How do you get electricity to a garden room?

Power is the part of a garden room that turns a nice shed into somewhere you can work all winter. It is also the part most likely to be underspecified, because nobody sees the cable once the trench is filled in. Here is how it is usually done, what it costs, and what to ask for.

The usual set-up

1. A new circuit at the house. A spare way in the house consumer unit, or a small new unit beside it, feeds the garden room. Older boards sometimes need upgrading first.
2. Armoured cable. Steel wire armoured (SWA) cable runs from the house to the room. It is tough, earthed through its armour and designed to be buried.
3. A trench. Usually 450 mm deep under lawn and borders, 600 mm under paths or drives, with warning tape above the cable.
4. A consumer unit in the room. A small board with its own protective devices feeds the sockets, lights and heater.
5. Testing and a certificate. The electrician tests the installation and issues an Electrical Installation Certificate, and the work is notified to building control.

Part P: who is allowed to do it

A new circuit to an outbuilding is notifiable work under Part P of the building regulations in England. In practice that means a registered electrician, one who belongs to a competent person scheme, does the work and self-certifies it. You then get a building regulations compliance certificate in the post.

If someone else does the work, it has to be notified to building control before it starts and inspected, which usually costs more than using a registered electrician in the first place. Keep the certificates with the house deeds; a buyer’s solicitor will ask for them.

What it costs

These are typical ranges from published price lists we reviewed in October 2026, not quotes. The total for most garden rooms lands at about £1,200 to £2,500.

Things that push the cost up

A long run

Over roughly 20 to 25 metres, voltage drop means the cable has to be a larger size, which costs more per metre. Rooms at the bottom of long gardens often need this.

Hard ground

Trenching through lawn is quick. Trenching through stone flags, setts or a concrete path means lifting and relaying them. In older Kirklees gardens with flagged yards and stone steps, this is often the biggest single variable.

Heavy loads

A panel heater, a few sockets and lights are a modest load. A hot tub, a sauna, an electric shower or a car charger in the same building needs a bigger cable and possibly a bigger supply. Say so at the start.

Internet: do it in the same trench

Wi-Fi from the house is the default, and it often disappoints. Thick stone walls, which many houses around Huddersfield have, block a lot of signal. The cheapest reliable fix is a Cat6 data cable laid in the same trench as the power, ending at a socket or access point in the room. Adding it once the trench is filled costs far more.

Powerline adaptors can work but are less dependable over a separate consumer unit. Mesh systems with a node near the back of the house are the next best option.

Lighting, heating and sockets

Plan the furniture before the electrics. For an office, put double sockets at desk height either side of where the desk will go, one by the door for a heater or vacuum, and one high on the wall for a router or screen. For a gym, a socket for a fan and one for a treadmill. Outside lights by the door and along the path are worth adding at the same time.

A 1 to 1.5 kW panel heater on a timer suits most well-insulated rooms. An air conditioning unit heats and cools, and costs £1,500 to £3,000 fitted.

Questions to ask

• Is the electrician registered with a competent person scheme?
• What size cable, and how deep will it be buried?
• Will a data cable go in the same trench?
• Does the house consumer unit need changing?
• Will I get an Electrical Installation Certificate and a building regulations certificate?

If you are pricing a garden office or a games room, the electrics are usually included in the price, but it is worth seeing them listed line by line.