Loft Conversion Cost London and Hertfordshire 2026
How much does a loft conversion cost in London? This is your complete guide to loft conversion prices in London and Hertfordshire for 2026, covering every type of conversion with detailed cost breakdowns. LCCL Construction provides full design and build pricing with no hidden costs. LABC Award Winners 2024. Over 200 reviews rated 4.7 out of 5.
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How Much Does a Loft Conversion Cost in London?
Loft conversion costs in London vary depending on the type of conversion, the size of the property and the level of specification. Here is a comprehensive breakdown of loft conversion costs in London and Hertfordshire for 2026:
Velux loft conversion: £18,000 to £48,000.
Dormer loft conversion: £30,000 to £65,000.
Hip to gable loft conversion: £35,000 to £85,000.
L-shaped loft conversion: £40,000 to £95,000.
Mansard loft conversion: £65,000 to £150,000.
All prices are for full design and build including architectural design, structural calculations, building regulations, construction, staircase, electrics, plumbing, plastering and decoration.
Please note: Every project is bespoke and individually designed to suit your property. All costs are indicative and subject to final architectural drawings, structural engineer calculations, finishing specification, project location, size and scope of works, any additional alterations, surveys and party wall agreements. A detailed written quote will be provided following your consultation.
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What Affects the Cost of a Loft Conversion?
Several factors influence the final cost:
Type of conversion: Mansard and L-shaped conversions cost more than dormers because they involve more structural work.
Property type: Terraced houses are generally cheaper than semi-detached or detached because they have fewer external walls to alter.
Staircase position: A straightforward staircase above the existing one is cheaper than a complex route that requires structural changes to the floor below.
Bathroom specification: A basic en-suite costs less than a premium bathroom with underfloor heating, walk-in shower and high-end fittings.
Access and logistics: Properties with difficult access may cost more.
Location: Properties in Barnet, Finchley, Hendon, Muswell Hill, Edgware and Hertfordshire fall within standard range. Prime areas such as Hampstead, Highgate and Kensington may be higher.
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What Is Included in the Price?
LCCL Construction provides full design and build pricing covering: consultation, measured survey, architectural design, planning applications, building regulations, structural calculations, party walls, all construction, staircase, electrics, plumbing, plastering, decoration, building control sign-off and optional 10-year LABC warranty. Transparent pricing with no hidden costs.
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How to Get a Quote
Instant quote online: lcclconstruction.co.uk/instant-quote.
Free consultation: lcclconstruction.co.uk/book-online.
Call us: 020 8037 7332, Monday to Saturday 8am to 6pm.
Frequently Asked Questions
What is the cheapest type of loft conversion?
A Velux or rooflight conversion is the cheapest, starting from £18,000. It works best when the existing loft has at least 2.2 metres of headroom. The next most affordable is a dormer from £30,000.
What is the average cost of a loft conversion in London?
The average cost is £50,000 to £68,000 for a standard dormer or hip to gable conversion with full design and build including bedroom and en-suite bathroom.
Are there hidden costs with loft conversions?
LCCL Construction provides transparent pricing. Our quotes cover the full design and build scope. Items that may be additional include bespoke joinery, premium bathroom fittings and any upgrades to the agreed specification.
Is a loft conversion cheaper than moving?
In most cases, yes. Moving costs in London typically total £50,000 to £100,000. A loft conversion costing £30,000 to £75,000 adds equivalent space and value for less.
Do you offer staged payments?
Yes. LCCL Construction uses a staged payment schedule tied to project milestones. Payment stages are agreed before work begins.
How do I get a quote?
Get an instant quote at lcclconstruction.co.uk/instant-quote, book a free consultation at lcclconstruction.co.uk/book-online, or call 020 8037 7332.