One-Off House Design in Barnet

A one-off house — sometimes called a bespoke, individual or self-build home, or simply a new-build house — is a single new dwelling designed specifically for one plot and one client, rather than one of many repeated units in a developer's scheme. The defining feature is that everything is bespoke. The footprint, the massing, the internal layout, the structure, the materials, the environmental strategy and the relationship to the site are all designed from first principles for this house, on this plot, for these people. That is what separates it from a volume house-builder's product, where a standard house type is dropped onto a serviced plot with minor variations.

One-off houses come about in several ways in Barnet. You may already own a plot — perhaps a large garden that can take a new house alongside the existing one, a gap in a street, or a piece of land that has come up for sale. You may own a tired, poorly designed or structurally failing house that is worth demolishing and replacing with something better suited to modern living — a replacement dwelling, or 'knock-down-rebuild'. You may have found a backland site behind existing houses, an unusual corner plot, or the last undeveloped piece of a road. Or you may be a self-builder or custom-builder who has secured a plot and wants a home designed around exactly how you live. Each of these is a one-off house project, and each has its own planning and design challenges.

What they all share is that a new, self-contained dwelling is being created where there was not one before (or a materially different one is replacing an old one), and that this is a substantial undertaking touching every discipline: architecture to design the house, structural engineering to make it stand up, building services and energy design to make it comfortable and compliant, and planning and building-control expertise to get it consented and signed off. A one-off house is the project where all of those disciplines have to work together most closely, because on a single house there is nowhere to hide a clash between the plan, the structure and the systems.

The reward is a home that is genuinely yours: designed around your life, your plot and your aspirations, built to modern energy and comfort standards, and — done well — worth considerably more than the sum of the land and the build cost. The risk is that a one-off house is unforgiving. Get the design or the planning strategy wrong and you face refusal, redesign and delay; get the engineering or coordination wrong and you face problems, cost overruns and compromises on site. This is precisely the kind of project where an integrated architecture-and-engineering practice earns its keep.

The clients who build one-off houses in Barnet are a varied group, but they tend to fall into a few types. The largest is the homeowner who has land — most often a generous plot in one of the borough's leafier neighbourhoods, such as Totteridge, Mill Hill, Hadley Wood, Arkley, Finchley or Whetstone, where houses sit on large gardens that can, in the right circumstances, accommodate a second dwelling. For these clients the question is whether the plot can be subdivided and a new house built without harming the character of the area or the amenity of the existing home — a question that turns entirely on Barnet's design and density policies and the specifics of the site.

The second type is the replacement-dwelling client: someone who owns a house that no longer works — perhaps a small, dated interwar house on a good plot, a poorly built post-war house, or a home that is simply the wrong shape for how they want to live — and who has concluded that demolishing it and building a new, better house is the right answer. Replacement dwellings are common in Barnet's suburban streets, and they are one of the most reliable routes to a genuinely new one-off house, because the principle of a house on the plot is already established. The design challenge is to build something better without overdeveloping the site or jarring with its neighbours.

The third type is the self-builder or custom-builder — an individual or family who has actively sought out a plot in order to build their own home, and who wants a house designed around their specific needs rather than bought off a shelf. Self-build and custom-build are actively supported in national policy, and local authorities including Barnet keep a register of people seeking plots. These clients are often the most engaged in the design process, with a clear vision of how they want to live, and a one-off house is the ideal vehicle for realising it.

Finally there are developers and investors building a single high-quality house for sale — a bespoke home on a good plot in a desirable Barnet neighbourhood, where the value of a well-designed one-off house comfortably exceeds a standard product. For all of these clients the fundamentals are the same: a plot, a brief, a set of policies to satisfy, and the need for a design that is both consentable and buildable. We work with each of them, and the first conversation is always the same honest assessment of what the plot and the policies will actually allow.

Barnet is a large, green and predominantly suburban borough in north London, and understanding its character is essential to designing a house that will be consented here. The name comes from the Old English 'bærnet', meaning a place cleared by burning, and the settlement was recorded as 'Barneto' around 1070. Its strategic position on the Great North Road — the main route between London and St Albans — made it a market and coaching town through the Middle Ages, and Chipping Barnet (the 'Chipping' denotes a market, granted at the end of the twelfth century) still holds a market to this day. The tower of Barnet's parish church, St John the Baptist, at the top of Barnet Hill, is said to stand at one of the highest points on the road north.

The borough's most famous historical event is the Battle of Barnet, fought on Easter Sunday, 14 April 1471, a decisive Yorkist victory in the Wars of the Roses in which Edward IV defeated and killed Richard Neville, Earl of Warwick — the 'Kingmaker'. The battlefield is commemorated by the Hadley Highstone, a stone obelisk erected in 1740 by Sir Jeremy Sambrooke near the junction of the Great North Road and Kitts End Road. Nearby Monken Hadley, with its church tower of 1494 and its surrounding common, is one of the borough's most historic and best-protected corners, and one of many conservation areas that shape what can be built.

Barnet's landmarks tell the story of a place that grew from market town to leafy suburb. The Royal Air Force Museum at the former Hendon Aerodrome holds more than eighty aircraft on the site of one of British aviation's birthplaces. Hampstead Garden Suburb, laid out from 1907 to a formal plan by Raymond Unwin and with buildings by Edwin Lutyens, is one of the finest planned settlements in the world and among the most tightly controlled residential areas in Britain. Totteridge and Mill Hill retain a genuinely rural feel, with farmland, stables and open ridgelines that mark the edge of the Green Belt. The borough is unusually green: roughly a third of it is Green Belt or Metropolitan Open Land, both given the strongest protection in the Local Plan.

