How much does a loft conversion cost in London in 2026?
2 min read
Most London loft conversions land between £90,000 and £115,000 ex VAT. A recent 28 m² conversion we priced came to around £92,000, and a 34 m² third floor conversion with party wall work reached around £111,000. That is roughly £3,300 per square metre of new living space.
These are indicative figures from real London projects priced by the same engine that powers the instant estimator on this site, current as of August 2026. Treat them as a realistic starting point rather than a quotation. Every roof is different, and all figures exclude VAT.
What lofts actually cost: figures from our own priced jobs
Rounded figures from real take offs priced in August 2026, all ex VAT:
- Loft conversion of around 28 m², typically a bedroom and shower room: around £92,000.
- Loft conversion of around 34 m² forming a third floor, including party wall matters: around £111,000.
- As a rule of thumb across both: roughly £3,300 per square metre of finished loft space.
A loft is one of the most cost effective ways to add a bedroom in London because the structure already exists. You are converting a roof, not building one, and the price reflects that compared with extending.
What moves the number most
Four things separate the bottom of the band from the top:
- 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, as the third floor figure above shows.
- 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.
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.
Good to know
Frequently asked questions
- How much does a loft conversion cost in London?
- Between £90,000 and £115,000 ex VAT for most projects, based on real jobs we priced in August 2026. A 28 m² conversion came to around £92,000; a 34 m² third floor with party wall work reached around £111,000.
- What is the cost per square metre of a loft conversion?
- Roughly £3,300 per square metre of finished loft space ex VAT in inner London as of August 2026. Rooflight conversions sit below that rule of thumb; mansard and hip to gable conversions sit above it.
- Is a loft conversion cheaper than an extension?
- Per square metre they are closer than most people expect, 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.
