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Permitted developments for Loft Conversions and Roof Dormer Extensions


Where do I begin?

If you’re planning on extending the living space in your home and don’t have the space to at either side or back of your property to build an extension. You may be considering utilising your loft space.

The first check you can do is look at the available existing head room which is available to you within the loft space. You can take a measurement from the top of the ceiling joist to the underside of the ridge which should give you a rough idea of what space is available.

If the measurement you take is around 2.4 – 2.8 meters or more. Then you’ll probably be able to get your loft converted at a lower as there’ll be less structural work necessary.

If it is lower than this, then most likely need to reduce the ceiling height of the floor level directly below to provide you with the additional head height required in your loft to meet current building regulations approval.

Do I need planning permission for my loft conversion or Dormer Extension?

Depending on the type of loft conversion you’re looking at constructing and the area you live will determine the type of planning permission you require. For a permitted developments you don’t need planning permission but you will require prior planning approval from your local planning authority.

What is under Permitted Development?

Permitted Development allows a loft conversion and a dormer extension to be added providing the dormer is:

  • situated at the rear of your house.

  • The dormer is set back at least 200mm from the eaves of your existing roof and is lower than the existing ridge of your main roof.

  • The volume of the dormer extension doesn’t exceed 50 cubic meters on a detached or semi-detached house 40 cubic meters on a terraced house.

  • Roof lights cannot protrude more than 150mm off the existing main roof plain and the window opening must be at least 1.7 meters off the existing floor.

  • Any side elevation windows must be obscured.

  • The hips of the roof can be altered to create a pitch roof to increase the volume of your home if you live in a detached or semi-detached property.

Although there is no minimum head height for a loft conversion in a permitted development. However, the staircase leading into the loft requires a minimum head clearance height of 2 meters.

What is not permitted under the permitted development?

  • You cannot have an extended platform, balcony, or Verandah.

  • Loft conversions are not permitted in designated areas, which include national parks, areas of outstanding natural beauty, conservation areas and world heritage sites. Work on listed buildings would also not be permitted.

Do I need engage building control to inspect my loft conversion if it is a permitted development?

The answer is yes. Although, planning permission isn’t required. You’ll still be required to engage building control to inspect your loft conversion and dormer extension. To summarise they’d look at the following items:

  • Supporting structure (floor and roof support)

  • Fire safety (fire doors, smoke detection and means of escape

  • Thermal insulation to the new elements (walls roof and floors)

What drawings will I need for my loft conversion or dormer extension?

You will initially require architectural drawings to submit to your local planning authority to be considered for approval.

Where there are any alterations to your homes existing structure. You’ll require structural engineers’ drawings. Building control will need to assess and approve the structural calculations to ensure the proposed structural alterations doesn’t compromise the structural integrity of your existing structure and what additional supports are required to ensure the modifications are structurally compliant.

For more information

For more advice and guidance on loft conversions and Dormer extensions contact Gibbons Construction Management.

Gibbons Construction Management

Build | Extend | Renovate | Repair

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