For a one-off house, this context is not decoration — it is the planning framework. Barnet is characterised, in the council's own words, by relatively low-density suburban housing with an attractive mix of semi-detached and detached homes, where much of the established character comes from consistent groups of houses of similar style, size and form built by a single builder at the same time. A new house has to sit comfortably within that grain. Depending on where your plot is, you may be building in or beside a conservation area, on land adjoining the Green Belt, or in a street with a strong and consistent character that any new dwelling must respect. The design must respond to all of it — and the strongest applications are those that show a real understanding of the specific place.

Almost every one-off house in a built-up borough like Barnet is a form of urban intensification — putting a new home onto land that already has a use, or replacing an existing building. The four most common plot types each carry a distinct planning story, and identifying which one you have is the first step, because it determines the policies that apply and the case you will have to make.

An infill plot is a gap in an otherwise developed frontage — a genuine space in a street where a house could sit alongside its neighbours in the established building line and rhythm. Infill is generally the most straightforward one-off house scenario, because a well-designed house that completes a frontage and matches the plot widths and building line of its neighbours can sit very naturally in the street. The key tests are the building line, the spacing between houses, the plot width and the relationship to neighbours' light and privacy.

Garden land — the subdivision of a large garden to create a plot for a new house — is far more contentious. Barnet, like most councils, is cautious about 'garden-grabbing', the loss of back gardens and the erosion of the spacious, verdant character that defines many of its neighbourhoods. National policy allows councils to resist inappropriate development of residential gardens where it would harm the local area, and Barnet's design policies weigh heavily against schemes that cram a new house into a back garden, breach the established pattern of development, or leave either the new or the existing house with inadequate garden space. Garden-land schemes can succeed — but only where the plot is genuinely large enough, the new house respects the character and spacing of the area, and both dwellings retain proper amenity.

A replacement dwelling — demolishing an existing house and building a new one — has the advantage that the principle of a house on the plot is already established. The debate is about the scale, siting and design of the replacement rather than whether a house should be there at all. Barnet is specifically concerned about the loss of larger family homes through demolition and redevelopment, so a replacement that reduces the family-housing offer, or that is markedly bigger and more dominant than what it replaces, will be scrutinised. A well-judged replacement — similar in scale to its neighbours, better designed than the original, and respectful of the street — is one of the most reliable one-off house routes in the borough.

Backland development — a new house on land behind existing houses, typically accessed by a narrow drive between them — is the hardest of all. It raises acute questions about access, overlooking, noise and disturbance from a new driveway, the 'tandem' relationship of a house behind a house, and the introduction of a dwelling into what was private garden land. Barnet resists backland schemes that would harm the character of an area or the amenity of surrounding homes, and many are refused. Where a backland plot is genuinely capable of accommodating a house — with proper access, adequate separation and no serious amenity harm — it can be done, but it needs exceptionally careful design and a realistic assessment of the risks at the outset.

The single most important thing to understand about a one-off house is that it almost always needs full planning permission. Creating a brand-new dwelling is not permitted development. The permitted development rights that homeowners rely on for extensions, loft conversions and outbuildings apply to the improvement of an existing house within its curtilage; they do not allow you to build a separate new home. A genuinely new dwelling — whether on an infill plot, garden land, a backland site or replacing a demolished house — is a new building for a new use and requires a full planning application, determined by Barnet Council against the whole of its development plan.

This is different from the change-of-use and prior-approval routes that apply to converting existing buildings, and it is important not to confuse the two. There is no 'prior approval' shortcut for building a new house from scratch. The full-application route means the council assesses everything: the principle of a new dwelling on the site, the design and its impact on the character of the area, the scale and massing, the effect on neighbours' amenity (daylight, sunlight, outlook, privacy and noise), the standard of the new home itself, access and parking, trees and landscaping, drainage and sustainability, and — where relevant — heritage, Green Belt and biodiversity. It is a comprehensive test, and the application has to answer all of it.

There are a small number of nuances. A replacement dwelling still needs full planning permission for the new house, and the demolition of the existing building may itself need prior approval or, in a conservation area, conservation-area consent considerations. Very occasionally a new house on genuinely isolated land in the countryside can be justified under the 'exceptional design' provision of national policy (paragraph 84 of the National Planning Policy Framework, formerly paragraph 79/55), which allows an isolated new home of truly outstanding design — but this is a rare and demanding route, largely irrelevant to Barnet's suburban plots and applicable, if at all, only in its rural fringes and Green Belt where the bar is very high. For the overwhelming majority of one-off houses in Barnet, the route is a straightforward full planning application, done well.

Because the full-application route is so comprehensive, the quality of the application is decisive. A one-off house application is not a form-filling exercise; it is a designed proposal supported by a coordinated set of drawings and a suite of documents that make the case policy by policy. The houses that get consented are the ones where the design and the supporting material anticipate every question the council will ask and answer it before it is raised. That is the standard we work to.

A one-off house in Barnet is judged against the Barnet Local Plan 2021-2036, which the council formally adopted on 4 March 2025 after an examination in public and the Inspector's report found it sound. This is a genuinely new plan — it replaced the older 2012 Core Strategy and Development Management policies — and any application submitted now is assessed against it. The plan contains 51 policies and 58 site proposals, and it sets a minimum housing requirement of 35,460 new homes by 2036 (the council's overall ambition runs to around 44,000). It works alongside the Mayor's London Plan (2021), which forms the other half of Barnet's statutory development plan.

The plan's approach to new housing is what the council calls 'design-led'. Rather than fixing rigid density figures, it treats indicative site capacities as a starting point and expects development to optimise the use of land through good design — the right amount of development for the specific site, established by designing it properly rather than by applying a formula. For a one-off house this matters because it puts the quality of the design at the centre of the decision: a well-designed house that suits its plot is more likely to be supported than a poorly designed one that merely hits a number, and equally an overdeveloped plot will be resisted however the numbers are dressed up.

