Loft conversion or extension: which adds more space for your money?

A loft conversion doesn't touch your garden and often costs less than an extension of similar floor area, since the walls and much of the structure are already there. The limiting factor is head height. If your roof pitch is too shallow, you'll need a dormer or a rear roof raise to get a usable room, which adds cost and sometimes needs planning permission.

Loft conversions also tend to suit bedrooms and home offices better than kitchens, since plumbing a bathroom or kitchen into a loft space costs more than doing the same at ground level.

An extension gives you more flexibility on layout and is the better option if what you actually want is a bigger kitchen or living space rather than another bedroom. The trade-off is garden space and, usually, a bigger build.

Plenty of our clients end up doing a single-storey extension for living space and a loft conversion for an extra bedroom, rather than treating it as an either-or decision. If that's on the table, it's worth planning both together even if you build them in stages, so the drainage, structural work and access don't end up working against each other later.