Radlett · Hertsmere · Hertfordshire
Radlett houses, from Victorian pairs in the old centre to detached homes on long garden plots, are designed, engineered and built by one London team working out of our Finchley Road studio in Hampstead, NW3.
Radlett sits in the valley of Tykes Water with Green Belt on every side, two conservation areas at its centre and a neighbourhood plan of its own. Before a line is drawn we settle which of those, and which of the three bungalow Article 4 directions, touch the exact address. Policy that applies across the whole borough is set out on our Hertsmere page.
Serving Radlett from our Hampstead studio · NW3 6DN
020 7101 3168
Radlett projects
01 Whole house
Refurbishment of a Radlett house, from rewiring, heating and new windows to repaired joinery and roof coverings. Conservation area controls and the building regulations are mapped onto the house before any strip-out begins.
02 More space
Rear, side and wrap-around additions designed to the council's extension guidance and to the plot's own limits. Green Belt edges, the brook buffer and the neighbours' windows are tested first.
03 Kitchens
Kitchens rebuilt where they are, opened into the next room or moved into a new rear addition. Extract, new circuits and the fire protection of the stair are drawn alongside the layout from the outset.
04 Bathrooms
Family bathrooms, shower rooms and en suites, upstairs or under the roof. Waste runs, extract and the wiring zone beside each bath or shower are fixed before tiles are chosen.
05 Roof space
Dormer and rooflight conversions, tested against Class B, the conservation areas and the council's dormer guidance. Floor, stair and escape route are worked out as a single design.
06 Below ground
Basements considered only where the flood zone and the ground allow one, which close to the brook they may not. Flood, groundwater and tree checks come before any design.
Radlett homes
Radlett grew around its railway. The station opened in 1868, yet building only really began in the 1890s, when the large estates of Kendals, Newberries and Aldenham Lodge started to sell land: first the ground west of Watling Street, then Aldenham Lodge in 1910 and lastly the Newberries estate in 1935. By 1939, the neighbourhood plan records, the present road layout was largely in place.
Those phases still read on the ground. The plan describes the older centre as a few streets of Victorian semi-detached and terraced houses. The council's design guidance, which the plan quotes, sees around it twentieth-century suburban housing of varying form, bungalows among it and most with generous rear gardens, and an area of post-war council-built housing to the west. The first post-war houses went up on Willow Way, in 1947, and the Newberries estate was completed in the 1950s and 1960s.
Aldenham Parish Council's own survey of residential plots, made in 2015 for the plan, counted 2,639 residential buildings. Of those, 1,465 were detached, 634 semi-detached and 295 terraced, with 108 bungalows and 63 chalet bungalows besides. The plan finds many substantial detached houses with large gardens, and plots that are often very long and negotiate changes of level.
We read Radlett's 2021 Census figures from two wards, Aldenham East and Aldenham West, and they are not the town's alone: Aldenham parish, which covers Radlett, also takes in Aldenham, Letchmore Heath and Round Bush. Aldenham East held 1,918 households, 1,131 of them in detached houses; Aldenham West held 2,010, of which 732 were detached and 547 semi-detached.
At the first visit we place the house in one of these layers. A Victorian semi off the High Street, a 1930s detached house and a post-war bungalow each need a different survey and a different planning conversation.
Sources: Aldenham Parish Council / Hertsmere Borough Council: Adopted Radlett Plan 2020-2036 (low resolution); ONS Census 2021 TS044 accommodation type via Nomis (NM_2062_1), 2022 wards for radlett; Hertsmere Borough Council: Parish and Town Councils
Approvals
Two layers of plan meet in Radlett. The Radlett Neighbourhood Plan covers the urban area of Radlett within Aldenham parish and forms part of the borough's development plan; the rules that run across the whole borough, among them the Green Belt test and the design guide's basement advice, sit on our Hertsmere page. The cards take them in the sequence a Radlett project meets them.
Applications for Radlett houses are decided by Hertsmere Borough Council. The neighbourhood plan has been made since 8 May 2021, so an application is read against its housing and design policies as well as the borough's own. The WD7 postcode district also reaches into St Albans district, so we confirm the council for each address before anything else.
Three Article 4 directions cover bungalows that the Radlett Plan identified as making a positive contribution to the local environment. The Secretary of State modified two of them on 14 June 2023, in relation to Part 1, Class AA and Part 20, Classes AC and AD; the third, confirmed on 12 June 2024, names bungalows on Goodyers Avenue, Links Drive and The Close.
