"THE 45-DEGREE RULE" Sunlight, Daylight And Your Proposed Extension

What is the 45-Degree rule?

The 45-degree rule also known as the 45-degree code and 45-degree guide is a method used by Local planning authorities to measure the impact from a proposal on sunlight and daylight to neighbouring properties.

If you’re planning on building an extension, have you considered its impact on your neighbours? When planning authorities receive an application to develop a property one of the things they will consider is the effect of the proposal on neighboring properties. This includes natural sunlight and daylight.

So before we continue, what do we need to know about the sun:

  • The sun rises in the East and sets in the West
  • The Sun is due South at noon
  • The Sun is also at its maximum height around noon
  • The sun is lower during winter months with shorter days
  • The sun is higher during the summer months making our days longer
  • Direct sunlight is brighter than ambient daylight
  • Daylight is the natural light created between dawn and dusk

It’s your local authorities responsibility when considering an application to safeguard the neighbouring properties amenities.

When designing an extension we need to consider the level of sunlight and daylight currently enjoined by the neighboring properties. Some extensions can be poorly designed and sited, resulting in shadowing that can adversely affect the amenities to your neighbours main inhabited rooms to unacceptable levels.

Rooms such as bathrooms, halls, utilities and landings/stairs are not generally considered and overshadowing to garden areas rarely constitute sufficient grounds to justify a planning refusal.

Protecting existing daylight

Extensions and new buildings should be designed to minimize shadowing on to neighboring properties.

Factors effecting shadowing:

  • Height of the proposed development
  • Size of the plot
  • Building orientation
  • Distance from boundary
  • Topography

Your local planning authority will generally follow BRE guidelines and apply the “45-degree guide” in cases where a proposed development may affect neighboring properties.

The purpose of the 45-degree guide is to make sure the proposal does not take away too much daylight. It is based on the notion that it is reasonable to expect a certain level of light and unobstructed view from a habitable room window.

There are two methods used for applying 45-degree rule.

Method 1: Considers the depth and width of the extension.

Method 2: Considers the height of the extension.

If the proposed extension breaks one of the 45-degree splay lines you local authority may view your proposal as unacceptable.

To make these methods more clear please see the diagrams below.

Method 1:

In method 1 we mark the centre point of the neighbours nearest window and draw a 45-degree splay line towards the proposed extension.

45degree bev 1a.png


Example A is to the left and B is to right.

In example A the extension is reduced in depth where it is located outside of the 45-degree splay. This would normally be considered an acceptable development.

In example B the extension depth is too much and the new proposal falls within the 45-degree splay. This would normally be considered unacceptable.


Method 2:

In Method 2 we mark the centre point from the middle of the nearest habitable ground floor window of your neighbouring properties. From this point we draw our 45-degree splay line out towards the proposed extension.



Example A is to the left and B is to right.

In example A the proposed extension height is located outside the 45-degree splay line. This would normally be considered acceptable.

In example B the proposed extension height is too great and falls within the 45-degree splay. This would normally be considered unacceptable.


Developments under Permitted Development?

The 45-dregree rule does not apply to Permitted Development legislation.


Garage conversions? Convert your garage to a living space

Do you still park your car in your garage? We've lost count of how many homes we've visited with garages, it's a lot. Out of all those garages the total number that actually had vehicles parked in them was two, yes two! One had a vintage car under a old dusty blanket and the other had a quad bike. So if you do actually use your garage for parking your car, in our opinion you're in the minority.

What if you could make efficient use of your garage and convert it to extra living space? Which could also make pretty good financial sense too. Garage conversions that have been converted to high standards could increase your property value by 10%-12% and that's quite a substantial increase.

So you may now be wondering, do you need planning permission to convert your garage?

Firstly we advise you to check whether you have permitted development rights for your house and that there are no restrictions on the garage when it was originally granted planning permission preventing other uses. If you do not have permitted development rights, you will automatically need to apply for planning permission for your proposed changes.

If you do have permitted development rights and want to convert an integral/attached garage, then as long as the work is internal and does not involve enlarging the building, you will not usually require planning permission.