The design policies are the heart of the framework. Policy CDH01 (Promoting High Quality Design) requires all new development to be of high architectural and urban-design quality, with regard to the National Model Design Code, Barnet's Sustainable Design and Development Guidance and its Design Code for Small Sites, and to incorporate biodiversity, water management and sustainable drainage. Policy CDH02 (Sustainable and Inclusive Design) sets requirements for accessible housing and for energy performance. Policy CDH07 (Amenity Space and Landscaping) requires proper private outdoor space, hard and soft landscaping and the retention of trees of value — and, notably, it removed the ability to provide amenity space off-site, so a new house has to include real, usable garden space as an integral part of the design.

Alongside the Local Plan, the council relies on supplementary guidance — most importantly its Residential Design Guidance SPD, which sets out how new development should respond to local character, density, built form, car parking and amenity, and its newer Sustainable Design and Development Guidance and Design Code for Small Sites. The plan also introduced a Design Review Panel, which can be asked to comment on the design of significant schemes. Together this framework is unusually focused on design quality and on protecting Barnet's suburban character — which is both a challenge and an opportunity. It is a challenge because a weak design will not pass; it is an opportunity because a genuinely good, contextual design is exactly what the policies are written to support.

More one-off house applications are refused in Barnet on character and overdevelopment grounds than on almost anything else, so getting the scale and siting right is fundamental. The council's starting point, set out in its Residential Design Guidance, is that new development should respect the character of the area — and in much of Barnet that character is defined by consistent, spacious groups of houses: regular plot widths, generous gaps between buildings, a clear building line set back from the road, front gardens, and mature planting. A new house that ignores that rhythm — too wide for its plot, too close to its neighbours, too far forward or too tall — reads as an intrusion and invites refusal.

The building line is one of the first things we test. In most Barnet streets there is a well-established line that houses sit behind, and a new house should generally respect it rather than pushing forward of its neighbours. So too with the spacing between houses: the gaps between buildings, and the visibility of front gardens and side space, are often central to a street's character, and a new house that closes up those gaps can harm it. Plot width matters too — a house squeezed onto a plot narrower than the established pattern looks cramped and out of place.

Height and massing are the next test. A new house should generally sit comfortably in scale with its neighbours — usually no taller, and often designed with a roof form, eaves height and proportions that echo the surrounding houses. This does not mean pastiche: Barnet consents contemporary houses as well as traditional ones, and Policy CDH01 asks for high-quality design, not imitation. But whether the design is modern or traditional, it has to relate in scale and rhythm to its context. Overly tall, bulky or dominant houses — and houses with excessive roof volume or over-large rear projections — are a common refusal reason.

Density, in Barnet's design-led framework, is really a question of whether the plot can comfortably accommodate the house without harm. A plot that is genuinely large enough for a well-proportioned house, with proper gardens front and back, adequate separation from neighbours and space for parking and planting, can support a new dwelling; a plot that can only take a house by cramming it in cannot. This is why we always start with a careful, honest study of what the plot can actually hold. It is far better to design a slightly smaller, beautifully judged house that gets consented than a maximised one that gets refused — and the smaller, well-designed house is very often worth more in the end.

Barnet has an unusually high number of protected areas, and whether your plot falls within one changes the design task considerably. The borough has many conservation areas — among them Monken Hadley, Totteridge, Wood Street, Mill Hill and the exceptional Hampstead Garden Suburb — where the council has a statutory duty to preserve or enhance the area's special character. A new house in a conservation area is not impossible, but it must be of very high quality and must respond closely to the historic context; the design bar is higher, and a heritage statement will be needed to explain how the proposal preserves or enhances the area.

Hampstead Garden Suburb deserves particular mention because it is among the most tightly controlled residential areas in the country. Laid out from 1907 on a formal plan and built out to the late 1930s, the Suburb is protected not only as a conservation area with Article 4 directions (which remove many of the permitted development rights homeowners rely on elsewhere), but also by the Hampstead Garden Suburb Trust under its 1974 Scheme of Management, which regulates alterations to buildings and landscapes independently of the council. Building or substantially altering a house in the Suburb requires both planning permission and the Trust's separate approval, and the standards are exacting. A one-off house here is a specialist undertaking, and the earliest possible engagement with both the council and the Trust is essential.

The Green Belt and Metropolitan Open Land are the other major constraint. Around a third of Barnet is designated Green Belt or MOL, concentrated in the north and west around Totteridge, Mill Hill, Arkley and Hadley, and the Local Plan gives these designations the strongest protection. New dwellings in the Green Belt are, in principle, inappropriate development and will be refused unless the applicant can show 'very special circumstances', or unless the proposal falls within one of the limited exceptions — such as the replacement of an existing dwelling with one that is not materially larger. A knock-down-rebuild in the Green Belt is often possible where the replacement is comparable in size to the original, but a new house on open Green Belt land, or a replacement significantly larger than what it replaces, faces a very high hurdle.

The practical upshot is that the very first thing we establish on any Barnet one-off house is the plot's designations. A plot in an ordinary suburban street is one project; the same-sized plot inside a conservation area, in Hampstead Garden Suburb, or on Green Belt land is a very different one, with different tests, different consents and a very different chance of success. We check all of this at the outset and give you an honest view of what is achievable before you commit — because on a designated site, a realistic assessment early is worth far more than optimism later.

Replacing an existing house with a new one is one of the most common one-off house projects in Barnet, and for good reason: the principle of a dwelling on the plot is already accepted, so the debate is about the design of the replacement rather than whether a house belongs there. That said, a replacement is not a free hand. The new house is assessed as a full planning application against the same design, character and amenity policies as any other new dwelling, and Barnet has specific concerns that a replacement scheme has to navigate carefully.

