London Borough of Hounslow

Adopted Documents We Assess Against

Development plan: Hounslow Local Plan 2015-2030 (adopted 15 September 2015)

Documents are re-checked against the council's own website weekly. A detected change flags "Policy Update Available" for human review — live assessment standards are never replaced automatically.

London Borough of Hounslow standards at a glance

14 numeric standards taken from London Borough of Hounslow's own adopted documents, each shown with the paragraph it comes from. Figures differ between councils — these are this one's.

Rear extension depth

up to 3.05m

For a terraced house in Hounslow, the council's guideline for a single-storey rear extension is about 3 metres deep. Go deeper and you will need to show it does not box in or overshadow your neighbours. REGs section 4.3

up to 3.65m

For a semi-detached house in Hounslow, the guideline depth for a single-storey rear extension is about 3.65 metres. Anything deeper needs a good case that your neighbour's light and outlook are protected. REGs section 4.3

up to 4.25m

For a detached house in Hounslow, the guideline depth for a single-storey rear extension is about 4.25 metres. REGs section 4.3

Side extension form

at least 1m

A side extension in Hounslow should sit at least 1 metre behind the front of your house so the street does not read as one continuous wall. REGs section 4.4

Two storey rear

up to 2.5m

An upstairs rear extension in Hounslow should stick out no more than 2.5 metres and cover no more than half the width of the house. REGs section 4.6

at least 2m

Keep an upstairs rear extension at least 2 metres away from your neighbour's side wall so you do not block their light. REGs section 4.6

Basement

up to 1

The council restricts a front lightwell to 1m. Hounslow basement guidance section 4.3

up to 2

The council restricts a rear lightwell to 2m. Hounslow basement guidance section 4.3

at least 1

The council requires 1m of reinstated soil over a basement under the garden. Hounslow basement guidance section 4.3

Highways access

at least 4.8m

A car parked at right angles to the road needs 4.8 metres of depth on your property. Parking along the frontage instead is judged differently and needs a much wider forecourt. Residential Crossovers and Off-Street Parking Policy paragraph 3.6

at least 2.4m

The parking space needs 2.4 metres of width, and the 1.2 metre path to your door has to sit beside it, not across it. Residential Crossovers and Off-Street Parking Policy paragraph 3.6

at least 1.2m

You need a clear 1.2 metre path from the street to your front door that is NOT the driveway - somewhere to walk that a parked car cannot block. This is the exact point a Jersey Road application was refused on. Residential Crossovers and Off-Street Parking Policy paragraph 3.6

at least 3.6m

A single dropped kerb has to be between 2.4 and 3.6 metres wide - too narrow fails as well as too wide. A double is possible up to 4.2 metres if your frontage is 6 metres or more. Residential Crossovers and Off-Street Parking Policy paragraph 3.22

at least 2.4m

Both sides of the dropped kerb need a 2.4 by 2.4 metre clear triangle with nothing over 600mm high in it, so drivers and people on the footway can see each other. Usually that means the front wall comes down at the corners. Residential Crossovers and Off-Street Parking Policy paragraph 3.12

Standards are what the council normally expects, not a guarantee. A scheme outside them can still be approved on its merits, and one inside them can still be refused for another reason.

Authored Policy Library

29 local policy checks, each citation-locked to the adopted document. National policy (NPPF, national space and daylight standards) applies alongside these.

