By the Meridian Contractors team, Chatham. Last updated September 2026.
TL;DR: Most single storey rear extensions in Medway do not need planning permission, provided they stay within permitted development limits: no more than 4 metres beyond the rear wall for a detached house (3 metres for any other house), a maximum height of 4 metres, and no more than 3 metres high at the eaves within 2 metres of a boundary. Two storey extensions, side extensions, and any work on a home inside one of Medway's Article 4 conservation areas (Upnor, Brompton, Gillingham Park and others) almost always need a full application. A standard householder application in Medway costs £548 in 2026 (rising to £575 from 8 December 2026) and has a statutory target of 8 weeks. Always check with Medway Council or a qualified contractor before you start digging.
What counts as "permitted development" versus "planning permission"?
Permitted development rights are a general planning permission granted by national law, not by your local council. If your extension fits within the government's set limits, you can build without submitting an application at all. Planning permission, by contrast, is a formal application to Medway Council that a planning officer has to assess and approve before you start work.
The confusion most Medway homeowners run into is assuming that "small" automatically means "permitted." It doesn't. The rules are based on precise measurements, not on how the extension looks or feels from the street.
Do you need planning permission for a single storey extension in Medway?
Usually not, as long as you stay inside these limits:
- A single storey rear extension cannot go beyond the rear wall of the original house by more than 4 metres for a detached house, or 3 metres for any other type of house (semi-detached or terraced).
- Maximum height is 4 metres.
- Where the extension comes within 2 metres of a boundary, the eaves height cannot exceed 3 metres.
You can go larger, up to 8 metres for a detached house or 6 metres for any other house, using the "prior approval" route. This is a lighter-touch process than a full application: you notify Medway Council, they consult your neighbours, and if no one objects on valid grounds within 21 days, the extension is treated as permitted development.
What about two storey and side extensions?
These are treated more strictly:
- A rear extension of more than one storey must not extend beyond the original rear wall by more than 3 metres, and must not come within 7 metres of any boundary opposite the rear wall.
- The roof pitch should match the existing house as closely as practical, and any upper floor windows on the side must be obscure-glazed and non-opening below 1.7 metres.
- Any side extension of more than one storey needs a full householder planning application. There is no permitted development route for this.
If your home sits on designated land, which includes conservation areas and other Article 2(3) land, even a rear extension of more than one storey needs full permission.
Quick answer: single storey vs two storey extension rules
| Extension type | Max depth beyond rear wall | Max height | Planning permission needed? |
|---|---|---|---|
| Single storey, detached house | 4m (8m with prior approval) | 4m | Usually not, if within limits |
| Single storey, semi/terraced house | 3m (6m with prior approval) | 4m | Usually not, if within limits |
| Two storey, rear | 3m, and 7m+ from opposite boundary | Match existing roof pitch | Often, always if two storey side extension |
| Any extension in an Article 4 area | N/A | N/A | Yes, in almost all cases |
Does living in a Medway conservation area change the rules?
Yes, and this is the point where a lot of Medway homeowners get caught out. Medway Council has Article 4 Directions covering several conservation areas, which remove permitted development rights that would normally apply anywhere else. The affected areas include:
- Upnor (Admiralty Terrace, Admiralty Road, High Street, Barrack Hill)
- Brompton (Mill Road, Saunders Street, St Georges Road, Trinity Road, Marlborough Road)
- Gillingham Park (Park Avenue, Oxford Road, Cleave Road, Nelson Road and others)
- Maidstone Road and New Road, Chatham
- New Road / Star Hill, Rochester (High Street, Hammond Hill and surrounding historic properties)
- Watts Avenue / Roebuck Road, Rochester
- Upper Bush, Cuxton
In these areas, changes that would be permitted development anywhere else, such as replacing windows and doors, altering a roof, adding a porch, re-cladding a wall, or laying a new driveway, all need planning permission. Extending your house in one of these areas needs a full application as a matter of course. If you're not sure whether your street falls inside one of these zones, check with Medway Council or ask your contractor to check before you commit to a design.
How much does a planning application cost in Medway in 2026?
A householder application for alterations or an extension to a single dwelling costs £548 as of 2026, rising to £575 from 8 December 2026. This is a national fee set by government, not a Medway-specific charge, so it's the same whether you're in Chatham, Rochester, Gillingham or Strood. On top of the council fee, budget for a planning drawings package from an architect or architectural technologist, which is typically a separate cost from the build itself.
How long does planning permission take in Medway?
Householder planning applications in England have a statutory target of 8 weeks from the date the application is validated. In practice, a straightforward, well-prepared application in Medway is often decided within that window, but applications that need neighbour consultation, additional information, or committee input can take longer. Prior approval notifications for larger single storey extensions have their own faster 21-day neighbour consultation period, which is one reason contractors often recommend that route where it applies.
What happens if you build without planning permission?
If your extension needed permission and you didn't get it, Medway Council can serve an enforcement notice requiring you to alter or demolish the work, and in some cases pursue this as a criminal matter if the notice isn't complied with. There is a four-year rule for most unauthorised building work, after which enforcement action generally cannot be taken, but relying on this is a poor substitute for doing it properly. An unauthorised extension can also cause serious problems when you come to sell, since a buyer's solicitor will ask for a completion certificate and lawful development evidence you may not be able to provide.
How Meridian Contractors helps Medway homeowners get this right
Every extension and renovation project we take on starts with the same question: does this need an application, and if so, who is handling it? Our project management service covers exactly this, from checking permitted development limits and liaising with Medway Council through to handover, so you're not left chasing planning officers or reading legislation in the evenings.
If you're planning a single storey extension, a two storey rear extension, or a full renovation of a Medway home, our renovations and extensions team can tell you within a short site visit whether your plans are likely to fall under permitted development or need a full application, and what that means for your timeline and budget.
Get in touch with Meridian Contractors for a free, no-obligation chat about your extension before you commit to drawings.
Frequently asked questions
Do I need planning permission for a single storey rear extension in Medway?
Usually not, provided it stays within 4 metres of the rear wall for a detached house (3 metres for a semi-detached or terraced house), is no taller than 4 metres, and doesn't exceed 3 metres at the eaves within 2 metres of a boundary. Larger extensions, up to 8 metres or 6 metres, can use the prior approval route instead of a full application.
Do I need planning permission for a loft conversion in Medway?
Many loft conversions also fall under permitted development, subject to separate volume limits and rules on roof extensions and dormer windows, but this depends heavily on the type of conversion and whether your home is in a conservation area. Always get written confirmation rather than assuming.
What is an Article 4 Direction?
An Article 4 Direction is a local order that removes some or all permitted development rights in a specific area, usually a conservation area, so that changes which would normally be automatically allowed instead require a full planning application. Medway has Article 4 Directions covering areas including Upnor, Brompton, Gillingham Park and parts of Chatham and Rochester.
How much does a householder planning application cost in 2026?
£548 in 2026, rising to £575 from 8 December 2026, for alterations or an extension to a single dwelling house in England.
How long does it take to get planning permission in Medway?
The statutory target for a householder application is 8 weeks from validation, though complex applications or those needing neighbour consultation can take longer.
Can I extend my house without planning permission at all?
Yes, if the work fits within permitted development limits and your property doesn't have restricted rights (such as an Article 4 Direction, being a flat, or being a listed building). It's still worth getting written confirmation from the council or a Lawful Development Certificate so there's no ambiguity later, especially if you plan to sell.
Sources: Medway Council planning permission guidance and Article 4 Directions pages; Planning Portal permitted development guidance for extensions; Planning Geek 2026 planning fees guide.