Dormer Roof Extensions and Windows

Dormers: Roof Extension & Dormer Windows

Double Dormer conversion

The word dormer originates from the Latin for sleep, 'dormir'.

Sleeping rooms, 'dormers', today describe one of two styles of roof loft:

1. A vertical window set into a gable projecting from a sloping roof.
2. A loft conversion or extension generally with a flat roof and vertical sides.

Structural difference between dormer windows and extensions tends to be one of scale.

1. Dormer Windows

Dormer windows are an attractive and stylish roof addition.

Dormer windows increase headroom within a loft and often span only the width between adjoining rafters, using them as support for the dormer frame.

2. Dormer Extensions

Eyebrow dormer

Dormer extensions require a much broader roof frame and removal of rafter sections during framing.

The existing roof is reinforced with RSJs (Reinforced Steel Joists) to support the ceiling and vertical walls.

Dormer Design

Dormer conversions create very versatile rooms because of the additional headroom when compared with many loft conversions.

Dormer Extension

Internally, design ideas include greater use of vertical windows and walls. Externally, designs are often not subject to planning permission but building regulations.

External design of roof extensions needs to consider the visual impact, and it is generally best to keep dormer design and appearence within character of the house. Usually this involves reproducing the house style and using sympathetic materials.

Dormer Planning Controls

Under NEW regulations that came into effect from 1 October 2008 a loft or dormer conversion or small dormer extension is considered a permitted development, and generally does not require planning permission.

See the Planning Portal Animation (opens new tab/window)

Permission is required if you plan to extend or alter the roof space more than specified limits and conditions:

• Volume increase of 40 cubic metres terraced houses or 50 cubic metres for detached & semi-detached houses. (2-3 bedroom houses generally will be ok for dormers)
• No extension beyond the plane of the existing roof slope of the principal elevation that fronts the highway. (i.e. no dormer to face the street)
• No extension to be higher than the highest part of the roof. (dormer does not increase the roof height)
• Materials to be similar in appearance to the existing house. (in keeping with house and street)
• No verandas, balconies or raised platforms. (in keeping with house and street)
• Side-facing windows to be obscure-glazed; any opening to be 1.7 metres above the floor. (so neighbours are not over looked and for safety)
• Dormer extensions, excluding hip to gable dormers (chimney wall to roof edge), are set back, as far as practicable, at least 20cm from the eaves (2 rows of tiles or a row of slates). (for aesthetics preventing a "3rd storey" appearance)
• Roof extensions not permitted development in designated areas, i.e. National Parks, ANOB, conservation areas, World Heritage Sites.

The majority of loft conversions including those with quite large dormers do not require Planning Permission as the development can be completed under Permitted Development Rights.

Building Regulations approval is always necessary when creating habitable areas though as these ensure the loft is converted to an appropriate standard for safety and structure. Building plans specify the details of the work and materials required to meet these regulations.

Planning Permission

Should your dormer require planning permission, and many now do not, then planning controls may govern the broad design and style of a dormer roof extension. The controls are there to protect amenity and the environment in the public interest, rather than an individual home owners interest.

Planning departments are guided in what plans they can approve by Parliament. As experienced builders we design dormers to maximise the potential of your loft according to Planning and Building Regulations.

Some specific regulations covering dormer extensions and dormers (windows) are the need to be within character, so extensions and windows are constructed in a design and to a style that generally blends with the existing look and feel of your property.

Many Councils require 'they are not out of character with the ... area'.

Many dormers are only built on rear facing roof sections as there are fewer controls than for street facing windows.

Whether you need us to work to existing architectural and building plans, or you need to obtain planning permission using our specialist architectural surveyors, we can expertly construct your dormer conversion to agreed designs.

When designing a loft development, from survey to permission Boarshurt Lofts bring their expertise, understand and experience into a project from the outset.

This allows us to understand the requirements you have for your loft, the usage plans and the design implications. We bring you the best of modern design and materials and space saving innovations that design in maximum economy, comfort and convenience.

Dormer Renovation

Repair and renovation to existing dormers does not require additional planning permission.

Residential and domestic roof structures are constructed from timber and are subject to damage through decay and misalignment caused by natural bowing, warping or kinking.

Our experienced and qualified surveyors and joiners can assess, renovate and repair all types of dormer window and extension.

Professional Builders

All our dormer windows and dormer extensions are designed and expertly constructed to the individual property requirements of your home.

When building your dormer extension or window, we use roofing materials sympathetic to your existing roof. We professionally and efficiently carry out the construction work.

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