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Architects Registration BoardRIBA

RIBA Chartered

Special Offers

  • 1 Hrs Free Consultation with Chartered Practice Architect

Practice Areas

  • Education
    Carrying out design work for Crèche Facilities, Schools, Colleges or simply carry out extension works any of these type of buildings.
  • Residential
    Specializing in the design of Extensions, New Builds, Extra Care Homes and Housing Layout Sites.
  • Office
    New Build, Refurbishment or Extension of Offices and some Retail experience with Restaurant/Estate Agent Design.
  • Leisure
    We are working on numerous Rugby Clubs and an Events Centre in England. We cover all aspects of Leisure including sports facilities, events buildings, village community hall/buildings and numerous others .
  • Research
    Currently working on Flood Risk within buildings. Please email for further details.


Building an extension – What you need to know




Guide to Building an Extension

Building an extension is one of the most popular ways of improving your living space, whilst avoiding the hassle and expense of moving. Having an extension may well also add value to your existing property.

Building an extension is a big commitment and there is a lot of information you need to know before embarking on your project.

What Permissions/Consents do I require before Building an Extension?

Planning Permission

Depending on the size and position of your extension, you might not require planning permission. This will depend on whether your proposed extension complies with Permitted Development (PD).

 The easiest way of determining whether your proposed extension falls under permitted development is by referring to the interactive house on the planning portal website.

 For Wales:

For England:


Permitted development rights can be restricted in designated areas, such as: Areas of Outstanding Natural Beauty, Conservation Areas, etc. There are also situations where they do not apply, for example: if your property is a Listed Buildings or if the original house’s planning consent had a condition which restricts permitted development.

 RA Architects can help you to understand whether your proposed extension complies with permitted development guidelines, and if not, how likely your project is to gain planning consent. Call now to book a site visit with one of our team members.

 What is a Lawful Development Certificate? And Do I Need One?

A Lawful Development Certificate (LDC) merely provide confirmation (from the Local Authority Planning Department) that a proposed extension meets PD requirements. So, getting a Lawfulness Certificate is not necessary if you are confident the proposed extension meets these criteria. However, you might want to get a Lawfulness Certificate anyway, to keep with the deeds of the house, so that any future purchaser knows that the extension is lawful. A Lawful Development Certification application costs £103 in England or £95 in Wales.

Listed Buildings

All alterations to listed buildings, including internal ones, require consent and it is a criminal offence to alter a listed building without it. If these alterations would usually not require planning permission, then consent can be sought through a Listed Building Consent application.

The planners will always regard the existing listed property as more important than what you are proposing to add to it. Any extension will therefore have to respect the character, appearance and historic material used in the construction of the original house.


Building Regulations

Whether you require planning consent or not, if you are proposing a heated extension to your home, you will need to make sure you comply with Building Regulations. There are two methods of getting Building Control Approval:

Full Plan Submission: send detailed plans to your local authority building control or approved inspector prior to get approval for the proposed scheme. The building inspector would then visit the site at several stages to check that the works are being completed in line with the approved drawings.

 Building Notice: With this method, you submit an application to the local authority building control or approved inspector, notifying them of the work shortly before it starts (check individual company for the required notice). Building inspectors will then inspect the work at various stages to ensure it complies with Building Control requirements.

A Building Notice is the riskier option as you may only find out you have a compliance issue once building work has started. This may be costly to correct.

Having a set of detailed drawings from an Architect can help avoid this issue.  RA Architects can provide comprehensive detail drawings and notes, to help your contractor to price accurately and ensure the proposed works comply with the Building Regulations.


Party Wall Consent

If building your extension involves either:

  • Excavating, or excavating for and constructing foundations for a new building or structure, within 3 metres of any part of a neighbouring owner’s building or structure, where any part of that work will go deeper than the neighbour’s foundations
  • Excavating, or excavating for and constructing foundations for a new building or structure, within 6 metres of any part of a neighbouring owner’s building or structure, where any part of that work will meet a line drawn downwards at 45° in the direction of the excavation from the bottom of the neighbour’s foundations

You must inform the Adjoining Owner or owners by serving a notice. A Party Wall Surveyor can advise you further on this process and what to do if your neighbour does not accept the notice.

For further information, refer to:


Build Over Sewer Consent

Should you find yourself with a sewerage system within 3 metres of your property, it is mandatory for you to apply for a build over sewer agreement with your water supplier. This is carried out with an assessment and trace of the sewer line which will also determine ownership. This is difficult to receive so keep this in mind when planning your build. For further information regarding these, please follow the link –


What other things should I Consider Before Building an Extension?

Site Access

How easy will it be for equipment and materials to be delivered to your home when building an extension? You’ll need to consider how deliveries of large items will be undertaken. You’ll also need to determine where a builder and their sub-contractors will park and store their tools.

Demands upon Your Services

We recommend giving your current services a review. It is important to confirm whether your current services will be able to sustain the added room. For example, while replacing the boiler is an option, you could also look at alternatives such as electric underfloor heating, this is a beneficial way of heating a room without over working the facilities.


It is important to notify your home insurer of the proposed work. Some may not provide cover during the works and others will offer dedicated extension insurance products.