Guide figures, not quotes. Every price on this page comes from the same figures as our cost calculator and the cost cards on the site. Guide figures for fitted rooms, including VAT. Not a quote: your written quotes depend on your plot. Your builders' written quotes decide the real price.
How a garden room price is built
Builders do not price a garden room from a single rate. They start with a basic insulated room of a given size, then add the parts your plot and your use need. Our calculator works the same way: a size base, plus a room-type step, plus any extras, plus an access step. The low ends are added together, and so are the high ends, then both are rounded to the nearest £500.
That gives a range, not a point. The gap between the low and high end is real. It is the difference between a lean spec on easy ground and a generous spec on a hard plot. The sections below show every block so you can see where a quote sits in the range.
Prices by size band
Size sets the starting point because more floor, walls and roof means more of everything. These are the base figures for a standard insulated office, fitted, including VAT.
| Size band | Typical size | Guide base |
|---|---|---|
| Small | About 3 × 3 m | £12,500 – £18,000 |
| Medium | About 4 × 3 m | £18,000 – £29,000 |
| Large | 5 × 4 m and up | £32,000 – £58,000 |
The same bands appear on our town pages as "Up to 3 × 3 m", "About 4 × 3 m" and "5 × 4 m and up". The step from medium to large is the biggest jump: the large band starts at £32,000, which is £14,000 above the low end of the medium band. A larger room also tends to be taller, and height can decide how far it must sit from the boundary. See planning permission for garden rooms.
Prices by room type
The baseline is an insulated room with power, lights and heating, which is the garden office. Other room types add a step on top of the size base.
| Room type | Added to the size base | Why |
|---|---|---|
| Garden office | Nothing: the baseline | An insulated room with power, lights and heating is the baseline. |
| Garden gym | £1,000 – £2,000 | Gyms usually need a stronger floor, better ventilation and extra sockets. |
| Garden studio | £1,000 – £2,500 | Studios put more into light, sound and finish. |
| Garden annexe | £4,000 – £7,000 | A room someone sleeps in needs building regulations sign-off and more heating. |
Garden office: from £16,500
The simplest build: an insulated room with power, lights and heating.
- 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
Garden gym: from £21,000
Heavy kit and hard training need a stronger, cooler room.
- 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
Garden studio: from £18,500
Light and sound decide the spec.
- Sound insulation if you play or record
- Bigger glazing or roof lights for even daylight
- A sink needs a water supply and waste run
Garden annexe: from £39,000
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
The "from" figures above are the typical starting prices shown on the cost cards across the site. The calculator builds up from the size base instead, so the two will not match to the pound. Use the calculator when you know your size, and the card when you only want a feel for the room type.
Size band by room type, no extras
This grid combines the two tables above for a room with no extras and easy access. Each cell is the calculator result, rounded.
| Size band | Garden office | Garden gym | Garden studio | Garden annexe |
|---|---|---|---|---|
| Small About 3 × 3 m | £12,500 – £18,000 | £13,500 – £20,000 | £13,500 – £20,500 | £16,500 – £25,000 |
| Medium About 4 × 3 m | £18,000 – £29,000 | £19,000 – £31,000 | £19,000 – £31,500 | £22,000 – £36,000 |
| Large 5 × 4 m and up | £32,000 – £58,000 | £33,000 – £60,000 | £33,000 – £60,500 | £36,000 – £65,000 |
Read across a row to see what the room type costs at one size. At the medium band, an office is £18,000 – £29,000, a gym £19,000 – £31,000, a studio £19,000 – £31,500 and an annexe £22,000 – £36,000. An annexe sits well above the rest because sleeping space brings building regulations and more heating. A small annexe is a stretch: the small band is meant for a one-person office.
