House extension pods

What people mean by a pod

The word gets used for three different things, and firms selling each will turn up in the same search. A garden pod is a separate building at the end of the lawn. A bathroom pod is a factory-made bathroom slid into a larger building during construction. A house extension pod, the subject of this page, is a single habitable room attached to your home with a door cut through from inside.

The difference matters for the rules. A small detached garden building can often go up with no building regulations approval at all. An attached room that you heat and sleep in cannot: it is an extension, and it is inspected like one.

Why pods stay under 2.9 metres wide

The size of a pod is set by the road, not the garden. A load up to 2.9 m wide can travel on British roads without special notice. Go wider and the haulier must warn every police force on the route two clear working days ahead; past 3.5 m an attendant has to ride along. None of that is forbidden, but each step adds cost and a date that can slip.

So most pods are drawn between 2.4 and 2.9 m wide and as long as the room needs, commonly 3 to 5.5 m. Inside, after the wall thickness, that leaves a room about 2.3 to 2.6 m across: right for a single bed and a desk, tight for a double bed with space on both sides. If the room has to be wider, ask for the module to be turned so its long side meets the house.

Getting a pod into a garden with no room for a crane

A small pod weighs far less than a full module, which opens up options. A lorry-mounted crane can lift it straight off the trailer if the drive runs alongside the plot. A compact tracked crane can travel down a side passage about a metre wide and assemble in the garden. Where neither works, some makers send the pod as four or five large panels that two people can carry through and bolt together in a day.

The panel route gives up some of the factory finish, because joints must be sealed and decorated on site. Still, for a mid-terrace with no rear access it is often the only way, and it remains quicker than laying bricks. The delivery guide explains what a firm will want to measure.

Shower rooms and ground-floor bedrooms

A pod with a toilet or shower needs a drain connection, and that decides where it can sit. The closer it is to the existing soil stack or an inspection chamber, the cheaper the groundwork. A pod on the far side of the house from the drains can still be done with a pumped waste, but pumps need power, make noise and eventually need replacing.

If the room is for someone disabled, two things are worth knowing. Building a bathroom, washroom or toilet for a disabled person in their own home can be zero-rated for VAT, which takes a fifth off that part of the bill; the firm applies it, with a signed declaration from you. And in England and Wales your council may offer a Disabled Facilities Grant towards the work. Raise both before the quote is written.

Ask for a level threshold between house and pod. It is easy to build in at the factory and miserable to correct afterwards.

Planning and building regulations

Planning treats a pod as an extension. Behind an English house, at one storey and reaching no further than 3 m out (4 m where the house is detached), it normally counts as permitted development. On the side it must be no wider than half the original house and no taller than 4 m. On the front, or on the side of a house in a conservation area, you will need to apply. The outside must look similar to the house for permitted development to hold, so a pod in contrasting cladding may need permission that a brick-faced one would not.

In Scotland the limits are different and a building warrant is needed before work starts. Across Great Britain, building regulations apply in full: structure, insulation, fire escape from a bedroom, ventilation and electrics. Expect the maker to supply the calculations and the local building control body to inspect the base, the connection and the finished room.