If your garage is detached from the house it may not require planning permission if the proposed conversion is to be used 'incidental' to the enjoyment of the main house. However if the conversion involves the installation of a kitchen, bathroom or sleeping accommodation then your conversion may require 'change of use' planning permission to convert the building to habitable rooms, due to the greater degree of independence from the main house.

So, planning to convert a detached garage to an annexe under permitted development could be possible if it's only to be occupied by guests or dependents of the main house. However, if you want to let it out, you will have to obtain planning permission for independent use. Our advice here is to seek help as this can seem like a grey area and internet research can leave you even more confused about whether you need planning permission or not. 

The issue here is the potential for the garage to become a self contained unit as a dwelling house is only considered as one planning unit. So now the converted garage becomes an 'ancillary' use rather than an 'incidental' use. In simple terms ancillary use would mean it could possibly be used as a standard house (separate unit), where as if the use was incidental it could not exist without the main house. In this case you would likely require planning permission.

In both situations if you intend to develop within your permitted development rights, we would advise applying for a certificate of lawful development (CLD) for the proposed use. A CLD will mean you'll receive a legally binding decision as to whether a proposed development is lawful and doesn't require planning permission.

Building Regulations:

In most instances you will require building regulations to bring your garage conversion up to date with building regulations. Each garage will be different and require different works to bring the building up to standard, such as moisture proofing, insulation, fireproofing, means of escape, ventilation and structural soundness. An inspector will want to check your project as its constructed and will issue you with a completion certificate when satisfied with the finished conversion.

We hope this helps answer your questions with regards to converting your garage. As always if we can be of any further assistance then please get in touch or email us at enquiries@1MoreRoom.co.uk

Do I need planning permission for a shed or garden room?

summer house_1.png

Lately we are getting a lot of questions about planning permissions and permitted development rights. One of the most popular planning permission queries are shed’s (outbuildings).

A shed or garden room will come under the subject of outbuildings and it’s easier to discuss this topic that way.  An ancillary outbuilding could be a garage, summer house, garden office, pool house, kennel, garden studio, home gym or a storage room (shed). So if you are thinking about adding any of these to home, you will need to assess whether you need to gain planning permission or not.

If you are already thinking about adding an outbuilding, you probably have an idea of the size of the building in mind and what you want to use it for. If you have permitted development rights on your property, we can now move forwards and check if your proposed building falls within those rights. If so, then the good news is you will not require planning permission for your proposed outbuilding.

shed permitted development

Keeping your proposed building in mind. Does it conform with the following?

  • Outbuildings on land in front of the principal elevation require planning permission and do not come under permitted development.
  • Outbuildings and garages are to be single storey.
  • Maximum eaves height of 2.5 metres.
  • Maximum overall ridge height of 4 metres for a dual pitched roof.
  • Maximum overall height of 3 metres for any other roof.
  • Maximum height of 2.5 metres in the case of a building, or container within 2 metres of a boundary of the curtilage of the house.
  • Decking and raised platforms are permitted development, but must not exceed a maximum height of 300mm.
  • Balconies, verandas or raised platforms are not included under permitted development rules and require planning permission.
  • No more than half (50%) the total area of land around the "original house"* would be covered by additions or other buildings.  (This includes extensions.)
  • In places such as National Parks, the Broads, (AONB) and World Heritage Sites, there are additional constraints. The maximum area to be covered by buildings, enclosures, containers and pools more than 20 metres from house are to be limited to 10 square metres.
  • On designated land* buildings, containers and enclosures at the side of properties do not come under permitted development rights and will require planning permission.
  • A proposed outbuilding within the curtilage of a listed building will require planning permission.
  • New buildings that are separate, self-contained, living accommodation or have TV antennas do not come under permitted development rights and require planning permission.

*The term "original house" means the house as it was first built or as it stood on 1 July 1948 (if it was built before that date). 

If you can comply with the above for your proposed outbuilding, it is now important to understand whether or not your property has permitted development rights. Permitted development rights apply to houses but do not include flats, maisonettes or other buildings.

Why is it important for you to check that your house has these rights?

It is possible that permitted development rights have been removed by the local authority by “Article 4 directions”. For this reason we would always advise that you check with your council whether permitted development rights apply to your house.

