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Edgware and Canons Park HA8 · House refurbishment

House refurbishment in Edgware and Canons Park

Canons Park’s design guide and the houses east of the A5

This page is for houses on both sides of the A5. In Harrow’s Canons Park Estate conservation area, the December 2013 appraisal carries its own design guide for matters such as extensions, roofs, porches and garage doors. Harrow’s 2011 assessment describes the 1930s semis along Whitchurch Lane, and on the Barnet side the planning register records applications for a replacement house and for basement extensions. Confirm which council decides for your address before any drawing starts.

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House refurbishment in Edgware and Canons Park at a glance

Which guidance shapes your house depends first on the council and then on the conservation area. In Harrow’s Canons Park Estate, the December 2013 appraisal includes a residential design guide of its own, with sections on topics such as extensions, loft conversions, porches, garages and satellite dishes. Across the borough, Harrow’s Residential Design Guide of 2010 gives general guidance on extending a semi. On the Barnet side, Part 4 of Barnet’s design SPD applies where planning permission or prior approval is needed, but it is not intended for homes in conservation areas or for locally or nationally listed buildings, though it says it may still be pertinent in certain instances.

Harrow: Canons Park Estate Conservation Area Appraisal and Management Strategy, December 2013 (PDF) · Harrow: Residential Design Guide Supplementary Planning Document, adopted 15 December 2010 (PDF, file 23276) · Barnet Sustainable Design and Development Guidance SPD, adopted 15 June 2026: Part 4, guidance on residential extensions and alterations (not intended for conservation areas or nationally or locally listed buildings)

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

Approved guide prices

What does a house refurbishment cost in Edgware and Canons Park?

Cost in Edgware and Canons Park 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

Canons Park, Whitchurch Lane and Barnet’s streets east of the A5

Three groups of houses meet here: the Canons Park Estate’s planned houses, the 1930s semis Harrow describes along Whitchurch Lane, and Barnet’s streets east of the A5, where the register shows applications to rebuild and to dig down.

Harrow’s appraisal records demand for significantly extending Canons Park houses to the side, sometimes over the garage, and says this is likely to harm the house and the street by creating a terraced effect and not being clearly subordinate to the original design. On the smaller houses of the side roads it warns against raising the roof pitch to create a crown roof. Read those two warnings before you decide how much space the house must gain, because they shape every later choice about rooms, stairs and the roof.

Harrow: Canons Park Estate Conservation Area Appraisal and Management Strategy, December 2013 (PDF)

Harrow’s 2011 Character Assessment describes Whitchurch Lane’s west and central sections as mainly 1930s semi-detached houses, with some detached, grouped by style: brick and render semis with shallow angular bays and low eaves at the sides around Howberry Road, mainly rendered semis with hipped and half-hipped roofs around Donnefield Avenue, and suntrap pairs with large forward-projecting hipped roofs over the bays around St Lawrence Close. Photograph the other half of your pair as well as your own house before planning the roof or the front.

Harrow: Character Assessment of Harrow’s Residential Areas, 2011 (PDF)

Barnet’s register shows applications to rebuild and to dig down. An application made in 2025 on Penshurst Gardens, a road it addresses as Edgware, to demolish a house and build a two-storey house with a basement level and rooms in the roof space was approved subject to conditions. One made in 2022 at another house on the road, for basement and ground-floor rear extensions, a garage converted into a habitable room and an enlarged side dormer among other works, was also approved subject to conditions. Check the address, the council and your own home’s planning history first.

Barnet planning register: public access search (planning, building control and licensing)

Permissions and local rules

What Harrow and Barnet check on an Edgware house

Extensions on the Canons Park Estate

How should an extension sit against the house?

Harrow’s Canons Park design guide recommends setting extensions back from the main or front elevation so that they read as subordinate, with the roof of a two-storey extension set down from the main roof, and says extensions wrapping round two or more elevations can greatly detract from the house. A single-storey rear extension should ideally take a pitched roof matching the main roof; on occasion a flat roof with a brick-on-edge on tile creasing detail may be appropriate. Flat or crown roofs on two-storey extensions are not usually appropriate.

Harrow: Canons Park Estate Conservation Area Appraisal and Management Strategy, December 2013 (PDF)

Loft rooms and dormers in Canons Park

How far can a dormer go?

The Canons Park design guide cites Harrow’s general guidelines: a dormer at least 1 m up from the eaves, with no part closer than 0.5 m, ideally 1 m, to either side of the roof edge or a chimney. It says more distance will normally be needed on the estate, that dormers should usually be the scale of window openings rather than boxy roof extensions, and that raising a ridge or changing a roof’s pitch is not usually appropriate. Plan the loft room around a modest rear dormer.

Harrow: Canons Park Estate Conservation Area Appraisal and Management Strategy, December 2013 (PDF)

Porches and garage doors

The Canons Park Estate has a variety of porch designs, among them tiled porches and porches recessed under an arch, and Harrow’s design guide encourages keeping them or replacing them in replica. Most houses have traditional single timber garage doors in the Tudor Revival style, and the guide says modern plastic doors are not usually a suitable replacement. Record both before the joinery is priced.

Harrow: Canons Park Estate Conservation Area Appraisal and Management Strategy, December 2013 (PDF)

Tree orders on Barnet’s side

Planning Data records Barnet tree preservation orders on the Barnet side, among them a 1973 order named for Queens Close, Edgware, and a 2018 order for land at Rectory Lane and adjacent land in Heronsgate. A rear extension, a basement or a new drive near a protected tree changes the foundations, the excavation and the work around the roots, so check the address and council, then ask Barnet whether an order covers the trees on or beside your plot before the structure is designed.

