Mansard Roof Extensions in Harrow

Which Harrow postcodes does this mansard roof extension service cover?

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

Which Harrow neighbourhoods suit a mansard roof extension best?

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

• Pinner (HA5) — Tudor and 1930s village defines Pinner, where tudor fragments, edwardian villas, 1930s semi-detached set what a mansard roof extension can do. Edwardian parapets give a mansard a clean base line across HA5. Any Pinner mansard roof extension is validated by Harrow Council, with Pinner High Street the usual Pinner reference point on the site plan.
• Stanmore (HA7) — a mansard roof extension in Stanmore starts from 1930s semi-detached, edwardian villas, and Stanmore reads as 1930s semi-detached, Green Belt fringe. Edwardian parapets give a mansard a clean base line in HA7. Harrow Council assesses Stanmore mansard roof extensions against its own Stanmore character guidance, and the location plan we draw for Stanmore references Stanmore Tube.
• Harrow Weald (HA3) — 1930s semi-detached, Green Belt defines Harrow Weald, where 1930s semi-detached set what a mansard roof extension can do. Mansards are rare on 1930s stock — the hipped roof form works against the geometry across HA3. Any Harrow Weald mansard roof extension is validated by Harrow Council, with Harrow Weald Common the usual Harrow Weald reference point on the site plan.
• Kenton (HA3) — mansard roof extension work in Kenton means 1930s semi-detached. Kenton is 1930s semi-detached. Mansards are rare on 1930s stock — the hipped roof form works against the geometry throughout HA3. Harrow Council decides the Kenton application, and Kenton station anchors the Kenton location plan.
• Wealdstone (HA3) — mansard roof extension work in Wealdstone means 1930s semi-detached, post-war flats. Wealdstone is 1930s semi-detached, post-war. Mansards are rare on 1930s stock — the hipped roof form works against the geometry throughout HA3. Harrow Council decides the Wealdstone application, and Wealdstone High Street anchors the Wealdstone location plan.
• North Harrow (HA2) — mansard roof extension work in North Harrow means 1930s semi-detached. North Harrow is 1930s semi-detached. Mansards are rare on 1930s stock — the hipped roof form works against the geometry throughout HA2. Harrow Council decides the North Harrow application, and North Harrow Tube anchors the North Harrow location plan.
• South Harrow (HA2) — mansard roof extension work in South Harrow means 1930s semi-detached. South Harrow is 1930s semi-detached. Mansards are rare on 1930s stock — the hipped roof form works against the geometry throughout HA2. Harrow Council decides the South Harrow application, and South Harrow Tube anchors the South Harrow location plan.

What local planning policy applies to a mansard roof extension in Harrow?

Conservation areas covering Harrow: Harrow Council runs 29, and Pinner Village, Stanmore, Harrow Weald are the ones Harrow owners meet most. A mansard roof 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 Harrow Weald a mansard roof extension is judged on the street elevation first.

Article 4 and your Harrow mansard roof extension: Harrow Council has made no borough-wide direction, so permitted development for a mansard roof extension in Harrow generally survives outside Harrow conservation areas and listed curtilages. A Lawful Development Certificate at £274 is how a HA1 owner records that a mansard roof extension was lawful.

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

Sources for this Harrow mansard roof 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.