We also recommend to people that it is good practice to apply for a Certificate of Lawful Development (CLD) when proposing to construct an outbuilding. A Certificate of Lawful Development means you will receive a legally binding decision as to whether your proposed development or alterations is lawful and doesn't require planning permission.

Building Regulations

You may also be exempt from submitting building regulations, this will generally depend on the size of the outbuilding and its type of construction.

So to provide you with some general information to help you comply with Building Regulations when building a new outbuilding within the boundaries of your existing property, such as garages, carports, a summerhouse, sheds or greenhouse you need to consider the following:

Any outbuilding containing sleeping accommodation will require building regulations.

Attached Garages and Carports:

If you are building a new garage that will be attached to the existing home, then you would normally need building regulations approval for the construction. If you are constructing a new attached carport (Carports must be open on at least two sides) then you would not normally require building regulations approval if its floor area is less than 30 square metres.

Detached buildings:

If you are building a detached garage or other outbuildings with a floor area of less than 30 square metres you would also not normally need building regulations approval if:

A)   The floor area of the garage is less than 15 square metres.

B)   The floor area of the detached garage or outbuilding is between 15 square metres and 30 square metres, provided the building is a minimum of 1 metre from any boundary, OR it is constructed from substantially non-combustible materials.

We hope this helps answer your questions with regards to outbuildings for your property. As always if we can be of any further assistance then please get in touch or email us at enquiries@1MoreRoom.co.uk

Financial boost to London skyline for homeowners?

George Osborne believes the overcrowded capitals needs to expand upwards and he's going to make it easier to do so.

Terraced homes - London

Terraced homes - London

New proposals unveiled this week by the Treasury could mean It may soon be possible for London homeowners to add more than one storey extensions, without having to gain planning permission. As long as the proposed development is not higher than their neighbours property.

This is going to be part of a set of reforms to relax planning rules to help bump up home construction due to the shortage of homes here in the UK.

This movement has been proposed to help homeowners. For example, a growing family could add extra space to their home by adding extra storeys, without needing to gain planning permission!

This will be based on the Neighbour Consultation Scheme. Meaning the home owner will still need to notify the council. The council will then notify adjoining properties informing the neighbours of the proposed development, giving them the option to object or not. (An objection needs a valid reason for the local authority to be able to refuse your proposal).

The proposal will follow the general Permitted Development rules and apply to houses but not flats or maisonettes.

Do I need planning permission for a conservatory?

conservatory planning

This is one of our most common questions and is normally followed up by will we need building regulations too?

Firstly I want to give you a building regulation definition of a conservatory, this is important as these factors determine to your local council the difference between your conservatory being a conservatory or an extension:

“A single storey part of a building at ground floor level, where the roof and walls are substantially glazed with a translucent or transparent material, intended for growing plants, but often used as occasional living space. A conservatory has not less than three-quarters of the area of its roof and not less than one-half of its external walls made of translucent material."

This development although the roof is over 75% translucent and has over 50% translucent walls would not be considered a conservatory due to not being separated from the main house. In this case this development is not exempt of building regulations.

This development although the roof is over 75% translucent and has over 50% translucent walls would not be considered a conservatory due to not being separated from the main house. In this case this development is not exempt of building regulations.

So we want to address this as simple as possible to make it understandable for all. Do you need planning permission?

There are some exceptions but in general no. Your conservatory can be built under permitted development rights, subject to the limits and conditions below:


  • Conservatories (including any previous extensions) must not exceed more than half the area of land around the "original house"*. This includes other buildings including sheds and outbuildings.
  • The conservatory is not forward of the front or side elevation facing a road (highway).
  • Rear conservatories must not extend beyond the rear wall of the “original house”* by more than three metres if an attached house, or by four metres if a detached house.
  • In addition, outside Article 1(5) designated land** and Sites of Special Scientific Interest the limit is increased to 6m if an attached house and 8m if a detached house until 30 May 2016.These increased limits (between 3m and 6m and between 4m and 8m respectively) are subject to the neighbour consultation scheme.
  • The maximum height of a single-storey rear conservatory is four metres.
  • A conservatories maximum eaves height that is constructed within two metres of the boundary must be no more than three metres high.
  • Maximum eaves and ridge height of conservatory must be no higher than the existing house.
  • Side conservatories are to be single storey with maximum height of four metres and a maximum width of no more than half the width of the “original house”*.
  • On designated land* there is no permitted development for rear extensions or conservatories of more than one storey; no cladding of the exterior; no side extensions or conservatories.
  • The permitted development allowances above apply to houses only.
  • Flats, maisonettes and other buildings are not included in the permitted development regime.
  • Conservatories proposed to a listed building need listed building consent.

