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Northwood HA6 · House refurbishment

House refurbishment in Northwood

Lime mortar, cat-slide dormers and hedged estate plots

Hillingdon describes Northwood’s houses in some detail: an appraisal that lists the town centre’s traditional materials, local list entries for individual houses, and its conservation officer’s account of the Gatehill Farm Estate. This page reads those records alongside the council’s rules for rear, side, roof and front extensions, and sets out what a whole-house refurbishment here should decide before drawings begin.

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Start here

House refurbishment in Northwood at a glance

Start from the record that covers your house, because Hillingdon’s documents differ from one part of Northwood to the next. In the Northwood Town Centre, Green Lane conservation area, the 2019 appraisal marks positive buildings on its audit map and says that change to each must be managed to conserve and, where appropriate, enhance its significance. For the Northwood-Frithwood conservation area, the council’s November 2009 leaflet asked owners to respect the original plan of the house, keeping a relationship with its original form, and asked that boundary treatment be in keeping with the street scene. Elsewhere, check the local list and the Areas of Special Local Character.

Hillingdon: Northwood Town Centre, Green Lane Conservation Area Appraisal, adopted September 2019 (PDF) · Hillingdon: Northwood-Frithwood Conservation Area leaflet, November 2009 (PDF) · Hillingdon: locally listed buildings · Hillingdon: areas of special local character

For the whole area, including conservation areas, permissions and working hours, read our Northwood renovation guide.

Approved guide prices

What does a house refurbishment cost in Northwood?

Cost in Northwood depends on depth of work. A cosmetic refurbishment that keeps the existing layout runs £650–£1,250/sqm (typically £90,000–£180,000), while a back-to-brick renovation runs £2,250–£3,250/sqm (typically £275,000–£475,000), excluding VAT. A written scope and site assessment are needed before any project price can be fixed.

Scope of workGuide rateTypical total
Cosmetic — existing layout retained£650–£1,250/sqm£90,000–£180,000
Back-to-brick renovation£2,250–£3,250/sqm£275,000–£475,000
Typical programme16–32 weeks on site

Guide rates exclude VAT and are set by depth of work, not by postcode. Compare scopes in our London refurbishment cost-per-square-metre guide or try the cost calculator.

The buildings

Northwood houses as Hillingdon’s records describe them

The appraisal, the local list and a conservation officer’s comments describe some Northwood roads, individual houses and the Gatehill Farm Estate. Each record speaks for its own date, so check what still survives on your house before anything is drawn.

The 2019 appraisal lists the traditional materials of the town centre conservation area, among them hand-made red, brown and yellow brick laid in lime mortar; roofs of slate, clay tile and lead; painted timber windows, doors, barge boards and porches; terracotta chimney pots; painted roughcast render; and leaded lights in the windows. It also counts chimney stacks and their pots as part of the roofscape, from the small stacks on the Green Lane shopping parades to tall, prominent ones such as the stack of 20 Maxwell Road.

Hillingdon: Northwood Town Centre, Green Lane Conservation Area Appraisal, adopted September 2019 (PDF)

On Murray Road the appraisal describes a group of three handsome double-fronted Victorian villas of the 1890s, from the road’s earliest phase, in red brick with stone lintels and steeply pitched pantiled roofs. Two of them keep their terracotta ridge tiles and finials, and two have closed in the recessed porch where the original doors sat. The local list adds 24 Murray Road, an 1889 house by R. A. Briggs, brick below and rendered above, with cranked gables at each end, a rounded turret by the entrance and rendered chimney stacks; its entry calls it a key landmark.

Hillingdon: Northwood Town Centre, Green Lane Conservation Area Appraisal, adopted September 2019 (PDF) · Hillingdon: locally listed buildings in Northwood · Hillingdon local list entry 164: 24 Murray Road, Northwood, May 2010 (PDF)

The local list also describes houses elsewhere in Northwood. Its May 2010 entry for Crownhurst, 122 and 122a Ducks Hill Road, records a large 1920s house, mainly of two storeys, with two prominent roughcast gables, barge boards, half-timbering and a central hipped dormer, now divided into two houses. Its July 2011 entry for 23-25 Wieland Road, in the Gatehill Farm Estate, records a 1920s two-storey lodge in white render under a hipped tile roof, with a central archway that was the entrance to Potter Hill House, now St John’s School; the lodge has been converted into two houses.

Hillingdon: locally listed buildings in Northwood · Hillingdon local list entry 150: Crownhurst, 122 and 122a Ducks Hill Road, Northwood, May 2010 (PDF) · Hillingdon local list entry 295: 23-25 Wieland Road, Northwood, July 2011 (PDF) · Hillingdon: Gatehill Farm Estate, Northwood, Area of Special Local Character map (PDF)

Permissions and local rules

Hillingdon’s rules for the outside of a Northwood house

Rear extensions: two separate tests

How deep can a rear extension go?

