Home Extension Price: What You Really Need to Know Before You Start

When you think about adding space to your home, the home extension price, the total cost to build an additional room or level onto your existing house. Also known as a house extension, it’s one of the most common ways UK homeowners gain extra space without moving. But here’s the thing—what you see in a magazine or on a TV show rarely matches what ends up on your invoice. A simple single-story extension can start around £30,000, but if you’re adding a second floor, dealing with poor soil, or need planning permission, that number can jump fast. It’s not just about bricks and mortar. It’s about permits, structural work, utilities, and whether your neighbor’s fence gets in the way.

That’s why understanding the building extension costs, the full range of expenses tied to expanding your living space, including materials, labor, and hidden fees matters more than the square meter rate. A £1,500 per m² quote might sound fair—until you realize it doesn’t include the £5,000 for new drainage, the £3,000 for a structural engineer’s sign-off, or the £2,000 you’ll spend fixing the kitchen you had to gut to connect the new space. And don’t forget the home renovation expenses, the broader financial impact of remodeling, including temporary relocation, furniture moves, and unexpected delays. Many people forget these until they’re sleeping on an air mattress in the living room while the builders finish the roof.

What drives the cost? Location plays a big part. Extensions in London or the South East cost more than in the North, not just because labor is pricier, but because permits take longer and materials need to travel farther. The type of extension matters too. A side-return kitchen extension is simpler and cheaper than a full two-story rear extension with a roof terrace. Even small choices—like whether to use standard or custom windows, or if you want underfloor heating—can add thousands. And if your house is old? You might hit hidden issues like crumbling foundations, asbestos, or outdated wiring. These aren’t just repair costs—they’re project changers.

There’s no single answer to the home extension price question. But there are clear patterns. Most people who plan well end up spending between £35,000 and £70,000 for a decent-sized project. Those who skip research, skip quotes, or trust a builder’s verbal promise often end up paying double. The posts below give you real examples—what one family paid for their loft conversion, how much a basement extension cost in Manchester, why a simple kitchen extension went over budget, and what actually gets you the most value for your money. You won’t find fluff here. Just facts, numbers, and lessons learned from people who’ve been there.