* The term "original house" means the house as it was first built or as it stood on 1 July 1948 (if it was built before that date). Although you may not have built an extension to the house, a previous owner may have done so.

** “Article 1(5) designated land” - this is land within a National Park, the Broads, an area of outstanding natural beauty, an area designated as a conservation area, and land within World Heritage Sites.


If you are still in doubt you should always check with your local councils planning department or your architectural service professional. Although planning may not be required you can also obtain a “certificate of Lawfulness”.

A certificate of lawfulness is confirmation from you local councils planning department that your proposed conservatory doesn’t require planning permission.


Does my conservatory require building regulations?

Conservatories are normally exempt from building regulations but there are limits and conditions to check before you start construction:

A Building Regulation application will be required for a conservatory in the following situations:-

a) If the conservatory is to be located in a position that will obstruct access by ladder to an escape window e.g. first floor inner room, second floor alterative escape window, etc. (Regulation 3 (2) material alteration affecting B1 – Means of escape).

b) If the conservatory is likely to obstruct access or facilities for the Fire Service (Regulation 3 (2) material alteration affecting B5 – Access and facilities for the fire service).

c) If the conservatory is likely to affect access or facilities for disable people (Regulation 3 (2) material alteration affecting Part M – Access and facilities for disabled people).

d) If the position of the conservatory is likely to impair the airflow across a balanced flue and subsequently the correct functioning of a boiler (Regulation 3 (2) material alteration affecting a controlled fitting).

If the above items (a) to (d) are met, a conservatory will be exempt from the requirements of the Building Regulations providing:-

1) It is single storey at ground level.

2) Your conservatory has a floor area that does not exceed 30m2.

3) Has at least 75% of its roof and 50% of its exterior walls made of translucent material as stated above in the definition of a conservatory.

4) Has glazing that satisfies Part N of Schedule 1 in the most recent Building Regulations document.

5) It is separated from the dwelling by existing doors or windows. (must not be open to the existing dwelling.

6) For energy conservation the conservatory should be unheated, but if fixed heating installations are proposed, they should have their own separate temperature and on/off controls.

As of the 1st January 2005 any electrical work within the conservatory (the source of which is located within or shared with the dwelling) should be carried out by a person registered under a ‘Competent Person Self-Certification Scheme’ https://www.gov.uk/competent-person-scheme-current-schemes-and-how-schemes-are-authorised#current-schemes


We hope this article helps you with your conservatory planning permission questions. This article has been written as advice and we always advise you to thoroughly research your project before making those steps to construction. If you have any question please do not hesitate to get in contact with us here at www.1moreroom.co.uk.

20 Top Architects In Southampton (Architects and Architectural Services)

architects southampton

We are fortunate in Southampton to have a plethora of practices providing Architectural services. With that said we have done our online research and would like to provide 20 popular and reputable architects in Southampton based on the popularity of our searches. We’re 100% sure that in this list there is an architectural practice providing the service you require.

To stop the list becoming over whelming in information we have bullet pointed 3 or more of the services each company provide and have also given a very short description of the first 10 businesses.



Tel: 02381 842389 Web: www.1moreroom.co.uk

To start this list we want to introduce you to 1moreroom.co.uk. We specialize in residential development and cover all aspects from simple house extensions to large new dwellings. We operate in a 40 mile radius of Southampton, predominantly dealing with Southampton, Test Valley, Eastleigh and Winchester borough councils.

•Architectural design •Planning •Permitted development •Building regulations •Certificate of lawfulness •Extensions •Loft conversion •New houses •Alterations •Structural calculations •Sustainable development •Conversions •Change of use •Outline planning


Stride Treglown

Tel: 02380 671991 Web: www.stridetreglown.com

Stride Treglown are one of the bigger firms in the area offering a wide array of services for large developments. Stride Treglown’s work also expands past UK boarders to other countries.

