How much does a home extension cost?

Most home extensions cost between £30,000 and £120,000, depending on size, design, location and specification. Larger or more complex extensions can cost significantly more.

Does a home extension add value?

A professionally designed extension can substantially increase both usable living space and property value, particularly if it creates a larger kitchen, additional bedroom or family living area.

Do I need planning permission?

Many smaller extensions can be built under Permitted Development Rights, although larger projects and properties in conservation areas or with listed status often require planning permission.

How long does a home extension take?

Construction typically takes between eight and twenty-four weeks, although planning, design and approvals should also be considered when planning your project.

Can I live in my home during the build?

Many homeowners remain in their property while an extension is being built. However, projects involving significant structural alterations or kitchen relocations may require temporary alternative arrangements.

Is a single-storey or double-storey extension better?

A single-storey extension is generally more affordable and ideal for expanding living areas, while a double-storey extension creates additional space on both floors and often provides better value per square metre.

What's the difference between an extension and a loft conversion?

A home extension increases the footprint of your property, while a loft conversion creates additional living space within the existing roof structure. The best option depends on your property and available space.

When is the best time to build an extension?

Extensions can be built throughout the year, although spring and summer generally provide more favourable weather conditions for groundworks and external construction.

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Homeowner Hub › Home Extensions

Home Extensions

Add valuable living space without moving home. This guide covers extension costs, planning rules, timelines, popular extension types and how to find trusted local builders and specialist tradespeople.

Last reviewed: August 2026 · Reviewed by: The TopTenTrades Editorial Team

Planning a Home Extension

A home extension is one of the most effective ways to create additional living space while increasing the value and functionality of your property. Whether you're extending your kitchen, adding a larger family room or creating an extra bedroom, careful planning is essential to achieve the best results. Before starting your project, consider how the extension will connect with your existing home, how natural light will enter the space and whether your current heating, plumbing and electrical systems need upgrading. Investing in good design at the outset often saves money and prevents costly changes during construction.

Why This Project?

check_circleCreate larger kitchens
check_circleAdd family rooms
check_circleBuild additional bedrooms
check_circleCreate home offices
check_circleAdd utility rooms
check_circleImprove open-plan living
check_circleIncrease property value
check_circleAvoid moving house

Costs

Type	Typical Cost (UK)	Typical Duration
Small single-storey	£30,000–£50,000	8–12 weeks
Large single-storey	£50,000–£80,000	10–16 weeks
Double-storey	£70,000–£120,000+	12–24 weeks
Wrap-around extension	£80,000–£150,000+	16–24 weeks

FoundationsBrickworkRoofingStructural steelWindows and doorsInsulationPlumbingElectrical workPlasteringDecoration

Kitchen installations, bespoke glazing and premium finishes can significantly increase the overall project cost. Many single-storey extensions can be built under Permitted Development Rights, although planning permission may be required depending on the size, design and location of your property — Building Regulations approval is required for virtually all home extensions, and this isn't a DIY-friendly project.

Planning Your Project

Rear Extension

A popular option that extends into the garden to create additional living or kitchen space.

•Larger kitchens
•Family rooms
•Open-plan living

Side Return Extension

Ideal for Victorian and Edwardian terraced homes with narrow side passages.

•Kitchen enlargements
•Dining spaces

Wrap-Around Extension

Combines a rear extension with a side return to maximise ground floor space.

•Open-plan kitchen diners
•Family living

Double-Storey Extension

Adds space on both floors, making it ideal for growing families.

•Additional bedrooms
•Larger bathrooms
•Expanded living areas

Front Extension

Less common due to planning restrictions but can improve entrances, hallways or garages.

Do You Need Planning Permission?

Many smaller home extensions can be completed under Permitted Development Rights, provided they meet size and design limits. Planning permission is more likely if the extension exceeds Permitted Development limits, your property is listed, you live in a conservation area, the extension significantly changes the property's appearance, or previous extensions have already used your Permitted Development allowance. Building Regulations approval is required for virtually all home extensions.

Building Regulations

Building Regulations ensure your extension is safe, energy efficient and structurally sound, covering foundations, structural stability, fire safety, insulation, ventilation, drainage, electrical safety and energy efficiency. Inspections are normally carried out at key stages throughout construction.

Timeline

Stage	Typical Time
Design & surveys	2–6 weeks
Planning (if required)	8–10 weeks
Building Regulations & structural calculations	2–4 weeks
Construction	8–24 weeks
Final inspection	1 week

Which Tradespeople Will You Need?

Extension Builders

Builders manage the construction of foundations, walls, structural openings and the overall build, and can help prepare drawings and support planning applications where required.

Find trusted Builders near you

Roofers

Roofers construct and weatherproof the new roof, install roof coverings and fit roof windows where required.

Find experienced Roofers near you

Electricians

Electricians install new circuits, sockets, lighting, heating controls and consumer unit upgrades.

Find qualified Electricians near you

Plumbers

Plumbers install heating systems, pipework, radiators, kitchens, bathrooms and drainage.

Find trusted Plumbers near you

Carpenters

Carpenters install roof structures, flooring, doors, staircases and bespoke joinery.

Find skilled Carpenters near you

Checklist

check_circleSet your budget
check_circleDecide how the new space will be used
check_circleConfirm planning requirements
check_circleArrange architectural drawings
check_circleObtain structural calculations
check_circleSecure Building Regulations approval
check_circleChoose experienced contractors
check_circleOrder windows and doors
check_circlePlan electrical and plumbing layouts
check_circleAllow a contingency budget

DIY or Hire a Professional?

Suitable DIY Jobs	Professional Recommended
Decorating	Foundations
Landscaping	Structural work
Painting	Bricklaying
Furniture assembly	Roofing
Minor finishing	Plumbing
—	Electrical work

Common Mistakes to Avoid

check_circleUnderestimating the budget
check_circlePoor room layout
check_circleInsufficient natural light
check_circleInadequate storage
check_circleForgetting future needs
check_circleChoosing inexperienced contractors
check_circleDelaying material orders
check_circleIgnoring drainage requirements
check_circleNot planning heating upgrades
check_circleFailing to allow a contingency budget — set aside around 10–15% of the overall budget to cover unexpected ground conditions, specification changes or structural discoveries

Maintenance

Task	Frequency
Inspect roof	Annually
Check guttering	Annually
Test smoke alarms	Monthly
Service heating	Annually
Check exterior sealants	Every 2 years
Inspect brickwork	Every 2–3 years

Frequently Asked Questions

Related Home Improvement Guides

Loft Conversions Garage Conversions Kitchen Improvements Bathroom Renovations Roofing Flooring Garden Landscaping

Back to the Homeowner Hub Find trusted Builders near you Find experienced Roofers near you Find qualified Electricians near you Find trusted Plumbers near you Find skilled Carpenters near you

Our homeowner guides are written to provide practical, impartial advice for UK property owners. Content is reviewed regularly to reflect current building practices, regulations and homeowner priorities. Where specialist work is involved, we recommend using appropriately qualified and insured tradespeople.

Ready to Start Your Home Extension?

Don't leave it to chance — use this guide to plan ahead, save important details to your projects, and connect with trusted local tradespeople when professional help is needed.

•Save this project to My Projects and track it over time.
•Request quotes from trusted local tradespeople.
•Compare professionals based on experience, reviews and completed projects.

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