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Hertfordshire · 26 towns

Garden rooms in Hertfordshire

Garden room quotes from local builders in 26 Hertfordshire towns, from Berkhamsted and Tring in the west to Bishop's Stortford in the east. Pick your town for its planning note, or send one request and up to 3 builders who already work near you will quote.

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Cedar-clad garden office with black-framed glazing at the end of a lawn, lavender borders in golden light
Cedar-clad garden office with full-height glazing, lit by late-afternoon sun

Garden rooms in Hertfordshire: how it works

Hertfordshire has ten district and borough councils, and the one that decides whether your garden room needs permission is your local planning authority, not the county. We cover towns in all ten: Dacorum Borough Council, St Albans City and District Council, Watford Borough Council, Three Rivers District Council, Hertsmere Borough Council, Welwyn Hatfield Borough Council, East Herts District Council, North Herts Council, Stevenage Borough Council and Broxbourne Borough Council. The national permitted development rules are the same everywhere in England. What differs from street to street is whether your home sits in a conservation area, has had its rights removed by an Article 4 direction, or lies in the Chilterns National Landscape.

That is why this page is built around towns. Under each council below you will find every Hertfordshire town we cover, a short planning line taken from the national planning data, and links to the garden office, gym, studio and annexe pages for that town. Where we have not found something in the register, we say so, and we tell you which council to ask.

Hertfordshire towns we cover

26 towns, grouped by the council that decides planning applications. Each planning line comes from the national planning data queried for the area within about 1.5 km of the town centre, so treat it as a pointer and confirm your own address with the council.

Dacorum Borough Council

Planning information: Dacorum Borough Council planning pages. 5 towns: Berkhamsted, Northchurch, Tring, Hemel Hempstead and Kings Langley.

St Albans City and District Council

Planning information: St Albans City and District Council planning pages. 2 towns: Harpenden and St Albans.

Watford Borough Council

Planning information: Watford Borough Council planning pages. 1 town: Watford.

Three Rivers District Council

Planning information: Three Rivers District Council planning pages. 2 towns: Rickmansworth and Chorleywood.

Hertsmere Borough Council

Planning information: Hertsmere Borough Council planning pages. 4 towns: Bushey, Radlett, Borehamwood and Potters Bar.

Welwyn Hatfield Borough Council

Planning information: Welwyn Hatfield Borough Council planning pages. 3 towns: Hatfield, Welwyn Garden City and Welwyn.

East Herts District Council

Planning information: East Herts District Council planning pages. 3 towns: Hertford, Ware and Bishop's Stortford.

North Herts Council

Planning information: North Herts Council planning pages. 3 towns: Hitchin, Letchworth Garden City and Baldock.

Stevenage Borough Council

Planning information: Stevenage Borough Council planning pages. 1 town: Stevenage.

Broxbourne Borough Council

Planning information: Broxbourne Borough Council planning pages. 2 towns: Hoddesdon and Cheshunt.

Chilterns, Green Belt and conservation areas in Hertfordshire

The west of Hertfordshire sits on the edge of the Chilterns. The Chilterns National Landscape (formerly an Area of Outstanding Natural Beauty) reaches within about 1.5 km of the centre of Berkhamsted, Northchurch, Tring and Chorleywood. Inside the designation the permitted development rules are tighter: an outbuilding between the side wall of the house and the boundary needs planning permission, and anything more than 20 m from the house is limited to 10 m² in total. The designation is drawn on a map, not by town name, so a garden in Tring may be inside it while one in the same road is not. Check your exact address. The Chilterns Conservation Board publishes planning advice for the area.

Green Belt is the other label people worry about. Green Belt land lies within about 1.5 km of the centre of 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 and Cheshunt. Green Belt does not by itself remove your outbuilding rights. It matters mainly if an application is needed, because the council then weighs the proposal against Green Belt policy. If your room stays within permitted development, the Green Belt label does not change that. Our Green Belt guide goes through it.

Conservation areas are the most common restriction in Hertfordshire. The national register lists them in or near most of our towns, and St Albans has the longest list. In a conservation area an outbuilding at the side of the house needs planning permission, and a council can go further with an Article 4 direction. In the St Albans data, Article 4 directions for Cunningham Avenue, Sopwell Lane and Albert Street, and Verulam and Fishpool Street remove the right to build outbuildings without permission. If you live near one, ask St Albans City and District Council before you order.

