Garden room planning permission in Herts & Bucks

The short answer

Most garden rooms count as "permitted development". That means you can build without a planning application, as long as you stay inside a set of limits. The national rule is called Class E (of Part 1 of Schedule 2 to the General Permitted Development Order). It covers height, position, size, use and the type of land.

If you go past any limit, you need planning permission. That is common, not a problem. It adds time and a fee, and the council decides on the merits. Building regulations are a separate system again: see building regulations for garden rooms.

This page uses the GOV.UK technical guidance for householders and the Planning Portal outbuildings page. It is general guidance for England, not legal advice, and your council decides how the rules apply to your plot.

Every Class E limit

A garden room is permitted development only if it meets all of these at once.

A garden office or garden gym no higher than 2.5 m stays within the height rule even right up to the fence. The near-boundary guide goes deeper on the 2 m strip, and our sizes guide shows what fits.

Worked check: a 4 × 3 m flat-roof office

• Single storey: yes.
• Flat roof, so the overall limit is 3 m, and the eaves limit is 2.5 m. A flat roof with a 2.5 m wall and a slight fall stays under both.
• Set 1 m from the back fence: it is inside the 2 m strip, so the whole building must be no higher than 2.5 m. A 2.6 m room fails here.
• Moved 2 m or more from every boundary: the 3 m limit applies instead.

That is why moving a room a metre or so can change the answer. Measure from the boundary of the curtilage, not from the fence panel, if the two differ.

Designated land

Some land is "designated" (the technical term is article 2(3) land): National Parks, the Broads, areas of outstanding natural beauty (AONB), conservation areas and World Heritage Sites. The Planning Portal lists the extra rules like this.

• Side of the house. On designated land, a building, enclosure, pool or container on land between a side wall of the house and the boundary of the curtilage needs planning permission.
• Far from the house. In a National Park, the Broads, an AONB or a World Heritage Site, the total ground covered by buildings more than 20 m from any wall of the house is limited to 10 m².
• Roof extensions. Not permitted development on designated land, which matters for the house, not for a separate garden room.

In our area the usual designated land is conservation areas and the Chilterns National Landscape (an AONB). A garden room at the back of the garden, behind the house, is generally unaffected by the side-of-house rule. A narrow side garden is where conservation area rules most often bite. See our guide to conservation areas and the Chilterns.

Article 4 directions and old conditions

Government guidance is clear that a council can remove permitted development rights in all or part of its area by issuing an Article 4 direction. A past planning condition on the original permission for a house can also remove them for that one house. A new estate is the usual example: the developer's permission may have removed outbuilding rights.

The national planning register lists three Article 4 areas near the centre of St Albans that remove the Class E right: Cunningham Avenue, Sopwell Lane and Albert Street, and Verulam and Fishpool Street. If your house is on one of those streets you apply for planning permission even for a garden room that would otherwise pass every limit. St Albans also has 28 conservation areas within about 1.5 km of its centre, so the council's own advice on outbuildings is worth reading.

Other Article 4 directions do not touch outbuildings. For example, the Article 4(2) direction at Chorleywood Common covers windows, chimneys, front boundaries and hardstanding, and the council's page does not mention outbuildings. Check by street, not by town. The register can be incomplete, and a direction can be made after our data was pulled. Ask your council whether any direction covers your address before you order.

Listed buildings

If your house is listed, any outbuilding within its curtilage needs planning permission. The same applies to a building sited in the grounds of a listed neighbour if it is within the same curtilage, which is a question for the council. A listed building also needs listed building consent for works to the building itself, which is a separate matter. If you are unsure, ask the council before you spend money on design.

Green Belt

Green Belt does not by itself remove permitted development. The Class E limits and conditions in the government guidance do not list Green Belt among them. A garden room that meets Class E can be built under permitted development in Green Belt land in the same way as elsewhere.

Green Belt matters when you do need a planning application, because national policy on Green Belt then applies to the decision. Large parts of Hertfordshire and Buckinghamshire are Green Belt, including land close to St Albans, Hemel Hempstead and Chorleywood. Read our Green Belt guide for what to expect, and confirm with your council, because we have inferred this from the government guidance rather than from a statement about Green Belt in it.

Annexes, sleeping and other uses

Permitted development only covers a purpose incidental to the enjoyment of the house. The technical guidance gives examples of what that includes: sheds, storage buildings, garages and decking. It says a purpose incidental to a house does not cover normal residential uses, such as separate self-contained accommodation or the use of an outbuilding for primary living accommodation such as a bedroom, bathroom or kitchen.