Under Hillingdon’s borough-wide Article 4 direction, a single-storey rear extension going more than 4 metres past the original back wall needs planning permission. For planning applications, Policy DMHD 1 says single-storey rear extensions on terraced or semi-detached houses should not exceed 3.3 metres in depth where the plot is 5 metres wide or less, or 3.6 metres where it is 5 metres or more, and 4.0 metres on detached houses with plots of 5 metres or more. In conservation areas and Areas of Special Local Character, it expects a flat-roofed single-storey extension to have a parapet.

Hillingdon: Article 4 direction on large rear extensions · Hillingdon Local Plan Part 2: Development Management Policies, adopted 16 January 2020 (PDF) · Hillingdon: areas of special local character

Roofs and dormers

What does Hillingdon accept on the roof?

The town centre appraisal notes dormers on its residential roads that reflect their Arts and Crafts and vernacular character; Murray Road has several cat-slide examples. Policy DMHD 1 and Appendix A measure new roof extensions differently. The policy says they should be on the rear elevation only, no wider than two thirds of the original roof’s average width and below the ridge tiles, and the council will not support poorly designed or over-large ones, including converting a hipped roof to a gable. Appendix A’s guide is that they cover no more than a third of the main roof.

Hillingdon: Northwood Town Centre, Green Lane Conservation Area Appraisal, adopted September 2019 (PDF) · Hillingdon Local Plan Part 2: Development Management Policies, adopted 16 January 2020 (PDF)

Side extensions and the gaps between houses

How far can a side extension reach?

Gaps between houses carry weight here. At the end of Maxwell Road, the appraisal notes that the locally listed numbers 30 and 32 keep their historic gaps as detached houses, beside the long gap of the Northwood College sports grounds, and that the whole section has an openness unlike the road’s northern part. Hillingdon’s Appendix A guidance expects side extensions in conservation areas and Areas of Special Local Character to be set back one metre from the front wall of the main house, and says every side extension should be less than half the width of the original property.

Hillingdon: Northwood Town Centre, Green Lane Conservation Area Appraisal, adopted September 2019 (PDF) · Hillingdon: locally listed buildings in Northwood · Hillingdon Local Plan Part 2: Development Management Policies, adopted 16 January 2020 (PDF)

Fronts, bays and hedged boundaries

What can change at the front?

Hillingdon’s conservation officer described the Gatehill Farm Estate as detached houses on spacious plots, with vegetation such as mature hedges marking boundaries, particularly at the front. Policy DMHD 1 says, among other points, that alterations and extensions to the front of a house must be minor and not alter its overall appearance or dominate the street’s character, and at least 25 per cent of the front garden must be kept. Under Appendix A, new front bays need planning permission and are allowed only where they add positively to the area’s appearance and are an established, original feature of neighbouring houses.

Hillingdon: planning applications search (the council's planning register) · Hillingdon: Gatehill Farm Estate, Northwood, Area of Special Local Character map (PDF) · Hillingdon Local Plan Part 2: Development Management Policies, adopted 16 January 2020 (PDF)

Working hours, skips, parking and the conservation area maps for the whole area are in our Northwood guide. Local guidance checked ; requirements depend on the address, the building and the complete proposal.

What the work covers

What a whole-house scheme here deals with first

Walls, roofs and joinery repaired in kind

The survey establishes how the walls were built and finished before any repair is priced: brick laid in lime or in cement, roughcast or plain render, slate or clay tile, lead flashings, timber barge boards and porches. In the town centre conservation area, the appraisal’s list of traditional materials is the reference for matching repairs; elsewhere, the fabric that survives on the house itself is. Chimney stacks are inspected from a scaffold, not the ground, before anyone decides to rebuild or take one down.

Hillingdon: Northwood Town Centre, Green Lane Conservation Area Appraisal, adopted September 2019 (PDF)

Rainwater from extensions and paving

Hillingdon’s adopted plan says all minor new build developments, householder development included, are required to help reduce the rate of surface water run-off, which may include maximising soft landscaping, making hard surfaces permeable or draining them to permeable features, and green roofs and walls. Where a site is at risk of flooding, the council’s 2019 minor-development guidance adds that surface water from any extension must not connect directly to the sewer and must be controlled on site by soakaway or tank. So drainage is designed with the extension.

Hillingdon Local Plan Part 2: Development Management Policies, adopted 16 January 2020 (PDF) · Hillingdon: Minor Development Flood Risk Assessment Requirements, v2, March 2019 (PDF)

A new basement, if one is wanted

Digging a new basement brings Hillingdon’s own requirements. The adopted plan says applicants will be required to fund the independent assessment of their structural reports, and the council will also require assessments, including a site investigation, to determine the flood risk and show groundwater levels on the site over a period of time. Subterranean development extending the full length or full width of a property will not be supported, and margins should be left between it and the boundaries for on-site drainage and to prevent surface water run-off.

Hillingdon Local Plan Part 2: Development Management Policies, adopted 16 January 2020 (PDF)

How we work

How we run a Northwood house refurbishment

  1. Free feasibility visit

    We walk round the house with you and discuss what is feasible.

  2. Survey

    Rooms, levels and features to keep are measured, with opening-up or asbestos checks where needed.