•Building surveying •Historic Building Conservation •Town Planning •Landscape Architecture •Environmental Assessment •Architecture


Forum Architecture

Tel: 02380 682095  Web: www.forumarchitecture.co.uk

This architect practice is based near Ocean village. Forum Architecture was established in 2013.

•Commercial developments •Residential developments •Retail developments •Design consultants •Project architects •Project Architects


Concept Design & Planning

Tel: 02380 331010  Web: www.conceptdp.co.uk

This company helps provide contextual modernism to the area with their designs. The practice shows a great interest in sustainable development.

•Planning applications •Feasibility •Viability •Architectural design •eco-houses •commercial development •Residential development •BREEAM


OB Architecture

Tel: 01962 865344 Web: www.obarchitecture.co.uk

This practice is actually in Winchester, but they operate all over the country. OB architectures new home will certainly catch your attentions with their modern style designs.

•Commercial development •Interior Design •Residential development  •contemporary design •sustainable design •Open living



Tel: 02380 388688  Web: www.the-bcb.com

Building Consultancy Bureau are based in Bournemouth as well an office here in Southampton. BCB can cover all works that require the help of surveyors.

•surveys •commercial and Residential •building surveyors •Planning consultants  •Structural Engineers •Building defects •Party wall surveyors • Insurance claims •RICS •ISVA


Pope Priestly Architects

Tel: 02380 335228  Web: www.popepriestley.co.uk

Pope Priestly have been providing architecture work in the area for over 20 years, they cover most fields of development.

•Residential development •Retirement development •Commercial development •Leisure development •Office development• RIBA competitors


Owen Davies Architects

Tel: 01489 589923  Web: www.owendaviesarchitects.co.uk

Owen Davies practice provides extensive architectural experience. This includes work in the defense sector.

•Residential development •Refurbishments •Retail Leisure •Industrial development •Commercial development •educational development


Studio Four Architects

Tel: 02380 228923  Web: www.studiofourarchitects.com

Studio Four have offices in Southampton, Winchester and Romsey. They are a reputable company with great working knowledge of the surrounding areas.

•Residential development •Listed Building •Primary Healthcare •Commercial development •CDM regulations •Heritage •Conservation


ADP Architects

Tel: 0845 3651475  Web: www.adparchitectsltd.co.uk

ADP has been practicing for 30 years. The firm is Southampton based and operates across the south region. They work with national developers, house builders and other clients such as the ministry of defense and are a medium size practice.

•Commerical development •Residential Development •Mixed Use •Leisure Developments •RIBA •arb


Graham Ash Architects

Tel: 02380 641811  Web: www.grahamasharchitects.com

•Commercial buildings •Residential planning •Planning appeals


Derek Phillips architects

Tel: 01489 780211  Web: www.derekphillipsarchitect.co.uk

•Residential •Retail and commercial •Churches


LA Hally Architect

Tel: 02380 616698  Web: www.lahally.com

•Contemporary design •Open space living •Listed Buildings


Access Architects

Tel: 02380 769736  Web: www.access-architects.co.uk

•Commercial •Domestic •Conservation and listed buildings


JAGS Archtechs

Tel: 02380 767284  Web: www.jagsarchitechs.co.uk

•Architectural Design •Building surveys •Rural and historical buildings


AWD Design

Tel: 02380 841231  Web: www.awd-design.co.uk

•New dwellings •Structural design •Extensions


Architectural Verve

Tel: 02380 420839  Web www.home-design.co.uk

•Design services •Design concepts •Feasibility studies


Sanders Design Service

Tel: 02380 207195  Web: www.sandersdesignservices.co.uk

•Architectural design •Planning •Building regulations


Architectural Homepage

Tel: 02380 436096  Web: www.architecturalhomepage.com

•Architectural design •Planning •Small commercial development


Graham Barker Design

Tel: 02380 740392  Web: www.grahambarkerdesign.co.uk

•Planning •Building regulations •Architectural design


MDT Design

Tel: 02380 693924  Web: www.mdtdesign.co.uk

•Architectural design •Alterations •Building regulations



Tel: 02380 436096 Web: www.designaplace.com

•Commercial and Residential •Architectural design •Leasehold plans


IHD Architectural Services

Tel: 02381 780950  Web: www.ihd-architecturalservices.com

•Planning •Architectural design •Alterations •Certificate of lawfulness


Architecture & Planning Southampton

Tel: 02380 222269  Web: www.architecturesouthampton.co.uk

•Conversions •Licensing •Building Regulations


Thank you for using this list. We have kept in mind an array of possible development options. We have also kept in mind development sizes, as well as those searching value for money for smaller residential building work.

