Planning an extension? Or worrying about your neighbours? Our quick guide to the 45-degree code can help smooth any issues out and keep your neighbours on side. 

What is the 45-degree code?

The 45° Code is a measure used around the West Midlands by most councils (including Birmingham City Council) and Calthorpe Estates to ensure that any extension work done to a house does not impinge on your neighbours’ outlook or access to light.

This issue most often affects homeowners wanting to build rear extensions on semi-detached and terraced houses, but can also apply to side extensions too. 

The Code is designed to provide a fair balance between the wishes of the property owners who want to build and improve their homes and the ‘right to light’ of the people living in the neighbouring properties by protecting the outlook from the rooms of the neighbouring properties and to guaranteeing daylight into them. It is also designed to take into consideration differences in ground levels, where needed.

Councils apply the code by ensuring that any new building work proposed – whether single or double storey – does not cross an imaginary 45° line drawn from the middle of the nearest front or rear window of the neighbouring accommodation that might be affected by the new extension. 

A window you take the measurement from must be the main source of light to a ‘habitable room’ such as living rooms, bedrooms, kitchens and conservatories but not bathrooms, utility rooms, halls, landings or garages, as people generally don’t spend a lot of time in these rooms. 

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45-degree code, 'Right to Light' and Permitted Development Rights

At Lapworth Architects we recommending taking the 45 degree Code seriously if you are applying for an extension under Permitted Development Rights, as your neighbour has the right to contest the development if their right to light is breached. This could mean you have to stop building and redesign your project. 

On small developments or extensions this concept is often overlooked, and the first a homeowner knows that their neighbour objects is when the received a letter from their neighbour’s solicitor – so it pays to be aware of the issue, inform your architect and avoid any potential conflict.

Although the 45 degree Code is an important part of ‘Right to Light’, it’s not the whole story, and involves other calculations done by a specialist to create a report. If needed, we also offer a specialist Right to Light specialist service to ensure that your relationship with your neighbour remains cordial, that your extension is legal and to help you get your Lawful Development Certificate from your local council, or consent from Calthorpe Estates if you’re project is located in Harborne or Edgbaston.

Single-storey extensions and conservatories under PDR

The 45° Code will often apply  to larger single-storey rear extensions or conservatories, as a lot will depend on how close you are to your neighbour or if you live in a semi-detached house. 

The project on the right is a typical example of applying the code to a semi in suburbs of Birmingham, where houses are fairly close together. On this occasion we were able to maximise the size of the extension without affecting the neighbours right to light, and the unusual shape suited the contemporary style of this 1930s house. 

To meet the requirements for Permitted Development Rights, single-storey builds should be sympathetic to the character of your main property in design and materials, and subservient in terms of scale – i.e. not visibly different to the main house.

Planning ahead is also important – if you think you might want to add an extra storey in the future, the ground floor extension should be designed and located to make sure that any future first floor builds would also meet the Code for two storey extensions. 

How to maximise your size and meet the 45-degree code

For conservatories, the colour of the window frame should match the house.  Where properties are in a Conservation Area or are a Listed Building, uPVC windows are not unacceptable, and conservatories should be timber framed and painted rather than stained. You also can’t build conservatories where bathroom and kitchen windows would open, as ventilation and light are key. 

Double-storey extensions

The extension should retain the character of your street in terms of the relationship between buildings and spaces, as well as any established views. It should respect neighbouring properties, taking into account the 45° Code. 

To ensure that the two or more storey extension becomes an integral part of the existing building, roofs should be pitched, either gabled or hipped, to match the roof style of the existing building. 

Extensions on the side of a building should retain a minimum distance of at least 1m (3ft 3in) between the proposed extension and the boundary between your and your neighbours’ property, and a distance of at least 2m (6ft 6in) between adjacent buildings

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Double-storey extension in Harborne

Local considerations of the 45-degree rule and Calthorpe Estates

The Code has been widely adopted around the West Midlands, but not every council has integrated it into their official planning documentation, so you might need to check with your local areas as to whether it’s a concern or not. 

It is specified as a consideration for Birmingham and Coventry City Councils, as well as Dudley and Solihull and Walsall borough councils, whereas Wolverhampton and Sandwell have no specific guidance on this particular area, and so gets applied on what might seem like a random basis. 

As mentioned, the Calthorpe Estate’s Scheme of Management specifies this right to light and privacy in the Residents’ Handbook, and Consent from them must be obtained in addition to the usual approvals from Birmingham City Council. We can draw up this specialist report for you, detailing any effect your proposed extension or build might have on your neighbours.

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The 45 degree Code: A helpful guideline

Although it’s not the be all and end all of the issue of Right to Light, the 45-degree Code can help point you in the right direction when designing and planning your project, and it’s good to be aware of it before time to avoid headaches further down the line. 

At Lapworth Architects, we include this code into all our designs as a matter of course, and should you need further detail in the form of a Right to Light survey for a larger development or on the Calthorpe Estate, we’re more than happy to provide one for you to get the consent you need to move forward.

If you’ve got any questions about the 45-degree Code, you can call us on 0121 455 0032, write to us on our live chat feature, or drop us a message in the section at the bottom of the page. Let’s get your project started!

Why Lapworth Architects?


Our 20+ years of work mean great design and good relationships with planning departments across the region to give our projects the best chance of getting your planning permission and starting building.


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Our breadth of knowledge makes us an efficient and sustainable choice of local architect, and we have a real vested interest in improving our own built environment right here in the West Midlands.


At whatever stage you’re at with your project, if you’re looking for honest, quality advice from professionals, chat to us, leave us a message or call us on the number at the top of the page. Let’s talk!

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