Granny annexe builders

Two routes to an annexe

There are two ways to create a granny annexe. The first is converting something that already exists: an integral or detached garage, a large outbuilding or a ground-floor wing of the house. The second is building new, either as an extension to the house or as a separate building in the garden. Which route suits depends on what you already have, the garden, and how independent the annexe needs to be.

Converting an existing structure is often the simpler and quicker route because the walls and roof are already there. Building new gives a clean sheet for the layout but brings foundations, a new structure and usually a planning application.

What an annexe needs to be liveable

An annexe is a small home, not just an extra room. It needs proper insulation in the floor, walls and roof so it is cheap to heat, ventilation, heating, hot and cold water, drainage for a bathroom and kitchen area, and electrics to a domestic standard. Fire safety and sound separation matter, especially where the annexe shares a wall with the main house.

The practical details make the difference to daily life: level or ramped access if mobility is a consideration, a bathroom planned for the long term, good natural light, and a front door of its own so the person living there has genuine independence.

Planning permission and Building Regulations

This is the part to get right early. An outbuilding used as incidental accommodation, such as a guest room, may fall within permitted development, but a self-contained annexe with its own kitchen and bathroom is often treated differently and can need a planning application. Councils usually want the annexe to remain ancillary to the main house, occupied by a family member, rather than becoming a separate dwelling.

Building Regulations apply in full to an annexe because it is living accommodation: structure, insulation, fire safety, ventilation, drainage and electrics all have to comply. We talk through the position for your property at the site visit and point you to the council before anything is designed.

Services and connections

Water, drainage and power have to reach the annexe, which usually means new pipe runs and a connection to the existing drains, sometimes with a soakaway or pumping arrangement depending on levels. Heating can extend from the house system or be independent. These runs are groundworks, and planning them with the build avoids digging up a finished garden later.

Designing for the person who will live there

An annexe works best when it is designed around its occupant rather than as a generic extra room. Level thresholds, a shower room rather than a bathroom with a step-over bath, sensible door widths and good lighting all make daily life easier and future-proof the space. A small private sitting-out area outside the annexe door gives independence without anyone feeling shut away.

Privacy cuts both ways: the annexe should feel separate enough that both households have their own front door and their own space, but close enough that help is seconds away. Window positions, paths and planting all play a part in getting that balance right.

Storage and sound are easy to overlook. A small home still needs somewhere for hoover, coats and luggage, and good sound insulation in any shared wall or floor keeps television and conversation from carrying between the households. Thinking about these at design stage costs little; adding them afterwards costs a lot.

How we approach annexe work

Annexe projects combine conversion, extension, masonry and groundwork skills. We build the structure ourselves and liaise with the other trades the job needs. Every project starts with a site visit, an honest view on the planning position, and a free written estimate.