Tool one
The extension planner
The house extension planner runs in your browser. You upload the floorplan of your existing home, set the scale, then sketch the extension you have in mind on top of it. As you draw, it gives you an instant build cost estimate for what you have sketched.
- Free, with no sign-up, no email and no download.
- Your floorplan stays on your own device — it is never uploaded to a server.
- Cost estimates are drawn from a database of 1,200+ UK projects.
The ranges behind the estimate are the ones we publish openly: a single-storey rear extension at £2,400–£2,900/m² for a standard finish, up to £3,800–£5,200/m² for luxury; a loft conversion at £1,600–£2,200/m² standard, up to £2,900–£3,600/m² luxury; a garden room or outbuilding at £2,000–£2,800/m² standard, up to £3,800–£5,000/m² luxury. So a 25 m² rear extension at a standard finish lands around £60,000–£72,500.
It is a sketching and costing tool, not a drawing set. It will tell you whether the room you want fits and roughly what it costs — it will not produce something you can submit to a council.
Tool two
The free renovation report
The free renovation report is personalised to one specific house. You start by typing your address and picking your home from the list, then describe what you are thinking of doing. You add your contact details before the report is produced, and the report comes back with three things: a likely build cost range for your idea, the planning context that matters early on for that address, and the value the finished work could add.
It takes about three minutes. There is no charge and no obligation to go any further.
