Premium House Extensions
Builders in London
✔️ Free House Extensions Conversion Quotes
✔️ 100% Bespoke Design & Build Service
✔️ House Extension Interior Design Support
✔️ Insurance Backed Deposit & Warranty
✔️ Stress-Free Construction with Expert Project Manager
Get in touch for a free no obligation quote today on your dream loft conversion...
As London's leading design-and-build firm, we transform homes into extraordinary living spaces through our bespoke, high-end extensions.
Discover Your Ideal Extension For Your Home:
Envision your ideal home. We can help you transform your space with a custom house extension tailored to your needs and budget. Home extensions come in all shapes and sizes. Let's help you narrow down your choices and find the perfect solution for your space.
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Rear Extensions
Most popular option: Adds space to the back of the house, often incorporating kitchen and dining areas.
Benefits: Increased living space, better connection to the garden, improved natural light.
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Side Return Extensions
Maximizes unused space: Takes advantage of the narrow side of the house, creating additional rooms like bathrooms or utility areas.
Benefits: Improved layout, additional storage, increased property value.
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Wrap-Around Extensions
Combines best of both: A combination of rear and side return extensions, creating a larger, open-plan living space.
Benefits: Dramatic transformation of the home, increased natural light, improved flow.
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Double-Story Extensions
Significant space gain: Adds an entire floor to the property, creating multiple new rooms.
Benefits: Substantial increase in living space, potential for self-contained accommodation.
What is the house extension process in London?
House extensions can seem overwhelming, with countless steps and potential pitfalls. Traditionally, homeowners have faced a complex and fragmented journey. But it doesn't have to be that way.
At Mammoth Design & Build, we streamline the entire process, providing a seamless experience from start to finish. Let us handle the complexities while you enjoy the transformation of your home.
To get started, most projects involve these key stages:
Detailed property measured survey
Planning permission acquisition
Budget planning
Bespoke 2D and 3D design creation
Structural engineering assessment
Party wall agreement (if applicable)
Building regulations compliance
Selecting a building contractor
Do I need planning permission to extend my house?
Planning permission requirements vary based on your extension. Our planning experts can assess your project and help you navigate the process smoothly.
How much does a house extensions cost?
Before diving into your home extension, it's crucial to establish a solid budget. Mammoth's expert team can guide you through the process and create a cost-effective plan.
Flat-pack house extensions in London:
Starts from £750 and £1,140 per square metre
Mid-range would cost between £1,275 and £1,800
High-end would cost between £1,650 and £3,600
Rear house extensions in London:
Ground floor: £40,000 - £100,000
Double storey: £70,000 - £150,000
Terraced house extensions in London:
Approximately £1,200 to £3,300 per square metre
Semi-detached house extension in London:
Ground floor: £40,000 - £100,000
Double-storey: £70,000 - £150,000
Side of house: £50,000 - £90,000
Side of house extension in London:
£50,000 - £90,000
Front house extension in London:
Approximately £1,500 to £3000 per square metre.
Ready to simplify your house extension project? Get a free quote today.
We’ve built our business on recommendations
from loyal clients…
Why choose us for you house extension project
✔️ A dedicated Account Manager to help you through the process
✔️ Keep your project on time & budget
✔️ Qualified and experienced team
☎️ Speak to an expert
Still not sure? Book a free 30-minute phone consultation and see how your project can come to life with Mammoth Design and Build.
E: hello@mammoth-builds.co.uk
M: 07878 719 909