Planning Data: Barnet tree preservation order, Queens Close, Edgware, 1973 (TPO/CA/54) · Planning Data: Barnet tree preservation order, Rectory Lane and adjacent land in Heronsgate, Edgware, 2018 (18/TPO/026)

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

What the work covers

The work on an Edgware or Canons Park house

Rear and side additions

A survey of the house and its earlier additions, then drawings for the extension it can take. In Harrow’s Canons Park Estate that means its design guide’s roof forms and set-backs; on the Barnet side, where permission is needed for a house outside Part 4’s exclusions, Part 4 asks a two-storey side extension to keep a gap of at least 1 metre to the boundary at first floor, to be set back at least 0.5 metre from the front wall and set down 0.5 metres from the ridge.

Harrow: Canons Park Estate Conservation Area Appraisal and Management Strategy, December 2013 (PDF) · Barnet Sustainable Design and Development Guidance SPD, adopted 15 June 2026: Part 4, guidance on residential extensions and alterations (not intended for conservation areas or nationally or locally listed buildings)

Roof, chimneys and the loft

A survey of the roof structure, the tiles, the chimneys and any original dormers, then a loft plan sized to the roof the house has rather than one that needs a higher ridge. Rewiring, heating and insulation are planned at the same time, so that new pipes and cables run once through the roof space and the ceilings below are opened only once.

Front garden, drive and boundary

Harrow’s appraisal says front gardens on the estate should remain gardens, not car parks, and that Lake View in many cases serves as a warning to keep hard surfacing to less than half of the front garden, after its soft landscaping was considerably reduced. A new drive, path or boundary is therefore drawn with planting kept as the larger share, and with surface water that drains into the garden.

Harrow: Canons Park Estate Conservation Area Appraisal and Management Strategy, December 2013 (PDF)

How we work

How we run a Edgware and Canons Park 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 Edgware and Canons Park. 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. Confirm the council and the map

    Send us the full address. If it is in Harrow, check Harrow’s map for the Canons Park Estate conservation area; if it is in Barnet, open any past application for the address in Barnet’s register and read its constraints tab for tree orders. Tell us what you found.

  2. Photograph what survives

    Photograph the porch, the front door, the garage doors, the chimneys, the roof tiles and the front boundary, and for a semi the other half of the pair. These records settle what is original and what must be matched, before any drawing is made.

  3. Gather the planning history

    Collect earlier decisions, drawings and completion certificates for the house, and note any extension already built. In Canons Park and on Barnet’s side alike, what was approved before tells us how much the house has already grown.

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 Edgware and Canons Park: questions

Can I build over my garage in Canons Park?

Harrow’s appraisal says that significantly extending a Canons Park house to the side, sometimes over the garage, is likely to harm the house and the street by creating a terraced effect and not being clearly subordinate to the original design. That does not settle your plot, but it means a side scheme needs a strong design case. Ask Harrow’s view early, and compare it with a rear extension drawn to the design guide.

Harrow: Canons Park Estate Conservation Area Appraisal and Management Strategy, December 2013 (PDF)

Could I replace my Canons Park house with a new one?

Harrow’s appraisal records that a few proposals had been put forward to replace historic houses on the estate with more classical designs or with larger, grander Tudor Revival houses, and says each needs careful consideration case by case, a more classical design usually being inappropriate in the estate’s rustic setting. A replacement is therefore a planning question of its own, separate from a refurbishment. Compare the two options on your plot before paying for detailed drawings of either.

Harrow: Canons Park Estate Conservation Area Appraisal and Management Strategy, December 2013 (PDF)

Where should solar panels or a satellite dish go?

Harrow’s Canons Park design guide says satellite dishes, other antennae and micro-generation equipment such as solar panels and wind turbines can spoil the traditional appearance of the houses and should be sited as sensitively as possible, with rear elevations away from the street and rear gardens the most suitable places. Plan panel positions, cable routes and any inverter together with the roof work.

Harrow: Canons Park Estate Conservation Area Appraisal and Management Strategy, December 2013 (PDF)

What does Harrow’s 2010 guide say about the loft of a semi?

Harrow’s Residential Design Guide prefers a hip-to-gable with a rear roof extension or dormer for the loft of a semi-detached or terraced house, set in at least 500 mm from the party boundary and 1,000 mm from the gable end, and set back at least 1,000 mm from the eaves. Dormers should generally be subordinate, should not wrap round the hips and should never rise above the ridge. Check whether your address is in a conservation area first.

Harrow: Residential Design Guide Supplementary Planning Document, adopted 15 December 2010 (PDF, file 23276)

Is flood risk a question for a Barnet-side house?

It can be. Barnet’s Local Plan says Edgware Town Centre is in effect surrounded by floodplains, particularly on its eastern and southern edges, from the Edgwarebury Brook, Deans Brook and Edgware Brook flowing into the Silk Stream, and names confluences south of Brook Avenue and south of Deansbrook Road. If you plan a basement or a lower floor near them, ask Barnet about flood risk at the address before the design is fixed.

Barnet Local Plan 2021–2036, adopted 4 March 2025: the plan and its adoption documents

How much does a house refurbishment cost in Edgware and Canons Park?

It depends on scope. In Edgware and Canons Park, 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 Edgware and Canons Park house

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

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

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