A ground-floor flat
“Living / kitchen in new extension and bedrooms to the front of the house”
Adam Davis
Architectural Technologist,
PlotScope
11 October 2026
Worth pursuing
In short
This is our honest view from the public records and guidance. The decision rests with the council.
You told us you want "Living / kitchen in new extension and bedrooms to the front of the house". For your ground-floor flat, this is usually called a single-storey side or wraparound extension, about 2 m deep and 2.5 m high, with changes inside.
The likely route is a full planning application. Flats have no householder permitted development rights (the national rules that let some house extensions go ahead without an application), so the quicker routes are not open to you. The council fee is £309, with an 8-week target from validation.
Three things will shape it most. First, flood risk. The flat is in Flood Zone 3, a high-probability zone, so the application needs a flood risk assessment, and new sleeping space at ground level needs particular care. Second, consent. As a flat, the owner's lease and freeholder consent also need checking. Third, local record. Within 150 m, 19 side or wraparound extensions were approved and none refused, so similar proposals on this street have generally been approved.
Next, confirm the consent position. Pre-application advice from the council is also possible, though timings vary. The sections that follow set out the detail.
Your property
The property is a one-bedroom, ground-floor garden flat in a mid-terrace building in Chiswick, in the London Borough of Hounslow. It has a back garden and generous ceiling heights.
The energy certificate, inspected on 2 January 2019, records about 38 m² of internal floor area and three habitable rooms. It gives the building's age as 1900-1929 and records no extensions.
Our checks on the council's map found that the building is not listed or locally listed, and is not in a conservation area. You are not sure what the walls, floors and roof are made of, so we have not described them.
What applies to your property
| Article 4 direction | Dwellinghouses (C3) to small HMOs (C4) - borough-wide Article 4 DirectionThis direction covers other kinds of development; it doesn't affect extensions or alterations to a house. |
|---|---|
| Flood zone | Flood Zone 3Flood Zone 3 (high probability). A planning application here needs a flood risk assessment; for a householder extension the Environment Agency's standing advice usually covers it. Basements and new sleeping space at ground level need particular care. |
| Listed building | Not a listed building: we checked Hounslow interactive map on 9 October 2026. No record found within 50 m in the national dataset, which is complete for England. |
| Tree preservation order area | No record found. The council doesn't publish this information online, so we'll confirm it with them. |
| Archaeological priority area | Not in an archaeological priority area: we checked Hounslow interactive map on 9 October 2026. |
| Conservation area | Not in a conservation area: we checked Hounslow interactive map on 9 October 2026. |
| Locally listed building | Not a locally listed building: we checked Hounslow interactive map on 9 October 2026. |
Your property’s planning history
We found no planning applications for your property in the London-wide records, which go back to 1991 here. Older or missing records can be on the council's own system; we'll check if it matters.
What’s been done nearby
For a single-storey side or wraparound extension like yours, the pattern nearby is encouraging. Within 150 m we found 19 similar applications, all approved and none refused. On the same street, six were approved and none refused. Similar proposals on this street have generally been approved.
Rear extensions are a wider group. Within 150 m, 110 were approved and 13 refused. On the same street, twenty-nine were approved and four refused. This is also a pattern of general approval, though refusals do happen.
Close to you, single-storey extensions have been approved at two houses on the same street: a rear side extension in 2012 and a rear infill extension forming a wraparound in 2026.
Your proposal is about 2 m deep and 2.5 m high. It sits within a pattern that has mostly been approved locally, so it looks a realistic project to pursue. This is a guide to the local pattern, not a view on how the council will decide your application.
| Where | What | Decision | Year |
|---|---|---|---|
| A house on the same street | Erection of a single storey rear side extension. | Approved | 2012 |
| A house on the same street | Erection of a single storey side extension and a rear roof extension incorporating a Juliet balcony and two front roof windows to the house | Not recorded | 2016 |
| A house on the same street | A proposed reconstruction of the existing side extension; change from a tiled roof to a glass roof and replacement of the rear door | Approved | 2024 |
| A house on the same street | Certificate of Lawfulness for the erection of single storey rear/side extension to dwellinghouse. | Approved | 2004 |
| Two houses on the same street | Erection of a rear and side extension to both properties | Approved | 2013 |
| A house on the same street | Erection of single storey rear infill extension to the house to form a wrap around extension and a rooflight to existing single storey rear extension. | Approved | 2026 |
| The same house and its neighbour | Erection of a side infill extension to both properties, in addition, a replacement rear extension to the first house with new roof-lights. | Approved | 2026 |
| A house on a nearby street | Certificate of lawfulness for erection of a single storey side extension | Approved | 2018 |
The guidance that will matter
Two adopted plans set the local rules: the Hounslow Local Plan 2015–2030, adopted on 15 September 2015, and the London Plan 2021. A newer Hounslow Local Plan 2020–2041 is still in examination and is not adopted. Officers may give its emerging policies some weight, so we check how much in recent reports. The National Planning Policy Framework, published on 17 August 2026, applies to every decision in England alongside the local plan.
