Do I Need Planning Permission?

Do I Need Planning Permission?

Planning Permission heading stamped with a red PENDING rubber stamp.One of the biggest problems that owners of detached and semi-detached houses come across is knowing how to extend their homes. Space is always a difficult topic for homeowners, because having to go through the process of selling a house and buying a bigger one is time-consuming and not always possible. Growing families do need their space, though, and gaining planning permission to extend the home is the answer for those who don’t want to buy again. A house can be extended to be an extremely livable space while maintaining privacy and peace for neighbouring homes. There are ways to extend the home without the need for planning permission and your local Council will always encourage you – the homeowner – to do this. If your ideas are grander than that, though, you will need planning permission. One of the most common questions we get is when do I need planning permission? This is exactly what this guide will cover.


When Planning Permission Is Needed

Getting planning permission for the extension of your dreams or even for essential maintenance can be difficult for some. The regulations surrounding planning are complicated for some and some mistakes can be made over what requires planning permission and what doesn’t. If you do go ahead and build onto your home, you need to be sure that you have the right permission for it, otherwise, you can and will be served with a notice that orders you to undo those changes that you spent money making to your home. It’s not worth the risk – or the loss of cash, or the reversal of work. So, it’s always best to know exactly when planning permission is required for the changes to your home.


The 45 Degree Rule

As an indicator when first assessing proposed extensions, the council applies a degree rule. This is to make sure that there is a good aesthetic relationship maintained between the existing building and the extension that has been proposed.


When an extension is being planned, it’s measured at an angle of 45 degrees from the midpoint of the closest window in a habitable room of a neighbouring property. If the proposed extension lies within that 45-degree angle – whether measured horizontally or vertically – it could cause a loss of daylight that is not acceptable. This could mean that planning permission is refused and you have to rethink your extension. If the window of your neighbour is a door, the 45-degree angle gets measured from 1.6m above the ground on the centre line of the window.


Parking Requirements

When you are planning an extension to your home, you have to maintain an adequate parking space. This should be maintained within the adopted Parking Standards that the council have already laid out. If new parking spaces are going to be created in the area where the front garden sits, at least a third of the garden must be kept as a planted garden instead of a hard surface. It’s recommended that 2-3 bedroom homes have 2 parking spaces and 4+ bedroom homes have 3+ parking spaces. You can check the local council website for your council’s Parking Standards guidance.



Anyone who is planning to build an extension to their home should make sure that – at all times – adequate garden space is left open for bin storage, maintenance, drying clothes and to ensure resident safety when it comes to light and air.


when do i need planning permi


Separation Distances

For facing windows of the rooms of the home, there must be a distance of 21 metres at the minimum. If there is a blank wall facing a window, there has to be a distance of 13.5 metres maintained.


Do’s & Don’t’s


  • Front Dormer


    • You must ensure that at least two-thirds of the original roof plane is retained
    • Materials must match
    • Windows mustn’t be larger than the existing ones
    • The roof must be pitched rather than flat
    • The party walls must have at least a 1-metre distance
    • Do not exceed the ridge height of the original roof
    • Do not make the extension too big
    • The flat roof is a poor design
    • Aesthetics need to be considered.



  • Rear Dormer


    • If your property is in an area of conservation, it’s unlikely that you will receive planning permission due to the character impact that it would cause to the history of the area.
    • A dormer roof should be set lower than the original ridge height, from both side boundaries.
    • The materials should match the original roof, too.



  • Ground Floor Rear Extensions


    • Always include a sloping roof.
    • You should endeavour to prevent a loss of daylight or the overshadowing of other neighbouring houses.
    • You must ensure to retain some of the garden space for maintenance, outdoor bins and drying clothes.
    • A ground floor rear extension should not have a flat roof.
    • You should not site the extension where adjacent properties do not have an extension.
    • The extension should not be the full length of the garden.
    • Your proposed extension should not be overshadowing the next door rear window.


There are some conditions that will be considered before planning permission is given, and these are:

  • Number, location and the size of the extension at adjoining properties
  • The position of the property compared to the sun
  • Whether the site is sloping or has a different ground level
  • The location of the bedroom windows and living room windows in the property next door
  • The design of the extension compared to the original house



  • Two Storey Rear Extensions


Usually, these require planning permission, but applications are generally rejected because a two-storey extension close to neighbouring houses can encroach the living conditions of the neighbours. This occurs through overshadowing, loss of privacy or dominance. There are certain situations where they may be acceptable, and these are:

  • The site is sloping, as overshadowing can be minimised if the site is lower than the immediate neighbour.
  • If your neighbours build an extension at the same time as you, you can minimise overshadowing and dominance.
  • Sometimes, overshadowing certain windows and rooms is acceptable, but you need to check the 45-degree rule mentioned earlier to know whether it’s okay.
  • Building an extension next to an existing one on an adjoining house can lessen the dominance.
  • If the extension is built on the outer edge of the building, away from the nearest neighbour, planning permission may be given.



