House Extensions in Preston, Lancashire and the North West

What kinds of house extension are there?

Most extensions fall into a few common shapes. The right one depends on your plot, how the house is laid out now and what the new space is for.

• Single storey rear extension. The most common type. It usually opens up the back of the house into a larger kitchen, dining and living space.
• Kitchen extension. A rear or side extension designed around a new kitchen, often with roof lights or large glazed doors to bring in light.
• Side or side return extension. On many terraced and semi detached houses there is a narrow strip of land beside the rear part of the house. Building into it widens the ground floor.
• Wraparound extension. A side return and a rear extension built together in an L shape, which gives the biggest ground floor gain.
• Two storey extension. Adds space on both floors, for example a bigger kitchen below and an extra bedroom above. It needs more design work and usually planning permission.

Do I need planning permission for an extension?

Not always. In England, many single storey extensions to houses are allowed under permitted development rights, within set limits. The main ones are:

• a single storey rear extension can go out up to 3 metres on a semi detached or terraced house, or 4 metres on a detached house
• under the prior approval process, those depths can go up to 6 metres and 8 metres, after the council has notified your neighbours and considered any objections
• single storey extensions can be up to 4 metres high, with the eaves no higher than 3 metres if they are within 2 metres of a boundary
• a single storey side extension can be no wider than half the width of the original house and no higher than 4 metres
• extensions and outbuildings together cannot cover more than half the land around the original house
• materials should look similar to the existing house

Two storey extensions have tighter limits, and nothing can be built under permitted development in front of the main face of the house. Flats, homes in conservation areas and houses where a planning condition has removed these rights need planning permission for more types of work. We confirm the position for your house before any work starts, and apply for planning permission or prior approval where it is needed.

What building regulations apply to an extension?

Almost every extension needs building regulations approval. Building control check the work at key stages and issue a completion certificate at the end. The main areas are:

• Foundations. Their depth depends on the ground and on any nearby trees, and building control inspect the trenches before concrete goes in.
• Structure. Steel beams where the extension opens into the house, and roof and floor structures designed to carry the loads.
• Drainage. New drains, and protection for any existing drains under or near the extension.
• Energy efficiency. Insulation to current standards. Very large areas of glazing may need extra calculations to show the extension still meets the rules.
• Ventilation and fire safety. Extract fans in kitchens and utility rooms, background ventilation and a safe way out of the house.

What if there is a drain where I want to build?

Many houses have a shared public sewer running across the back garden. Building over or close to one usually needs agreement from the water company before work starts, which is United Utilities across most of the North West. The design may need to protect the pipe or reroute it. We check for drains at the survey so it is allowed for in the quote rather than found halfway through.

How will an extension affect my neighbours?

If you dig foundations within 3 metres of a neighbour's building, or build on or against a shared wall, you usually need to serve notice under the Party Wall etc. Act 1996 before work starts. Neighbours are also consulted when you apply for planning permission or prior approval. Good design helps too, for example keeping the height down near a boundary so the extension does not take light from next door.

Can I stay at home while the extension is built?

Usually, yes. Most of the work happens outside until the extension is weathertight. The disruptive part is opening up the back wall of the house to join the old and new spaces, especially when the kitchen moves. We plan that stage with you before work starts so you know when it will happen.

Should I extend or convert the loft?

It depends on the space you need. A ground floor extension suits a bigger kitchen, living or family space. A loft conversion suits an extra bedroom and bathroom and does not use any garden. Many families end up doing both over time. We can talk through both at the survey, and the loft conversions guide covers the loft side.

What affects the cost of an extension?

• The size, and whether it is single or two storey
• The roof type and the amount of glazing
• Foundations, ground conditions and drains
• The opening into the house and any steel beams
• The kitchen, flooring and finish inside

Two extensions of the same size can differ a lot in price, so we do not publish one figure. After a site visit we give you a written, fixed price quote, so the price is agreed before work starts.

How does an extension project run?

1. Survey and written quote

   We look at the plot, the ground, drains, boundaries and how the extension will join the house, then give you a written, fixed price quote.

2. Design and approvals

   Drawings, planning permission or permitted development and prior approval where they apply, building regulations approval, party wall notices and any agreement needed to build near a public sewer.

3. Groundwork and shell

   Foundations and drainage, then walls, roof and windows, so the extension is weathertight before the house is opened up.

4. Opening up and finishing

   The opening into the house is made, usually on a steel beam, then electrics, plumbing, plastering, flooring and any kitchen, and building control sign off.

Timescales depend on the size and type of project and are confirmed in your written quote.

Why choose Introspec Construction for an extension?

Introspec Construction is a builder based in Preston, Lancashire. The team has more than 100 years of combined experience and has completed hundreds of extensions. We are fully insured, and every job is priced with a fixed price quote.