House extensions
House Extension Builders in Sevenoaks, Kent & London
Create more space, natural light and long-term value with a professionally planned extension, from single-storey rear additions to larger wrap-around schemes.
500+
Projects completed
15+
Years experience
5★
Rated on Checkatrade
Transform Your Home Without Moving
A well-designed extension can create the extra room your family needs – whether that means an open-plan kitchen-diner, larger living space, home office or utility room.
Builders of London can coordinate the project from early design and approvals through to construction and final finishes, giving you one team to deal with throughout.
Start with a free initial project assessment. If a detailed technical site visit is needed before we can quote, we’ll agree the scope and any fee with you first.
★★★★★ 5-star rated on Checkatrade
How we build
Six Main Construction Stages
Our extension builders help clients create extra living space without the cost and disruption of moving home. A single-storey rear extension typically takes around 10-12 weeks from start to completion. BOL can coordinate the full six-step process from early design and structural planning through construction, kitchens, services and finishes, giving you one team responsible for the project from planning through to completion.
01
Foundations
Site clearance, excavation, approvals and concrete foundations, with initial structural steel preparation where required.
02
Brickwork
Masonry, damp-proofing and required inspections as the walls progress to roof-plate level.
03
Structural Work
Openings into the existing house, removal of designed walls and installation of supporting steel beams.
04
Roof Construction
Roof structure, coverings and detailing completed to make the new extension weather-tight.
05
Internal Works
Drainage, partitions, first-fix plumbing and electrics, insulation, boarding and plastering.
06
Finishing
Kitchen, doors, skirtings, flooring and decoration completed as required.
Extension types
What Kind of Extension Do You Need?
01
Single-Storey Rear Extension
Extend the ground floor to create a larger kitchen, dining or living space. Often suitable for permitted development, subject to the property and proposal.
02
Double-Storey Extension
Add valuable space on two floors at once – ideal for an extra bedroom upstairs with a larger living area below.
03
Side Return Extension
Make better use of the narrow space beside the property, particularly on Victorian and Edwardian terraces, to open up the ground floor.
04
Wrap-Around Extension
Combine rear and side-return additions to maximise ground-floor space and create a generous open-plan kitchen and living area.
05
Over-Structure Extension
Build above an existing garage or single-storey part of the house to add a bedroom, bathroom or home office without losing garden space.
06
Orangeries & Garden Rooms
Create an insulated year-round room with a solid roof and generous glazing – a more substantial alternative to a traditional conservatory.
Our work
Recent Extension Projects
How it works
Our Extension Process
A clear process from the first visit through to final handover.
01
Project Review & Next Steps
Send us your project details, photos and drawings for a free initial assessment. If an on-site technical review is needed to price the extension properly, we’ll agree the scope and any fee before booking.
02
Design & Planning
Drawings, planning or permitted-development requirements and the key design decisions are coordinated before construction.
03
Detailed Quote
You receive a clear written quotation setting out the agreed works, assumptions and inclusions before the build begins.
04
Build & Project Management
Our team coordinates the groundworks, structure, roof, glazing, services and internal finishes through one point of contact.
05
Snagging & Handover
We complete final checks and snagging before handover so the finished extension is ready for you to use.
Why choose us
Why Homeowners Choose Builders of London
✓
Full project management
One team and one point of contact from the first construction stage through to final decoration and handover.
✓
Planning handled for you
We can coordinate drawings, planning submissions and the information needed for Building Regulations approval.
✓
Fully accredited & insured
Qualified and accredited trades are used where required, with appropriate insurance maintained for our works.
✓
Transparent pricing
Clear written quotations set out the agreed scope and commercial assumptions before work starts.
✓
Local expertise
We work throughout Sevenoaks, Kent and London and understand the practical requirements of building in occupied homes.
✓
Guaranteed workmanship
We stand behind the quality of our work and complete snagging before the project is handed back to you.
Client stories
What Our Clients Say
★★★★★
“Builders of London extended our kitchen and created a fantastic open-plan space. The team was professional, tidy and kept everything moving to programme.”
Rachel & Tom H.
Sevenoaks
★★★★★
“From the first survey through to the final clean-up, the process was straightforward and well managed. We are delighted with the finished double-storey extension.”
James M.
Tonbridge
Common questions
House Extension FAQs
Do I need planning permission for a house extension?
It depends on the size, position and previous changes to the property. Some extensions may fall within permitted development, while others require planning permission.
How long does a house extension take?
Programme length depends on size and complexity. We confirm a realistic construction programme once the design and scope are sufficiently developed.
How much does a house extension cost?
Cost depends on size, structure, access, specification and the amount of internal work. We provide a written quotation based on the agreed design and scope.
Will I need to move out during the build?
Many clients remain at home during extension works, although this depends on how much of the existing house is affected and the services being altered.
Do you handle building regulations approval?
We can coordinate the Building Regulations information and work with the relevant professionals and inspectors required for the project.
Project enquiry
Ready to Start Your Extension Project?
Tell us about your extension and send any photos or drawings you have for a free initial project assessment. If a detailed technical site visit is needed before we can quote, we’ll explain the scope and agree any fee before booking.
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LOCAL BUILDING SERVICES
Looking for a builder in your area?
Builders of London works across Sevenoaks, Tonbridge, Tunbridge Wells and selected areas of Kent and South East London. Explore our local pages for the services we provide in each area.