Expert House Extensions Across Dulwich, Greenwich, Blackheath & South East London
Need more space? JT Allen designs and builds beautiful house extensions that seamlessly blend with your existing property.
With over 35 years of experience, we create extra living space that adds value and enhances your lifestyle. Our extensions are designed to complement your home’s architecture while meeting your practical needs.
Why Choose JT Allen for Your House Extensions
- 35+ years of extension building experience
- Specialists in Victorian and Edwardian properties
- Full architectural design service
- All planning and building control handled
- 10-year structural guarantee
- Minimal disruption to your daily life
Request a Quote
Contact Swanbourne Construction for a free, no-obligation quote.
Types of House Extensions We Offer
Rear Extensions
— From £45,000
The most popular choice for South East London homes. A rear extension opens up your ground floor, typically creating an open-plan kitchen-diner with doors onto the garden. Perfect for modern family living.
Side Return Extensions
— From £35,000
Ideal for Victorian and Edwardian terraces with narrow side passages. Converting this ‘dead’ space creates a wider kitchen or living area, transforming dark, narrow rooms into bright, spacious areas.
Wraparound Extensions
— From £60,000
Combines rear and side extensions for maximum impact. Perfect for corner plots and properties with suitable side access. Creates substantial additional floor space.
Two-Storey Extensions
— From £70,000
Double your new space by building up as well as out. Adds both ground floor living space and additional bedrooms above. Excellent value per square metre.
Our House Extensions Process
Free Consultation
Discuss needs & assess property
Design
Architectural plans tailored to your home
Planning
We handle applications and building regulations
Construction
Expert building with minimal disruption
Completion
Finished extension ready to enjoy
What's Included
- Foundations and groundwork
- Structural walls and roof
- Windows and doors (bi-folds, sliding, French)
- Electrical installation
- Plumbing if required
- Plastering and decoration ions complianc
- All building regulations compliance
House Extensions FAQs
Do I need planning permission for an extension?
Many extensions fall under Permitted Development, but this depends on size, position, and whether your home has been extended before. Conservation areas have stricter rules. We check this during our free consultation.
How long does it take to build an extension?
A single-storey rear extension typically takes 10-14 weeks. Two-storey extensions take 14-20 weeks. Weather and planning factors can affect timelines.
What's the cost per square metre?
Single-storey extensions typically cost £1,800-£2,500 per sqm, two-storey extensions £2,200-£3,000 per sqm. These are building costs; kitchen/bathroom fit-out is additional.
Can you match the extension to my existing house?
Absolutely. We specialise in creating extensions that look like natural parts of your home, using matching materials and sympathetic design.
Get Your Free Quote Today
Ready to start your project? Contact JT Allen for a free, no-obligation consultation.
- 07734 975051
- sales@jtallen.co.uk
- 12 Waterford, Battlesbridge, Essex, SS2 7GT