Loft conversion cost calculator
Get an instant ballpark estimate for your loft conversion based on type, finish, and region.
Estimated cost
conversion.
This covers structural work, insulation, staircase, and a basic fit-out. It doesn't include planning/building control fees (loft conversions often fall under permitted development, but check with your local authority) or high-end fixtures.
Free to post. Vetted builders respond directly to you.
Before you post
How much deposit should you pay a builder?
A reasonable deposit protects the builder's costs. An unreasonable one is a warning sign.
How to check if a builder is insured (and why it matters)
Public liability insurance protects you, not just them. Here's what to ask for and how to verify it.
Questions to ask a builder before you hire them
A short list of practical questions that separate a good hire from a stressful one.
How this is calculated
Velux conversions are the cheapest since they don't alter the roof structure. Dormers add usable headroom and floor space at moderate extra cost. Hip-to-gable conversions (common on semi-detached and detached houses with a sloped side roof) and mansards (a near-flat rebuild of the whole roof slope) involve the most structural work and cost the most. Region and en-suite plumbing are added on top, same as our other calculators.
Other calculators