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Garden annexes in Berkhamsted

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

Cedar garden annexe at dusk with string lights, a made double bed and a lamp glowing through the glass

What a garden annexe is for

Garden annexes near me in Berkhamsted HP4

If you searched for garden annexes near you in Berkhamsted, you are in the right place. Garden Room Match covers Berkhamsted and the HP4 postcode area in Hertfordshire, and it works the way a short phone call would: you tell us about your garden and what you want to build, and we pass the request to builders who already work around Berkhamsted.

We do not build anything ourselves. What we do is match you with up to 3 local builders who then visit for free, measure up and send written quotes. The choice of builder, and whether to go ahead at all, stays with you.

A garden annexe in Berkhamsted is a popular project because a teenager who wants their own space. Every request is read by a person on our side before it goes to builders, so a postcode in HP4 that is outside a builder's range does not get passed on by mistake.

Local garden annexe builders in Berkhamsted

A garden annexe is built on your plot, in your soil, under your council's rules. The builders we match with you work in Berkhamsted and nearby, so they have usually met the same planning officers, ground and access problems before.

Every builder we work with is insured and established: public liability cover and three or more years trading. They give written quotes, so you compare the same things across 3 quotes instead of three different conversations. There is no fee to you; builders pay for introductions. We cannot promise a particular builder will be free on your dates, which is why you get up to 3 to choose from.

Cedar-lined garden snug with a linen sofa, wool rug and small wood-burning stove beside glazed doors, an example of the kind of garden annexe builders near Berkhamsted HP4 are asked for
Cedar-lined garden snug with a linen sofa, wool rug and wood-burning stove. Design idea, not a real project.

How it works in Berkhamsted: three steps

  1. 1

    Tell us about your garden

    Answer a few questions: the room you want (garden annexe), roughly how big, and your HP4 postcode. It takes about a minute and costs nothing.

  2. 2

    Up to 3 Berkhamsted builders visit

    We pass your request to up to 3 builders who work near Berkhamsted. Each visits for free, measures the plot, checks access and asks what you want from the room.

  3. 3

    Compare written quotes

    You get written quotes to compare like for like. Pick one, ask questions, or walk away. Expect to hear back within 48 hours.

What a garden annexe costs in Berkhamsted: guide prices by size

The table below shows guide prices for a fitted garden annexe in Hertfordshire, including VAT. They are the same figures our cost calculator uses, so a price here matches the number you see there. They are guide figures, not quotes: your written quotes from Berkhamsted builders show the real price for your plot.

A room someone sleeps in needs building regulations sign-off and more heating. For a garden annexe the calculator adds £4,000 to £7,000 on top of the size price. Typical price: from £39,000, fitted, including VAT.

Guide figures for fitted rooms, including VAT. Not a quote: your written quotes depend on your plot. Prices assume easy access to the garden. If materials have to be carried through the house, the calculator adds £1,000 to £2,500.

Guide prices for a garden annexe by size in Berkhamsted
SizeGarden annexe guide price
SmallAbout 3 × 3 m£16,500 to £25,000
MediumAbout 4 × 3 m£22,000 to £36,000
Large5 × 4 m and up£36,000 to £65,000

Guide figures including VAT, rounded to the nearest £500 as in the calculator. Not a quote.

What a garden annexe adds to the basic build

A room someone sleeps in is the biggest step up.

  • Building regulations sign-off for sleeping space
  • Shower room or WC with drainage to the main sewer
  • Kitchenette, more heating and often planning permission

Common extras and what they add

ExtraAdds (guide)
Reinforced floorFor racks and heavy kit£1,500 to £3,000
Sound insulationPlaying or recording£1,000 to £2,500
Shower room / WCNeeds drainage£5,000 to £9,000
KitchenetteSink, worktop, water£2,500 to £5,000
Air-conHeating and cooling£1,500 to £3,000
Extra glazing / roof lightsMore daylight£1,500 to £4,000
Long power / water runFar from the house£1,000 to £3,000
Through the houseMaterials carried in by hand£1,000 to £2,500

Work out your own figure in the cost calculator · Garden room costs guide

What affects the price of a garden annexe on a Berkhamsted plot

Size sets the starting point, but the plot decides the rest. On a typical Berkhamsted garden the biggest swings come from foundations, the length of the power and water run, and the route materials take to reach the back lawn.

