Loft Conversion Quote Calculator

How this estimate is put together

The demo prices a conversion from its type, the way most loft specialists frame a first conversation: a rooflight or Velux conversion, which works within the existing roof shape and is the cheapest route where the head height already allows it, a dormer, which adds a box-shaped extension to the rear slope and is the most commonly built option, a hip-to-gable, which squares off a hipped end to add usable floor and width and typically applies to semi-detached and detached houses with a hipped roof, and a mansard, which rebuilds most of the roof slope to nearly vertical and gives the most space but is also the most involved build. Choosing a room with an en-suite adds a line for the extra plumbing, waterproofing and a second fitted space, the property type nudges the range for the access, scaffolding and scale a terrace, semi or detached house typically involves, and bespoke storage or a balcony are priced as optional extras since not every project wants either. Plans, structural calculations, party wall agreements and building regulations sign-off are stated as a separate line rather than folded quietly into the headline range, because that is how the cost actually falls: a different professional, a different invoice, a genuinely different job. None of these numbers is special: when we build a calculator for a real loft conversion firm, the rates, the ranges, the questions and the rules are all theirs, entered once and changed whenever they like.

The point is not the arithmetic, which is deliberately simple. It is that the homeowner gets an honest range and an honest feasibility check in under a minute, and the loft specialist gets a lead that already contains the conversion type, the rooms wanted, the property and the customer's expectations. The conversation that follows starts from "let's book the survey" rather than "how much roughly for a loft".

Why the head-height question matters more than the price

Most loft conversion enquiries stall on one quiet worry: will my roof even take it. Around 2.2 metres at the ridge is the usual rule of thumb a surveyor checks first, and a roof that falls short is not automatically a dead end, a dormer or a mansard can often manufacture the height a rooflight conversion cannot, but it is a real constraint that changes both the answer and the price. Stating that plainly, rather than quoting a single confident number and letting a survey quietly overturn it later, builds more trust than it costs: a homeowner who sees the caveat named upfront trusts the range around it, and books a survey to get a definite answer instead of ringing round for a second opinion. That is the enquiry a loft specialist actually wants, someone who understands roughly what they are buying and why a person still has to come and measure the roof before anyone signs anything.