Sources: Planning Portal outbuildings, GOV.UK technical guidance, Chilterns Conservation Board planning advice. Checked 21 October 2026.

More detail: conservation areas and the Chilterns, garden rooms in the Green Belt, lawful development certificates.

Permitted development limits for a garden room

Outside the tighter areas above, an outbuilding is normally permitted development if it meets all of these limits. They are national rules for England, so they apply across Hertfordshire.

  • It must be single storey, with eaves no higher than 2.5 m.
  • It can be up to 4 m high with a dual-pitched roof, or 3 m high with any other roof.
  • If any part is within 2 m of a boundary, the whole building can be no higher than 2.5 m.
  • Height is measured from the highest ground right next to the building.
  • It must not sit forward of the front wall of the house (the principal elevation).
  • All extensions and outbuildings together must cover no more than half the land around the original house.
  • No verandas, balconies or raised platforms. A platform must be no higher than 0.3 m.
  • The use must be "incidental" to the house. A bedroom, bathroom or kitchen does not count.

General guidance for England, not legal advice. See our planning permission guide and building near a boundary.

Building regulations bands

Building regulations are separate from planning. For a detached garden room the floor area and the sleeping question decide it. Building control sits with your council in Hertfordshire, so the same office that answers planning questions can usually answer these.

  • Under 15 m² floor areaBuilding regulations do not normally apply, as long as nobody sleeps in it.
  • 15 m² to 30 m²Building regulations do not normally apply, as long as nobody sleeps in it and it is either at least 1 m from every boundary or built mostly of non-combustible materials.
  • Over 30 m²Outside these exemptions, so building regulations approval is normally needed.
  • Any size with sleeping spaceThe exemptions do not apply once a room has sleeping accommodation.

Source: Planning Portal building regulations. Electrics must meet Part P: Planning Portal electrics. Read building regulations for garden rooms.

What a garden room costs in Hertfordshire

These are guide figures for a fitted room including VAT, with easy access and no extras. They come from the same figures as our cost calculator. They are not quotes: your written quotes depend on your plot.

Guide prices by room type and size
RoomSmall (about 3 × 3 m)Medium (about 4 × 3 m)Large (5 × 4 m and up)
Garden office£12,500 to £18,000£18,000 to £29,000£32,000 to £58,000
Garden gym£13,500 to £20,000£19,000 to £31,000£33,000 to £60,000
Garden studio£13,500 to £20,500£19,000 to £31,500£33,000 to £60,500
Garden annexe£16,500 to £25,000£22,000 to £36,000£36,000 to £65,000

Extras that add to the price

Guide additions, added to the room price
ExtraAddsWhat it is for
Reinforced floor£1,500 to £3,000For racks and heavy kit
Sound insulation£1,000 to £2,500Playing or recording
Shower room / WC£5,000 to £9,000Needs drainage
Kitchenette£2,500 to £5,000Sink, worktop, water
Air-con£1,500 to £3,000Heating and cooling
Extra glazing / roof lights£1,500 to £4,000More daylight
Long power / water run£1,000 to £3,000Far from the house
Through the house£1,000 to £2,500Everything is carried through the house, which adds labour time.

Guide figures for fitted rooms, including VAT. Not a quote: your written quotes depend on your plot. Read how garden room prices are built, or how big a garden room should be.

Garden office, gym, studio or annexe in Hertfordshire

Garden offices in Hertfordshire

A warm, quiet room for working from home, a short walk from the back door. Tell us what you need and up to 3 local builders quote.

The simplest build: an insulated room with power, lights and heating. Guide price from £16,500, fitted. It usually adds: armoured power cable dug in from the house; data cable or mesh Wi-Fi for video calls; heater or air-con for year-round use.

Most garden offices fit within permitted development if they meet the height, position and size limits.

BerkhamstedNorthchurchTringHemel HempsteadKings LangleyHarpendenAll garden offices

Garden gyms in Hertfordshire

Train when you want, steps from the house. A garden gym needs a strong floor and good air. Up to 3 local builders quote for yours.

Heavy kit and hard training need a stronger, cooler room. Guide price from £21,000, fitted. It usually adds: reinforced floor or concrete slab for racks and dropped weights; ventilation or air-con: a working room heats up fast; rubber flooring, mirrors and extra sockets.

