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Loft Conversions

Expert Loft Conversions Across Dulwich, Greenwich, Blackheath & South East London

Transform your unused attic into valuable living space with JT Allen. We’ve been helping homeowners across South East London unlock the hidden potential of their properties for over 35 years.

A loft conversion is one of the most cost-effective ways to add space without moving or extending into your garden. Whether you need an extra bedroom, home office, playroom, or peaceful retreat, we create stunning, functional rooms tailored to your needs.

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Why Choose JT Allen for Your Loft Conversions

  • 35+ years of loft conversion experience
  • 100+ loft conversions completed across South East London
  • All types: Velux, dormer, hip-to-gable, mansard
  • Full service from design to completion
  • Planning permission and building regulations handled
  • 10-year structural guarantee
  • Fully insured with £2M public liability
Request a Quote

Contact Swanbourne Construction for a free, no-obligation quote.

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Types of Loft Conversions We Offer

Velux (Roof Light) Conversions

— From £30,000

The most affordable option, ideal for lofts with good existing head height. We install high-quality Velux windows to flood your new space with natural light. Perfect for bedrooms and home offices.

Dormer Loft Conversions

— From £45,000

The most popular choice in South East London. A dormer extension projects from the roof slope, creating full-height space with vertical walls. Rear dormers are particularly effective on Victorian and Edwardian terraces.

Hip-to-Gable Conversions

— From £60,000

Ideal for semi-detached and detached homes with hipped roofs. We extend the sloping side of your roof to create a vertical gable wall, significantly increasing usable floor space.

L-Shaped Dormer Conversions

— From £65,000

Maximises space on properties with rear extensions. The L-shape follows the existing roof lines, creating generous rooms perfect for master suites with en-suite bathrooms.

Mansard Conversions

— From £70,000

The most extensive option, effectively creating a new storey. Features a flat roof with steeply sloping walls containing windows. Usually requires planning permission but maximises space potential.

Our Loft Conversions Process

Free Survey

We assess your loft's potential and discuss your requirements

Design & Planning

Architectural drawings and planning applications if needed

Building Control

We handle all building regulations approval

Construction

Our team builds your conversion with minimal disruption

Completion

Final inspection, sign-off, and handover

What's Included

  • Structural work including steel beams
  • Dormer or roof alterations
  • New staircase
  • Insulation and plasterboard
  • Windows (Velux or dormer)
  • Electrical installation
  • Plumbing for en-suite if required
  • First and second fix carpentry
  • Plastering and decoration
  • Building regulations sign-off
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Loft Conversions FAQs

Do I need planning permission?

Most loft conversions fall under Permitted Development. You may need permission if you’re in a conservation area, planning a mansard, or exceeding volume limits. We advise during your free survey.

Typically 6-10 weeks depending on complexity. Velux conversions are quickest; mansard conversions take longest.

Yes. We access through scaffolding wherever possible and maintain a clean, safe site throughout.

Yes. A professionally completed loft conversion typically adds 15-25% to property values in South East London, particularly where extra bedrooms increase market appeal.

Loft Conversions by Location

Get Your Free Quote Today

Ready to start your project? Contact JT Allen for a free, no-obligation consultation.

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