The council's most notable concern is the loss of larger family homes. Barnet's evidence base identifies a real need for family-sized housing, and the plan flags the loss of larger homes through demolition and redevelopment as a particular concern. In practice this means a replacement dwelling that maintains or improves the family-housing offer — replacing a house with a good family home — is looked on more favourably than one that reduces it (for example by replacing a single family house with something that could not function as family accommodation). It also means the council watches carefully where a replacement is used as a springboard to a much larger or subdivided scheme.

Scale and dominance are the other key issues. A replacement dwelling that is markedly larger, taller or bulkier than the house it replaces — or than its neighbours — will be scrutinised for its impact on the character of the street and on neighbours' amenity. The most successful replacements are those that sit comfortably in their context: broadly comparable in scale to the surrounding houses, better designed and better performing than the original, and respectful of building lines, spacing and neighbours' light and privacy. A modern, well-insulated, well-planned house that replaces a tired original of similar scale is exactly the kind of scheme the design-led plan is written to support.

There are practical dimensions too. Demolition itself has to be handled properly — with a demolition method statement, party wall procedures where the existing house adjoins others, and, in a conservation area or Green Belt, particular care over what is demolished and what replaces it. A new-build replacement is also assessed for its full-house obligations: the Community Infrastructure Levy on the net new floorspace, current energy standards, drainage and sustainability. We design replacement dwellings as complete new houses — architecture, structure and services together — and handle the demolition, the party wall matters and the application as one coordinated project.

Once the plot and the planning strategy are understood, the real work of a one-off house is designing a home that is a genuine pleasure to live in — and that meets the standards the council will hold it to. A one-off house is the purest architectural project because every part of it is designed for you: the way you enter and move through the house, where the living spaces sit in relation to the sun and the garden, how the kitchen relates to family life, where the bedrooms and bathrooms fall, how much light each room receives, and how the house feels from the street and from within. This is where the value of a bespoke design over a standard house type is most obvious.

The house also has to meet space standards. Under London Plan Policy D6, new homes in Barnet must meet the nationally described space standard: a one-bedroom two-person home must be at least 50 square metres, a two-bedroom four-person home at least 70 square metres, a three-bedroom five-person home at least 93 square metres, and so on, with minimum bedroom sizes and built-in storage on top. The London Plan adds requirements beyond the national standard — a floor-to-ceiling height of at least 2.5 metres over 75 per cent of the internal area, and private outdoor space of at least 5 square metres for a one- or two-person home, plus 1 square metre for each additional occupant. For a family one-off house these minimums are rarely a constraint, because a bespoke home is usually generous by design, but they set a floor that the layout must respect and that we annotate on the drawings so the council can check them directly.

Beyond floor areas, good house design in Barnet is about daylight and outlook, storage and circulation, and the relationship to the garden. Barnet's amenity policy (CDH07) requires proper private outdoor space as an integral part of the design, and its design guidance expects gardens front and back, planting and, where trees are present, their retention. We design the house and its garden together, so the outdoor space is real and usable rather than a leftover strip, and so the house opens to it properly. Accessibility matters too: Policy CDH02 and the London Plan require new homes to meet accessibility standards (typically the Building Regulations optional requirement M4(2) for accessible and adaptable dwellings), which shapes entrances, circulation and ground-floor provision.

Crucially, we design the layout in the knowledge of how it will be built and serviced. A beautiful plan that cannot be structured economically, or that leaves nowhere sensible for the services, is not a good design. Because we do the architecture, structure and services together, the layout is developed with the structural grid, the plant, the risers and the drainage in mind from the start — so the house you see in the drawings is the house that can actually be built, at a sensible cost, and that performs as intended.

A one-off house is a complete new structure, from the ground up, and the structural design is one of the most important — and most site-specific — parts of the project. Unlike an extension, which ties into an existing building, a new house has to be conceived structurally as a whole: the foundations that carry it, the frame or loadbearing walls that hold it up, the floors and roof that span it, and the way all of that responds to the specific ground conditions of the plot. We provide the structural engineering in-house, so the frame is designed alongside the architecture rather than bolted on afterwards.

Foundations are the first and most consequential decision, and they depend on the ground. Much of Barnet sits on London Clay, a shrinkable clay soil that moves with moisture and is strongly affected by nearby trees — and Barnet is a heavily treed borough. Clay soils and trees together often dictate deep foundations, such as bored piles or deep trench fill, to reach below the zone of seasonal movement and tree influence. Where the plot has been previously developed there may be old foundations, drains, made ground or contamination to deal with. A ground investigation — trial pits or boreholes with soil testing — is usually essential to design the foundations properly, and getting this right is what prevents the cracking and movement that plague poorly founded houses.

The superstructure — the frame — can be built in several ways, and the right choice depends on the design, the budget, the programme and the energy strategy. Traditional masonry (blockwork and brick) remains common and suits Barnet's suburban context; timber frame and structural insulated panels offer speed and good thermal performance; steel or engineered timber can achieve the large openings, long spans and open-plan spaces that a modern one-off house often wants. Whatever the system, the structure has to be designed for the loads it carries, for wind and for stability, and coordinated with the architecture so that beams, columns and loadbearing walls fall where they can be accommodated cleanly.

The structural design also has to anticipate everything else the house needs. Large glazed openings to the garden require careful beam and lintel design; open-plan spaces need thought about lateral stability; a basement — increasingly common on constrained Barnet plots to gain floor area without extra bulk above ground — is a significant structural and waterproofing undertaking requiring retaining design, waterproofing to Building Regulations, and often a basement impact assessment. Because we design the structure and the architecture together, these decisions are made as one, and the drawings that go to building control and to your contractor are coordinated, buildable and complete.

A new house needs a complete set of building services — mechanical, electrical and plumbing (MEP) — designed for it from scratch. This is everything that makes the house work: the heating and hot water, the ventilation, the electrical installation, the water supply and the drainage. On a one-off house these systems can and should be designed to a high standard, because you are starting with a clean sheet and are not constrained by an existing installation. We design the services alongside the architecture and structure, so the plant, risers, runs and outlets are accommodated in the design rather than squeezed in afterwards.

