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27th May 2023

Buying a house with extension built without planning permission 20 years ago

Acquiring a house can be a significant milestone, and prospective buyers should carefully consider all aspects before making their decision. Sometimes prospective buyers come across properties with extensions built without planning permission; this article seeks to provide a comprehensive guide for anyone considering such properties in the UK, specifically targeting extensions constructed without proper permission more than two decades ago.

Buying a house with Extension over 20 years old

Understanding the Situation

1. Gather Facts: Determine when and with what permission the extension was built, gathering as much information about its history and legality as possible.

2. Timeframe: The UK has specific rules regarding planning permission and unapproved development projects, so if your extension was built over 20 years ago without any enforcement action taken against it during that period it could be exempt from further regulatory enforcement action.

3. Retroactive Planning Permission: Property owners seeking to legalize an illegal extension can apply for retrospective planning permission by submitting an application with their local planning authority, who will then evaluate the case based on current regulations and make a determination.

Assessing Risks and Implications


1. Local Planning Authority: Speak with your local planning authority about the situation to gain their perspective and understand potential repercussions or restrictions associated with an illegal extension. They will advise you accordingly.

2. Legal and Financial Considerations: Before purchasing a property with an unapproved extension, consult a solicitor experienced in property law to assess its legal ramifications and any risks or restrictions it might impose in terms of future alterations or selling the home. They can offer guidance about potential risks that could limit future modifications or selling options.

3. Lender’s Viewpoint: Notify your mortgage lender of the situation. While some may reject financing properties with illegal extensions outright, others may consider this matter on an individual basis; to protect yourself and ensure a seamless mortgage application experience it is important to identify potential options and potential limitations beforehand.

 Conduct Thorough Due Diligence

A comprehensive title investigation should be performed prior to making any decisions about an extension project, in order to examine its legal history, including any potential planning disputes or enforcement actions related to unapproved extensions.

Structural Integrity and Safety

Hire a qualified surveyor to conduct an inspection on the extension to ensure its structural integrity and safety are not posing any immediate or long-term risks.

 Insurance Considerations

Check with your insurer about coverage for properties with unauthorised extensions, and discuss their potential impact on premiums as well as any exclusions related to them.

Negotiating Your Purchase

Should you decide to go forward with the purchase, negotiate for a lower purchase price to account for potential risks and restrictions associated with an unauthorized extension.

Future Considerations

1. Regulations

Following purchase of the property, it may be wise to pursue retrospective planning permission or a Certificate of Lawfulness to legalize its extension fully and offer peace of mind while increasing property value.

2. Renovations and Alterations

Be mindful that any future alterations or extensions to your property may require approval from local planning authorities before taking steps to alter existing structures. Be sure to contact them and find out which modifications can be made safely to existing structures.

What are Permitted Development Rights (PDRs)?

Dormer extension


Permitted Development Rights (PDRs) in the UK are a set of planning regulations which permit certain forms of development without formal planning permission, providing homeowners and developers with greater freedom and autonomy when making specific changes to their properties without going through formal permission processes. It should be noted, however, that there are restrictions and conditions associated with permitted development rights that must be considered before use.

Here are a few key points about permitted development rights:

1. Types of Developments: Permitted development rights typically encompass modifications and additions to residential properties, such as extensions, loft conversions, conservatories, outbuildings and changes to their external appearance as well as conversion of commercial buildings into residential units.

2. General Restrictions: While permitted development rights grant certain freedoms for development projects, certain restrictions exist to ensure they stay within reasonable parameters. These include restrictions on size, height and location as well as rules designed to maintain visual amenity of an area while protecting neighbors’ privacy as well as considering any impact to nearby listed buildings or conservation areas.

3. Prior Approval Process: For permitted development projects, prior approval from their local planning authority may still be necessary. This process entails providing specific details and plans to the authority for assessment against specific criteria such as impact on neighbors, highway safety issues and flood risk considerations.

4. Permitted Development Rights and Flats: Compared to houses, permitted development rights for flats tend to be more limited and there may be additional considerations and limitations in place to safeguard both their residents as well as the surrounding community.

5. Changes to Permitted Development Rights: Over time, the specific rules and restrictions related to permitted development rights can change over time as regulations change and evolve; due to this fact it is wise to consult the latest guidance provided by your local planning authority in order to remain compliant.

