The cost of a home extension varies significantly based on size, complexity, location (London is generally more expensive), materials, and chosen finishes. As a very rough guide, a basic single-storey extension might start from £1,800-£2,500 per square metre, while a more complex or high-spec build can easily exceed £3,000-£4,000 per square metre. This excludes professional fees, VAT, and a contingency. Always get specific quotes for your project.

Not always. Many smaller extensions can be built under 'Permitted Development' rights, which means you don't need full planning permission from the council. However, there are strict limits on size, height, and proximity to boundaries for these rights. Properties in Conservation Areas, National Parks, or listed buildings often have fewer or no Permitted Development rights. It's crucial to check with your local planning authority or apply for a Lawful Development Certificate to be sure.

Planning Permission focuses on the impact of your proposed extension on neighbours and the local environment, including its appearance, size, and use. It's about whether you can build it in a specific location.

Building Regulations are separate and ensure the structural integrity, safety, accessibility, and energy efficiency of your build. Even if you don't need planning permission (e.g., under Permitted Development), you will always need to comply with Building Regulations. Your architect and structural engineer will prepare detailed drawings for this approval.

The initial design phase with an architect can take several weeks or months, depending on the complexity and how quickly you make decisions. A planning application typically takes 8-13 weeks for the local council to issue a decision. Building Regulations approval usually runs concurrently or immediately after planning, and can also take several weeks for formal approval, though work can sometimes start earlier under an initial notice. Overall, expect the planning and design phase to take 6 to 18 months before construction can even begin.

The Party Wall etc. Act 1996 is a piece of legislation in England and Wales that aims to prevent and resolve disputes in relation to party walls, boundary walls, and excavations near neighbouring buildings. If your extension involves building on or astride the boundary line, excavating within a certain distance of a neighbour's property, or altering a shared wall, you will need to serve a formal 'Party Wall Notice' to your affected neighbours. This is a legal requirement.