Loft Conversion London - Vetted Builders, 3 Free Quotes

Q: Do I need planning permission for a loft conversion in London?

Velux loft conversions and most dormer conversions qualify as permitted development and do not require planning permission, subject to size limits and height restrictions. Mansard conversions always require planning permission. Any loft conversion in a conservation area, on a listed building, or that alters the roofline beyond permitted development limits requires a full planning application. Building regulations approval is required for all loft conversions.

Q: How long does a loft conversion take in London?

A Velux loft conversion takes 4–6 weeks on site. A dormer loft conversion takes 6–10 weeks on site. A mansard conversion takes 10–16 weeks on site. Add 6–12 weeks before work starts for design, structural calculations, building regulations approval, planning permission where required, and party wall notices. Total project time is typically 3–6 months from start to completion.

Q: Do I need a party wall agreement for a loft conversion?

A party wall agreement is required for most dormer and mansard loft conversions on London terraced and semi-detached houses where the work affects a shared wall or is within 3 metres of a neighbouring property's foundations. Velux conversions within the existing roof slope typically do not trigger party wall obligations. A party wall surveyor must be appointed and notices served before work begins — typically costing £700–£1,500 per affected neighbour.

Q: Does a loft conversion add value to a London property?

A loft conversion typically adds 10–20% to a London property's value. On a £600,000 property that equates to £60,000–£120,000 in added value. A loft conversion that creates a master bedroom with en-suite — the most in-demand configuration among London buyers — delivers the strongest return. Adding a bedroom via loft conversion is consistently the best-value way to increase a London property's bedroom count.

Q: What is the difference between a dormer, mansard, and Velux loft conversion?

A Velux loft conversion installs roof windows into the existing roof slope without altering the roofline — the most affordable type (from £25,000) but limited by existing headroom. A dormer loft conversion extends vertically out from the roof slope to create a flat-roofed box with full-height windows, significantly increasing usable floor area (from £45,000). A mansard loft conversion replaces the entire rear roof slope with a near-vertical wall and flat roof — the most space-efficient type, common in inner London, but always requires planning permission (from £65,000).

Submit your loft conversion brief in 3 minutes. We match you with vetted loft conversion specialists experienced in London's planning rules, party wall requirements, and structural constraints and send you competing quotes with full cost breakdowns.

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What are you renovating?

Select the category that best fits your project.

🍳 Kitchen From £8,000

🚿 Bathroom From £4,500

🏗️ Extension From £2,500/m²

🏠 Loft conversion From £38,000

🔨 Full refurbishment From £1,100/m²

🪵 Flooring From £15/m²

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We review your brief and match it with vetted builders who specialise in your project type.

Matched builders review your brief and may contact you to clarify details before quoting.

You receive up to 3 competing quotes with full cost breakdowns. Choose with no obligation.

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WHAT WE COVER

What types of loft conversion can you get quotes for in London?

London’s Victorian and Edwardian terraced housing stock is well-suited to loft conversion, but the right type depends on your roof structure, headroom, and planning constraints. We match you with specialists who know your property type and your borough’s planning history.

🪟 Velux Loft Conversion

Roof windows fitted into the existing slope; no structural changes to the roofline. The most affordable and quickest loft conversion type, ideal where headroom is already sufficient. From £25,000–£45,000

🏠 Dormer Loft Conversion

An extension built vertically out from the existing roof slope, creating a flat-roofed box with vertical walls and full-height windows. The most popular loft conversion type in London. From £45,000–£75,000

📐 Hip-To-Gable Conversion

Extending a hipped roof end outward to create a vertical gable wall significantly increases usable floor area. Common on semi-detached and detached London properties. From £55,000–£90,000

🏢 Mansard Loft Conversion

Replacing the entire rear roof slope with a near-vertical wall and flat or shallow-pitched roof. The most space-efficient conversion type common in inner London. Requires planning permission. From £65,000–£120,000+

🔗 L-Shaped Dormer

Two dormers combined into an L-shape, one on the rear slope and one on the side return roof. Maximises space on Victorian and Edwardian London terraces with back additions. From £60,000–£95,000

🛁 Loft Conversion with En-Suite

Adding a bedroom and bathroom in the loft the conversion type that delivers the strongest ROI and is most in demand among London buyers. Requires careful structural and drainage planning. From £55,000–£100,000+

HOW IT WORKS

How do you get loft conversion quotes in London?