Heating and hot water are now central to the design because of the direction of energy policy. New houses are moving decisively away from gas boilers towards low-carbon heating — principally heat pumps — and the design has to accommodate the heat pump, its external unit, a hot-water cylinder, and heat emitters (larger radiators or underfloor heating) sized for a lower flow temperature. Getting this right depends on a well-insulated, airtight building fabric, so the fabric and the services are designed together. Mechanical ventilation with heat recovery (MVHR) is increasingly used in airtight new houses to provide fresh air efficiently, and it too needs to be designed into the plan, with ductwork routes planned from the start.

The electrical design covers the consumer unit and circuits, lighting, power, data and increasingly the provision for an electric-vehicle charging point (now generally required for new homes with parking) and for solar photovoltaic panels and battery storage. The water and drainage design covers the incoming supply, the internal plumbing, and the foul and surface-water drainage leaving the house — which has to connect appropriately to the public sewer or an alternative, and which brings in sustainable drainage, covered separately below. On a one-off house all of these can be integrated into a genuinely high-performance, comfortable and future-proofed home.

The advantage of designing services in-house, alongside the architecture and structure, is coordination. The commonest problems on a new house — a plant location that eats into a room, ducts that clash with beams, a riser that has nowhere to go, drainage that cannot achieve its falls — all come from designing the services separately and late. We resolve them on the drawings, so the house is comfortable, efficient and buildable, and so the mechanical and electrical work on site follows a clear, coordinated design rather than being improvised by trades.

Every new dwelling has to demonstrate its energy performance to comply with Part L of the Building Regulations (conservation of fuel and power), and this is assessed through an energy calculation — historically SAP (the Standard Assessment Procedure), now SAP 10.3. A SAP assessment models the house's fabric, heating, ventilation and any renewables to show that it meets the required carbon-emission and energy-efficiency targets, and it produces the Energy Performance Certificate. On a one-off house the SAP assessment is done at design stage (to prove compliance and inform the design) and confirmed on completion, and it should shape the design rather than be an afterthought.

The standard is rising sharply. New homes are currently built to the Part L 2021 uplift, which requires around a 30 per cent reduction in carbon emissions compared with the previous standard and effectively pushes towards better fabric, low-carbon heating and, often, solar panels. But the big change is the Future Homes Standard. The government published the Future Homes Standard and the associated Approved Documents on 24 March 2026, with the new requirements coming into force on 24 March 2027 (and a transitional period after that for work already begun). Under the Future Homes Standard, new homes must produce at least 75 per cent less carbon than a home built to the 2013 standards — a step-change from Part L 2021 — achieved principally through low-carbon heating (heat pumps rather than gas boilers), high-performance fabric and renewables.

For a one-off house being designed now, the practical implication is clear: even where the Future Homes Standard does not yet strictly apply, it makes little sense to design a new house around a gas boiler and modest fabric when the direction of travel is so firmly towards heat pumps, excellent insulation, airtightness and renewables. Designing to something close to the Future Homes Standard from the outset produces a better, cheaper-to-run, more valuable and more future-proof house, and avoids the risk of a design being overtaken by the regulations before it is built. Barnet's own Policy CDH02 and the London Plan already push new homes towards high energy and sustainability standards, so a well-designed one-off house should be aiming high on energy in any case.

We integrate the energy design with the architecture, structure and services from the start — because energy performance is not a bolt-on, it is a consequence of how the whole house is designed. The fabric (walls, roof, floor and windows), the airtightness, the heating and ventilation and the renewables all interact, and the SAP assessment ties them together. Designing them as one is how you get a house that is genuinely comfortable and low-cost to run, meets the regulations comfortably, and is ready for the standards coming into force.

A new house creates new demands on drainage and new areas of hard surface, and how it deals with water — both foul (from the house) and surface (rain from the roof and paving) — is a genuine part of the planning and building-regulations case, not a technicality. Barnet's design policies (CDH01 among them) require new development to incorporate water management and sustainable drainage, and both national and London policy require new development to manage surface water sustainably and to avoid increasing flood risk elsewhere.

Foul drainage — the waste from the house — normally connects to the public sewer, and the design has to show a workable connection with the right falls and access. Where a plot cannot readily connect to the sewer, an alternative (such as a package treatment plant) may be needed, which has its own consents. Surface-water drainage is where sustainable drainage (SuDS) comes in: rather than piping all the rain straight into the sewer, the aim is to manage it on the plot — through permeable paving, soakaways, rain gardens, water butts, green roofs or attenuation storage — so that the rate and volume of run-off leaving the site is controlled and, ideally, reduced. This lessens the burden on the drainage network, reduces flood risk, and brings biodiversity and amenity benefits that the design policies value.

The right SuDS strategy depends on the ground. On Barnet's London Clay, which drains poorly, simple soakaways may not work well, so the design often relies on a combination of measures and controlled discharge with attenuation. Where a plot is in or near a flood-risk area, a flood risk assessment will be needed, and the layout and levels of the house designed with flood resilience in mind. On garden-land and backland plots in particular, the loss of previously permeable garden to a new house and its access can raise surface-water concerns that the drainage design has to answer.

We design the drainage and SuDS as part of the whole-house engineering, integrated with the structure (foundations and any basement affect where and how water can be managed), the levels and the landscape. A well-conceived drainage strategy, presented clearly in the application, removes what can otherwise be a stumbling block — and it produces a house that manages water sensibly for its whole life.

Many one-off house projects — replacement dwellings especially, but also plots where an old building is cleared — involve demolition, and this has its own procedures. The demolition of a building generally requires notification and, in some cases, prior approval for the method of demolition and site restoration; in a conservation area the demolition of a building can be a more sensitive matter requiring particular care and consent considerations. A demolition method statement, dealing with how the building will be taken down safely, how the site will be managed and how neighbours will be protected, is part of a well-run project.