What each extra adds
Extras are priced separately because not every room needs them. Each one is added to the size base. These are the seven in the calculator.
| Extra | Adds | What it covers |
|---|---|---|
| Reinforced floor | £1,500 – £3,000 | For racks and heavy kit |
| Sound insulation | £1,000 – £2,500 | Playing or recording |
| Shower room / WC | £5,000 – £9,000 | Needs drainage |
| Kitchenette | £2,500 – £5,000 | Sink, worktop, water |
| Air-con | £1,500 – £3,000 | Heating and cooling |
| Extra glazing / roof lights | £1,500 – £4,000 | More daylight |
| Long power / water run | £1,000 – £3,000 | Far from the house |
The most expensive single extra is the shower room or WC at £5,000 – £9,000, because it needs drainage as well as plumbing. Extra glazing has the widest spread, £1,500 – £4,000, because bifold doors cost far more than one extra window. For the wiring side, see our guides to garden room electrics and heating and air-con.
Access to your garden
| Access | Adds | Meaning |
|---|---|---|
| Easy access | Nothing | Side gate or open route |
| Through the house | £1,000 – £2,500 | Materials carried in by hand |
Everything is carried through the house, which adds labour time. If your home has no side gate or passage, as can be the case in towns such as Watford, Hitchin and Aylesbury, measure your route before you ask for quotes. Ask each builder how they would get the materials to the plot.
Worked examples
Each example below is summed from the tables above, low ends together and high ends together. The last line is the rounded calculator result. The totals are guide figures that include VAT.
A 3 × 4 m garden office with a power run and air-con
This is the plain medium office plus two extras. The room is the first £18,000 – £29,000. The power run and the air-con add the rest.
| Medium room base (about 4 × 3 m) | £18,000 – £29,000 |
| Long power / water run | £1,000 – £3,000 |
| Air-con | £1,500 – £3,000 |
| Sum | £20,500 – £35,000 |
| Guide total, rounded | £20,500 – £35,000 |
A small 3 × 3 m office for one, with easy access
The cheapest line in the calculator: the small base alone, with nothing added.
| Small room base (about 3 × 3 m) | £12,500 – £18,000 |
| Sum | £12,500 – £18,000 |
| Guide total, rounded | £12,500 – £18,000 |
A medium garden gym with a reinforced floor and air-con, carried through the house
A gym adds a room-type step, a stronger floor and cooling. Carrying materials through the house adds labour time on top.
| Medium room base (about 4 × 3 m) | £18,000 – £29,000 |
| Garden gym adjustment | £1,000 – £2,000 |
| Reinforced floor | £1,500 – £3,000 |
| Air-con | £1,500 – £3,000 |
| Through the house | £1,000 – £2,500 |
| Sum | £23,000 – £39,500 |
| Guide total, rounded | £23,000 – £39,500 |
A medium music studio with sound insulation and extra glazing
Studios put more into sound, light and finish, so both the room-type step and the extras count.
| Medium room base (about 4 × 3 m) | £18,000 – £29,000 |
| Garden studio adjustment | £1,000 – £2,500 |
| Sound insulation | £1,000 – £2,500 |
| Extra glazing / roof lights | £1,500 – £4,000 |
| Sum | £21,500 – £38,000 |
| Guide total, rounded | £21,500 – £38,000 |
A large annexe with shower room, kitchenette and a long service run
The top end of the calculator. Bathrooms, kitchens and long runs of power and water each add a separate block.
| Large room base (5 × 4 m and up) | £32,000 – £58,000 |
| Garden annexe adjustment | £4,000 – £7,000 |
| Shower room / WC | £5,000 – £9,000 |
| Kitchenette | £2,500 – £5,000 |
| Long power / water run | £1,000 – £3,000 |
| Sum | £44,500 – £82,000 |
| Guide total, rounded | £44,500 – £82,000 |
The 3 × 4 m office with a power run and air-con comes to £20,500 – £35,000. A good quote for it may land anywhere in that range, which is why the spec matters more than the headline number. Try your own mix in the cost calculator.
What moves the price
Beyond the calculator blocks, builders weigh these things, listed from cheapest to dearest to change:
- 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
- Access: can materials reach the garden?
Five of those six are about the build and one is about your plot. Foundations, for example, depend on your ground, your slope and the weight of what goes inside: a gym with racks and dropped weights asks more of the floor than an office. Our foundations guide sets out the options, and the insulation and cladding guides cover the wall and roof choices.
