Do you need planning permission for a granny annexe?

It depends on the site, the size and whether the annexe is used as an independent dwelling or as ancillary accommodation. Check with your local planning authority before you order.

How much does a granny annexe cost?

Pricing is per module with most of the fit-out included. Design one in the builder for an estimate.

Can it have a shower and toilet?

Yes, subject to water supply and drainage. Grouping them on one wall reduces the groundworks.

How is it connected to the house?

Power, water and drainage are usually run from the main house. The route is agreed before installation.

Is it warm in winter?

Walls, floor and roof are insulated and glazing is double glazed, so heating demand is modest.

How long does installation take?

The base and connections are the main site work; the modules themselves are craned into place in a day on most sites.

Modular Homes

Granny Annexes & Garden Annexes

A granny annexe is a self-contained building in the garden or grounds: a bedroom, a shower room, a kitchenette and a living space, close to the main house but independent of it.

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Granny Annexes & Garden Annexes — modular building by Adacon UK

Independent, but close by

Annexes are usually specified around accessibility and comfort rather than size: a level threshold, a walk-in shower, good heating and enough daylight. Connections normally run from the main house, so the position on the plot matters as much as the layout.

Level threshold and step-free entry
Walk-in shower room with grab-rail provision
Kitchenette with sink, worktop and appliance space
Bedroom and living space separated by a partition
Heating and full insulation for year-round use
Services routed from the main house where practical

Example configurations

Each P600 module is approximately 13 m². Modules join side by side and stack over two storeys.

1 module

approx. 13 m²

Bedroom with a shower room — an annexe at its most compact.

2 modules

approx. 26 m²

Bedroom, living space, kitchenette and shower room.

3 modules

approx. 39 m²

Separate bedroom and living room, with a larger kitchen.

Granny Annexes — key facts

Product: P600 modular building
Module dimensions: 5900mm × 2200mm (5.9m × 2.2m)
Module footprint: approx. 12.98 m²
Price per module: £10,750 + VAT (£12,900 inc. VAT)
Configuration: Single module or multiple connected modules
Storeys: Up to two storeys, subject to final project design
Delivery: UK mainland and Northern Ireland, included in the price

The Adacon P600 modular building measures 5.9m × 2.2m (5900mm × 2200mm) with a module footprint of approx. 12.98 m², and costs £10,750 + VAT per module. Each module can include a kitchen, toilet, shower, internal partitions, windows, doors, lighting, sockets and a consumer unit, and modules can be joined side by side or stacked to two storeys.

What's available

Bedrooms and internal partitionsShower room and WCKitchen or kitchenetteInsulated walls, floor and roofDouble-glazed windows and doorsFull-height glazingHeating provisionLED lighting and power socketsTerrace, decking or balconyPer-wall cladding style and colour

Granny Annexes example configuration 1 — Adacon modular building

Granny Annexes example configuration 2 — Adacon modular building

Granny Annexes example configuration 3 — Adacon modular building

Whether a building can be used as a permanent dwelling, and what Building Regulations, planning permission, foundations and energy-performance requirements apply, depends entirely on your site and how the building will be used. We make no blanket claim that a standard configuration constitutes a compliant dwelling — this must be confirmed for your specific project.

Granny Annexes — common questions

Design your annexe

Choose the layout, shower room and finishes and get an estimated price.

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Related homes

One Bedroom Modular Homes

One bedroom modular homes built from the Adacon P600 system — bedroom, living space, kitchen and shower room, delivered fitted out. Design yours online.

Guest & Garden Accommodation

Modular guest accommodation for the garden — a self-contained guest room with shower room and kitchenette, insulated and delivered fitted out.

Modular Bungalows

Single-storey modular bungalows built from joined P600 modules — level-access layouts with wide doorways, open living space and no internal stairs.

All modular homes

An Adacon P600 module costs £10,750 + VAT fully fitted, with UK mainland and NI delivery included. See what drives the price of a modular building.

Do Modular Buildings Need Planning Permission?

Whether a modular building needs planning permission depends on its use, size, siting and duration. Read how the common cases usually work in the UK.

Do Modular Buildings Need Foundations?

Modular buildings need a level, load-bearing base rather than traditional deep foundations. Learn what base types suit garden rooms, site offices and two-storey builds.

All guides