In practice:

• Home office, gym, music or art studio, playroom, hobby space: normally incidental.
• Occasional guest use of a room that is mainly a studio: grey area. Ask your council, and see the garden annexe rules.
• A bedroom, a bathroom or a kitchen, or a self-contained home for a relative: not incidental. It usually needs a planning application, and building regulations approval.
• Letting the room out or running a business with staff or visitors: a change of use that may need permission. See garden office tax and ask your council.

For a relative who will sleep in the building, read the annexe for elderly parents guide. Cost-wise, a sleeping room is the biggest step up, as the garden room costs guide shows.

Lawful development certificate: how to get certainty

A lawful development certificate (LDC) is an optional decision from your council that a proposed building is lawful for planning purposes. If you build exactly what the certificate describes, it is presumed lawful unless something material changes before work starts.

The process

• Describe the building precisely: size, height, roof, position on the plot and use. Vague descriptions can justify a refusal.
• Send a scaled plan and elevations with the council's application form and fee.
• The council tests the facts against planning law. Planning merits are not relevant, and neighbours have no right to be consulted.
• If it is satisfied, it grants the certificate. If it refuses, you can appeal to the Secretary of State in certain circumstances.

The fee

GOV.UK guidance says the fee for a certificate for a proposed development is half the fee for applying for planning permission for the same development. Councils publish the pound figure, so check yours, or use the council link below. We have not quoted a figure here because it is a national scale that changes.

The limits

• A certificate covers planning law only. It does not remove the need for building regulations or listed building consent.
• A material change before you start can undo the presumption, for example a new Article 4 direction or an amendment to permitted development rights.

It is worth having when the answer is close, when you are near a 2 m boundary or the 50% limit, or when you may sell and want paper for the buyer's solicitor. Our LDC guide covers the decision.

What happens if you build without permission

Carrying out development without the required planning permission is a breach of planning control. So is breaking a limit or condition of permitted development. Here is how the system works, according to GOV.UK and Planning Portal guidance.

• The council can invite you to submit a retrospective planning application for the work already done. It will be judged in the usual way, so it is not granted automatically.
• If the retrospective application is refused, the council can issue an enforcement notice that requires you to put things back as they were.
• Councils have time limits for enforcement. For operational development, such as erecting a building, that was substantially completed on or after 25 April 2024, the general time limit is 10 years. For work completed before that date it is 4 years. Deliberate concealment can extend the period.

The sensible route is to settle the question first. A room that needs permission and has none can also trouble a house sale, since the buyer's solicitor will ask. If you find yourself in this position, speak to your council's planning enforcement team early, and consider a planning adviser.

What this means in Herts and Bucks

Many towns we cover have conservation areas, listed homes or protected countryside nearby. The planning notes on each town page come from the national planning data register for roughly a 1.5 km box around the town centre, so they are a guide to what is nearby, not a ruling on your address.

• Much of Berkhamsted is in a conservation area, and the land around the town is part of the Chilterns National Landscape. Dacorum Borough Council handles planning there, and in Tring and Hemel Hempstead.
• In St Albans and Harpenden, planning goes to St Albans City and District Council.
• In Chesham, Amersham, Great Missenden and Beaconsfield, planning goes to Buckinghamshire Council.

Planning page for each council

Use these to find your address on the council's conservation area, Article 4 and planning maps, to ask a planning question, or to check the fee table for a lawful development certificate.

Not sure which council covers you? Use the Planning Portal local planning authority finder.

Six checks before you commit

• Is your home a house, not a flat, maisonette or a converted building?
• Is it listed, or in a conservation area or the Chilterns National Landscape?
• Has the council removed permitted development rights with an Article 4 direction, or an old planning condition?
• Will the room be more than 2.5 m high, or within 2 m of a boundary?
• With the room added, will all the buildings in the garden cover more than half of the land around the original house?
• Will anyone sleep in it?

If any answer is yes, or you are not sure, ask your council first. For certainty, apply for a lawful development certificate.

Planning notes by town

Each town page carries a planning note for that area. Hertfordshire:

Berkhamsted, Northchurch, Tring, Hemel Hempstead, Kings Langley, Harpenden, St Albans, Watford, Rickmansworth, Chorleywood, Bushey, Radlett, Borehamwood, Potters Bar, Hatfield, Welwyn Garden City, Welwyn, Hertford, Ware, Hitchin, Letchworth Garden City, Stevenage, Baldock, Bishop's Stortford, Hoddesdon, Cheshunt.

Buckinghamshire:

Chesham, Amersham, Great Missenden, Aylesbury, Beaconsfield, Gerrards Cross, High Wycombe, Marlow, Princes Risborough, Wendover, Buckingham, Little Chalfont, Chalfont St Giles, Chalfont St Peter.