The Party Wall etc. Act 1996 is the other major boundary matter. Where a new house or its foundations are built up to or near a boundary with a neighbour, or where demolition or excavation takes place close to a neighbour's building, the Act requires notice to be served on the affected neighbours and, often, a party wall award to be agreed through surveyors. This is a legal process separate from planning and building regulations, and it protects both you and your neighbours; ignoring it can bring the works to a halt. On a new house near boundaries — common on Barnet's suburban plots — party wall matters need to be identified early and handled properly.

Beyond the formal procedures, neighbour relations are a practical reality on a one-off house. Neighbours are consulted on the planning application and can object, and their concerns — about loss of light, overlooking, noise, construction disruption and the character of the street — are exactly the issues the council weighs. A design that respects neighbours' amenity from the outset, and a considerate approach to the construction phase, make for a smoother application and a smoother build. We design with the neighbours' amenity in mind and can advise on managing the relationship through the process.

Trees are a frequent neighbour and site issue in leafy Barnet. Trees on or near the plot may be protected by Tree Preservation Orders or by conservation-area status, and works to or removal of protected trees need consent. A new house often has to be designed around trees worth keeping — both for planning reasons and because Barnet's amenity policy values them — and an arboricultural assessment and a tree-protection plan are commonly required. We factor trees into the design and the foundations (roots and clay heave being a real structural issue) from the start.

A new house creates new floorspace, and new floorspace attracts the Community Infrastructure Levy (CIL) — a charge, calculated per square metre, that councils levy on development to help fund infrastructure. In Barnet a one-off house pays two CILs: the borough's own Barnet CIL and the Mayor of London's CIL (MCIL2). Barnet's charging schedule sets a residential rate of the order of £300 per square metre, applied to residential development, and it came into effect for permissions granted on or after 1 April 2022. The Mayoral CIL2 applies on top; Barnet sits in the Mayor's Zone 2, and the residential rate is around £69 per square metre. Both figures are index-linked and rise over time, so the applicable rates are confirmed at the point of permission.

Crucially, CIL is charged on the net additional floorspace. For a new house on a genuinely vacant plot, that is essentially the whole gross internal area of the house. For a replacement dwelling, the floorspace of the building being demolished can, subject to conditions (principally that it has been in lawful use for a continuous period), be offset against the new floorspace — so you pay CIL only on the increase in floorspace, not on the whole new house. This offset can make a substantial difference to the CIL bill on a knock-down-rebuild, and it is worth getting the calculation and the supporting evidence right.

There are also reliefs. Self-build housing — where you are building a house to occupy as your own home — can qualify for full CIL relief, provided the strict procedural steps are followed exactly: claiming the relief and having it granted before starting work, submitting a commencement notice, and then meeting the ongoing requirements (occupying the house as your main residence for at least three years). The self-build exemption is valuable but unforgiving of procedural error — a missed form or an early start on site can lose the relief entirely — so it has to be handled carefully and in the right sequence. We flag CIL and any available relief at the outset so it is planned for, not discovered late.

Beyond CIL, larger schemes can attract planning obligations under a Section 106 agreement — for example contributions towards affordable housing or infrastructure. A single one-off house is usually below the thresholds that trigger significant obligations, but it is something to check on larger plots or where more than one dwelling is proposed. We set out the likely CIL, any available relief and any obligations as part of the feasibility, so the full cost of the project is clear before you commit.

A one-off house is delivered through a sequence of design stages, and at each one we produce a specific set of drawings and documents. The industry framework for this is the RIBA Plan of Work, and understanding it helps you see what you are getting and when. It runs, in essence, from establishing the brief, through concept and developed design, to the technical information needed to obtain permissions and build, and then to construction and handover.

At the early stages (RIBA Stages 1-2), we establish the brief and prepare feasibility studies and a concept design: a measured site survey, an appraisal of the plot and its constraints, and initial designs that test what the plot can hold and establish the character and layout of the house. This is where the fundamental decisions are made and where an honest view of what is achievable is formed. At the planning stage we develop the design (Stage 3) into a full planning application: existing and proposed site plans, floor plans, elevations and sections, a design and access statement explaining and justifying the design, and the supporting documents the scheme needs — heritage statement in a conservation area, arboricultural report where there are trees, flood risk assessment where relevant, drainage strategy, energy and sustainability statement, and any others the site calls for.

Once planning permission is granted, we prepare the technical design (Stage 4) — the detailed, coordinated information needed for Building Regulations approval and for construction. This is the building-regulations package: detailed architectural drawings, structural design and calculations, the building-services design, the energy/SAP compliance, construction details and specifications. It is the level of information a contractor needs to price and build the house accurately, and the level building control needs to approve it. Because we do the architecture, structure and services together, this package is genuinely coordinated rather than a set of separate consultants' drawings that have to be reconciled on site.

Through construction (Stages 5-6) we can provide the information the contractor needs, answer queries, review the building against the design, and help see the house through to completion and handover, including the building-control sign-off and the completion certificate. The point of the RIBA structure is that each stage builds on the last, decisions are made at the right time, and the house is fully designed and coordinated before it is built — which is how you avoid the expensive changes and compromises that come from designing as you go.

The process for a one-off house has two consenting strands — planning permission and Building Regulations — and they run in that order, with feasibility before both. It begins with the plot: we survey it, establish its designations (conservation area, Green Belt, TPOs, flood risk), take your brief, and prepare a feasibility study that tells you honestly what the plot can support and what the planning strategy should be. On a one-off house this stage is worth a great deal, because it is where the whole project is set up for success or failure.

