House extensions in Stroud and across Gloucestershire

A single-storey extension is the most common way to add space on the ground floor. It is often used to create an open kitchen, dining and family room, a utility room, a downstairs toilet or a ground-floor bedroom. Because it only adds one level, it usually has less effect on neighbours and is more likely to fall within permitted development limits.

The roof can be pitched, lean-to or flat, depending on the house and the look you want. Rooflights and glazed doors bring daylight into the middle of the plan, which matters when the extension takes over the space where windows used to be. Where the extension opens into the existing house, a steel beam is normally needed to carry the walls above, designed by a structural engineer.

A double-storey extension adds space on two floors at once, typically a larger kitchen or living room below and a bedroom or bathroom above. Because the foundations and roof are shared across both floors, a two-storey extension often gives more floor area for the money than building on one level.

These extensions are more visible, so the design needs to work with the existing roof, the windows and the neighbouring houses. They usually need planning permission, and the council will consider the effect on neighbours' light and privacy. Joining a new roof neatly to the old one is one of the details that makes the biggest difference to how the finished house looks.

Rear extensions are the most popular type, because the back of a house is usually where there is room to build and where a connection to the garden is most useful. A full-width rear extension can turn a separate kitchen and dining room into one bright space with doors onto a patio.

As a general guide, permitted development allows a single-storey rear extension of up to 3 metres on a semi-detached or terraced house, or 4 metres on a detached house, with a maximum height of 4 metres. Larger single-storey rear extensions can sometimes be built through the prior approval process. These rules have conditions and exceptions, so always check the current guidance or ask your council before relying on them.

A side extension uses the space beside a house, whether that is a driveway, a strip of garden or the narrow side return found on many terraced homes. It can add a utility room, a study or a wider kitchen, and a side and rear extension can be combined into an L shape for a much larger room.

Under permitted development, a side extension must be single-storey and no wider than half the width of the original house. Side extensions are not permitted development in conservation areas or the Cotswolds National Landscape, so in much of our area they need planning permission. Building close to a boundary also often brings the Party Wall etc. Act 1996 into play.

Planning permission is about whether an extension is acceptable in its location: its size, position and appearance. Building regulations are about how it is built: foundations, structure, insulation, ventilation, drainage and fire safety. They are separate, and almost every extension needs building regulations approval even when planning permission is not required.

If you think your extension falls within permitted development, a Lawful Development Certificate from the council confirms it in writing, which is useful when you sell. Listed buildings need listed building consent for works that affect their character, and flats and maisonettes do not have permitted development rights for extensions at all.

Every extension is different, but most follow a similar sequence. Knowing what to expect makes it easier to plan around the work.

• Setting out the extension, digging and pouring the foundations, and building inspections of the trenches
• Diverting or extending drainage, then building the walls up to roof level
• Fitting the roof, windows and doors so the extension is weathertight
• Opening up into the existing house, usually with a new steel beam
• First fix plumbing and electrics, insulation and plastering
• Second fix, flooring and finishes, followed by building control sign-off

Gloucestershire has a strong building tradition, and in many towns the local Cotswold stone is part of what people love about their homes. An extension that matches the existing walls, whether in natural stone, reconstituted stone, brick or render, will look as though it belongs. In conservation areas and the Cotswolds National Landscape, councils usually expect materials to match closely.

A contemporary extension in contrasting materials can also work well, especially at the back of a house. The choice depends on the property, its setting and what you want, and it is worth settling early because it affects the cost and the planning approach.