Distance matters because power is dug in from the house in an armoured cable, and water and waste add pipework. The "long power / water run" extra (£1,000 – £3,000) stands in for that. A room at the far end of a long garden costs more than one near the back door, even at the same size.
Costs that are easy to miss
A quote can look cheap because something is left out. These are the usual gaps. Ask about each one by name.
- Groundworks. Clearing, levelling and removing spoil. Sloping or tree-rooted ground costs more to prepare. Confirm which foundation type the price is for.
- Electrics. Power to a garden room is usually a new circuit from the house consumer unit. Ask whether the trench, the armoured cable, the consumer unit work and the electrician's certificate are in the price. The Planning Portal explains the rules in its electrics guidance.
- Drainage. A shower room or WC needs a waste run. Check whether connection to the main drain is included.
- Delivery and access. Crane or hand-carry costs, and skip hire for waste, may be extra.
- Finishing. Decking, paths, lighting outside, curtains or blinds, and internal fit-out such as shelving are often outside the base price.
- Fees. See the next section.
Planning, lawful development and building control fees
Many garden rooms need neither planning permission nor building regulations approval, so many buyers pay no fees at all. If yours does, the fees are paid to the council on top of the build price.
- Planning application. Needed if the room goes past a permitted development limit, for example in a conservation area at the side of a house. Fees are set nationally and published by your council. Read our planning guide first.
- Lawful development certificate. An optional paper from the council that confirms a proposed room is lawful. GOV.UK guidance says the fee for a proposed development is half the fee for the equivalent planning application, so check your council's fee table for the pound figure. The certificate guide explains when it is worth having.
- Building regulations. Apply if anyone will sleep in the room. They can also apply to larger rooms close to a boundary. Fees come from your building control body. See building regulations for garden rooms.
We have not put pound figures on these fees because they vary by council and project. Ask your builder who applies and who pays, and make sure the answer is in the quote.
How to compare quotes
Get at least two written quotes, and up to three if you can. Put them side by side against a checklist rather than the bottom line.
- Same floor area and same internal and external height on every quote.
- Foundations: the type, and why the builder chose it for your ground.
- Insulation: what goes in the floor, walls and roof.
- Glazing: how many windows and doors, the type, and whether any roof lights are included.
- Electrics: how far the cable runs, whether the trench is in the price, and whether a registered electrician certifies it.
- Heating or air-con: which unit, and whether it is installed or only supplied.
- VAT, delivery, site clearance, waste removal and any fees: in or out.
- The start date, the build time and the guarantee, in writing.
When two quotes differ by thousands, ask each builder to explain the difference line by line. The explanation usually shows which spec was cut. See our guide to choosing a garden room builder for questions to ask on the site visit.
A note on VAT
Our guide figures include VAT, as the calculator states. This matters when you compare. Some sellers advertise a price excluding VAT, and the same room then looks cheaper than it is. Ask every builder to confirm, in writing, whether the figure on the quote includes VAT and what rate applies. If you are buying through a limited company or for a business use, ask your accountant what you can reclaim. Our garden office tax guide sets out the general position, and it is not advice.
Payment stages
Garden rooms are normally paid for in stages rather than in one lump. The exact split is for you and your builder to agree, and it should be written into the quote or contract before you sign.
- Agree how many stages there are and what triggers each one: order, delivery to site, frame up, weathertight, completion.
- Link each payment to work you can see, not to a date alone.
- Keep the final payment until the room is finished, the electrical certificate is handed over and you have walked round it.
- Get a receipt for every payment and keep copies of every document.
- Ask what happens to your deposit if the start date slips.
Local quotes in Herts and Bucks
Builders price in their own areas, and a builder who already works near you knows the access, the ground and the council. We match you with up to 3 local builders. Browse local detail for 26 Hertfordshire towns:
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.
And 14 Buckinghamshire towns:
Chesham, Amersham, Great Missenden, Aylesbury, Beaconsfield, Gerrards Cross, High Wycombe, Marlow, Princes Risborough, Wendover, Buckingham, Little Chalfont, Chalfont St Giles, Chalfont St Peter.
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