservation status, listing and property type — confirmed for the exact address before drawings begin
Statutory determination time8 weeks for most householder applications (13 weeks for major applications)
Where most projects startPlanning Route Review — £395 inc. VAT, credited in full against your package if you proceed. Find my package →

The most valuable move on a Hendon semi is usually not the deepest rear extension available but the combination of a modest rear addition with a widening of the plan. Where the house has a side gap, a garage, or a passage beside the kitchen, taking that width brings the kitchen up to the full width of the house and allows a proper working run with a table beside it. Adding two or three metres of depth on top of that produces a room that genuinely functions, while leaving more of the garden than a deep rear box would. On these plots the garden is long enough that depth is available, which is precisely why it is worth resisting the temptation to use all of it.

The structural work follows from the plan. Opening the rear reception room into the new kitchen means removing a load-bearing wall, with a beam sized by an engineer and padstones spreading the load into the remaining masonry. On a semi that wall may also be doing something at the party wall, so the connection into the neighbour’s structure has to be understood before it is cut. The beam depth determines the finished ceiling across the widest part of the room, so it is sized before the kitchen layout is set rather than after.

Extract and drainage are the usual pair with a Hendon variation. Part F of the building regulations requires mechanical extract at a defined rate for a kitchen, which a recirculating hood does not provide, so the duct route to an external face has to be planned. On a semi there are two options — the rear elevation and the flank wall — and the flank usually gives a shorter, quieter run, which is worth exploiting rather than defaulting to the rear. Drainage is generally more straightforward than on a Victorian terrace because the runs are better recorded, but building over or within three metres of a public sewer still needs a build-over agreement with Thames Water.

Foundations are the largest cost variable here. Much of Hendon sits on clay, which requires deeper foundations, and the depth increases substantially near trees — both existing ones and any removed within the last few years, since ground dried by a mature tree for decades can heave for a long time afterwards. On plots with mature garden trees or a neighbouring boundary tree, a site investigation at feasibility informs the design and turns the biggest open contingency in the budget into a known figure.

Local analysis

What matters in Hendon

Why width usually beats depth on a Hendon plot

On a semi-detached house with a side gap the instinctive move is to extend straight back, and it is frequently the wrong one. The problem with the original plan is not that the kitchen is shallow; it is that it is narrow and cut off, occupying about half the width of the house with a wall between it and the rear reception room. Extending rearwards without addressing the width produces a longer narrow kitchen and leaves the awkwardness intact. Taking the side gap, or converting an attached garage into the plan, brings the room to the full width of the house and lets the kitchen, the dining area and a route to the garden coexist properly rather than queueing behind one another. The additional depth then only needs to be enough to make that width usable — often two or three metres rather than the maximum available. The result uses less garden, costs less to build per useful square metre, and produces a plan with more daylight in the middle because the room is not as deep. It also usually retains a permitted development or prior approval route that a very deep extension might not. We model both approaches at feasibility so the comparison is concrete rather than theoretical.

Keeping the middle of the plan bright

Extending the back of a Hendon semi pushes the original rear windows into the middle of the plan, where they light nothing, and the dim zone that results is the commonest complaint about finished extensions. Fixing it is a design decision rather than a budget one, and four moves do most of the work. Rooflights placed over the working part of the kitchen rather than over the circulation route put daylight where it is used, and a few well-positioned ones outperform a larger number spread evenly. Making the rear opening tall rather than merely wide pushes light further in, because the height of the head determines how deep daylight penetrates. Lifting the ceiling where the new roof crosses the line of the old rear wall gains volume and creates a light shelf. And on a semi, a window or rooflight in the flank wall — often available where a terrace has no such option — brings in light from a second direction, which transforms a deep plan. All four cost little at design stage and are expensive or impossible to retrofit, which is why they are settled before the structure is fixed.

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Local planning

Planning & conservation context

A single-storey rear kitchen extension on an undesignated semi-detached or detached house can fall within Schedule 2, Part 1, Class A permitted development, and the prior approval procedure allows a materially deeper one in exchange for neighbour notification. Those allowances are larger than for a terrace, so a substantial extension is often available without a full application.

Barnet is the authority throughout the Hendon research area. Ten of its conservation areas are covered by or have Article 4 directions in force, and within one of those both the permitted development and prior approval routes close, so the designation check comes first.

