Dormer vs Hip-to-Gable vs Mansard: Which Loft Conversion Type Is Right for Your London Home?

Choosing the right loft conversion type for your London home depends on your roof shape, property type, budget and how much space you need. The three most popular types are dormer, hip-to-gable and mansard conversions, each with different advantages, costs and planning requirements. LCCL Construction has completed hundreds of all three types across London and Hertfordshire and can advise on the best option for your property.

Dormer vs Hip-to-Gable vs Mansard: Which Loft Conversion Is Right for Your London Home?

Dormer Loft Conversions

A dormer conversion extends outward from the existing roof slope to create additional floor space and full standing headroom. A box dormer across the rear of the property provides the most usable space. Dormers are suitable for most property types including terraced, semi-detached and detached houses. Most rear dormers fall under permitted development and do not require planning permission. Dormer conversions typically cost £56,400 – £80,400 inc. VAT (£47,000 – £67,000 + VAT) and take 8 to 10 weeks to build. They are the most popular type of loft conversion in London due to their versatility and value for money.

Hip-to-Gable Loft Conversions

A hip-to-gable conversion extends the sloped hip end of a roof to create a vertical gable wall, significantly increasing the usable floor area inside the loft. This type is ideal for semi-detached and detached houses with hipped roofs. It is often combined with a rear dormer for maximum space. Hip-to-gable conversions typically cost £60,000 – £114,000 inc. VAT (£50,000 – £95,000 + VAT) and take 10 to 12 weeks to build. Most hip-to-gable conversions on semi-detached houses fall under permitted development, though detached houses may need planning permission depending on the scale.

Mansard Loft Conversions

A mansard conversion alters the entire roof structure to create near-vertical walls at 72 degrees with a flat roof on top. It provides the most space of any loft conversion type and effectively creates a full additional storey. Mansards are popular on Victorian and Edwardian terraced and semi-detached houses in London. They almost always require planning permission because they significantly alter the roofline. Mansard conversions typically cost £76,800 – £148,800 inc. VAT (£64,000 – £124,000 + VAT) and take 10 to 14 weeks to build. They offer the most space but are the most expensive option.

Which Loft Conversion Type Is Right for Your Home?

For terraced houses with a simple pitched roof, a rear dormer is usually the best and most cost-effective option. For semi-detached houses with a hipped roof, a hip-to-gable combined with a rear dormer maximises space. For terraced or semi-detached houses where maximum space is the priority and budget allows, a mansard provides the most room. For properties where planning permission may be difficult, a dormer or hip-to-gable within permitted development limits is the safest choice. L-shaped conversions, combining a rear dormer with a side dormer, are ideal for Victorian terraced houses with rear outriggers.

Get Expert Advice from LCCL Construction

LCCL Construction has completed hundreds of dormer, hip-to-gable, mansard and L-shaped loft conversions across London and Hertfordshire. We offer free consultations to assess your property and recommend the best type of conversion for your needs and budget. Our loft conversion prices start from £32,400 inc. VAT (£27,000 + VAT) for Velux conversions and our complete design and build service covers everything from design to completion. Call 020 8037 7332, email info@lcclconstruction.co.uk, or book at lcclconstruction.co.uk/booking-calendar/free-consultation-call.