For the planning application, we develop the design and prepare the full application — drawings, design and access statement and the supporting documents — and submit it to Barnet Council through the Planning Portal. The council validates it, consults neighbours and statutory consultees, and a case officer assesses it against the Local Plan and the London Plan. A straightforward householder-scale new dwelling is often determined under delegated powers within the statutory period (around eight weeks for minor development, longer for larger schemes or where a committee decision is needed); more contentious or larger schemes can take longer and may go to the planning committee. We manage the application throughout, respond to the case officer, and negotiate amendments where that will secure approval.

Barnet offers pre-application advice, and on a one-off house it is very often worthwhile — particularly on garden-land, backland, conservation-area, Green Belt or replacement-dwelling schemes where the council's view on the principle and the design is decisive. A written pre-application steer lets us develop the scheme in the right direction and go in with an application the council is minded to support, rather than testing the water with a full submission. On sensitive or significant schemes, the Design Review Panel introduced by the new plan may also comment on the design, and in Hampstead Garden Suburb the separate approval of the Trust runs alongside the council's process.

Once planning permission is granted (and any pre-commencement conditions discharged), the Building Regulations strand takes over. The detailed technical package is submitted to a building-control body — either Barnet's building control or an approved inspector — which approves the design and inspects the works at key stages during construction, issuing a completion certificate at the end. Because we prepare a coordinated technical package covering architecture, structure and services, and because we can stay involved through construction, the transition from a planning consent to a built house is far smoother than on projects where the disciplines are handled separately and the building-regulations design is left to be worked out on site.

The cost of a one-off house has several distinct parts, and it helps to see them separately. First is the land, if you do not already own the plot. Second is the design and consultancy fee — our work designing the house, engineering it and running it through planning and building regulations, together with the specialist reports the scheme needs. Third are the statutory and council costs — the planning application fee, the Building Regulations fees, and the Community Infrastructure Levy on the new floorspace. Fourth, and largest, is the construction cost of actually building the house. We scope our own work to your specific project and quote a clear, fixed fee for it before any drawing work begins, so you know where you stand on that part from the outset.

The specialist reports — a ground investigation, arboricultural assessment, flood risk assessment, heritage statement, energy assessment and so on — carry their own costs, and which are needed depends on the plot. We tell you at feasibility which your scheme will require, so there are no surprises. The council's application fee is set nationally and depends on the type of application; the CIL, as covered above, runs to several hundred pounds per square metre in Barnet once both the borough and Mayoral levies are counted, though a replacement dwelling can offset the demolished floorspace and a self-build can be exempt if the procedure is followed exactly.

On construction cost, a one-off house varies enormously with size, specification, site conditions and design ambition — a straightforward suburban replacement dwelling is a very different figure from a bespoke architect-designed house with a basement on a difficult clay plot. We can give you realistic budget guidance at feasibility and help you understand the cost implications of design decisions as they are made, so the house is designed to a budget rather than priced after the fact. Designing the structure and services in-house also helps control cost, because the design is buildable and coordinated and does not generate expensive surprises on site.

On timescales, a realistic programme for a one-off house runs from feasibility and design (a few months), through planning (typically two to four months for a straightforward scheme, longer for a contentious or committee decision, plus pre-application time), to the technical design and building-regulations approval, and then construction (commonly a year or more for a whole house). It is a substantial project measured in a year to two years overall, and the front-loaded effort — getting the design and the consent right — is what makes the later stages run smoothly. We give you a realistic overall programme for your specific scheme at the start.

Understanding why new-house applications fail in Barnet is the best way to make sure yours does not. By some distance the most common reason is harm to the character of the area through overdevelopment — a house that is too large, too bulky or too dominant for its plot, that breaks the established building line or spacing, that cramps a plot that is really too small, or that erodes the spacious, verdant, suburban character the council's design policies exist to protect. This is the classic garden-land and backland refusal, and it is also why over-scaled replacement dwellings come unstuck. The remedy is to design to the plot and the street from the outset, not to the maximum.

Harm to neighbours' amenity is the second major reason. A new house that would take light from a neighbour, overshadow their garden, overlook their windows or private space, or loom over their boundary will be refused on amenity grounds. Barnet's design guidance sets expectations for separation distances, for daylight and sunlight, and for privacy, and a scheme that breaches them invites objection and refusal. Careful design of the house's position, height, windows and boundaries — tested against the neighbours' amenity — is what avoids this.

Poor design quality is a refusal reason in its own right under the design-led plan. Policy CDH01 requires high-quality design, and an application with a weak, generic or poorly resolved design — one that does not respond to its context and does not meet the standard the National Model Design Code and Barnet's guidance expect — can be refused simply for not being good enough. In conservation areas and Hampstead Garden Suburb the bar is higher still, and a design that fails to preserve or enhance the area's special character will not pass. Other common reasons include inadequate parking, loss of trees, unresolved drainage or flood risk, harm to the Green Belt or its openness, and the loss of a family home where the replacement reduces the family-housing offer.

Our approach is to anticipate every likely refusal reason and answer it in the application itself: a design scaled and sited to suit the plot and street; separation, daylight and privacy tested against the neighbours; a genuinely high-quality, contextual design supported by a proper design and access statement (and heritage statement where needed); trees, drainage and parking resolved; and the Green Belt or conservation-area tests met head-on. We are honest at feasibility if a plot faces an insurmountable problem, because there is no value in designing an application that is going to be refused.

To make the process concrete, consider a common Barnet scenario: a family owns a tired 1950s detached house on a generous plot in a settled suburban street in, say, Finchley or Mill Hill. The house is small, cold, poorly planned and expensive to run, but the plot is good and the location is exactly where they want to stay. They want to demolish it and build a new, larger, modern family house — a replacement dwelling. This is one of the most reliable one-off house routes in the borough, but whether it works depends on getting the scale, the design and the details right.

