If you’re considering house extensions or looking to increase your home’s space without the hassle of a full planning application, you’re in luck. Thanks to permitted development rights in the UK, you may be able to build an extension without formal planning permission—as long as you meet specific criteria. But what are these rules, and What size extension can you build without permission ?
At KT5 Construction, expert extension builders in Surrey and London, we specialise in helping homeowners understand their options and deliver compliant, beautifully designed extensions stress-free.
Understanding Permitted Development Rights (PDR)
Permitted development rights (PDR) are a set of rules granted by the government that allow homeowners to carry out certain building works without needing full planning permission. They are especially useful for simpler extensions that don’t affect neighbouring properties or change the appearance of the local area.
To qualify:
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Your property must be a house (not a flat or maisonette).
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It must not be listed or located in a conservation area.
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The property must not have already been extended beyond the allowed limits since 1 July 1948.
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Before proceeding, it’s wise to consult your local authority or a construction expert like KT5 to confirm your eligibility. Additionally, it’s essential to understand that permitted development is not unlimited. It has specific rules around size, height, location, and appearance to maintain harmony within neighbourhoods and ensure privacy and safety for surrounding residents.
What size extension can you build without permission ?
Single-Storey Rear Extensions
Under permitted development:
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Detached homes can extend up to 4 metres from the rear wall.
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Semi-detached or terraced homes can extend up to 3 metres.
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With prior approval:
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Detached houses can extend up to 8 metres.
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Other houses can extend up to 6 metres.
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Prior approval is a streamlined version of the traditional planning application, designed to assess the impact of your proposed extension on your neighbours.
Double-Storey Rear Extensions
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May extend up to 3 metres from the rear wall.
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Must be at least 7 metres away from the property boundary at the rear.
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Additionally, the roof pitch must match that of the existing house, and any upper-floor side windows must be obscure-glazed and non-opening unless positioned at least 1.7m above floor level.
Double-storey extensions require careful planning, especially when it comes to light and overlooking issues. We recommend working with experienced professionals, like our team at KT5 Construction, to ensure compliance and design excellence.
Side Extensions
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Must be single-storey only.
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Cannot exceed 4 metres in height.
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Can only extend up to half the width of the original house.
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Side extensions are ideal for creating utility rooms, and playrooms or widening existing kitchen areas. They can often be built quickly and cause minimal disruption.
Front Extensions
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Must be single-storey.
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Cannot extend more than 3 metres.
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Must not front directly onto a highway.
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Front extensions are less common and more restricted under permitted development due to their visual impact. Always check with your local planning authority if you’re unsure.
Other Restrictions
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Extensions must not cover more than 50% of the land around the original house.
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Materials must be similar to those used in the existing structure.
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Extensions near boundaries must comply with height restrictions: eaves cannot exceed 3 metres if within 2 metres of a boundary.
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It’s also important to note that permitted development rights may have been removed from some properties by condition (known as an Article 4 Direction), so always double-check.
KT5 Construction: Your Local Experts
With over 25 years of experience in building high-quality house extensions, KT5 Construction is the go-to choice for homeowners in Surrey and London. Our team understands the intricacies of permitted development and ensures every extension we build meets all necessary regulations.
Why homeowners trust KT5 Construction:
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Free initial consultations and expert guidance
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Full compliance with UK planning and building regulations
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Friendly, transparent service from start to finish
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Custom designs tailored to your home and lifestyle
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End-to-end project management
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Benefits of Extending Without Planning Permission
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Time Efficiency: The process is faster without the need for a full planning application.
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Lower Costs: Avoiding planning fees can save thousands.
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Fewer Uncertainties: With rules clearly outlined, you know what is permitted.
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Greater Certainty in High-Refusal Areas: Especially beneficial in areas where planning permissions are often denied.
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By staying within permitted development, you reduce the risk of project delays and disputes. You also benefit from more control over your project timeline and avoid the unpredictability of planning committee decisions.
FAQs – What Size Extension Can You Build Without Permission?
1. What is the maximum size extension without planning permission?
For rear extensions, 4m for detached and 3m for semi-detached/terraced homes. With prior approval, this increases to 8m and 6m respectively.
2. Can I build a small extension without building regs?
Building regulations still apply regardless of whether planning permission is needed. These cover structural integrity, energy efficiency, ventilation, and fire safety. Failing to comply can result in enforcement action or difficulty selling your property in the future.
3. What is the maximum height you can build without planning permission?
The height must not exceed the original house, and side extensions must not exceed 4m in height. If the extension is within 2m of a boundary, the eaves must not exceed 3m.
4. Do I need planning permission for a 4m extension?
A 4m rear extension on a detached house typically does not require planning permission but may require prior approval. Semi-detached and terraced homes would need approval if extending beyond 3m.
Let’s Build Your Dream Space
Thinking of extending your home? Don’t let planning worries slow you down. Get in touch with KT5 Construction today for a stress-free consultation and discover how we can help you transform your home.
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