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Permitted Development in Somerset, North Somerset & Bristol: Guidance

The majority of homes in the Somerset & North Somerset Districts have Permitted Development (PD) Planning Rights, and this means that some types of building works do not need full Planning Permission. PD rights can be very useful once understood properly for the following reasons:

  • You do not need to apply for Planning Permission, which save's time and money

  • The design does not have to meet local planning policy, so theres more freedom

  • You might be able to build more than if you got Planning Permission, so you have the potential to add more value

Situations where PD rights are usually NOT applicable include Listed Buildings, Conservation Areas and Areas of Outstanding Natural Beauty (AONB's). At ArchiWest we specialise in these types of property so please get in touch if you fall into one of these categories in the Somerset, North Somerset, Bristol or surrounding areas.

More advice regarding these categories will be explained in more detail in future posts.



The following checklists give useful guidance for projects that would fall within Somerset, North Somerset & Bristol PD rights;

Single Storey Rear Extensions

  • Max height 4m

  • Max height 3m if within 2m of any boundary

  • Extension depth max up to 8m if detached house

  • Max extension up to 6m if semi-detached or terraced house

  • No cladding in Conservation Area

Two Storey Rear Extensions

  • Max height to match existing house

  • Height max 3m if within 2m of any boundary

  • Max extension from rear wall of 3m

  • Side windows fixed and obscure glazed to 1.7m above floor

  • Not in Conservation Area

Roof Extensions

  • Max increase in loft volume of 50m3 (40m3 for terraced house)

  • Max height of dormer or loft extension to match existing roof

  • Eaves retained and extension set in 200mm

  • Side windows fixed and obscure glazed to 1.7m above floor

  • No extension forward of original front roof slope

  • Not in Conservation Area

Side Extensions

  • Max height 4m

  • Single storey only

  • Max width 50% of original house

  • Not in Conservation Area

Roof Lights

  • Roof lights can be built in Class C of the PD rules. They can be built on any roof slope, including the front, and are even allowed in Conservation Areas.

  • Max protrusion 150mm above roof slope

  • Roof lights on side roof slopes fixed and obscure glazed to 1.7m above floor


  • Max roof height 4m, reduced to 2.5m if within 2m of boundary

  • Max eaves height of 2.5m

  • Must not be used as a separate house

  • Not built in front of house, and not at side of house if in Conservation Area

Front Porches

  • Max external area 3m2

  • Max height 3m

  • Not within 2m of boundary with highway


  • Must be made of porous material if at front of house

  • Must not be a raised more than 300mm


  • Max height 1m higher than existing roof

  • Not on front or side roof pitches facing road in Conservation Area

*New Rules for Larger Permitted Development Extensions

For a detached house the max Permitted Development extension depth has increased from 4m to 8m. For all other types of house, the max Permitted Development extension depth is increased from 3m to 6m. There are some additional rules that must be met if you do want to use this relaxation. But in short, you must let the Council know about your plans so that they can consult with your neighbours. This is known as Householder Prior Approval.


Lawful Development Certificates

You can build under Permitted Development if the above criteria applies to your project and should not require planning permission, BUT to confirm it is usually a good idea to make an application for a Certificate of Lawful Development. This will prove that the work is Permitted Development, and can be kept in your files.

The following indicates the correct procedure to ensure all goes well;

  1. Use an experienced architectural design firm such as ArchiWest to plan and draw up the work.

  2. Make sure to show all the key dimensions on the drawings, including north point and scale bar.

  3. Use the Planning Portal to set up the application form

  4. Make sure to state on the form the correct applicable PD Class. Give all of the key sizes to clearly indicate PD compliance.

  5. Include the correct fee in the submission (usually less than half the cost of a full householder planning submission). This can usually be paid online, over the phone or by cheque.

  6. Wait for approx 6 weeks for the council to confirm compliance

If you need any help with your project or design advice then please drop us a line. We can provide consultations for planning approvals in Somerset and surrounding areas to discuss potential projects, offer advice and best practice.


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