Dormer loft conversions

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Dormer loft conversions can add that extra space your loft requires

Dormer loft conversions are one of the most common in the UK! especially the flat roof dormer, which consists of a vertical extension, coming from the sloping roof.

The reason they are so popular is that they can transform a cramped loft into something more spacious, giving more headroom, natural light and ventilation.

Ideal in houses where the loft has limited space, flat roof dormer loft conversions can make your loft space a very inviting and practical space for family use.

Unlike other loft conversions, inside the room would have vertically straight walls, which often means it ends up a bigger room than you imagine.


Dormer loft conversions are suitable for most houses and can be done on terraced, end of terraced, detached and semi detached properties.


Dormer loft conversions are often seen as a permitted development, meaning it does not require planning permission. Below are the details of loft conversion limitations before planning permission is required.

  • A volume allowance of 40 cubic meters additional roof space for terraced houses

  • A volume allowance of 50 cubic meters additional roof space for detached and semi-detached houses

  • No extension beyond the plane of the existing roof slope of the principal elevation that fronts the highway

  • No extension to be higher than the highest part of the roof

  • Materials to be similar in appearance to the existing house

  • No verandas, balconies or raised platforms

  • Side-facing windows to be obscure-glazed; any opening to be 1.7m above the floor

  • Roof extensions not to be permitted development in designated areas

  • Roof extensions, apart from hip to gable ones, to be set back, as far as practicable, at least 20cm from the original eaves

  • The roof enlargement cannot overhang the outer face of the wall of the original house.

Dormer loft conversions still require plans and construction specification to submit to building control, to ensure the build is done to requirements and is safe for use.

At LSM Builders, we are up to date with all requirements and we can design and build your loft conversion from start to finish,  to create that modern space you desire!

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