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    Finished lower-ground gym in a basement conversion

    Basement Conversions

    Basement Conversions & Extensions in London & the South East

    Our basement construction service revamps your basement into a practical and inviting area, customised to suit your requirements.

    • Since 2017
    • 800+ projects
    • Workmanship guarantee

    Award-winning · FMB & TrustMark approved · Fully insured

    Reply in 24h

    Fast & free basement estimate

    Free assessment · No obligation

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    Real Projects

    Watch Real Projects Come Together

    See the work behind the finish — on-site, walkthroughs and start to handover.

    4.9★ from 500+ reviews on Google, Houzz, Reviews.io & TrustATrader

    South Croxted Road · SE21Infill kitchen extension — from the air and on site
    Vitali Close · SW15Rear Extension — Vitali Close
    Wallington, Surrey · SM6Rear extension & full renovation
    Sunbury · BuildOn-site with the homeowner
    Colwith Road · BuildInside the build
    Woodend Road · E17Woodend Road — Extension complete
    Loft ConversionEdward — Loft conversion
    Real projectOn-site with LINX
    Real projectKitchen extension & porch — completed project
    Real projectRear extension & bathroom — completed project
    East HorsleyHome ExtensionView
    Arlington SquareFull RenovationView
    SudbourneLoft ConversionView
    Architectural walk-throughView

    Client Stories

    Hear From Our Clients

    Real projects, real results — straight from the people we've worked with.

    South Croxted Road · SE21Infill kitchen extension walkthrough
    Sunbury · CompleteFinished extension walkthrough
    Colwith Road · HammersmithRear extension & renovation

    How your project works

    Six clear stages, from first enquiry to completion — whether we design and build, or build from your drawings.

    For clients who need the whole project managed: design, planning, building regulations and construction, from initial enquiry through to completion.

    1. Step 1: Initial Consultation & Feasibility

      Timeline: 1–3 days

      Initial consultation to discuss requirements, ideas and budget.

    2. Step 2: Architectural Design & Drawings

      Timeline: 1–4 weeks

      Architectural drawings and proposed layouts.

    3. Step 3: Planning Permission

      Timeline: 6–12 weeks (estimated)

      Planning application preparation and submission.

    4. Step 4: Structural Engineering & Building Regulations

      Timeline: 1–3 weeks, depending on complexity

      Structural calculations and drawings.

    5. Step 5: Contract & Building Works

      Timeline: Typically 4–20+ weeks, depending on project type

      Begin construction and manage all building works.

    6. Step 6: Completion & Handover

      Final client walkthrough and handover.

    All timelines are indicative. Your project-specific schedule is confirmed before construction.

    Starting from
    £28,000
    Typical duration
    8–12 weeks
    Projects delivered
    800+
    Guaranteed in writing
    Fixed price

    Six steps from first call to handover — see how your project works.

    Our Services

    Our Basements Service

    Whether you wish to expand your living space, craft a home cinema, or fashion a snug retreat, our skilled team manages every aspect from design to construction, prioritising quality workmanship and meticulous attention to detail.

    With a dedication to structural integrity and innovative use of space, we transform your basement into a valuable house extension, enhancing both the comfort and worth of your home.

    • Free consultation and assessment
    • Workmanship guarantee on all work
    • Competitive pricing guaranteed
    • Expert basement construction guidance
    Home cinema with tiered leather seating in a converted basement
    Basement conversion
    Thomas Phillips, Head of Design at LINX Design and Build

    Free Design Consultation

    Free consultation with our head designer, Thomas

    Talk your project through with Thomas Phillips, our Head of Design. Get honest advice on what you can build, planning, budget and next steps — pick a time that suits you.

    Book with Thomas
    Free No obligation Video, phone or in-person

    Full transparency

    Basements – What's Included

    Convert existing spaces such as garages, basements and outbuildings into functional, habitable rooms.