  • Side Extensions


    • Always match the roof shape of the original house
    • Plan your extension based on the 45-degree rule
    • Do not project your extension beyond the original front of the house
    • When looking at the original roof, always have a lower ridge
    • Keep a gap of at least a metre between properties
    • Always match the materials, window styles and positions of the extension
    • The first floor should always set back from the front of the house by 1.5m and all eaves that are planned to be added should match the existing ones.
    • Never have a flat roof on a side extension
    • Do not create a terracing effect
    • Do not project your home extension beyond the front build line
    • On the corner plots, you should endeavour not to project beyond the side build line.



  • Porches


    • When it comes to porches, always match the roof shape of the original house.
    • The style and the materials of the house should also be matched.
    • Your projection should be in keeping with the aesthetics and appearance of the neighbourhood and your extension should not take away from the character of the street.




  • Any dwarf walls that are planned should be matched with the materials of the house.
  • The 45-degree rule pertains here, and separation distances must be adhered to.



    • If the conservatory that you are planning is adjacent to the boundary with a neighbour, there must be an acceptable degree of privacy maintained. This means installing a solid side, obscure glazing or screening by a fence or wall on the side facing the neighbour.


When Planning Permission Is NOT Required

All of the above describes when planning permission is needed, and so we must go on to talk about when planning permission is not required.



  • Rear Dormer


      • The planned maximum additional volume of 50 cubic metres is maintained
      • Positioned below the ridge
      • Set back 20cm from the eaves
      • Materials match the existing roof
      • There must not be any verandas, balconies or raised platforms included.


  • Side Dormer


      • The same requirements as the above dormer apply
      • Windows must have obscure glazing
      • Windows must not open unless the opening is at least 1.7metres above the fl of the room


  • Roof Windows


      • You do not need planning permission for roof windows if it doesn’t project more than 15cm beyond the roof slope or higher than the ridge.
      • If additional volume is created, it could be treated as an extension, so you must be very careful about your window installation.
      • Always check with your council in case of restrictions on the property
      • If the property is a listed building or within the realm of a conservation area, you will require planning permission.


  • All front dormer extensions fronting a highway require planning permission.


  • Single Storey Rear Extensions



      • Projects no more than 4metres beyond the rear wall of the original house
      • The total garden area must not be encroached by more than 50% of the planned extension.
      • A maximum single storey height of 4 metres
      • Maximum eaves height of 3 metres if within 2 metres of the boundary
      • Materials have to be of a similar appearance to the existing aesthetics of the home
      • Must not include a balcony, raised platform or veranda
      • Must not exceed the height of the existing dwelling


  • Single Storey Side Extensions


      • Must not extend beyond a wall which fronts a highway
      • Must not exceed 50% of the original garden area
      • Must not exceed the height of the house
      • The eaves cannot be above the existing eaves height
      • Must not wrap around the rear of the house
      • Materials have to be of a similar appearance to the existing aesthetics of the home
      • Must not include a balcony, raised platform or veranda
      • Must not exceed the height of the existing dwelling


  • Two Storey Rear Extensions


      • Must not exceed 50% of the garden area
      • Must not be taller than the house
      • The eaves height mustn’t be taller than the existing eaves height
      • Must not project beyond the side of the original house
      • Always check with the council for restrictions on the property, because if there are any, planning permission will be required.


  • Porch


      • The ground area externally must not exceed 3sqm
      • Must not exceed 3m in height
      • Must not be within 2m of any boundary with the pavement or highway


  • Replacement Driveway


      • Must be made of a porous material where rainwater will soak through.
      • If not, rainwater must be directed to a porous area and not onto the road


  • Single Storey Outbuilding


      • The total ground area covered by buildings shouldn’t exceed 50% of the total area, excluding the original house.
      • No part of the building can be situated on land which is forward of the front wall of the house
      • For a dual-pitched roof, must not exceed 4m in height
      • Must not include a balcony or veranda


  • Renewable Energy

Solar Panel

The planning system allows for certain types of renewable energy developments on houses that do not require planning permission, as long as certain conditions are adhered to. These include:

    • Solar panels
    • Ground source heat pump
    • Water source heat pump
    • Flue for a biomass heating system or a combined heat and power system
    • Air source heat pump
    • A wind turbine as long as it doesn’t exceed 15m in height and for detached houses only.


What To Do Next

If you require planning permission for your home project, you need to speak to your council directly. Here is the link to Sheffield Council’s planning and Development page. You can then be advised whether your project requires you to have planning permission or not and what to do in terms of paying fees. You can have an agent draw up your plans and submit your application for you, or you can make the application yourself. The application will be shared with your neighbours to ask for their comments, and no decision will be made until 21 days past sharing with your neighbours. Their comments are taken into consideration.

Please get in touch for a free quote.