Three steps. No account required. No calls from builders we haven’t specifically matched to your extension type and borough.

Tell us about your Loft

Conversion type, property style, whether you need planning permission, rough budget, and your London postcode. We ask the right questions so specialists can price accurately.
3 MINUTES

We Match and Notify

We review your brief and send it to vetted loft conversion specialists covering your borough. They may contact you to discuss your roof structure and requirements before quoting.
24–48 HOURS

Receive and Compare Quotes

Up to 3 itemised quotes within 5 working days. Compare scope, structural specification, and timeline. Choose or don't, with no obligation.
WITHIN 5 WORKING DAYS

WHY IT MATTERS

Why does a loft conversion in London need a specialist?

A loft conversion on a London Victorian terrace is not a straightforward build. Structural constraints, planning rules, party wall obligations, and drainage requirements all vary by property type and borough. A loft conversion specialist who knows London specifically is a different proposition to one who doesn’t.

📐 Roof Structure Assessment

Older London properties often have traditional cut-roof or purlin roof structures that can be converted, but modern trussed roofs require significantly more structural work. Loft specialists identify this from the outset and price accordingly.

📋 London Planning Experience

Permitted development rules, conservation area restrictions, and borough-specific policies differ across London's 33 boroughs. Mansard conversions require planning permission in all cases. Our specialists have live planning experience in your specific area.

🤝 Party Wall Expertise

Dormer and mansard conversions on London terraced houses almost always trigger party wall obligations. Specialists on our network understand the notice process and surveyor requirements, reducing delays before work can start.

🏆 Verifiable Loft Conversion References

Every builder on our network must provide references from comparable loft conversion projects in London, not general building work. We check these before any specialist receives a lead.

SETTING EXPECTATIONS

What should a loft conversion quote in London include?

Loft conversion quotes vary significantly depending on structural requirements, conversion type, and specification. A single headline number tells you very little ; you need line-by-line detail to compare quotes meaningfully and avoid mid-project surprises.

QuoteMyRenovation specialists are briefed to provide itemised quotes covering all major cost elements. If a quote you receive isn’t sufficiently detailed, let us know, and we’ll follow up on your behalf. Loft Conversion London

Structural engineer's report and beam specification

Planning application (if mansard or conservation area)

Building regulations drawings and submission

Party wall surveyor costs (if applicable)

Roof structure alteration and steelwork

Dormer or mansard structure (walls, roof, weatherproofing)

Roof windows or dormer windows supply and fitting

Insulation to current building regulations (Part L)

Staircase design, supply, and installation

First and second fix electrics and lighting

Plastering and internal finishing

En-suite bathroom (if included) plumbing and drainage

Payment schedule tied to build milestones

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COMMON QUESTIONS

Frequently asked questions about loft conversion London

Questions homeowners ask us most often before submitting their loft conversion brief.

How much does a loft conversion cost in London?

Loft conversion costs in London range from £25,000 for a basic Velux conversion to £120,000+ for a full mansard. A dormer loft conversion typically costs £45,000–£75,000, a hip-to-gable £55,000–£90,000, and a mansard £65,000–£120,000+. An L-shaped dormer, the most popular type on London Victorian terraces typically costs £60,000–£95,000. See our full loft conversion cost London guide for a detailed breakdown by type, size, and borough.

Do I need planning permission for a loft conversion in London?

How long does a loft conversion take in London?

Do I need a party wall agreement for a loft conversion?

Does a loft conversion add value to a London property?

What is the difference between a dormer, mansard, and Velux loft conversion?

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Submit your brief in 3 minutes and receive up to 3 itemised quotes from vetted loft conversion specialists covering your London borough.

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