Design guidance also applies. This is the Character, Sustainability and Design Codes SPD (2024), which replaced the 2017 extensions guidance, along with the Climate Change Mitigation and Adaptation SPD (2025), the National Design Guide and the national Planning Practice Guidance. An SPD is a supplementary planning document: detailed council guidance that sits under the local plan. We check your plans against each of these.
The flat is in Flood Zone 3, and you plan significant internal changes with bedrooms to the front. The ground floor means any new sleeping space needs particular care on flood risk. The national space standard sets minimum internal sizes for new homes, including conversions, where the local plan adopts it. We will confirm whether Hounslow does.
Hounslow also has a borough-wide Article 4 direction on turning houses into small shared homes (HMOs). It matters only if you ever meant to let the flat to sharers. The council's validation checklist sets out what a valid application must include.
Your routes
General information, not a formal planning opinion.
Full planning application (flat or maisonette) Likely
Work to a flat or maisonette needs a full planning application; there's no householder permitted development.
Flats and maisonettes don't have the permitted development rights that houses have, so extensions and roof works need a full planning application.
We'll confirm the details of this route with you, and with the council where needed, before you rely on it.
Council fee £309 · 8-week target from validation.
Pre-application advice Possible
The council's view before applying. Worth it for conservation areas, listed buildings, basements and anything unusual.
Council charge; see the council's pre-application page. · Varies by council.
Permitted development Not available
Lawful Development Certificate (proposed) Not available
Prior approval for a larger rear extension Not available
Design pointers
You are proposing a single-storey side/wraparound extension, about 2 m deep and about 2.5 m high. A flat has no householder permitted development rights, so there is no set size limit to design to. The council would judge the size and shape on their merits through a full planning application.
Local precedent is encouraging for this type of extension. Within 150 m, 19 side or wraparound proposals were approved and none refused. On the same street, six were approved and none refused. Single-storey extensions at two houses on the same street, in 2012 and 2026, were both approved.
Two pointers to discuss. Your flat has generous ceiling heights, so we should check how a 2.5 m outside height translates to the room height inside the new living and kitchen space. You also want bedrooms at the front. New sleeping space at ground level in Flood Zone 3 needs particular care.
On materials, you are not sure what the existing walls and roof covering are made of. We would want to confirm this so the extension can be matched or deliberately contrasted.
Other things to plan for
Planning permission is only one part of this job. Building Regulations approval is a separate process. It covers structure, fire safety, insulation, drainage and ventilation, and most extensions and structural alterations need it.
You plan significant internal changes as well as the extension. You will probably need a structural engineer for steel beams, new openings in load-bearing walls and foundations. Their calculations go to Building Control. You weren't sure what the walls, floors and roof are made of, so that is worth establishing early.
The building is a mid-terrace, so the Party Wall etc. Act 1996 may apply if work is on or near a shared wall or boundary, or digs close to a neighbour's foundations. If it does, you'll need a party wall surveyor, and notices must go to the neighbours in good time before work starts.
As a flat, the owner's lease and freeholder consent also need checking.
The flat is in Flood Zone 3, so an application needs a flood risk assessment. Designs often raise floor levels or use flood-resilient construction, and new sleeping space at ground level needs particular care. Your plan for bedrooms at the front makes this relevant.
Costs and timing
What we’d do next
First, book the 30-minute call with us to talk this report through and settle your priorities for the extension.
Second, check the lease. As a flat, the owner's lease and freeholder consent also need checking.
Third, consider pre-application advice, where the council comments before you apply. It is possible here, but timing varies.
Then we prepare a full planning application. It needs a flood risk assessment, and new ground-floor bedrooms need particular care in Flood Zone 3. The council fee is £309, with an 8-week target once the application is validated (confirmed complete).
Limitations
This report is based on public records and published guidance available on the date shown, and on what you've told us about the project.
