How to add services to your garden room

Fitting a bathroom in your outbuilding isn’t a big deal, with a bit of planning and expertise.

It’s relatively straightforward to fit a shower room, toilet or full bathroom into a garden building. This is ideal when you want to use your building all day as a garden office, art studio or hobby room and if it’s a fair distance to the house. It’s pretty essential if you want to use it as a garden guest room, or if (lucky you) you have a pool and want a shower and pool house changing area nearby. 

Straightforward – if you think through a few basics first. The three main aspects involved are running power to the bathroom for lighting, water heating and ventilation; the supply of fresh water from the mains; and the discharge of wastewater. 

These three elements will vary in cost depending on the location of the garden room.  All three services can be laid to your garden building in the same trench, and this is ideally done during the groundworks stage before installing your log cabin, summer house or 4m x 3m garden room.


With electricity, clearly, safety is paramount. That means this is a job for certified electricians. As a minimum, electrical cables running underground or around the garden must be steel-wired armoured; depending on what kind of soil and subsoil you have, it may be best to run a conduit pipe to your cabin to protect wires, and with a bit of design forethought this can allow additional cables to be added later. 

You can save money (and gym fees) by digging a trench yourself, but if you decide to do a DIY electrical installation you need an inspection of completed works by a building control officer before you fill in the trench, and there’s a fee to pay (why not spend it on a flat pack annex instead?).

Accredited contractors are self-certifying, and they’re more than worth their money in dealing with issues such as the gauge of cable needed to run adequate amperage over a long distance, where to place RCD switches, separate metering if you need it, and so on.

To benefit from your sparky’s expertise, you need to think carefully upfront about how you’ll be using your garden room and its plumbing. Will you be running a water heater or an electric shower? Did you fancy a hot tub or sauna? These appliances can require over 10kW; most things are possible, but you need to supply adequate power to the building at the outset for what you want.


Ventilation is vital in any timber building, and a bathroom makes this all the more important. If possible, an opening window and an extractor fan with a run-on timer should be fitted.  You can also buy fans with humidity sensors.  

Saunas are traditionally found in outdoor timber buildings in Scandinavia, but as well as power they need design elements such as additional vents from the stove. These need to be designed in, ideally when you specify your garden room in the first place.


drainage for garden building
Water pipes need to be buried below the frost line, and insulated from cold where they run above ground. They need to be run to your building at a minimum distance from electrical cables, but waste pipes can run in the same trench as the water supply.


To take waste away, if the building is located below the level of the existing drains a simple domestic pumping station is installed. Again, the power required for this will need to be factored into the electrical installation.

A pumping station involves a small holding tank buried in the ground and a water pump with an integrated macerator is used to pump the waste to your sewer. These pumps allow you to move waste over gradient and distance, using a small bore pipe instead of having to lay traditional large-bore drainage pipes.

With a garden location, it’s interesting to consider if alternative water and waste options are available. Could rainwater feed a toilet flush? Could a soakaway or water butt cope with non-toilet wastewater? Start Googling and you’ll rapidly find as many solutions as dire warnings – the bottom line is that solutions like these are all site-specific, add to the cost and require specialist advice.

You must comply!

The only other point to bear in mind is that if you intend your garden room to be fit for permanent habitation, it will need to comply with building control regulations, this is where specialist planning advice should be sought.

Talk to an expert

Speak with our team of expert garden building designers about the possibility of a garden room with services.

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