Each direction removes the ability to make certain changes to the named bungalows without first applying for planning permission; Class AA is the right to add one storey to a single-storey house. The council says the directions are not meant to prevent other changes, including extending under other permitted development rights such as conventional loft conversions.
Inside Radlett North or Radlett South, the land under the house is article 2(3) land. Roof additions under Class B are then not permitted development at all, and a Class A extension may not reach beyond a side wall, nor have more than a single storey where it reaches beyond the rear wall. We check the address against the council's map of each area first.
The plan describes Radlett as surrounded by the Metropolitan Green Belt, and a neighbourhood plan cannot redraw Green Belt boundaries. For a house beyond the town's edge, Policy SADM26 requires an extension to stay subordinate to the original building; the Hertsmere page quotes the whole test.
Policy HD6 asks that development next to Tykes Water and its tributaries keeps a natural buffer of at least nine metres from the top of the bank, in line with the borough's 9m buffer under Policy SADM16. The brook is a main river, so works within 8 metres of it need a Flood Risk Activity Permit from the Environment Agency.
Hertfordshire Building Control runs the council's building control service. A private registered building control approver is the alternative. Approval under the regulations is separate from planning permission, and many Radlett projects need both.
Policy HD5 asks for healthy, good-quality trees, woodland and hedges to be kept, and in a conservation area an unprotected tree is still covered by section 211 of the 1990 Act. The plan warns that the online record of preservation orders is out of date, so the council's tree officer is the one to confirm a tree's status.
Sources: Hertsmere Borough Council: Neighbourhood Planning; Hertsmere Borough Council: Radlett Neighbourhood Plan 2020-2036, Regulation 20 adoption statement (24 May 2021); Hertsmere Borough Council: Radlett Neighbourhood Plan; postcodes.io (ONSPD-derived): outcode WD7; Hertsmere Borough Council: Radlett Bungalows Article 4; legislation.gov.uk: GPDO 2015 (SI 2015/596), Schedule 2 Part 1, development within the curtilage of a dwellinghouse (latest available revised); legislation.gov.uk: Town and Country Planning (General Permitted Development) (England) Order 2015 (SI 2015/596), article 2 (latest available revised); legislation.gov.uk: GPDO 2015 (SI 2015/596), Schedule 1 Part 1, Article 2(3) land (latest available revised); Hertsmere Borough Council: Radlett (North) Conservation Area Appraisal; Hertsmere Borough Council: Radlett South Conservation Area Appraisal; Aldenham Parish Council / Hertsmere Borough Council: Adopted Radlett Plan 2020-2036 (low resolution); Hertsmere Borough Council: Site Allocations and Development Management Policies Plan (adopted November 2016); Hertsmere Borough Council / AECOM: Level 1 Strategic Flood Risk Assessment (2023); Hertsmere Borough Council: Hertfordshire Building Control Limited; GOV.UK: Building regulations approval - when you need approval; GOV.UK: Tree Preservation Orders and trees in conservation areas (planning guidance)
Local policy
Both conservation areas were designated on 20 April 1988. The plan calls the High Street and village centre the heart of the conservation areas, holding some of the oldest buildings in Radlett, and notes 23 listed buildings within the neighbourhood area, Battlers Green House among them at Grade II*.
The council's page says it covers the High Street area. Its review in 2010 took out all six houses of Barn Close, a 1970s development, as not reflecting the more important periods in this part of Radlett's history. Inside it come design guidance, guidance for specific buildings, and a duty to tell the council about work to substantial trees.
Reviewed in October 2012 after a full appraisal and public consultation that split it into four character zones. Church Close and two properties on Christchurch Crescent were removed, the appraisal asked for careful management of further development on Loom Lane, and it proposed that Article 4 directions be considered in future for buildings it names.
Produced by Aldenham Parish Council and passed at referendum on 6 May 2021. Policy HD3 requires all development to respect local character and residential amenity, HD4 protects Radlett's green and verdant qualities, HD5 keeps healthy trees and hedges, and HD7 asks proposals affecting the identified bungalows to protect or enhance their contribution.
Part of the plan, it asks for ridge heights that take account of gradients and respect neighbouring houses, hard surfacing that is limited and permeable, durable local materials in keeping with their surroundings, and sufficient space between dwellings.
The town lies in the valley of Tykes Water, a stream running north from Aldenham Reservoir to the River Colne, and the Environment Agency names a flood warning area for the Radlett Brook at Radlett. In the council's 2023 flood risk assessment the heaviest concentration of Flood Zones 2 and 3 is along rivers that include the brook; it records brook floods in December 1979 and September 1992, and counts a flood storage reservoir on it among the borough's defences.