Residential Extension Guidelines SPD

• REGs section 4.3 — Rear extension depth (4 checks) For a terraced house in Hounslow, the council's guideline for a single-storey rear extension is about 3 metres deep. Go deeper and you will need to show it does not box in or overshadow your neighbours. For a semi-detached house in Hounslow, the guideline depth for a single-storey rear extension is about 3.65 metres. Anything deeper needs a good case that your neighbour's light and outlook are protected. For a detached house in Hounslow, the guideline depth for a single-storey rear extension is about 4.25 metres. If your house has already been extended, adding more depth on top of that is normally refused in Hounslow - the limits count from the house's original back wall, not the current one.
• REGs section 4.4 — Side extension form (2 checks) A side extension in Hounslow should sit at least 1 metre behind the front of your house so the street does not read as one continuous wall. A side extension should look clearly smaller than your house - lower than the upstairs windows and noticeably narrower than the original building.
• REGs section 4.6 — Two storey rear (3 checks) An upstairs rear extension in Hounslow should stick out no more than 2.5 metres and cover no more than half the width of the house. On a mid-terrace house, a two-storey rear extension is rarely approved in Hounslow - it walls in the neighbours on both sides. Expect a strong challenge. Keep an upstairs rear extension at least 2 metres away from your neighbour's side wall so you do not block their light.
• REGs section 3.6 — Amenity space After your extension, your back garden should still be at least as big as your house's original footprint - shrink it below that and refusal becomes a real risk in Hounslow.
• REGs section 4.10 — Roof form (2 checks) Squaring off a hipped roof usually gets refused in a Hounslow planning application unless next door has already lawfully done the same - though permitted development rules may let you do it without applying. Front-facing dormers are generally refused in Hounslow - keep roof extensions to the rear and as tucked-away as possible.
• REGs section 4.3 — Amenity neighbouring Using your extension's flat roof as a terrace is normally refused in Hounslow because it overlooks the neighbours.
• REGs sections 4.7 and 5.3 — Basement Hounslow allows single-storey basements with strict limits, and you will need an engineer's construction statement and often a flood report. Professional advice is essential before committing to one.
• Hounslow basement guidance section 4.3 — Basement (3 checks) The council restricts a front lightwell to 1m. The council restricts a rear lightwell to 2m. The council requires 1m of reinstated soil over a basement under the garden.
• REGs section 6.2 — Heritage constraints In a Hounslow conservation area the design bar is higher - extensions that would be fine elsewhere can be refused, and your materials and roofline matter a lot more.

Hounslow Local Plan 2015-2030

• Hounslow Local Plan Policy SC7 — Amenity neighbouring SC7 is the main policy Hounslow uses to judge house extensions. It asks two things: does it harm the neighbours (light, outlook, feeling boxed in), and does it sit comfortably with the house and the street. A refusal under SC7 will normally be about one or the other.
• Hounslow Local Plan Policy CC1 — Design character CC1 is about whether a proposal fits the particular character of its area - not a fixed standard, but a judgement about local context.
• Hounslow Local Plan Policy CC2 — Design character CC2 is about design quality and whether the scale and massing of what is proposed sits properly with the buildings around it.
• Hounslow Local Plan Policy CC4 — Heritage constraints CC4 applies where the site is in a conservation area or affects a listed building. The council must pay special attention to preserving the character of the area, and that duty comes from statute, not just from the Local Plan.
• Hounslow Local Plan Policy EC2 — Design character (provisional citation) EC2 covers driveways, crossovers and front boundary treatments where they affect highway safety. Refusals under it are often about missing information rather than a scheme that cannot work.
• Hounslow Local Plan Policy SC5 — Residential quality (provisional citation) Creating flats is not just about floor area. Hounslow will look at what each room looks out onto, whether ground floor windows have a buffer from the pavement, and whether each flat has real outdoor space. A scheme that meets the size standards can still be refused on these.

Residential Crossovers and Off-Street Parking Policy

• Residential Crossovers and Off-Street Parking Policy paragraph 3.6 — Highways access (3 checks) A car parked at right angles to the road needs 4.8 metres of depth on your property. Parking along the frontage instead is judged differently and needs a much wider forecourt. The parking space needs 2.4 metres of width, and the 1.2 metre path to your door has to sit beside it, not across it. You need a clear 1.2 metre path from the street to your front door that is NOT the driveway - somewhere to walk that a parked car cannot block. This is the exact point a Jersey Road application was refused on.
• Residential Crossovers and Off-Street Parking Policy paragraph 3.22 — Highways access A single dropped kerb has to be between 2.4 and 3.6 metres wide - too narrow fails as well as too wide. A double is possible up to 4.2 metres if your frontage is 6 metres or more.
• Residential Crossovers and Off-Street Parking Policy paragraph 3.12 — Highways access Both sides of the dropped kerb need a 2.4 by 2.4 metre clear triangle with nothing over 600mm high in it, so drivers and people on the footway can see each other. Usually that means the front wall comes down at the corners.

Local Validation Requirements

Documents this council requires with an application beyond the national baseline, requested only when your project actually triggers them.

• Construction Method Statement (engineer-certified) — Hounslow requires basement applications to be supported by a Construction Method Statement certified by a suitably qualified engineer, covering excavation, temporary works and construction techniques including impacts on neighbouring land assessed against the area's geology and hydrology.
• Flood Risk Assessment (basement) — Hounslow requires a site-specific Flood Risk Assessment for all basement development in flood zones 2 and 3, and in zone 1 where there is evidence of surface water, groundwater or sewer flooding risk.