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House Extension Mill Hill | Rear & Side Extensions
Expert house extension services in Mill Hill. Rear, side return, wraparound and double storey extensions. Free consultation & fixed-price quotes.
Looking for a professional house extension in Mill Hill? Fixiz Ltd specialises in rear extensions, side extensions, and wraparound extensions throughout Mill Hill and the wider North London area. Our expert team delivers high-quality house extensions that add valuable living space and increase your property value.
Why Choose Fixiz for Your House Extension in Mill Hill?
Fixiz Ltd has delivered high-quality residential construction projects across Mill Hill and North London. We handle every aspect of your extension from initial design through to final completion, including all planning permissions, building regulations, and structural calculations.
Our House Extension Services in Mill Hill Include:
Rear Extensions – The most popular choice for Mill Hill homeowners, typically adding 3–6 metres to your ground floor.
Side Return Extensions – Perfect for Victorian and Edwardian terraced houses in Mill Hill, utilising the narrow alleyway beside your property.
Wraparound Extensions – Combining rear and side extensions for maximum space, adding up to 30–50 square metres to your Mill Hill home.
Double Storey Extensions – For families needing significant extra space, providing additional bedrooms and bathrooms.
House Extension Costs Mill Hill 2026:
| Extension Type | Starting Price |
|---|---|
| Single storey rear extension (3m) | From £35,000 |
| Single storey rear extension (6m) | From £55,000 |
| Side return extension | From £30,000 |
| Wraparound extension | From £65,000 |
| Double storey extension | From £85,000 |
Our House Extension Process in Mill Hill:
- Free Consultation – We visit your Mill Hill property to discuss your requirements
- Design & Planning – Our architects create detailed plans and handle planning permission applications
- Building Regulations – We submit all necessary applications and ensure full compliance
- Construction – Our skilled team completes your extension to the highest standards
- Final Inspection – Building control sign-off and handover of your new space
How Much Value Does a House Extension Add in Mill Hill?
A house extension in Mill Hill can add between 15% and 25% to your property value. For an average North London property worth £550,000, that equates to an increase of £82,500 to £137,500.
Trusted & Accredited Extension Specialists
Fixiz Ltd is fully registered, insured, and committed to delivering the highest construction standards.
✓Fully InsuredPublic Liability Insurance
⌂Building RegsFull Compliance Guaranteed
⚒Registered CompanyCo. No. 14561967
★Quality GuaranteedSkilled In-House Tradesmen
Real Results From Real Homeowners
Don’t just take our word for it — here’s what our clients say.
★★★★★
“Fixiz completed a rear extension of our home in Mill Hill. The team demonstrated excellent project management, strong attention to detail, and high-quality workmanship.”
— Shalaka R., Mill Hill
★★★★★
“Side return extension in Mill Hill done on time and on budget. They handled planning permission, structural calculations, and Building Control seamlessly.”
— Robert K., Mill Hill
★★★★★
“Fantastic wraparound extension in Mill Hill. The new open-plan living area has completely transformed how we use our home. Excellent attention to detail.”
— Helen D., Mill Hill
House Extension Mill Hill FAQs
Quick answers to the most common questions.
Do I need planning permission for a house extension in Mill Hill?
Many single-storey rear extensions in Mill Hill fall under Permitted Development and don’t require planning permission. Side extensions, two-storey, or Conservation Area properties typically need a planning application. Fixiz advises on your specific situation and handles all applications if needed.
How long does a house extension take to build in Mill Hill?
A single-storey rear extension typically takes 8–12 weeks. A side return is usually 6–10 weeks. Two-storey and wraparound extensions can take 12–16 weeks. The design and planning phase adds 6–12 weeks before construction begins.
What is included in a Fixiz house extension in Mill Hill?
Everything from initial design to completion: architectural drawings, structural calculations, planning applications, Building Regulations submission, groundworks, brickwork, roofing, windows, doors, electrics, plumbing, plastering, and decoration.
Do I need a Party Wall Agreement in Mill Hill?
If your extension in Mill Hill involves building on or near a shared boundary, you’ll need to serve a Party Wall Notice under the Party Wall Act 1996. Fixiz guides you through the process and recommends experienced party wall surveyors.
What is the difference between a rear and side extension?
A rear extension adds space from the back of the house — ideal for larger kitchen-diners. A side return uses the narrow alley space beside the property, common in Victorian terraces. Both can be combined into a wraparound extension for maximum impact.
Get Your Free House Extension Quote Today
One of our extension specialists will be in touch within 24 hours to arrange your free, no-obligation site survey in Mill Hill.