Every Radlett address is checked against the Environment Agency's flood map for planning at the outset; the same service tells you whether a planning application there needs a flood risk assessment to go with it.
Sources: Hertsmere Borough Council: Site Allocations and Development Management Policies Plan (adopted November 2016); Aldenham Parish Council / Hertsmere Borough Council: Adopted Radlett Plan 2020-2036 (low resolution); Hertsmere Borough Council: Radlett (North) Conservation Area Appraisal; Hertsmere Borough Council: Radlett South Conservation Area Appraisal; Hertsmere Borough Council: Radlett Neighbourhood Plan; Hertsmere Borough Council: Radlett Neighbourhood Plan 2020-2036, Regulation 20 adoption statement (24 May 2021); Environment Agency flood-monitoring API: flood warning area 062FWF28Radlett; Hertsmere Borough Council / AECOM: Level 1 Strategic Flood Risk Assessment (2023); Environment Agency (GOV.UK service): Get flood risk information for planning in England (Flood map for planning)
Building fabric
Detached houses dominate the plan's 2015 count, with semi-detached pairs, terraces and more than a hundred bungalows making up the rest. Each type brings its own questions to a project.
What sets the High Street buildings apart?
Flint, brick and tile, red and buff stock brick and white or cream painted brickwork, under high pitched and gabled roofs with dormer windows and decorative detail.
We record original joinery, chimneys and roof coverings before anything is stripped out, and repair before we replace.
Why do Radlett extensions grow so large?
The plan links its long and narrow plots to the large number of applications to extend houses into even larger ones, and records concern about replacement houses with bulky crown roofs that overbear their neighbours.
We test every scheme against the neighbours' windows and the street before its size is settled.
Can a Radlett bungalow go up a storey?
Bungalows and chalet bungalows set the character of whole clusters of streets. On the bungalows named in the Article 4 directions an extra storey needs an application, and Policy HD7 asks a replacement to stay broadly commensurate with the existing ridge height.
Our first look is at the existing roof structure.
What happens when one half of a pair changes?
The council's extension guide will normally refuse turning a hipped roof into a gable because it would unbalance a pair or terrace; where the attached house already has one built under permitted development, matching it may be possible.
Shared walls also bring party wall notices, which we prepare with the drawings.
What changes beside Tykes Water?
The flood assessment calls the brook's catchment heavily urbanised and relatively steep, and any work within 9m of a watercourse needs the council's prior consent under its byelaws.
Floor levels, drainage and anything below ground wait until the flood position of the plot is known.
Does a big garden make extending easier?
Not on its own. The plan characterises Radlett by spacious plots, clear breaks between houses and mature trees visible in back gardens, and the council's guide expects most of the garden to remain after an extension.
An arboricultural survey comes early where roots run close to the proposed footprint.
Sources: Aldenham Parish Council / Hertsmere Borough Council: Adopted Radlett Plan 2020-2036 (low resolution); Hertsmere Borough Council: Radlett Bungalows Article 4; Hertsmere Borough Council: Planning and Design Guide Part E: Guidelines for Residential Extensions and Alterations (adopted 2006); GOV.UK: Party walls and building work - work you must tell your neighbour about; Hertsmere Borough Council / AECOM: Level 1 Strategic Flood Risk Assessment (2023)
On site
A new or widened driveway crossing involves Hertfordshire County Council: the dropped kerb must be built by its Highways department, and the crossing itself becomes part of the public highway.
Planning permission is needed for a crossing onto a classified road, meaning an A, B or C road, but not onto an unclassified one. Any fence, wall or hedge standing where the crossing will go has to be removed before construction can take place.
Parking is also a design matter here. The Radlett Design Code asks for parking integrated sensitively into the landscape and streetscene, with hard surfacing kept limited and permeable, and the council's extension guide warns that adding several bedrooms may call for more off-street spaces. Near the centre the plan itself records high levels of traffic congestion and a shortage of parking.
Ahead of the start date we settle with you where deliveries and any skip can stand, how the drive, verges and hedges are protected, how the neighbours still get in and out, and where materials are stored. That site plan becomes part of the written scope.
Sources: Hertsmere Borough Council: Dropped Kerbs and Crossovers; Aldenham Parish Council / Hertsmere Borough Council: Adopted Radlett Plan 2020-2036 (low resolution); Hertsmere Borough Council: Planning and Design Guide Part E: Guidelines for Residential Extensions and Alterations (adopted 2006)
Scope
A number on paper means little until the house, its route through planning and the limits of the plot are understood, so a Radlett quote is assembled from the steps below.
