Do I need planning permission for a home extension?


Building a home extension is a fantastic way to add extra much needed space, but how complicated can it be with planning permission requirements?


With the looming prospect of interest rates eventually rising at some point in the future, you may find that you're more than happy in the home you currently live in, and rather then sell and upsize into a larger property, you would prefer to instead increase the available space by building a home extension.


Building an extension would allow you to get the best of both world's, as you'll not only have a larger property that better accommodates the living needs of you and your family, but it'll also instantly add value to your property, so should the day you do look to sell ever arrive, you'll be able to list it with a significantly higher asking price.


One of the first questions homeowners ponder once they've set their hearts on a new home extension is whether or not they will need planning permission.


If you're one of those homeowners, then this information below is just for you!


Will I need to apply for planning permission for a home extension?


In many cases, no, you will not need planning permission to build a home extension in Wales provided it adheres to some limits and conditions and doesn't exceed a certain size - a little more about those finer details (and there are quite a lot) will be addressed a little later.


Back on September 30th, 2013, the Welsh Government introduced new regulations which changed the way in which building work could be carried out without the need for planning permission. You can view a technical guide on planning permission for home extensions on the Welsh Government website to help you better understand how permitted development rules may apply based on your personal circumstances, but if you'd rather just scroll and read them you can do that as well as we've included the information below for you.


A home extension is deemed to be a permitted development which doesn't require planning application, but this is still subject to strict limits and conditions. The limits and conditions that may apply to your home will depend on whether the property is a rear extension, side extension, single storey or more than one storey - so things can be a little tricky to fully understand.



Remember, if you fail to meet any of these limits and conditions it doesn't necessarily mean you cannot have the home extension you wanted - it simply means you will have to apply for planning permission and if you're fortunate, you'll be granted this permission.


These limits and conditions are listed below based on the type of home extension you're having, hopefully making the information a little clearer to digest:


Limits and conditions that apply to all home extensions in Wales

  • No home extension can be constructed in front of the principal elevation of the home.

  • No more than half of the area of land around the original property can be covered by a home extension.

  • The home extension must not be higher than the highest part of the roof of the existing dwelling house.

  • If the home extension is located within 2 metres of a boundary of the house, the eaves height of the extension must not exceed 3 metres.

  • If the home extension is located within 2 metres of a boundary of the house, it must not exceed 4 metres in height.

  • The visual appearance of any materials used in the home extension must match those used for the existing home as well as reasonably possible.

  • The likes of verandas, raised platforms, roof terraces or balconies cannot be built. A Juliet balcony with no platform, and which does not project from the home extension by more than 300mm, is not within 10.5m of the side boundary of the property, and is not fixed to the principal elevation of the house is permitted. Shutters on the principal elevation of the house are not permitted.

Limits and conditions that apply to single storey rear home extensions in Wales

  • Single storey home extensions cannot extend beyond the rear wall of the house by more than 4 metres, and must not exceed 4 metres in height.

Limits and conditions that apply to rear home extensions with more than one storey in Wales

  • The ground floor of a home extension must not extend beyond the rear wall of the house by more than 4 metres.

  • The upper floor of the home extension must not extend beyond the rear wall of the house by more than 3 metres.

  • The distance between the rear wall of the extended part of the property and the rear boundary of the property (typically a rear garden fence or wall) must be at least 10.5 metres.

  • Any upper floor window in the side elevation of the home extension must be obscure glazed and non-opening, unless the window is 1.7 metres above floor level.

  • The roof pitch of the home extension must, as far as is practical, match the pitch of the existing dwelling house.

  • Rear home extensions with more than one storey are not permitted in a conservation area, national park, an area of outstanding natural beauty or a World Heritage Site.

Limits and conditions that apply to single storey side extensions in Wales

  • Single storey side home extensions must not be closer to a highway than any wall in the side elevation of the existing dwelling house, or at least 10.5 metres from the highway -whichever is nearest to the highway.

  • Single storey side home extensions must not exceed 4 metres in height.

  • The width of the widest part of the resulting dwelling house must not exceed the width of the widest part of the original dwelling house by more than 50%.

  • If the property is located in a conservation area, national park, an area of outstanding natural beauty or a World Heritage Site, the home extension must not project from the side elevation of the property by more than 3 metres and must be set back from the principal elevation of the dwelling house by a minimum of 1 metre.

Limits and conditions that apply to side home extensions with more than one storey in Wales

  • Side home extensions with more than one storey must not be closer to a highway than any wall in the side elevation of the existing dwelling house or at least 10.5 metres from the highway - whichever is nearest to the highway.

  • The home extension is not permitted within 10.5 metres of a side boundary of the property.

  • The home extension must be set back from the principal elevation of the property by a minimum of 1 metre.

  • The width of the widest part of the resulting dwelling house cannot exceed the width of the widest part of the original dwelling house by more than 50%.

  • Any upper floor window in the side elevation of the home extension must be obscure glazed and non-opening, unless the window is 1.7 metres above floor level.

  • The roof pitch of the home extension must, as far as is practical, match the pitch of the existing dwelling house.

  • Side home extensions with more than one storey are not permitted when the property is located in a conservation area, national park, an area of outstanding natural beauty or a World Heritage Site.

All permitted development allowances that are included here apply to houses only - NOT flats, maisonettes or other buildings.


(MORE: View our home extension gallery >>)


Still unsure? Ask your expert builders

Planning permission can seem like a minefield, especially to those who are not involved in the building industry. If you have any uncertainty or questions surrounding your building work, don't hesitate to ask your professional expert builders - that's why we are here!


We have up-to-date knowledge and expertise so can advise you on all the legal matters related to your home extension, and if it transpires that your plans do require planning permission from the local council, we can assist you with that as well.



I have obtained planning permission for my home extension - can we start the work?

If you have obtained the relevant planning permission from the local council then that's great news, however, it may only be one consent that may be required before building work can commence.


Some properties state within their title documents covenant that may prevent home extensions from being built without the written consent from the original developer or owner of the property. Homeowners should always seek the relevant consent prior to any home extension being built. Failing to obtain all relevant consent could result in a breach of covenant and this can lead to an order for the home extension to be removed or for indemnity insurance to be taken out in respect of the breach of the covenant.


For those who purchase a property that already has a beautiful home extension, their conveyancing solicitors will make all relevant enquiries to ensure the home extension was built with any required planning permission. Some home extensions may not require planning permission but may still require building regulations. Planning laws and building regulations are always subject to change, so it'll be the job of your conveyancers to be aware of the legal requirements at the time the home extension was erected and make sure that all relevant consents were successfully obtained.


(MORE: Learn all about popular timber frame extensions)


Have you been thinking about building a home extension to add some stunning new space to your property in Cardiff? Perhaps you'd like some advice on the creative possibilities to see if we can bring your dream ideas to life? To learn more about the wide range of home improvement services we offer here at RGB Construction, don't hesitate to contact us today. Call us on 07946 452571, e-mail enquiries@rgbconstruction.info or complete our online contact form.


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