Harrow sends 1 in 8 to committee, basements among them

Where in Harrow does a basement extension actually get determined?

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

What changes about a basement extension in each part of Harrow?

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

• Pinner (HA5) — a basement extension 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 extensions against its own Pinner character guidance, and the location plan we draw for Pinner references Pinner High Street.
• Stanmore (HA7) — basement extension work in Stanmore means 1930s semi-detached, edwardian villas. Stanmore is 1930s semi-detached, Green Belt fringe. Edwardian houses rarely have a usable cellar throughout HA7. Harrow Council decides the Stanmore application, and Stanmore Tube anchors the Stanmore location plan.
• Harrow Weald (HA3) — 1930s semi-detached, Green Belt defines Harrow Weald, where 1930s semi-detached set what a basement extension can do. 1930s houses were built without cellars across HA3. Any Harrow Weald basement extension is validated by Harrow Council, with Harrow Weald Common the usual Harrow Weald reference point on the site plan.
• Kenton (HA3) — a basement extension in Kenton starts from 1930s semi-detached, and Kenton reads as 1930s semi-detached. 1930s houses were built without cellars in HA3. Harrow Council assesses Kenton basement extensions against its own Kenton character guidance, and the location plan we draw for Kenton references Kenton station.
• Wealdstone (HA3) — 1930s semi-detached, post-war defines Wealdstone, where 1930s semi-detached, post-war flats set what a basement extension can do. 1930s houses were built without cellars across HA3. Any Wealdstone basement extension is validated by Harrow Council, with Wealdstone High Street the usual Wealdstone reference point on the site plan.
• North Harrow (HA2) — a basement extension 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 extensions 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 extension 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 extensions against its own South Harrow character guidance, and the location plan we draw for South Harrow references South Harrow Tube.

What local planning policy applies to a basement extension in Harrow?

Conservation areas covering Harrow: Harrow Council runs 29, and Harrow on the Hill, Pinner Village, Stanmore are the ones Harrow owners meet most. A basement extension 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 Pinner Village a basement extension 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 extension 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 extension route in Harrow — construction, not postcode, sets what is achievable.

Who decides a basement extension on the edge of Harrow?

• Hillingdon — the Hillingdon boundary runs against Harrow, so a basement extension a street from Harrow is decided by Hillingdon Council instead. Hillingdon runs 29 conservation areas across HA4 and its neighbours, which is why basement extensions priced for Harrow are re-checked against Hillingdon policy whenever the Harrow address sits on that edge.
• Barnet — adjoining Harrow, with 20 conservation areas centred on N2. A basement extension on the far side of the Harrow line is determined by Barnet Council, so the Harrow quote for basement extensions is checked against Barnet guidance before it is issued.
• Brent — adjoining Harrow, with 22 conservation areas centred on NW2. A basement extension on the far side of the Harrow line is determined by Brent Council, so the Harrow quote for basement extensions is checked against Brent guidance before it is issued.

Sources for this Harrow basement extension 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.