These figures should be treated as early budgeting guides rather than fixed quotations.
 

The final cost can be lower or higher depending on the property, location, access arrangements, structural design and chosen finishes.
 

Prices in London and the Home Counties can be higher than national averages. Projects involving substantial roof alterations, difficult access or a high-end specification can exceed the upper end of the guide ranges.

 

Why Do Loft-Conversion Prices Vary So Much?

Two loft conversions that look similar from the outside can have very different costs.
 

The price may be affected by:
 

• the size and shape of the roof;

• the existing head height;

• whether the roof has traditional rafters or modern trusses;

• the type and size of the dormer;

• the staircase position;

• the amount of structural steelwork;

• whether the ridge height needs to be raised;

• whether a bathroom or en-suite is included;

• the quality of the windows and rooflights;

• the standard of internal finishes;

• fire-safety requirements;

• scaffolding and access;

• the age and condition of the property; and

• the location of the house.
   

A quotation should therefore be based on the proposed layout and drawings rather than a rough price per room.

 

Rooflight Loft-Conversion Costs

A rooflight conversion is usually the most economical option.
 

The existing shape of the roof remains largely unchanged. Rooflights are introduced to bring natural light into the space, while the internal structure is upgraded to create a habitable room.
 

This type of conversion may be suitable where the loft already has good head height and enough usable floor area beneath the existing slopes.
 

A rooflight conversion might create:
 

• a home office;

• a guest room;

• a teenager’s bedroom;

• a hobby room;

• a quiet reading room; or

• a modest additional bedroom.
   

The cost may still include a new structural floor, insulation, plastering, electrics, heating, a compliant staircase and fire-safety works.
 

A rooflight conversion should not be confused with simply boarding the loft for storage. A habitable room needs to comply with Building Regulations.

 

Rear Dormer Loft-Conversion Costs

A rear dormer is one of the most popular types of loft conversion.
 

The dormer extends out from the rear roof slope, creating vertical walls and improved head height. This can transform a narrow roof space into a much more practical room.
 

A rear dormer may provide enough space for:
 

• a comfortable bedroom;

• a principal bedroom suite;

• an en-suite shower room;

• a home office;

• built-in storage; or

• two smaller rooms in a wider property.
   

The price will depend on the width of the dormer, the structural design, external cladding, roofing details, windows and internal layout.
 

A modest dormer with a straightforward staircase will cost less than a full-width conversion with bespoke joinery and a bathroom.

 

Hip-to-Gable Loft-Conversion Costs

A hip-to-gable conversion is often suitable for a semi-detached, detached or end-of-terrace house with a sloping side roof.
 

The sloping hip is replaced with a vertical gable wall. This extends the ridge across the width of the property and creates more usable internal space.
 

The additional structural work makes this more expensive than a simple rooflight or dormer conversion.
 

A hip-to-gable alteration is often combined with a rear dormer to create a spacious new floor.
 

This may allow enough room for:
 

• a large principal bedroom;

• an en-suite bathroom;

• built-in wardrobes;

• two bedrooms;

• a bedroom and office; or

• a generous landing and storage area.
   

The extra cost can be worthwhile because the resulting space is often wider, easier to furnish and more valuable.

 

L-Shaped Dormer Loft-Conversion Costs

An L-shaped dormer can work particularly well on traditional terraced houses with an original rear addition.
 

The main dormer extends across the rear roof slope, while the second section continues over the roof of the rear addition.
 

This can create considerably more usable floor area than a standard rear dormer.
 

Depending on the property, an L-shaped dormer may accommodate:
 

• two bedrooms;

• a principal bedroom and en-suite;

• a bedroom, bathroom and home office;

• a larger landing;

• built-in storage; or

• flexible family space.
   

The additional structure, roofing, external finishes and internal complexity will normally increase the cost.
 

However, the extra space can make a substantial difference to the practicality of the completed loft.

 

Mansard Loft-Conversion Costs

A mansard conversion is generally one of the more substantial forms of loft alteration.
 

The roof is reshaped to create a flatter upper section and steep rear wall. This can maximise the usable head height and create a more conventional new floor.
 

Mansard conversions are often seen on Victorian and Edwardian terraced properties, particularly in London.
 

They can provide excellent space, but the work is more involved because much of the existing roof may need to be reconstructed.
 

Planning permission will usually be required.
 

A mansard conversion may be worth considering where the aim is to create the maximum practical accommodation, particularly where neighbouring properties have already been altered in a similar way.

 

Bungalow Loft-Conversion Costs

A bungalow can offer a large roof footprint and significant potential.
 

The project may create a substantial new upper floor containing bedrooms, bathrooms and flexible living space.
 

However, a bungalow loft conversion can also involve more extensive work than a typical house conversion.
 

There is no existing staircase to continue upwards, so a new stair position must be created within the ground-floor layout.
 

The design may also require:
 

• a new entrance-hall arrangement;

• dormers;

• hip-to-gable alterations;

• a raised ridge;

• extensive roof restructuring;

• a new structural floor;

• ground-floor reconfiguration; or

• substantial fire-safety works.
   

The higher budget can still represent good value because the conversion may transform a modest bungalow into a much larger family home.