A private home gym is normally incidental to the house, so permitted development can apply.

BerkhamstedNorthchurchTringHemel HempsteadKings LangleyHarpendenAll garden gyms

Garden studios in Hertfordshire

Room to paint, play, record or make, and leave it all out at night. Up to 3 local builders quote for a studio that suits your work.

Light and sound decide the spec. Guide price from £18,500, fitted. It usually adds: sound insulation if you play or record; bigger glazing or roof lights for even daylight; a sink needs a water supply and waste run.

A hobby studio for your household is normally incidental to the house, so permitted development can apply.

BerkhamstedNorthchurchTringHemel HempsteadKings LangleyHarpendenAll garden studios

Garden annexes in Hertfordshire

A place for family or guests to stay, in the garden but close to home. Annexes have the most rules, so local builders who know them matter.

A room someone sleeps in is the biggest step up. Guide price from £39,000, fitted. It usually adds: building regulations sign-off for sleeping space; shower room or WC with drainage to the main sewer; kitchenette, more heating and often planning permission.

Permitted development does not cover an outbuilding used as a bedroom, bathroom or kitchen. That is "primary living accommodation".

BerkhamstedNorthchurchTringHemel HempsteadKings LangleyHarpendenAll garden annexes

Garden rooms in Hertfordshire: questions people ask

Do I need planning permission for a garden room in Hertfordshire?

Often not. In England most garden rooms count as permitted development if they stay within the limits on height, position and size, and the use is incidental to the house. The rules are tighter in conservation areas, in the Chilterns National Landscape, on listed properties and where a council has made an Article 4 direction. Which council applies depends on your town: in Hertfordshire that is one of 10 councils. Your town page has a local planning note.

Which council do I ask about a garden room in Hertfordshire?

The council for your town. In our Hertfordshire towns that is Dacorum Borough Council, St Albans City and District Council, Watford Borough Council, Three Rivers District Council, Hertsmere Borough Council, Welwyn Hatfield Borough Council, East Herts District Council, North Herts Council, Stevenage Borough Council and Broxbourne Borough Council. Each is listed above with a link to its planning pages. For an exact answer about your address, ask that council before you order.

How much does a garden room cost in Hertfordshire?

Guide figures for a fitted medium room (about 4 × 3 m) start at £18,000 to £29,000 for a garden office, including VAT. Small rooms (about 3 × 3 m) and large rooms (5 × 4 m and up) are in the price table above. These are guide figures, not quotes. Foundations, glazing, cladding, the length of the power and water run and access to the garden all move the real price, and your written quotes show it for your plot.

Is my Hertfordshire home in the Chilterns National Landscape?

The designation is drawn on a map, not by town. In our data it reaches within about 1.5 km of the centre of Berkhamsted, Northchurch, Tring and Chorleywood. If your home is inside it, an outbuilding at the side of the house needs planning permission, and one more than 20 m from the house is limited to 10 m² in total. Check your address with your council or the Chilterns Conservation Board.

Does Green Belt stop me building a garden room in Hertfordshire?

Not by itself. Green Belt does not remove permitted development rights for outbuildings. It matters if you need to apply for planning permission, because the council then considers Green Belt policy. If your room fits within permitted development, you do not need to apply. If you are not sure, a lawful development certificate from your council confirms it in writing.

Do I need building regulations approval?

Not normally for a detached room under 15 m² with no sleeping space. Between 15 m² and 30 m² it is normally exempt if nobody sleeps in it and it is at least 1 m from every boundary or built mostly of non-combustible materials. Over 30 m², or with any sleeping space, building regulations approval is normally needed. Electrics still need to meet Part P, so use a registered electrician.

Can someone live or sleep in a garden room?

A room that people sleep in is a bigger step. Permitted development covers rooms used incidentally to the house, and a bedroom, bathroom or kitchen does not count as incidental. Sleeping space also takes the room outside the building regulations exemptions. An annexe usually needs planning permission and building regulations sign-off. Our annexe guide explains the rules, and your council has the final say.

How many quotes will I get, and what does it cost?

Up to 3, from builders who already work in your town. The service is free for homeowners. Builders pay us a fee for each introduction, and we never sell your details to anyone else.

Guides for Hertfordshire homeowners

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