  3. Design and consents

    Our own architects and structural engineers design the layout and structural openings, plan the service routes with them, and identify which consents and party wall notices apply.

  4. Price and contract

    A fixed written price and a JCT contract follow the survey, scope and specification. It records allowances, exclusions and how changes are priced.

  5. On site

    Work is inspected before it is covered, and a director reviews key decisions.

  6. Handover

    Testing, commissioning and snagging. Completed work carries a 12-month defects-rectification period under the JCT contract terms.

Real projects, clearly located

Examples of our house refurbishment work elsewhere in London

None of these projects is in Northwood. Each card names where the work was done, so you can judge the finish and the approach before you brief your own.

Your brief

Before you ask for a quotation

  1. Set out what has already been added

    List every extension, loft conversion, porch or garden building added since the house was built, with any planning letters or completion certificates you hold. Hillingdon’s rules look at the original house as well as what stands now, so earlier additions shape what is possible. If the address could lie in Three Rivers District, outside London, confirm the council first.

  2. Photograph the outside

    Send photographs of each elevation, the roof and chimneys, the porch and the front boundary, and any hedge or tree close to the work, with close-ups of brickwork, render and windows. They show which features the drawings must keep and what the scaffold should allow for.

  3. Describe how the house will be lived in

    Say who will live in the house and how, including any thought of an annexe for a relative, a garden room or a home office. Mention whether you plan to stay at home during the work, and which rooms, the kitchen and one bathroom especially, must stay usable.

Ready to take the next step? Send the address and a short outline of the work.

Book a free feasibility visit

Questions before you begin

House refurbishment in Northwood: questions

Can a Northwood house that has already been extended be extended again?

Hillingdon’s guidance is firm on this. Appendix A of its adopted plan, on rear extensions, says that conservatories or other extensions to buildings that have already been extended will not be permitted, and that full-width extensions are not normally acceptable in conservation areas. Policy DMHD 1 adds that full-width two-storey rear extensions are not considered acceptable in designated areas or as extensions to listed or locally listed buildings. Look first at what the existing footprint can do.

Hillingdon Local Plan Part 2: Development Management Policies, adopted 16 January 2020 (PDF)

Has Hillingdon refused a large rear addition in the town centre conservation area?

In one 2021 case, yes. For a house in that conservation area, the North Planning Committee refused, as officers had recommended, a two-storey rear extension and an enlarged habitable roof space with rear dormers. Members were told the Conservation Officer had raised strong objections that the rear additions would be disproportionately large in relation to the original house and would fail to enhance the conservation area, and they agreed the proposal was an unacceptable over-development of the site. It is one decision, not a rule, but it shows the questions to answer early.

Hillingdon: planning applications search (the council's planning register)

Does being on Hillingdon’s local list change what I can do?

It changes how an application is weighed. Hillingdon says it will take a locally listed building’s special local architectural or historic interest into account when considering planning applications for alterations and extensions. Northwood’s entries include Crownhurst on Ducks Hill Road and the former lodge at 23-25 Wieland Road. Listed building consent is a separate regime for listed buildings, which a local list entry does not create.

Hillingdon: locally listed buildings · Hillingdon: locally listed buildings in Northwood · Hillingdon: listed buildings

Do the Gatehill Farm Estate’s covenants still apply?

Possibly, so check your title. Hillingdon’s conservation officer has described the estate as begun in the early twentieth century by Messrs Harry Neal Ltd on land formerly associated with Gatehill farm, and developed further after the war into the 1960s and 1980s. The architect Archibald Soutar planned the original estate, with influences from his Hampstead Garden Suburb work, and covenants controlling issues such as density, fencing and road maintenance were adopted at that time. That description gives neither their present terms nor who holds them, so ask your conveyancer before planning boundary or extension work.

Hillingdon: planning applications search (the council's planning register) · Hillingdon: Gatehill Farm Estate, Northwood, Area of Special Local Character map (PDF)

Could part of the house become an annexe for an older relative?

Possibly, on Hillingdon’s terms. Its householder guidance says an annexe designed for a disabled or dependent elderly family member should be on the ground floor and fully accessible, should not have a separate private entrance and must be connected internally to the existing house. An annexe that could be used as, or easily adapted into, a fully self-contained home will not be permitted. Plan the shared entrance, kitchen and circulation with that in mind from the first sketch.

Hillingdon Local Plan Part 2: Development Management Policies, adopted 16 January 2020 (PDF)

How much does a house refurbishment cost in Northwood?

It depends on scope. In Northwood, a cosmetic refurbishment keeping the existing layout runs £650–£1,250/sqm (typically £90,000–£180,000); a back-to-brick renovation runs £2,250–£3,250/sqm (typically £275,000–£475,000), excluding VAT. A written scope and site assessment come before any fixed price.

Book a free feasibility visit

Talk to us about your Northwood house

Tell us the address and what you want to change in your Northwood house. We reply within one working day, Monday to Friday, 8am to 6pm.

Or call 020 7101 3168. We serve Northwood from our studio at Unit 3, Palace Court, 250 Finchley Road, London NW3 6DN.

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