House Extension in Harrow
As one of North West London’s trusted extension specialists, KT5 Constructions delivers a smarter, cost-effective way to expand your home in Harrow. From the first sketch to final handover, we align thoughtful design, transparent pricing, and practical cost-saving strategies—so your House Extension in Harrow adds space and value without the stress.
At KT5, clear communication is non-negotiable. We keep you in the loop at every stage so your brief, budget, and programme stay on track.
What We Do
Building Construction
New Builds, Extensions, Conversions, Renovations
General Building
Property Maintenance, Handyman Service, Decorating
Design
Planning, Design, Project Management, Quality Checking
House Extension in Harrow: What to Expect from Experienced Builders
Why Choose KT5 Constructions for Your Harrow Project
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Local insight that fits your street – We understand Harrow’s housing stock—1930s semis, post-war terraces, and conservation areas near Harrow-on-the-Hill—so designs maximise space while respecting character.
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Single accountable team – One design-and-build partner handling drawings, permissions, construction, and finishing.
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Fixed costs & clear programme – No surprises: defined scope, transparent schedule, and regular updates.
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Value engineering that protects quality – Specification choices that stretch budgets without compromising safety, durability, or aesthetics.
Extensions Delivered Across Harrow & Nearby Neighbourhoods
We tailor solutions to local property types and plots, including:
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Single-storey kitchen/dining extensions to open up the rear
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Side-return and wrap-around layouts to unlock family living space
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Two-storey additions for extra bedrooms, en-suites, and storage
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Loft conversions and dormers to maximise under-roof potential
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Garden rooms/orangeries for flexible office, studio, or leisure use
Every project is planned for quality, compliance, and minimal disruption on established residential streets.
Our Value-First Method
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Budget clarity – Fixed-price contracts with itemised scopes
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Specification smarts – Options that balance look, performance, and lifecycle cost
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Transparent comms – Detailed programmes, site updates, and clear payment schedules
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Long-term mindset – We build for resilience, easy maintenance, and real resale value
How Your Harrow Extension Happens
Consultation & Free Starter Design
We begin with a home or video visit to understand your goals, budget, and timeframe. Choose KT5 as your builder and we’ll include free architectural/structural starter design to get your scheme moving from day one.
Planning & Approvals
We handle permitted development checks, planning applications, party wall coordination, and building control approvals—streamlining the paperwork so you don’t have to.
Build & Site Management
A dedicated site manager coordinates trades, inspections, and quality checks—from groundwork and structure through to electrics, plumbing, and final finishes—so your extension is delivered safely, neatly, and to the standard agreed.
Client Testimonials
“You made it so simple” – Just wanted to say thank you for making what I thought would be a difficult process much easier than I had imagined.
Thank you for my brand new house! The refurbishment and attention to detail makes it feel like a brand new house, but without the expensive cost of moving.
Just wanted to thank you for the work carried out to my new bathroom, I will definitely be in touch shortly to talk about my proposed kitchen extension.
Why Harrow Homeowners Choose KT5 Constructions
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Proven local experience across Harrow and wider North West/South West London
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Fixed, transparent pricing with clear payment schedules
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Rated for punctuality, communication, and attention to detail
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Practical, long-lasting solutions that add real value
Make Room for Better Living
Planning a House Extension in Harrow that lands on schedule and within budget? KT5 Construction has you covered. Book a free consultation to see how our design-and-build approach cuts cost and complexity while shaping a home that truly fits your life.
Frequently Asked Questions
How much does a Harrow house extension cost?
Costs vary by size, design complexity, and specification. As a guide:
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£1,800–£2,500 per m² for well-specified standard builds
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£2,800+ per m² for high-spec finishes or complex structures
We provide fixed pricing and can phase works to suit your budget.
Do I need planning permission for an extension in Harrow?
Many extensions fall under Permitted Development if you meet specific criteria on height, depth, and materials. If permission is needed—conservation areas, larger/additional storeys, or design exceptions—KT5 will manage the application and liaise with the local authority and building control.
How long does an extension take?
Typical timelines (after approvals and pre-construction):
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Single-storey rear: ~8–12 weeks
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Wrap-around/side-return: ~10–14 weeks
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Two-storey: ~12–18 weeks
Final durations depend on scope, access, lead times, and finish level. We’ll confirm a clear programme before work starts.
Our Services
House Extensions
KT5 Construction provides professional house or Property Renovations Services in Ash, tailored to your unique needs. Whether you’re expanding your kitchen or creating an open-plan living area, we deliver high-quality results.
Kitchen Refurbishment
At KT5 Construction, we are specialists in kitchen refurbishment in Surrey and surrounding areas, delivering bespoke designs that enhance your living space and add value to your home.
Loft Conversions
At KT5 Construction, we specialise in creating stunning loft conversions in Surrey that add space, value, and style to your home. From dormer loft conversions to luxury loft designs, our expert team handles every detail with professionalism and precision.
Groundworks
At KT5 Construction, we pride ourselves on being the go-to groundwork Company in London, delivering top-quality services for residential and commercial projects.
Bathroom Design & Installation
Your bathroom should be more than just functional—it should reflect your personal style and offer a space to unwind. At KT5 Construction, we specialise in Surrey bathroom design and installation, delivering tailored solutions that blend elegance, practicality, and luxury.
Property Refurbishment
Our Ewell Road Surbiton Project showcases the full spectrum of our refurbishment expertise. By managing every detail, from architectural consultation to final finishes, KT5 ensures each element meets the highest standards.
New Build Homes
As a trusted New Build Builder in Surrey, KT5 Construction has been at the forefront of creating bespoke, high-quality homes designed to meet modern living standards.
Architecture & Design
Expert architectural planning & creative design solutions for residential and commercial projects in Surrey & London.
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