Whatever you’re looking for, whether that may be large commercial development or that little bit more space in your home, there is a company here for you.


• Southampton Architects • Architectural services Southampton • Best Architect Southampton • Hampshire Architects • Architectural services Hampshire 

What's the difference between planning permission and building control?

architects plans

We would like to run through the difference between planning and building control, many people get confused about these two permissions. It's important to find out whether you need these before you start your project. Some will need both, some will need one of them and other projects may need neither.

If you project meets policy, your planning permission will be provided by your local council.

Project that do not usually require planning permission are:

  • Some Extensions
  • Some loft conversions
  • most internal alterations
  • some garages

If your home is either, in a conservation area or a listed building, you're likely to require listed building consent. You will need to talk to the councils conservation department.

Some minor works can come under permitted development. This means they do not require planning permission. Please keep in mind, not all houses have permitted development rights so it is important to check before you continue with your project.

If you do require planning permission please keep in mind this takes time. You need to factor in the time it will take for your project to be ready to submit to planning. Then you will need to allow a minimum of 8 weeks for you planning application to run the process for a planning recommendation.

Planning application drawing.

Planning application drawing.

Just because you submit a plan doesn't mean your planning will be approved. Each application the council receive has to meet certain criteria, some of these areas are:-

  • National policies
  • Local policies
  • Location
  • Siting of development
  • Percentage of the plot
  • Appearance
  • Building height
  • Building size
  • Materials (including colour, type and match)

When you do obtain permission, there may be conditions you have to meet before you can begin construction.

Now on to building control...

Your planning permission doesn't cover building regulations, this is covered separately by a building control specialist. Your local council will have its own building control department, but there are also private companies that can also carry out the same responsibilities.

Building regulations drawing.

Building regulations drawing.

Building control covers the technical compliance of the proposed works. A building control officer will check your proposed building regulation drawings and will visit and inspect your development. The average extension normal requires about 5 visits from a building control officer at specific stages during the construction of the build. When your project is complete you will receive a completion certificate. This certificate is important as it indicates your works were carried out to building regulation standards.

Home owner tip: "Don't squash it!" Loft insulation.

One of our biggest problems with our homes is that we run out of space pretty quickly for one reason or another. Well that's why you come to us right? You want a bigger home!

Another big problem is the cost of keeping warm as gas and electric prices continue to rise.

Anyway a great place to utilise for storage when the house becomes cluttered is the loft. One of the biggest culprits for heat loss in the home is also "the loft"!

So you throw some boxes up there, and maybe put some boards down first so the boxes don't come crashing down through the ceiling and end up compacting the insulation. But thats ok right? as long as there is insulation there you're covered and well insulated!?

Well thats not the case, compressing the insulation will drastically effect its performance resulting in more heat loss. And to us that means a bigger heating bill.

See the image below (image source npl), as you can see the thermal resistance is halved when the insulation becomes squashed. A lower thermal resistance results in more heat loss.

loft insulation.jpg

This link "squashed loft insulation 50% less effective." will take you in to a little more depth if you want to read more about this.

Anyway lets share a solution with you. You can get the best of both worlds utilising your loft for storage whilst keeping its heat loss performance as high as possible. We suggest you check out Loft Zone, they are a UK company and provide a great system called StoreFloor

Alternatively, come to us and we'll design you an amazing loft conversion, somewhere thats efficiently warm to put boxes and the kids...

Looking for property investments? Have you checked out property auctions?


Fox and Sons auctions are your local property auction specialists. If you're interested in investment properties, auctions are a must to keep an eye on.

Some of these properties will have scope for further development such as extensions etc. We can provide all you architectural service needs, making your investment property worth that little bit extra.

You can view their auction catalogues at www.foxandsonsauctions.co.uk 

You can see us on page 24 of the auction catalogue.