What is an L-Shaped Dormer Loft Conversion?

It’s a double dormer that connects:

• A rear dormer on the main roof
• With a dormer built on the rear outrigger (often above the kitchen or bathroom extension)

This setup creates a massive, versatile loft space.

Best Suited For

• Victorian/Edwardian mid-terrace or end-of-terrace homes with rear extensions
• Homes in dense urban areas like London, Manchester, Bristol

Key Benefits

• Maximizes floor area — ideal for large bedrooms, bathrooms, or multiple rooms
• Creates a natural layout (e.g. master bed + en suite or 2 beds + bathroom)
• Adds huge value to the property
• Offers great natural light with more window options

Things to Consider

• More complex = more expensive
• Visual impact on rear of property (less of an issue in urban/terraced areas)
• May need planning if exceeding volume limits

Planning Permission

Often falls under Permitted Development, but:

• Must not exceed 40m³ (terraced) or 50m³ (semi/detached)
• Must not extend higher than the existing roof
• Check with local council if in conservation areas or Article 4 zones

Building Regulations

Required for:

• Structural support
• Floor strength
• Insulation, soundproofing
• Fire safety (especially stair placement and escape routes)

Estimated Cost (UK 2025)

£60,000–£90,000 depending on size, spec, and access

High-spec finishes or en suites may push it higher

Popular Layouts

• Master bedroom with luxury en suite
• Two good-sized bedrooms + bathroom
• Office + bedroom combo