What a garden annexe is for
- Guests or family who come to stay
- An older parent living close by
- A teenager who wants their own space
- A bedroom with a shower room and kitchenette
Garden annexes near me in Welwyn Garden City AL7
Looking for garden annexes near Welwyn Garden City AL7? This page is for homeowners in Welwyn Garden City, Hertfordshire. You describe the room you want, and we match you with builders who already take on work in and around Welwyn Garden City, so nobody has to drive across the county to see your garden.
Garden Room Match is a matching service, not a builder. Up to 3 local builders get your request, each visits your Welwyn Garden City plot for free, and each sends a written quote you can compare like for like.
A garden annexe in Welwyn Garden City is a popular project because guests or family who come to stay. Every request is read by a person on our side before it goes to builders, so a postcode in AL7 that is outside a builder's range does not get passed on by mistake.
Local garden annexe builders in Welwyn Garden City
The builders we work with already take on garden annexes in Welwyn Garden City and the area around it. That matters because a builder who knows Hertfordshire knows how Welwyn Hatfield Borough Council handles outbuildings, which ground is clay or chalk, and which roads are awkward for a delivery lorry.
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.
How it works in Welwyn Garden City: three steps
- 1
Tell us about your garden
Answer a few questions: the room you want (garden annexe), roughly how big, and your AL7 postcode. It takes about a minute and costs nothing.
- 2
Up to 3 Welwyn Garden City builders visit
We pass your request to up to 3 builders who work near Welwyn Garden City. Each visits for free, measures the plot, checks access and asks what you want from the room.
- 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 Welwyn Garden City: guide prices by size
These are guide prices, not quotes. They come from the same size bands as our garden room cost calculator and include VAT. A Welwyn Garden City builder who has seen your garden will give you a firmer figure in writing.
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.
| Size | Garden 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
| Extra | Adds (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 Welwyn Garden City plot
Builders in Welwyn Garden City tell us the same thing every time: the building is only part of the price. The rest is ground, access and services, and those are different on every road in AL7.
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.
Planning in Welwyn Garden City: check before you build
The national register lists 3 conservation areas within about 1.5 km of the centre: Ayot Green, Beehive and Welwyn Garden City; on designated land such as a conservation area, an outbuilding at the side of a house needs planning permission. 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 Welwyn Hatfield Borough Council.
Planning applications in Welwyn Garden City go to Welwyn Hatfield 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 Welwyn Hatfield Borough Council.
Planning a garden annexe in Welwyn Garden City: 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 Welwyn Garden City
Most garden annexes in England do not need a planning application because they count as permitted development, but only inside a set of limits. These are the national limits for outbuildings. They apply to Welwyn Garden City homes as they do everywhere else in England, and your builder checks them against your plot before you commit.
- 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 Welwyn Garden City
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 Welwyn Hatfield 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 Welwyn Garden City
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
Other garden room types in Welwyn Garden City
Not sure a garden annexe is the right room? The same Welwyn Garden City plot can take any of these. Each page shows prices, planning and questions for Welwyn Garden City.
Garden offices in Welwyn Garden City
The simplest build: an insulated room with power, lights and heating. From £16,500, fitted, including VAT.
Read more →Garden gyms in Welwyn Garden City
Heavy kit and hard training need a stronger, cooler room. From £21,000, fitted, including VAT.
Read more →Garden studios in Welwyn Garden City
Light and sound decide the spec. From £18,500, fitted, including VAT.
Read more →All garden rooms in Welwyn Garden City
Villages and areas we cover near Welwyn Garden City
We match Welwyn Garden City homeowners with builders who work across Handside, Panshanger, Hatfield, Welwyn, Hertford and Harpenden. If your home is on the edge of Welwyn Garden City, or in a village outside it, the same page and the same form apply: use the AL7 postcode of your house.
Each nearby town has its own page with its own council and planning notes: Hatfield, Welwyn, Hertford and Harpenden. Rules and councils differ even a few miles apart, so check the page for your own town too.
Guides to read next
Garden room planning permission in Herts & Bucks
Do you need planning permission for a garden room? The permitted development limits for outbuildings in England, and where Herts & Bucks rules are tighter.
Read the guide →Garden room costs: how a price is built
How garden room prices are built: size, foundations, cladding, glazing, services and access, plus what offices, gyms, studios and annexes add.
Read the guide →Garden annexe rules: planning and building regs
Planning permission and building regulations for a garden annexe in England: incidental use, sleeping space, and what to ask your council.
Read the guide →Garden annexe for elderly parents: planning, council tax and care
A granny annexe in the garden: planning permission, building regulations, council tax exemption for relatives over 65, and Disabled Facilities Grants. England guide.
Read the guide →
Garden annexes in Welwyn Garden City: questions people ask
Do I need planning permission for a garden annexe in Welwyn Garden City?
The national register lists 3 conservation areas within about 1.5 km of the centre: Ayot Green, Beehive and Welwyn Garden City; on designated land such as a conservation area, an outbuilding at the side of a house needs planning permission. 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 Welwyn Hatfield Borough Council. Planning applications in Welwyn Garden City go to Welwyn Hatfield Borough Council.
How much does a garden annexe cost in Welwyn Garden City?
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 Welwyn Garden City builders show the real figure for your plot.
Does a garden annexe in Welwyn Garden City 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 Welwyn Garden City?
Up to 3 written quotes from builders who already work in Welwyn Garden City and nearby areas such as Hatfield, Welwyn, Hertford. Each one visits for free first. The service is free for homeowners.
Which council handles planning in Welwyn Garden City?
Welwyn Hatfield Borough Council. Your builder checks the rules for your plot before you commit.
Do you cover villages near Welwyn Garden City?
Yes. We match homes across Handside, Panshanger, Hatfield, Welwyn, Hertford and Harpenden. 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.
