Basement Conversion Drawings in Harrow

Where in Harrow does a basement conversion actually get determined?

Every Harrow postcode district we draw in, the stock that dominates it and the authority that validates a basement conversion there. Harrow fees below are the statutory England rates for 2026, not basement conversion estimates.

How does a basement conversion differ street by street across Harrow?

Roof pitch, wall build-up and plot depth change every few Harrow streets, and each one changes what a basement conversion can achieve at that address.

• Harrow Weald (HA3) — 1930s semi-detached, Green Belt defines Harrow Weald, where 1930s semi-detached set what a basement conversion can do. 1930s houses were built without cellars across HA3. Any Harrow Weald basement conversion is validated by Harrow Council, with Harrow Weald Common the usual Harrow Weald reference point on the site plan.
• Kenton (HA3) — 1930s semi-detached defines Kenton, where 1930s semi-detached set what a basement conversion can do. 1930s houses were built without cellars across HA3. Any Kenton basement conversion is validated by Harrow Council, with Kenton station the usual Kenton reference point on the site plan.
• Wealdstone (HA3) — a basement conversion in Wealdstone starts from 1930s semi-detached, post-war flats, and Wealdstone reads as 1930s semi-detached, post-war. 1930s houses were built without cellars in HA3. Harrow Council assesses Wealdstone basement conversions against its own Wealdstone character guidance, and the location plan we draw for Wealdstone references Wealdstone High Street.
• North Harrow (HA2) — a basement conversion in North Harrow starts from 1930s semi-detached, and North Harrow reads as 1930s semi-detached. 1930s houses were built without cellars in HA2. Harrow Council assesses North Harrow basement conversions against its own North Harrow character guidance, and the location plan we draw for North Harrow references North Harrow Tube.
• South Harrow (HA2) — a basement conversion in South Harrow starts from 1930s semi-detached, and South Harrow reads as 1930s semi-detached. 1930s houses were built without cellars in HA2. Harrow Council assesses South Harrow basement conversions against its own South Harrow character guidance, and the location plan we draw for South Harrow references South Harrow Tube.
• Harrow on the Hill (HA1) — a basement conversion in Harrow on the Hill starts from georgian and victorian houses, listed buildings, and Harrow on the Hill reads as Georgian and Victorian conservation hilltop. Georgian houses here already have a vault and a lower-ground floor in HA1. Harrow Council assesses Harrow on the Hill basement conversions against its own Harrow on the Hill character guidance, and the location plan we draw for Harrow on the Hill references Harrow School.
• Pinner (HA5) — a basement conversion in Pinner starts from tudor fragments, edwardian villas, 1930s semi-detached, and Pinner reads as Tudor and 1930s village. Edwardian houses rarely have a usable cellar in HA5. Harrow Council assesses Pinner basement conversions against its own Pinner character guidance, and the location plan we draw for Pinner references Pinner High Street.

Does Harrow planning policy restrict a basement conversion?

Conservation areas covering Harrow: Harrow Council runs 29, and Pinner Village, Stanmore, Harrow Weald are the ones Harrow owners meet most. A basement conversion inside a Harrow conservation area loses permitted development, so the Harrow submission is a householder application at £548 decided in 8 weeks — not a £249 prior approval decided in 6 weeks. In Harrow on the Hill a basement conversion is judged on the street elevation first.

No blanket Article 4 over Harrow: Harrow Council has not withdrawn permitted development across Harrow, so a basement conversion outside a Harrow conservation area usually keeps it. The £274 Lawful Development Certificate is still the document a HA1 owner wants on file.

Harrow housing stock: 1930s semi-detached dominates; Edwardian villas in Harrow on the Hill and Pinner; Metropolitan Green Belt in Stanmore and Harrow Weald; post-war flats around Harrow Central. Outer north-west London suburban; Harrow on the Hill has exceptionally strict heritage controls; rest of borough permissive. Read that before choosing a basement conversion route in Harrow — construction, not postcode, sets what is achievable. Harrow Council charges £548 for a householder application and has 8 weeks to determine it.

What happens if a Harrow property sits on a boundary?

• Hillingdon — cross the Harrow boundary and Hillingdon Council takes the basement conversion instead, applying 29 conservation areas of its own around HA4. We re-price basement conversions at the Harrow edge because Hillingdon policy and Harrow policy rarely align on basement conversion depth.
• Barnet — the Barnet boundary runs against Harrow, so a basement conversion a street from Harrow is decided by Barnet Council instead. Barnet runs 20 conservation areas across N2 and its neighbours, which is why basement conversions priced for Harrow are re-checked against Barnet policy whenever the Harrow address sits on that edge.
• Brent — adjoining Harrow, with 22 conservation areas centred on NW2. A basement conversion on the far side of the Harrow line is determined by Brent Council, so the Harrow quote for basement conversions is checked against Brent guidance before it is issued.

Sources for this Harrow basement conversion page: borough policies maps and conservation-area registers (2025–26), Royal Mail postcode district boundaries, the Town and Country Planning (Fees for Applications) (England) Regulations, the Town and Country Planning (General Permitted Development) (England) Order 2015 as amended, and the Party Wall etc. Act 1996.