Before you compare quotes, check that each one covers the same things from this list, cheapest to dearest: size and height, foundations: ground screws, pads or a slab, cladding and roof finish, amount and type of glazing, distance for power, water and drains and access: can materials reach the garden?. A quote that leaves one of these out is not the same job as one that includes it.

As a worked example, a medium garden annexe with shower room / wc and kitchenette comes to £29,500 to £50,000 in the calculator. Use the cost calculator to build your own combination.

Cedar-clad garden office with black-framed glazing at the end of a lawn, lavender borders in golden light, an example of the kind of garden annexe builders near Berkhamsted HP4 are asked for
Cedar-clad garden office with full-height glazing, lit by late-afternoon sun. Design idea, not a real project.

Planning in Berkhamsted: check before you build

The national register lists 2 conservation areas within about 1.5 km of the centre: Berkhamsted and Northchurch; on designated land such as a conservation area, an outbuilding at the side of a house needs planning permission. The Chilterns National Landscape (AONB) reaches to within about 1.5 km of the centre, so check whether your garden falls inside it. Green Belt land lies within about 1.5 km; Green Belt does not by itself remove outbuilding rights and matters only if an application is needed. No register entry within that distance removes the outbuilding right, but the register can be incomplete, so check your street with Dacorum Borough Council.

Planning applications in Berkhamsted go to Dacorum Borough Council. If you are unsure, ask the council or apply for a lawful development certificate, which confirms in writing that a design is permitted development.

What your builder checks for your plot

  • The height of the room, and how near it is to your boundary
  • How far it is from the house, and its floor area
  • Whether your home is in a conservation area or listed
  • Whether anyone will sleep in it, because building regulations then apply

General guidance, not legal advice. Check the rules on the Planning Portal and with Dacorum Borough Council.

Planning a garden annexe in Berkhamsted: points for this room

  • Permitted development does not cover an outbuilding used as a bedroom, bathroom or kitchen. That is "primary living accommodation".
  • So an annexe someone sleeps in usually needs a planning application. Check with your council.
  • Councils often approve annexes on the basis that they stay linked to the main house, not a separate home. Check with your council.
  • Sleeping space removes the building regulations exemptions, so building control sign-off is needed at any size.
  • A shower room or WC needs drainage, and new circuits are notifiable under Part P.

Permitted development limits for a garden annexe in Berkhamsted

The national permitted development rules for outbuildings decide most Berkhamsted projects. They are listed here so you can check a design before you ask for quotes; planning applications in Berkhamsted go to Dacorum Borough Council.

  • 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.

Where the limits are tighter near Berkhamsted

Some land has stricter rules than the national limits. In Hertfordshire the ones that come up most are listed below. Whether your address is inside one is something to confirm with Dacorum Borough Council.

Conservation areas

An outbuilding between the side wall of the house and the boundary needs planning permission.

National Landscapes (AONB)

The side-wall rule applies. Anything more than 20 m from the house is limited to 10 m² in total. The Chilterns National Landscape covers parts of both Hertfordshire and Buckinghamshire, so check whether your address is inside it.

Listed buildings

Any outbuilding within the grounds of a listed building needs planning permission.

Flats and maisonettes

These permitted development rights do not apply.

Article 4 directions and old conditions

A council can remove permitted development rights in an area, or a past planning condition can remove them for one house.

Building regulations for a garden annexe in Berkhamsted

Building regulations are separate from planning permission. They cover how the room is built, and whether you need them depends mostly on floor area and whether anyone sleeps in it. These are the bands for detached outbuildings in England.