At feasibility, we establish the fundamentals first: the plot is not in a conservation area, is not Green Belt, and the existing house is lawful and in use, so the principle of a dwelling is established and demolished floorspace can be offset against CIL. We survey the plot, take the family's brief, and study what the plot can comfortably hold — testing the new house against the building line, the spacing of the neighbours, and the separation distances that protect their light and privacy. This drives the design: a house that is generous inside but sits comfortably in the street, no taller than its neighbours, set on the established building line, with proper gardens front and back. A scheme pushed to the maximum footprint and height would have risked refusal for overdevelopment and harm to amenity; a well-judged one does not.

The design develops into a full planning application: existing and proposed site plans, floor plans, elevations and sections showing a well-proportioned contemporary family house with room areas meeting the space standards annotated on the drawings, a design and access statement explaining how the design responds to the street, and the supporting documents the plot needs — an arboricultural report because there are mature trees to protect, a drainage strategy dealing with surface water on the clay ground, and an energy and sustainability statement showing the house will meet current standards with a heat pump and good fabric. Because the plot is straightforward, we submit without pre-application, though on a more sensitive plot we would use it.

In parallel, the engineering is developed with the architecture. The ground is London Clay with nearby trees, so the structural design uses deep foundations to reach below the zone of seasonal and tree-related movement; the frame is designed for the open-plan ground floor and large garden-facing openings the family want; and the services are designed around a heat pump, mechanical ventilation with heat recovery, and provision for solar panels and EV charging — all coordinated so the plant and risers have proper homes in the plan. The demolition of the old house is planned with a method statement and the party wall notices its proximity to the neighbours requires.

Barnet grants permission under delegated powers within the statutory period, because the scheme is well-scaled, respectful of its neighbours and properly designed. We then prepare the coordinated building-regulations package — architecture, structure, services and SAP together — submit it to building control, and support the family through construction to completion. Because the design, structure and services were developed as one from the start, and because the planning case was built around the policies rather than against them, the project runs from an idea to a finished, consented, buildable family home without the delays and compromises that come from doing it any other way.

A particular category of one-off house is the self-build or custom-build home — a house you commission to live in yourself, rather than to sell. Self-build is actively encouraged in national policy: the Self-build and Custom Housebuilding Act places duties on councils to keep a register of people seeking self-build plots and to have regard to demand, and Barnet, like other authorities, maintains such a register. If you are looking to build your own home, getting onto the register and understanding how the council is meeting demand can help, though it does not by itself provide a plot.

The self-build route has two practical advantages worth knowing. The first is the Community Infrastructure Levy self-build exemption: a genuine self-builder, building a house to occupy as their main residence, can claim full relief from CIL — which on a sizeable house in Barnet can be a very substantial saving. The exemption is generous but procedurally strict: it must be claimed and granted before work starts, a commencement notice must be submitted before starting on site, and the house must be occupied as the applicant's sole or main residence for at least three years after completion, with supporting evidence provided. A single procedural slip — starting work before the paperwork is in place, or missing the commencement notice — loses the exemption entirely, so it has to be handled with care and in the right order.

The second advantage is that a self-build is designed entirely around how you actually live, with no compromise to a developer's product or a buyer's assumptions. This is where a bespoke architectural design pays off most fully: the house can be shaped to your family, your routines, your accessibility needs and your aspirations, and built to the energy and comfort standard you choose. Self-builders are often the most engaged and rewarding clients precisely because it is their own home, and the result is a house that fits them exactly.

The design, planning and engineering process for a self-build one-off house is the same as for any other — full planning permission, the design and character tests, the space standards, the structural and services engineering, and the building-regulations approval — but with the added dimension of the CIL exemption and, often, a client closely involved in every decision. We guide self-builders through the whole of it, from finding what a plot can hold, through the planning application and the exemption paperwork, to a coordinated build, so that building your own home is the rewarding project it should be rather than a bureaucratic ordeal.

Crown Architecture designs one-off houses across Barnet and the surrounding boroughs, and we do it as a single, coordinated service: the architecture, the structural engineering and the building services under one roof. On a one-off house this integration matters more than on almost any other project, because a single house is where the plan, the structure and the systems are most tightly interdependent — there is nowhere to hide a clash between them. Designing them together means the house you see in the drawings is the house that can actually be built, at a sensible cost, and that performs as intended. It is the difference between a beautiful drawing and a beautiful home.

We know the Barnet framework specifically: the Local Plan adopted in March 2025 and its design-led approach; the design, amenity and sustainability policies (CDH01, CDH02, CDH07) that decide real applications; the Residential Design Guidance and the Design Code for Small Sites; the conservation areas and the exceptional controls of Hampstead Garden Suburb and its Trust; the Green Belt and Metropolitan Open Land that cover a third of the borough; and the character — the building lines, spacing and spacious suburban grain — that a new house has to respect. We use that knowledge to give you an honest view at feasibility of what your plot can actually support, before you commit.

We are also straightforward to work with. We tell you early and honestly whether a plot will take the house you have in mind, and by what route; we quote a clear fixed fee for our work; and we prepare a coordinated, self-consistent application that a case officer can support — designed to the policies, tested against the neighbours, and answering every question before it is raised. Where pre-application advice, a design-review comment or the Trust's approval will help, we build them into the process rather than being caught out by them.

And we stay with the project. We take it from the first survey and feasibility study, through the planning application and its determination with Barnet Council, into the coordinated building-regulations and technical design, and on through construction to completion — one accountable team from an idea to a finished, consented, buildable house. On a project as personal and as demanding as your own new home, that continuity, and that integration of architecture with real engineering, is exactly what makes the difference.

If you are thinking about a one-off house in Barnet — an infill plot, a garden you might subdivide, a house worth replacing, or a self-build you have dreamed of — send us the address and what you have in mind, and we will tell you honestly what is achievable, by which route, and how to get there.