Together we go round the house and garden, record when and how it was built, and work out where a site could be set up from the road.
Conservation area boundary, the bungalow directions, the Green Belt edge, flood zone, distance to the brook, protected trees and shared walls, each checked against this one address.
The house is recorded as built, with the places where older fabric or past alterations may hide behind later finishes.
Drawings follow whichever path the address permits: permitted development only where it genuinely applies, otherwise a planning application carrying the supporting statements the council looks for.
Openings, beams and foundations are designed by our structural engineer, and we settle who will handle building control before anything is priced.
The list runs from strip-out to handover, item by item, and the price is built from it rather than from a rate.
Our Hampstead base, serving Radlett
Our studio is in Hampstead on Finchley Road, at NW3 6DN. We serve Radlett from this office. Bring us the practical questions about your house, flat or bathroom and the result you want to achieve.
Contact the studio to discuss your brief and arrange the next step. If you already have drawings, a lease or planning correspondence, tell us what is available.
Book a free feasibility visitOur work
Projects in Radlett are taken on by our London team: in-house architects, designers and structural engineers, with Hampstead Chartered Surveyors & Building Consultancy for surveying. Hertsmere Borough Council decides the planning applications, and the building regulations are checked by Hertfordshire Building Control or, if you prefer, by a private registered building control approver.
We keep no premises in Radlett or elsewhere in the county. Design, drawings, applications and the management of each job are handled from the Hampstead studio; on site, our team and the project manager are at your house, and one named person is your contact from the first visit to the completion certificate.
Where it helps to see finished work of a similar kind before you commit to a design, we point you to a London house we know at first hand.
Outside Radlett, and in London rather than Hertfordshire: Project example: Belsize Park, NW3. That project of ours is a Victorian townhouse of five storeys; its case study records a basement conversion, a rear extension and loft work, carried out together with a full refurbishment of the interior.
Sources: Hertsmere Borough Council: Hertfordshire Building Control Limited; GOV.UK: Building regulations approval - when you need approval; Hampstead Renovations: Belsize Park Gardens, NW3 case study
Radlett questions
It may be in either, or in neither. Radlett North covers the High Street area and was last reviewed in 2010; Radlett South was last altered in October 2012, when Church Close and two properties on Christchurch Crescent were taken out. Both were first designated on 20 April 1988. We check the address against the council's boundary map for each area before design.
They stop the first without an application, not the second. The directions take away the permitted development right to build upward on the named bungalows, Class AA, which allows one more storey on a single-storey house. The council says they are not meant to prevent conventional loft conversions under other permitted development rights, though the loft must still meet those rules, and in a conservation area the roof rules do not apply at all.
Its housing and design policies apply to extensions as to any development. HD3 requires all development to respect local character and residential amenity, HD4 protects Radlett's green and verdant qualities, HD5 keeps healthy trees and hedges, and the Radlett Design Code asks for ridge heights that respect neighbours and sufficient space between dwellings. The plan also records how often houses are extended into much larger ones.
Under Policy SADM26 an extension must not be disproportionate to the original building, on its own or added to earlier extensions, and must stay subordinate to it. The original building means the house as it stood on 1 July 1948, or as first built if later, and the council compares the change in floor space, volume and site coverage. Our Hertsmere page quotes the policy in full.
The Environment Agency runs a flood warning area for the Radlett Brook at Radlett, and the council's flood assessment puts Flood Zones 2 and 3 most heavily alongside the brook, among other rivers. Whether a house is affected depends on where it stands in the valley, so the flood map for planning is checked for that precise address, and it also shows if a flood risk assessment must accompany an application.
Hertfordshire Building Control provides the council's building control service for Radlett addresses, and you can choose a private registered building control approver instead. Electrical work by an installer on a competent person scheme can be certified by that installer, which leaves nothing for you to apply for.
Hertfordshire County Council's Highways department carries out the work, not your builder. A crossing onto an A, B or C road also needs planning permission, while one onto an unclassified road does not, and once built the crossing is part of the public highway.
The studio on Finchley Road in Hampstead, NW3, is the only place we work from; nothing of ours is based in Radlett itself. Our London team of in-house architects, designers and structural engineers, with Hampstead Chartered Surveyors & Building Consultancy, runs design, applications and project management from there, while the site team works at your house. Because the WD7 postcode district also reaches into St Albans district, we confirm which council covers each address before anything is drawn.
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