Under 15 m² floor area

Building regulations do not normally apply, as long as nobody sleeps in it.

15 m² to 30 m²

Building 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 m²

Outside these exemptions, so building regulations approval is normally needed.

Any size with sleeping space

The exemptions do not apply once a room has sleeping accommodation.

Electrics matter whatever the size. A new circuit to a garden annexe is notifiable under Part P, so use a registered electrician or ask your builder who certifies it. Building regulations guide

Garden room builder measuring a lawn with a tape, wooden pegs and string lines before a free site visit quote, an example of the kind of garden annexe builders near Berkhamsted HP4 are asked for
A garden room builder measures the plot with a tape, pegs and string lines. Design idea, not a real project.

Other garden room types in Berkhamsted

Not sure a garden annexe is the right room? The same Berkhamsted plot can take any of these. Each page shows prices, planning and questions for Berkhamsted.

All garden rooms in Berkhamsted

Villages and areas we cover near Berkhamsted

Berkhamsted sits close to Northchurch, Tring, Hemel Hempstead and Kings Langley, and builders move between them. We also match homes in Northchurch and Potten End through this page.

Each nearby town has its own page with its own council and planning notes: Northchurch, Tring, Hemel Hempstead, Kings Langley and Chesham. Rules and councils differ even a few miles apart, so check the page for your own town too.

Guides to read next

Garden annexes in Berkhamsted: questions people ask

Do I need planning permission for a garden annexe in Berkhamsted?

The national register lists 2 conservation areas within about 1.5 km of the centre: Berkhamsted and Northchurch; on designated land such as a conservation area, an outbuilding at the side of a house needs planning permission. The Chilterns National Landscape (AONB) reaches to within about 1.5 km of the centre, so check whether your garden falls inside it. Green Belt land lies within about 1.5 km; Green Belt does not by itself remove outbuilding rights and matters only if an application is needed. No register entry within that distance removes the outbuilding right, but the register can be incomplete, so check your street with Dacorum Borough Council. Planning applications in Berkhamsted go to Dacorum Borough Council.

How much does a garden annexe cost in Berkhamsted?

Guide price for a fitted garden annexe: £16,500 to £25,000 for a small room, £22,000 to £36,000 for a medium room and £36,000 to £65,000 for a large one, including VAT. These are not quotes. Your written quotes from Berkhamsted builders show the real figure for your plot.

Does a garden annexe in Berkhamsted need building regulations?

Not normally under 15 m² if nobody sleeps in it. From 15 m² to 30 m² it is also normally exempt if it is at least 1 m from every boundary or built mostly of non-combustible materials. Over 30 m², or with any sleeping space, approval is normally needed. You can use the local authority building control service for your area or a registered building control approver.

How many garden annexe quotes will I get in Berkhamsted?

Up to 3 written quotes from builders who already work in Berkhamsted and nearby areas such as Northchurch, Tring, Hemel Hempstead. Each one visits for free first. The service is free for homeowners.

Which council handles planning in Berkhamsted?

Dacorum Borough Council. Your builder checks the rules for your plot before you commit.

Do you cover villages near Berkhamsted?

Yes. We match homes across Northchurch, Potten End, Tring, Hemel Hempstead, Kings Langley and Chesham. Enter your postcode in the form and we confirm whether builders cover your address.

What does Garden Room Match cost me?

Nothing. The service is free for homeowners. Builders may pay us a fee for each introduction.

How long does a garden annexe take to build?

Most installs take 4 to 8 weeks once the design is agreed. Lead times change through the year.

Garden room with bifold doors folded open onto a hardwood deck with loungers on a summer evening, an example of the kind of garden annexe builders near Berkhamsted HP4 are asked for
Garden room with bifold doors open onto a hardwood deck on a summer evening. Design idea, not a real project.