FREE EXTENSION COST CALCULATOR
Powered by KT5 Construction
Use our Extension Cost Calculator to receive a tailored estimate for your home extension in under 60 seconds. Whether you’re building an extension or renovating your current space, this free tool helps you understand realistic build costs, ensuring cost effectiveness from the very start.
Our calculator is designed for anyone planning an extension in the UK, giving you clarity and confidence when budgeting your next project.
How Our Extension Cost Calculator Works
Our simple build cost calculator makes estimating your project easy:
- Select your extension type — rear, side, wraparound, or double-storey.
- Enter key project details like size and finish.
- Choose interior and design preferences.
- Add any additional requirements.
- Receive your total estimate instantly.
Our tool uses regional data and industry-standard rates to generate an estimate you can rely on. It’s an ideal starting point for anyone planning to build or remodel — helping you understand what to bear in mind before requesting formal quotes.
What’s Included in Your Estimate
When you use KT5’s house extension cost calculator, you’ll receive a comprehensive breakdown that includes:
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Material costs (brickwork, roofing, windows, finishes)
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Labour charges for construction and installation
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Planning and compliance under UK building regulations
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Structural works and reinforcements
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Mechanical and electrical services including plumbing and lighting
This ensures you’re budgeting for the full picture — not just the basic structure.
Types of Extensions We Cover
Single-Storey Extensions
Perfect for expanding your ground floor or creating open-plan living. Our calculator covers every stage of building a single storey extension, including structure, roofing, and finishes.
Double-Storey Extensions
Add vertical space to your home with new floors, staircases, and reinforced foundations. Use our build costs calculator to estimate total outlay per square metre.
Kitchen Extensions
Transform your living area into a modern, light-filled kitchen space. The extension calculator helps you explore layouts and plan efficiently while keeping cost effectiveness in mind.
Why Use KT5 Construction’s Extension Cost Calculator
KT5 Construction’s Extension Cost Calculator provides transparent pricing, real-time estimates, and accurate projections tailored to your location and project size.
We combine over 25 years of experience in building an extension with a design-led approach to deliver precise and dependable pricing.
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Accurate & Instant: Results in seconds.
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Transparent & Honest: No hidden extras.
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Fully Compliant: Estimates factor in building regulations for all extensions in the UK.
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Flexible & Scalable: From single-storey builds to complex multi-level extensions.
For more insights, view our full Extension Cost Calculator Guide.
Hidden Costs to Consider
When planning your project, bear in mind that additional items can affect your overall build cost. These may include:
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Utilities & Services: Electrical, plumbing, and heating systems.
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Finishes: Flooring, tiling, painting, and lighting.
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External Works: Drainage, patios, or garden landscaping.
These costs are often overlooked, so it’s important to include them for a more realistic total. Our build cost calculator helps you factor these in early for maximum cost effectiveness.
Hidden Costs to Consider
How accurate is the Extension Cost Calculator?
Our calculator uses verified regional data to provide accurate, up-to-date pricing for any extension in the UK. A site visit will confirm the final figure.
How long does it take to get a quote?
Your tailored quote appears instantly once your details are submitted.
How can I quickly work out the cost of an extension before speaking to a builder?
Simply use KT5’s free Extension Cost Calculator — the fastest way to estimate your project build cost before contacting professionals.
Testimonials
Our clients consistently highlight the professionalism and precision of KT5 Construction. From early build cost estimates to completion, we’ve built a reputation for accuracy, reliability, and value.
Ready to Turn Your Plans into Reality?
Use our Extension Cost Calculator now to receive your instant estimate, or contact KT5 Construction for tailored advice on building an extension that meets your design goals and budget.
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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