Rear Dormer Loft Conversion — Hillingdon HA4

Which Hillingdon postcodes does this loft service cover?

Below: each Hillingdon postcode district we draw in, what stands on the ground there, and the authority that validates a loft at that address. The fees given are statutory England rates for 2026, not what a loft conversion costs.

What changes about a loft in each part of Hillingdon?

Plot depth, roof pitch and the make-up of the walls all change from one Hillingdon street to the next, and every change bears on what a loft can achieve at a given address. Who decides it is far more predictable than what sits on the plot: 5,529 of the council's 5,698 application decisions were taken by officers under delegated powers, or 97.0%, which matches London exactly. Fewer than three in a hundred reach a committee. On an ordinary rear dormer, in other words, the audience for your drawings is a single case officer rather than a room. Source: MHCLG live planning statistics

• Eastcote (HA5) — 1930s semi-detached defines Eastcote, where 1930s semi-detached set what a loft can do. The 1930s hipped roof here needs a hip-to-gable before a rear dormer works across HA5. Any Eastcote loft is validated by Hillingdon Council, with Eastcote Tube the usual Eastcote reference point on the site plan.
• Hillingdon (UB10) — loft work in Hillingdon means 1930s semi-detached. Hillingdon is 1930s semi-detached, post-war. The 1930s hipped roof here needs a hip-to-gable before a rear dormer works throughout UB10. Hillingdon Council decides the Hillingdon application, and Hillingdon Tube anchors the Hillingdon location plan.
• Uxbridge (UB8) — a loft in Uxbridge starts from georgian fragments, 1930s semi-detached, post-war flats, and Uxbridge reads as Georgian centre, 1930s residential. Georgian roofs here are shallow and often behind a parapet in UB8. Hillingdon Council assesses Uxbridge lofts against its own Uxbridge character guidance, and the location plan we draw for Uxbridge references Uxbridge High Street.
• Ruislip (HA4) — 1930s semi-detached, Tudor fragments defines Ruislip, where 1930s semi-detached, tudor cottages set what a loft can do. The 1930s hipped roof here needs a hip-to-gable before a rear dormer works across HA4. Any Ruislip loft is validated by Hillingdon Council, with Ruislip Lido the usual Ruislip reference point on the site plan.
• Northwood (HA6) — loft work in Northwood means 1930s detached, edwardian villas. Northwood is 1930s detached and semi-detached. Edwardian roofs run deeper front-to-back throughout HA6. Hillingdon Council decides the Northwood application, and Northwood Hills anchors the Northwood location plan.
• Hayes (UB3, UB4) — loft work in Hayes means 1930s semi-detached, post-war estates. Hayes is 1930s semi-detached, post-war. The 1930s hipped roof here needs a hip-to-gable before a rear dormer works throughout UB3. Hillingdon Council decides the Hayes application, and Hayes & Harlington anchors the Hayes location plan.
• West Drayton (UB7) — 1930s semi-detached defines West Drayton, where 1930s semi-detached, post-war set what a loft can do. The 1930s hipped roof here needs a hip-to-gable before a rear dormer works across UB7. Any West Drayton loft is validated by Hillingdon Council, with West Drayton station the usual West Drayton reference point on the site plan.

What local planning policy applies to a loft in Hillingdon?

Hillingdon conservation designations: twenty-nine areas carry designation across the borough, Harefield, Ickenham and Uxbridge among them. Designation is what closes off the permitted-development route. A loft at a designated address is pushed onto the £548 householder application over eight weeks, where an undesignated one could have used the £249 prior approval route in six. Whether any of the twenty-nine touches you is an address question rather than a borough question, so look yours up on the council's map before assuming it either way. Outside them, prior approval is a good bet here: 476 larger householder extensions were determined, 354 of them came back as not requiring approval, and just 45 were refused. That is a 9.5% refusal rate, well under London's 24.9%.

No blanket Article 4 over Hillingdon: permitted development has not been withdrawn borough-wide, so a loft at an address outside any conservation area normally keeps its rights intact. That still leaves the £274 Lawful Development Certificate as the piece of paper an HA4 owner wants in the file, because rights you kept are worth very little at resale if nobody ever documented them.

The building fabric around Hillingdon: 1930s semi-detached dominates; Metropolitan Green Belt covers much of north Hillingdon; Victorian cottages in Uxbridge and Ruislip villages; post-war housing near Heathrow. Largest outer west London borough; significant Green Belt; Heathrow noise contours affect planning decisions in Harmondsworth and Sipson. A loft in Hillingdon is scoped against that stock first.

What happens if a Hillingdon property sits on a boundary?

• Harrow — cross the Hillingdon boundary and Harrow Council takes the loft instead, applying 29 conservation areas of its own around HA1. We re-price lofts at the Hillingdon edge because Harrow policy and Hillingdon policy rarely align on loft depth.
• Ealing — cross the Hillingdon boundary and Ealing Council takes the loft instead, applying 30 conservation areas of its own around W3. We re-price lofts at the Hillingdon edge because Ealing policy and Hillingdon policy rarely align on loft depth.
• Hounslow — the Hounslow boundary runs against Hillingdon, so a loft a street from Hillingdon is decided by Hounslow Council instead. Hounslow runs 30 conservation areas across W3 and its neighbours, which is why lofts priced for Hillingdon are re-checked against Hounslow policy whenever the Hillingdon address sits on that edge.

Sources for this Hillingdon loft 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.