The first question most homeowners ask before any building project is whether they need planning permission. For a large number of common projects, the answer is no. Permitted development rights allow you to extend, alter and improve your home within defined limits without making a formal planning application. Understanding those limits can save you months of waiting and several thousand pounds in fees and professional costs.
What follows covers permitted development for dwellinghouses in England. Scotland, Wales and Northern Ireland operate under separate planning legislation with different permitted development rules. Even within England, a number of restrictions can remove or modify your rights, so always verify your specific situation before starting work.
What Permitted Development Actually Means
Permitted development is planning permission granted by the government in advance, through the Town and Country Planning (General Permitted Development) (England) Order 2015, as amended. Rather than applying to your local authority case by case, the government has decided that certain types of development are broadly acceptable and has granted permission for them generically. Your job is to check that your proposal fits within the parameters set out in that order.
This is not a free-for-all. Every class of permitted development has limits, conditions and restrictions that you must satisfy. Breaching any of those conditions means the work is not permitted development, and you'll need retrospective planning permission or, if the council refuses it, potentially face an enforcement notice.
Extensions Under Permitted Development
Single-storey rear extensions are probably the most common permitted development project. The rules are:
For a detached house, a single-storey rear extension can extend up to 4 metres beyond the original rear wall. For any other house type (semi-detached, terraced), the limit is 3 metres. These limits apply without any prior approval process. Under the larger home extension scheme (prior approval), you can extend up to 8 metres for a detached house and 6 metres for others, but you must notify the council and allow 42 days for neighbours to object.
Other key limits for single-storey extensions: the height cannot exceed 4 metres (or the height of the original roof, whichever is lower), materials must be similar in appearance to the existing house, and no extension can be forward of the principal elevation or within 2 metres of a boundary if it exceeds 3 metres in height.
Two-storey extensions have tighter restrictions: maximum 3 metres beyond the original rear wall, at least 7 metres from the rear boundary, no balconies or roof terraces, and upper floor windows in the side elevation must be obscure-glazed and non-opening below 1.7 metres.
Loft Conversions
Adding roof space is permitted development in many cases. The volume allowed depends on house type: 40 cubic metres for a terraced house, 50 cubic metres for detached and semi-detached. The extension cannot project above the plane of the original roof slope that faces a highway, cannot be higher than the existing roof ridge, and any side-facing windows must be obscure-glazed.
Dormers are permitted on rear slopes. Hip-to-gable conversions (popular on end-of-terrace and semi-detached properties) are allowed under permitted development provided the volume and height limits are observed.
Outbuildings and Garages
Garden rooms, home offices, sheds, garages and similar outbuildings can be built without planning permission under Class E, provided:
- They are incidental to the enjoyment of the dwelling (not used as a separate home)
- They are not forward of the principal elevation
- Single-storey only, with a maximum eaves height of 2.5 metres and overall height of 3 metres (4 metres for a dual-pitched roof)
- If within 2 metres of a boundary, maximum height is 2.5 metres
- The total area of all outbuildings, extensions and other additions does not exceed 50% of the curtilage (the land around the original house, excluding the house itself)
The 50% rule catches people out. If you've already built extensions that cover significant ground area, a new outbuilding might push you over the limit even if it's modest in size.
When Permitted Development Doesn't Apply
There are several situations where your permitted development rights are removed or restricted:
Article 4 Directions. A local authority can remove permitted development rights in a specific area by issuing an Article 4 Direction. These are common in conservation areas, Areas of Outstanding Natural Beauty, and some designated housing areas. If your property is in an Article 4 area, work that would normally be permitted development requires a full planning application. Check with your council.
Listed buildings. If your property is listed, permitted development rights do not apply at all. Every alteration, extension or addition requires Listed Building Consent and often full planning permission as well. This includes internal alterations that affect the character of the building.
Flats and maisonettes. The dwellinghouse permitted development order does not apply to flats. If you own or occupy a flat, you need planning permission for any external alterations.
New build properties. Some new build developments have planning conditions that remove permitted development rights for the estate. Check your planning permission documents or ask your conveyancer to confirm.
Previous extensions. Permitted development limits apply to the original dwelling as built in 1948 (or as first built, if later). If the property has already been extended, those extensions may have used up some of your permitted development allowance.
Never assume. The rules have changed multiple times since 2015 and interpretations vary. If there's any doubt about whether your project is permitted development, get a Lawful Development Certificate from your local planning authority before starting work.
Lawful Development Certificates
A Lawful Development Certificate (LDC) is a formal, legally binding confirmation from the local planning authority that your proposed development is lawful and does not require planning permission. It costs roughly half the price of a planning application (around £100-£200) and provides certainty that your interpretation of the rules is correct.
You don't have to get one. Permitted development is permitted development with or without a certificate. But there are very good reasons to apply:
If you sell the property, buyers' solicitors will ask whether any building works have planning permission or are confirmed as permitted development. Without a certificate, you may have difficulty completing the sale, or you may need to obtain retrospective confirmation at that point (which is harder to do years after completion).
If a neighbour or the council challenges the work, a certificate proves that you acted lawfully. Without one, you're relying on your own reading of the regulations, which may or may not be correct.
The LDC application process involves submitting drawings and a description of the work to the council. They have 8 weeks to respond. If they agree the work is lawful, they issue the certificate. If they disagree, they'll explain why, which at least tells you what you need to address.
Prior Approval
Some classes of permitted development require you to notify the local authority before starting and wait for confirmation that prior approval is not required (or, if it is required, to obtain that approval). The larger home extension scheme is one example. Solar panels on a house are another where conditions and prior approval can apply in some circumstances.
Prior approval is not planning permission and it's not an LDC. It's a lighter-touch process where the council checks specific matters (typically design, transport, flooding or contamination, depending on the development type) but cannot refuse the development on the basis of general planning policy.
The key point: if prior approval is required for your development and you don't apply for it, the work may be unlawful even if it meets all the dimensional limits. Check which development classes require prior approval notification before proceeding.