The allowances are measured against the original house rather than as you bought it, so a previous owner’s rear addition reduces what remains. Where a garage conversion is being combined with a rear extension, the interaction between the two needs checking rather than assuming they are independent.

Within Hendon Church End, Hendon The Burroughs, College Farm or Finchley Garden Village, a rear extension is assessed against the established pattern along the street: depth relative to neighbours, how much of the original rear elevation survives, and whether the roof form and materials read as subordinate.

Most Hendon addresses sit outside all four designations, which is why the check is quick but decisive: a negative result opens routes that a designation would close entirely.

On a run of matched semis the rear elevations are less visible from the public realm than the fronts, but where a side extension or garage infill changes the street-facing elevation, matching brick and window alignment matters regardless of designation.

For the wider local-authority picture — policies, timescales and application routes — see planning in Barnet.

Illustrative study — street elevation

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Nearby Kitchen Extension Architects pages

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Architecture in Hendon: FAQs

Do I need planning permission for a kitchen extension in Hendon?

Often not. On an undesignated semi-detached or detached house a single-storey rear extension within the Class A limits can be permitted development, and the prior approval procedure allows a materially deeper one subject to neighbour notification. Within one of Barnet’s conservation areas covered by an Article 4 direction both routes close and a householder application is required.

Should I extend the side or the rear?

Usually both, but with more emphasis on width than owners expect. The problem with the original plan is that the kitchen is narrow and cut off, not that it is shallow, so taking the side gap or an attached garage brings the room to the full width of the house. Two or three metres of added depth on top of that is often enough, uses less garden and produces a brighter room than a deep rear extension alone.

How deep can I go under permitted development?

Class A allows a set depth for a single-storey rear extension on a semi-detached or detached house, with height and eaves limits, and the prior approval procedure allows a materially deeper one subject to neighbour notification. The exact figures depend on the house type and current regulations, and the allowance is measured against the original house — so a previous owner’s extension reduces what remains. We check that as part of the route review.

How deep will the foundations be?

Deeper than on gravel, because much of Hendon sits on clay which shrinks and swells with moisture content. The depth increases substantially near trees, and ground where a large tree was removed in recent years can still be heaving. On plots with mature garden or boundary trees, a site investigation at feasibility informs the design and converts the largest budget variable into a known figure.

Where should the extract duct run?

On a semi you usually have two options and the flank wall often gives the better one. Part F requires mechanical extract at a defined rate for a kitchen, which a recirculating hood does not meet, so a duct must reach an external face. The flank route is typically shorter and quieter than running the full depth to the rear elevation, which is worth exploiting rather than defaulting to the back of the house.

How do I stop the middle of the room going dark?

Put rooflights over the working part of the kitchen rather than over circulation; make the rear opening tall rather than merely wide, since the head height determines how far light travels; lift the ceiling where the new roof crosses the old rear wall; and on a semi, use the flank wall for a window or rooflight so light arrives from a second direction. All four cost little at design stage and cannot easily be added later.

Can I combine a garage conversion with the kitchen extension?

Yes, and on these houses it often produces the best plan, because the garage sits exactly where the kitchen needs to widen. The two projects interact for permitted development purposes, so the combined proposal needs checking as a whole rather than as two independent works. It also means the garage floor level, wall build-up and the new structure are designed together, which is considerably cheaper than doing them separately.

What does a kitchen extension architect in Hendon charge?

We publish fixed-fee packages rather than quoting a percentage before seeing the house, beginning with a route review that establishes the remaining allowance and which consent route applies. Later stages cover the certificate, prior approval or planning drawings, then building regulations and tender information. Structural engineering, site investigation, drainage surveys and council fees sit outside the architectural fee.

How much does a kitchen extension cost in Hendon?

Fees for kitchen extensions in Hendon follow scope, consent complexity and whether freeholder or specialist input is required. Published packages start from a fixed fee once scope is clear; council, engineer and freeholder surveyor fees are usually separate. See our packages page for current fixed-fee bands — we confirm a fee only after the address and proposed work are understood.

Discuss a kitchen extension in Hendon

Send your Hendon address, photographs of the rear elevation, the side of the house and the existing kitchen, and note any mature trees nearby. We will model width-first against depth-first, confirm the consent route and the remaining allowance, and set out the fixed-fee stage that follows.

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