Best House Extensions: Types, Costs, and What Works in 2025

When people talk about the best house extensions, additions to a home that increase usable space without moving. Also known as home extensions, these projects are one of the most common ways UK homeowners boost their living space. Unlike moving, a well-planned extension adds value, fits your lifestyle, and keeps you in the neighborhood you love. But not all extensions are created equal—some cost more than they’re worth, others break planning rules, and a few even make your home harder to sell.

The real question isn’t just can you extend—it’s which kind works for your house, your budget, and your future. Build up vs expand, choosing between adding a second storey or spreading sideways. Also known as vertical vs horizontal extension, this decision changes everything—from cost and permits to how much light your home gets. A side extension might cost less upfront, but a loft conversion could give you more usable space without eating into your garden. And if you’re in London or Manchester, UK house extensions, projects governed by local planning rules, permitted development rights, and neighborhood restrictions. Also known as home additions in the UK, these are heavily influenced by where you live, not just what you want. A roof extension in Bristol might fly under the radar, but the same design in Brighton could need full planning permission.

What you’ll find in the posts below isn’t just a list of ideas—it’s a practical guide built from real costs, real projects, and real mistakes. You’ll see how much a 2000 sq ft home extension actually runs in 2025, why structural work is the biggest expense in a loft conversion, and whether building up really saves you money compared to going out. We’ll break down what makes a contractor worth hiring, how to spot a bad extension design before you sign anything, and why some of the most expensive home projects turn into nightmares because of poor planning. No fluff. No theory. Just what works, what doesn’t, and what you need to know before you start digging.