Loft Conversion Cost: What You Really Pay in 2025

When you think about adding space to your home without moving, a loft conversion, a structural renovation that turns unused attic space into a functional room. Also known as an attic conversion, it’s one of the most cost-effective ways to gain extra square footage in a UK home. Unlike building an extension, you’re working with what’s already there—your roof and walls—but that doesn’t mean it’s simple. The real cost isn’t just about materials or labor. It’s about whether your roof structure can handle it, if you need planning permission, and how much of the existing insulation, flooring, and electrical system you’ll have to replace.

A loft conversion, a structural renovation that turns unused attic space into a functional room. Also known as an attic conversion, it’s one of the most cost-effective ways to gain extra square footage in a UK home. isn’t just about adding a bedroom. It could be a home office, a guest suite, or even a bathroom. That’s why the price jumps so much. A basic dormer conversion with minimal finishes might start around £25,000. But if you’re adding a full bathroom, custom stairs, insulation upgrades, and structural beams, you’re looking at £45,000 or more. The biggest surprise? Permits. In many areas, you don’t need planning permission if you’re staying under volume limits—but you always need building regulations approval. That means structural calculations, fire safety compliance, and soundproofing standards. Skip those, and you risk a costly redo—or worse, a legal issue when you sell.

What really drives the cost isn’t the square footage—it’s the structural renovation, the process of modifying a building’s framework to support new loads or uses. If your roof trusses are old timber, they might need steel beams installed. If the floor joists aren’t rated for live loads, you’ll need to reinforce them. And if your stairs don’t meet current regulations, you’ll have to rebuild them from scratch. These aren’t optional upgrades. They’re legal requirements. A contractor who skips these steps isn’t saving you money—they’re putting your safety and future resale value at risk.

You’ll also see big differences depending on where you live. In London, labor rates are higher, and access to the roof can be tight, which adds to the cost. In rural areas, you might get better rates, but finding a contractor with experience in older homes can be harder. And don’t forget about the hidden stuff: moving radiators, rerouting plumbing, adding windows, and installing proper lighting. These aren’t extras—they’re part of the job.

Some homeowners try to cut corners by doing the work themselves. But a loft conversion isn’t like painting a room. It involves load-bearing changes, electrical wiring, and fire safety systems. One mistake, and you could crack a wall, weaken the structure, or create a fire hazard. That’s why most serious projects hire a structural engineer and a certified builder. The upfront cost is higher, but it saves you from a much bigger bill later.

Below, you’ll find real breakdowns from recent projects—what people actually paid, what went wrong, and how they avoided costly surprises. Whether you’re planning a simple storage loft or a full master suite, these posts give you the facts you need to make smart decisions without the sales pitch.