As permitted development rights vary depending on your location and local planning authorities may impose specific rules and restrictions, it is vital that you consult the planning authority or seek professional advice in order to fully comprehend which rights apply to a property or project.

Though permitted development rights provide certain latitude, it is still wise to consult professionals such as architects or planning consultants in order to ensure any proposed developments comply with regulations and won’t have an adverse impact on either your property or surrounding area.

At the other extreme, applying for planning permission and having it denied can be a source of great disappointment.

Yes, permitted development rights allow homeowners and developers to make changes without needing planning approval from local planning authorities, in certain instances it may still require planning approval – in such instances an application for planning permission may be denied by local authorities and it must abide with such decisions or be further discussed or appealed against.

Here are some important points to keep in mind regarding planning permission and possible refusal:

1. Planning Permission Process: For developments that exceed permitted development rights or their restrictions, applying for planning permission may be necessary. This typically involves submitting a comprehensive application with plans, drawings and supporting documentation outlining what exactly the proposed development involves to your local planning authority.

2. Reasons for Refusal: Planning permission can be denied for various reasons, including noncompliance with local planning policies, concerns over its impact on surrounding areas, objections from neighbours or failure to fulfil specific criteria or requirements. Each application is reviewed based on individual merits as determined by planning laws and policies applicable in your locality.

3. Appeal of Refusal: When planning permission is denied, applicants have two avenues available to them to appeal the decision: appealing it directly to an independent Planning Inspectorate and/or initiating a judicial review case. Essentially, this appeals process involves making their case to overturn it – providing additional evidence, responding to specific issues raised by local planning authorities or challenging interpretation of planning policies as part of this appeal process.

4. Seek Professional Advice: In the event that planning permission has been denied, seeking the advice of professionals such as planning consultants or architects who specialize in navigating the planning process may prove useful in understanding why it was denied, proposing possible amendments to improve it and building an appealing case if needed.

5. Revision and Resubmission: Resubmitted planning applications may sometimes be revised and submitted again after consideration has been given to their reasons for refusal and any necessary adjustments are made to address concerns raised by local planning authorities. Note, however, that this may incur additional fees as well as require further evaluation by said authority.

Decisions on planning permission rest with local planning authorities, though an unexpected refusal needn’t spell doom for your development plans. By consulting a professional advisor and understanding why an appeal or revision attempt was rejected, it may still be possible to overcome obstacles and reach successful conclusions for the proposed development project.

Locating when an extension was constructed will be essential in understanding its significance.

Ascertaining when an extension was constructed is vital in understanding its potential ramifications. Here are some steps you can take to discover this information:

Review Property Documents: Begin your investigation of a property by carefully perusing its documentation, such as deeds, surveys and planning applications or permissions from previous planning applications and permissions. These documents could reveal important insights into its history as well as any recorded extensions.

Consult the seller or estate agent: Before undertaking any extension projects on a property, reach out to its seller or estate agent and inquire about its extension. They may have information regarding its construction, permissions or any documents which can provide insight into its history.

Consider Engaging a surveyor

Hiring a professional surveyor who specializes in property surveys or building inspections may provide invaluable insight into the state and construction of any extensions or any signs that they are becoming aged. They can inspect the property in question and produce a comprehensive report outlining information such as construction dates as well as signs that it needs maintenance or age related problems.

Local Planning Authority Records

Reach out to the local planning authority responsible for your area and submit an inquiry regarding an extension project at their planning department. They may be able to search their records for planning applications or permissions related to this extension project and provide more details.

Reach Out

Connect With Neighbours and Local Community

To make sure the extension was built on time and with minimal complications, reach out to neighbours who have lived nearby for some time – they might know when it was completed and any conversations about its construction.

Gather information on the construction timeline of an extension to gain insight into whether or not it was built more than 20 years ago without planning permission, helping you assess its possible implications and take the appropriate actions – such as seeking retrospective planning permission or reviewing any risks associated with buying property with unapproved extensions.

Be sure to consult professionals, such as solicitors or planning consultants, who can offer expert guidance based on the unique circumstances surrounding the property and relevant planning regulations in the UK.


Acquiring a property with an extension built without planning approval two decades ago requires careful thought and due diligence. By consulting experts and being mindful of potential ramifications, prospective buyers can navigate this complex landscape and make an informed decision when purchasing such an unauthorised extension.