Cost of Loft Conversion in Merton (2026)
Loft Conversion in Merton works out at £36,600 to £91,500 per conversion in 2025, give or take. Merton runs a bit over the UK average, which mostly comes down to Greater London labour rates and what the local housing stock demands. Straight like-for-like jobs hit the lower end; anything that needs pipework or structural changes pushes you up.
About loft conversion in Merton
Merton is a large city of around 206,000 in Greater London. The housing is mostly South West London housing leans Victorian and Edwardian with pockets of 1930s semis and modern flats. That matters: older properties usually mean more pipework, rewiring and retrofit surprises, while newer builds in districts like SW19, SW20 tend to be quicker jobs with standardised fittings. Local trade prices sit on the expensive side for UK trade work. That's mostly wage levels plus the cost of running a van and a yard in and around Greater London.
London's the deepest trade market in the country, and also the priciest. ULEZ, congestion charge, parking permits, higher van insurance — it all feeds into the day rate. Most decent firms charge a callout and central boroughs run a clear premium over zones 4 and 5. Book two to three weeks ahead if you can.
Building jobs are labour-heavy, and materials have moved fast — brick, timber, steel, insulation and board are all 20 to 40 percent up on pre-2022. FMB and TrustMark are your best signposts for a proper builder. On anything bigger than a loft conversion, get a Building Control officer involved from day one; fixing non-compliance later costs a fortune.
Loft Conversion cost breakdown in Merton
Simple Velux conversion with no structural changes
Dormer conversion with new stairs and ensuite
Hip-to-gable or mansard conversion, two rooms plus ensuite
What affects the price of loft conversion in Merton?
- Type (Velux, dormer, hip-to-gable, mansard)
- Structural steel requirements
- Ensuite addition
- Party wall agreements
- Planning permission (where PD is insufficient)
Merton vs the UK average
Merton sits in the building & construction market at a cost multiplier of 1.22× the UK national average. That puts Merton loft conversion prices at £36,600–£91,500 versus the UK average of £30,000–£75,000 per conversion.
Loft Conversion cost calculator — Merton
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What's typically included in a loft conversion quote
- Structural calcs and Building Control
- Steels, joists and floor
- Stairs and Velux/dormer
- First and second fix
- Plastering and decoration
Frequently asked questions
How much does loft conversion cost in Merton?
Budget £36,600 to £91,500 per conversion for loft conversion in Merton. Prices here are around 22% more expensive than the UK average. What moves a quote inside that range is mostly building contractor day rates in Greater London and the specific material list for your job.
How long does loft conversion take in Merton?
A straightforward loft conversion job in Merton runs to 8–14 weeks. You can lose days to things outside the contractor's control — parts on backorder, awkward access, or a firm slotting your job around existing bookings. Ask for a start date and expected finish up front.
What's included in the price of loft conversion in Merton?
A proper loft conversion quote in Merton should cover: Structural calcs and Building Control; Steels, joists and floor; Stairs and Velux/dormer; First and second fix; Plastering and decoration. If any of those aren't itemised on your quote, push back and ask. A written guarantee with a clear warranty period is reasonable to expect on this kind of work.
Is loft conversion cheaper in Merton than the UK average?
Loft Conversion in Merton runs around 22% more expensive than the UK average. The UK-wide benchmark for this job is £30,000 to £75,000 per conversion; Merton quotes tend to land between £36,600 and £91,500. Handy to know what the average actually looks like before you price round.
Do I need planning permission for loft conversion in Merton?
Permitted Development covers many loft conversions in England (40m³ terraced, 50m³ semi/detached). Dormers to the front, conservation areas and listed buildings require planning consent. If the property sits in a conservation area or is listed, ring Greater London Council before you book anything in. It's a free call and saves a world of grief later.
See all loft conversion prices across the UK or browse all tradespeople costs in Merton.