It is an informed view of what is likely, not a promise of any outcome. The decision rests with the council.
It is not legal advice and not a survey. We haven't inspected the structure, drains or boundaries.
Structural, legal, party wall, ecological and flood matters need the relevant professional; we've flagged where.
Public datasets can be incomplete. Where we found no record, we've said so rather than assuming there is nothing.
Sources and glossary
- Planning Data: Article 4 direction, https://www.planning.data.gov.uk/dataset/article-4-direction-area, retrieved 9 October 2026
- Planning Data: Flood zone, https://www.planning.data.gov.uk/dataset/flood-risk-zone, retrieved 9 October 2026
- Planning Data: Listed building, https://www.planning.data.gov.uk/dataset/listed-building, retrieved 9 October 2026
- Planning Data: Tree preservation order area, https://www.planning.data.gov.uk/dataset/tree-preservation-zone, retrieved 9 October 2026
- PlotScope check: Hounslow interactive map, https://hounslow.statmap.co.uk/map/Aurora.svc/run?script=%5CAurora%5Cfind_your_nearest.Aurorascript%24&resize=always, checked 9 October 2026
- Planning London Datahub (Greater London Authority), https://www.london.gov.uk/programmes-strategies/planning/digital-planning/planning-london-datahub, retrieved 9 October 2026
- The Town and Country Planning (General Permitted Development) (England) Order 2015, Schedule 2, Part 1, https://www.legislation.gov.uk/uksi/2015/596/schedule/2/part/1, checked 9 October 2026
- Hounslow Local Plan 2015–2030 (volumes one and two), https://www.hounslow.gov.uk/local-plan/local-plan-1, checked 9 October 2026
- Hounslow Local Plan 2020–2041 (Local Plan review), https://www.hounslow.gov.uk/local-plan/local-plan-review, checked 9 October 2026
- The London Plan 2021, https://www.london.gov.uk/programmes-strategies/planning/london-plan/london-plan-2021, checked 10 October 2026
- National Planning Policy Framework, https://www.gov.uk/government/publications/national-planning-policy-framework--2, checked 10 October 2026
- Character, Sustainability and Design Codes SPD (2024), https://www.hounslow.gov.uk/planning-policy/character-sustainability-design-codes-spd, checked 9 October 2026
- Planning Practice Guidance, https://www.gov.uk/government/collections/planning-practice-guidance, checked 10 October 2026
- National Design Guide, https://www.gov.uk/government/publications/national-design-guide, checked 10 October 2026
- Technical housing standards – nationally described space standard, https://www.gov.uk/government/publications/technical-housing-standards-nationally-described-space-standard, checked 10 October 2026
- Climate Change Mitigation and Adaptation SPD (2025), https://www.hounslow.gov.uk/downloads/file/13744/cc-spd-final, checked 9 October 2026
- Article 4 directions, https://www.hounslow.gov.uk/planning-policy/article-4-directions, checked 9 October 2026
- Planning application validation checklist, https://www.hounslow.gov.uk/downloads/download/2254/planning-application-check-list, checked 9 October 2026
- MHCLG: Fees for planning applications in England from 1 April 2026, https://assets.publishing.service.gov.uk/media/69a073bb07d7bff3604d6df6/Planning_fees_-_annual_indexation_from_1_April_2026.pdf, checked 10 October 2026
- PlotScope general guidance on other approvals, checked 10 October 2026
- Energy certificate register, retrieved 9 October 2026
Glossary
- Permitted development
- Building work that national rules allow without a planning application, within set limits on size, height and position.
- Lawful Development Certificate
- A certificate from the council confirming that a project is permitted development. Optional, but it gives certainty and is often asked for when you sell.
- Prior approval
- A lighter process than a planning application, used for larger single-storey rear extensions. The council tells your neighbours and considers any objections.
- Conservation area
- An area the council protects for its special character. Permitted development is reduced, and designs need more care.
- Article 4 direction
- A council order that removes some permitted development rights in a particular area, so those works need planning permission.
- Pre-application advice
- A paid service where the council gives its informal view on a proposal before you apply.
- Building Regulations
- National standards for how building work is done, covering structure, fire safety, insulation and drainage. Separate from planning.
- Party Wall etc. Act 1996
- The law that sets out how to give neighbours notice of work on or near a shared wall or boundary.
- Flood risk assessment
- A report showing how a proposal deals with flood risk. Needed with planning applications in Flood Zones 2 and 3.
- Validation
- The council's check that an application has everything it needs before it can be considered.