How much does a loft conversion cost in London in 2026?
· 3 min read
Typical London rear dormer loft conversions priced on our estimator land between £68,000 and £81,000 ex VAT. One adding about 20 m² of new floor at a high specification priced at around £70,000, and a larger one adding about 28 m² at a standard specification priced at around £78,000, each including a new stair from the floor below. Both price windows, rooflights, sanitaryware, tiles and wood flooring for fitting only, with the products supplied by you.
These are indicative figures from typical London jobs priced by the same engine that powers the instant estimator on this site, current as of October 2026. Treat them as a realistic starting point rather than a quotation. Every roof is different, and all figures exclude VAT.
What lofts cost: typical jobs priced on our estimator
Rounded figures from typical London jobs priced on our estimator in October 2026, all ex VAT:
- Rear dormer loft adding a bedroom and shower room, about 20 m² of new floor at a high specification plus the new stair (around 28 m² worked on in all): around £70,000.
- Rear dormer loft adding a bedroom and en suite, about 28 m² of new floor at a standard specification plus the new stair (around 34 m² worked on in all): around £78,000.
Both include the building work to party walls. The party wall surveyors' fees are extra. Divide by floor area with care: the new stair and the works in the house below are in the price but add no loft floor. Our free estimate allows for them in its rate of £2,550 to £3,150 per square metre of new loft floor.
A loft adds a bedroom without groundworks or any loss of garden, which is much of its appeal in London. It is not a cheap way to add floor area, though. Divided by its new floor purely for comparison, the standard specification loft comes to about the same per square metre as our £2,650 to £2,900 extension band, and the high specification one costs more, both for its finish and because its stair, steel and shower room fall on a smaller area.
What moves the number most
Four things move a loft's price most:
- The conversion type: rooflight conversions are the gentlest on budget, dormers buy real headroom for a moderate uplift, and mansards or hip to gable conversions sit at the top because they rebuild much of the roof.
- Bathrooms: nearly every London loft adds an en suite, and the wet room is a meaningful slice of the total. A loft without one prices noticeably lower.
- Party walls: semi detached and terraced houses usually need party wall agreements, and working on shared structure carries real cost. Both examples above include the building work to party walls, but not the party wall surveyors' fees, which are extra.
- Stairs and structure: where the new staircase lands, and how much steel the floor needs, are decided early and shape the budget more than any finish choice, which is why the structural engineer belongs at feasibility.
How prices change across London
Our figures are calibrated to inner west London, the Fulham, Chelsea and Wandsworth belt. From our regional pricing research: prime central projects often price 8 to 25 percent above these figures, and outer London commonly runs 10 to 20 percent below. Conservation areas and listed buildings add planning constraints that show up in both programme and price wherever the house stands.
How to get your number
Your roof is not an average. The instant estimator on this site prices your loft from your own description: tell it about the house and what you want up there, answer a short set of tailored questions, and a realistic priced range arrives on screen and in your inbox within minutes.
Planning work like this? See how MVV handles loft conversions in London.
Good to know
Frequently asked questions
- How much does a loft conversion cost in London?
- Typical London rear dormer loft conversions priced on our estimator in October 2026 came to between £68,000 and £81,000 ex VAT, indicative. One adding about 20 m² of new floor at a high specification priced at around £70,000; a larger one adding about 28 m² at a standard specification priced at around £78,000, each with a new stair.
- What is the cost per square metre of a loft conversion?
- Our free estimate prices every type of loft, from rooflights only to a mansard, at £2,550 to £3,150 per square metre of new loft floor, ex VAT at a standard finish, so about 25 m² comes to £64,000 to £79,000. The rate carries the new stair and the works in the house below, which add no loft floor. Our two rear dormer examples, priced on our estimator in October 2026, came to around £70,000 for about 20 m² of new floor and around £78,000 for about 28 m², indicative and ex VAT.
- Is a loft conversion cheaper than an extension?
- Not per square metre on our figures: divided by its new floor, one rear dormer priced on our estimator came to about the same as extending and the other to more. But a loft usually needs no groundworks and no loss of garden, and it adds a bedroom where London values it most. An extension wins when you need ground floor living space rather than another bedroom.
- Do I need a party wall agreement for a loft conversion?
- In a terraced or semi detached house, almost always. Party wall matters take time and carry genuine cost, so start the conversation with your neighbours early.
- How do I find out what my loft conversion would cost?
- Use the instant estimator on this site. Describe the house and the loft you want, answer a few tailored questions, and a realistic priced range for your project lands on screen and in your inbox in minutes.
