Local plan
Hounslow’s adopted borough plan is the Local Plan 2015–2030, adopted on 15 September 2015, read alongside the London Plan and West London Waste Plan. [1][3]
For home projects, start with SC5 on space, SC6 on conversions, SC7 on extensions and alterations, CC4 on heritage and EQ3 on flood risk, rather than treating householder guidance as the whole policy test. [2]
SC6 requires at least 130 m² net original internal floor area for conversion or subdivision, with a ground-floor family unit of at least two bedrooms/four persons unless the location is unsuitable for families; neighbour amenity and living conditions also matter. [2]
The replacement 2020–2041 plan remains under examination: the council published suggested modifications on 30 September 2026 and further evidence on 1 October, not an adoption decision. [4]
Council guidanceHouseholder design guide
Use Part A5: Residential Extension Guidelines within the Character, Sustainability and Design Codes SPD adopted on 14 May 2024. [5][6]
The council explicitly states that this SPD supersedes the 2017 Residential Extensions Guidelines, despite a separate webpage still describing that older guide; it also replaces the 2013 shopfront guidance and 2014 character study. [7][39]
Read A5 alongside the common considerations in Part A2 and the relevant neighbourhood guidance in Part B; Part A3 separately addresses site types including backland, infill and upwards extensions. [5]
The Climate Change Mitigation and Adaptation SPD, adopted on 27 August 2025, provides complementary building-fabric and services guidance, so its adoption should not be confused with the earlier consultation wording still present on the webpage. [9][10]
Council guidanceValidation list
Start with the council’s application-specific checklist, including separate householder and full major/minor documents, and read it together with the live submission webpage. [11][12][13][14]
That webpage expressly requests fire-safety information for non-major applications, including householder extensions: plans identifying unobstructed fire-equipment and evacuation areas, and a statement addressing London Plan D12A. [14]
The householder checklist also identifies a Construction Method Statement for basement excavation or extension, alongside relevant tree, flood-risk and other supporting information. [12]
Confirm the project-specific checklist with the council, applying DM2 of the NPPF published on 17 August 2026. Additional local assessments must have development-plan support and be proportionate; not every report applies to every proposal. [12][13][15][40]
Council guidanceArticle 4 directions
The confirmed C3-to-C4 HMO direction took effect on 4 September 2023, but excludes mapped open land, industrial areas, Chiswick Business Park, Bedfont Lakes Business Park and Mogden Sewage Works. [17][18]
A separate confirmed Class MA/ZA direction controls specified commercial-to-residential changes and demolition/rebuilding in mapped centres and employment locations: its confirmation notice gives 22 April 2025, whereas the sealed instrument retains 19 April 2025, so obtain clarification for cases affected by that commencement discrepancy. [19][20]
Bedford Park and Gunnersbury Park heritage directions were confirmed on 24 July 2001 and apply to scheduled properties and specified works, not an unrestricted prohibition on every alteration throughout either conservation area. [21][22][23]
The council records that the Brentford Dock enclosure direction was withdrawn in March 2023; its original proposal must not be presented as a current restriction. [16]
Council guidanceConservation areas
Check the council’s conservation-area map and the appraisal for the actual address before designing alterations, rather than relying on a neighbourhood name alone. [24][25]
The published Bedford Park appraisal explains that the historic estate extends into Ealing, so this Hounslow page does not determine controls for the Ealing part. [26]
The November 2018 Gunnersbury Park appraisal identifies separate character areas, including the park, estate and cemetery, while the heritage-direction property schedules establish which addresses have additional controls. [27][22][23]
The council says its appraisals are being reviewed; check for replacement documents and boundary changes, or contact conservation@hounslow.gov.uk / 020 8583 2340, rather than assuming an older appraisal’s references to legislation or another council’s controls remain current. [24][25][26]
Council guidanceBasement policy
Hounslow has explicit basement controls in SC7 and adopted Part A5, whose guidance limits excavation to one subterranean floor. [2][8]
For larger properties, A5 illustrates possible rear-garden projections of 3.05 m for terraces, 3.65 m for semis and 4.25 m for detached houses—horizontal projections, not excavation depths—with at least 1 m of soil reinstated above garden extensions. [8]
The guide excludes self-contained dwellings, main living areas and sleeping accommodation in basements, and expressly rules out basements in Bedford Park Conservation Area. [8]
It requires an engineer-certified Construction Method Statement through conditions and a site-specific Flood Risk Assessment in Flood Zones 2/3, or Zone 1 where surface-water, groundwater or sewer-flood evidence exists; the submission checklist also asks for the construction statement with basement proposals. [8][12]
Council guidanceCIL rates
Hounslow’s schedule effective 24 July 2015 sets residential unindexed base rates of £200/m² in Zone 1 East, £110/m² in Zone 2 Central and £70/m² in Zone 3 West, using the schedule’s charging-zone map. [29]
These are not 2026 payable rates: the current council webpage supplies the 2026 index value, 400, so request the applicable indexed rate and calculation from the council before budgeting. [28]
The GLA separately publishes a 2026 Mayoral CIL2 rate of £72.73/m² for Hounslow’s ordinary Band 2 category; that is only the Mayoral component, not a combined charge or a project-specific liability. [30]
Do not deduct proposed temporary London borough-CIL relief unless the final implementing rules establish that the development is eligible. [38]
Council guidancePre-application advice
The published 2026–2027 VAT-inclusive tariff lists householder advice at £408.44 for a written response, £558.55 for a response and meeting, or £769.87 for the site-visit category. [31]
It lists £1,232.82 for a householder extension to a listed building, £1,216.90 for conversion of one house to flats and £1,450.92 for conversion of one house to an HMO, so do not assume an ordinary extension fee covers a conversion or listed-building proposal. [31]
Send the completed advice form and drawings to planningcomments@hounslow.gov.uk, checking the applicable category and any combined-work charges before payment. [32][33]
Advice is not a binding permission; the linked service guide is labelled 2025/2026, so its older fees are not substituted for the later online tariff. [31][33]
Council guidanceBuilding control
For council building-control enquiries, the approval webpage lists 020 8583 5454 and buildingcontrol@hounslow.gov.uk. [34]
Request inspections through the council’s booking page with at least one working day’s notice; for a job the council is already inspecting, it also publishes BC.siteinspection@hounslow.gov.uk. [35]
Fees depend on the work and application route, with individual quotations available, rather than a single borough-wide extension price. [34]
The linked Scheme 9 tariff is dated 27 March 2026, but retains a 1 April 2024 applicability sentence and gives the general email with an extra dot, building.control@hounslow.gov.uk; confirm the charge and contact route by telephone rather than treating either discrepancy as resolved. [36]
Council guidance