    Typically includes

    • Structural assessment & preparation
    • Damp-proofing & insulation
    • Electrical & plumbing installation
    • Flooring & wall finishes
    • Window & door installation
    • Heating & ventilation
    • Decoration and completion

    How You Pay

    Milestone Payment Plan

    No large upfront deposits. You pay in stages as work is completed, inspected and approved by your project manager.

    Calculate Your Payment Plan

    Adjust the slider to see how milestone payments break down for your project budget.

    Your Project Value

    £55,000
    £20,000£10,000,000

    Illustrative Example — The amounts shown below are based on a £55,000 project for illustration purposes only. Your actual payment schedule will be tailored to your specific project scope, specifications and agreed contract value. Milestone percentages remain consistent across all project sizes.

    1

    Contract Signing

    10%

    £5,500

    Contract signed, design finalised & demolition scheduled

    Upon signed contract & project programme agreed
    First Payment
    2

    Strip-Out & Demolition

    10%

    £5,500

    Full internal strip-out, waste removed & structural opening prepared

    Upon strip-out complete & site cleared
    3

    Structural Works

    15%

    £8,250

    Wall removals, steel beams, floor strengthening & underpinning

    Upon structural works signed off by engineer
    4

    First Fix M&E

    15%

    £8,250

    Full rewire, re-plumb, heating system & underfloor heating

    Upon first fix electrics & plumbing inspected
    5

    Plastering & Insulation

    10%

    £5,500

    All surfaces plastered, insulation upgraded & walls dried

    Upon plastering complete throughout property
    6

    Kitchen & Bathrooms

    15%

    £8,250

    Kitchen installed, bathrooms fitted, tiling & waterproofing

    Upon kitchen & bathrooms functional & tiled
    7

    Second Fix & Decoration

    15%

    £8,250

    Flooring, doors, skirting, architraves, painting & finishes

    Upon snagging walkthrough with client
    8

    Completion & Handover

    10%

    £5,500

    Final snagging, deep clean, Building Control sign-off & handover

    Upon completion certificate & client sign-off
    Discuss Your Payment Plan

    No obligation • Free consultation • Reply within 24 hours

    Get started today

    Ready to Start Your Basement Project?

    Get a free, no-obligation quote today. Our experts are ready to transform your basement into a valuable living space.

    from 500+ reviews
    4.9★
    workmanship
    Guaranteed
    projects completed
    800+
    London & the South East
    Est. 2017
    Award winning on HouzzBest of Houzz 2026 — ServiceBest of Houzz 2024 — ServiceBest of Houzz 2019 — ServiceBest of Houzz 2018 — ServiceHouzz RecommendedHouzz 100 Saves

    Featured projects

    All projects
    Hedgley Street Renovation by LINX Design and Build
    Renovation

    01 / 36

    Hedgley StreetRenovation

    What we do

    One team. Every discipline.

    From the first sketch to the final handover: architecture, residential, commercial and new builds, delivered under one accountable roof.

    Looking for something specific?

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    4.9★ from 500+ reviews

    What our clients say.

    Customer Reviews

    Read what our customers say about our services

    • ★★★★★

      Our new loft conversion has us utterly thrilled! Our underused attic was turned by the Linx team into a lovely, light-filled, and cosy area that is ideal for living, working, and unwinding. The workmanship, craftsmanship, and attention to detail were superb. Everything fits in well with the rest of our house. Excellent outcomes and service. Strongly suggested!

      Jordan R. · Reviews.io ·

    • ★★★★★

      Our expectations were surpassed by LINX Design's outstanding office and warehouse development. The crew showed exceptional professionalism, technical know-how, and attention to detail from the first free site evaluation to the last handover. We had total confidence from the start thanks to the fixed-price quote, and the job was handled effectively all along the way. Their seamless integration of design, fabrication, and installation services produced a contemporary, useful, and aesthetically pleasing workstation. Every element of the construction demonstrates the high calibre of workmanship, and the warranty added even more assurance. We are thrilled with the completed building and would heartily suggest LINX Design for any commercial or industrial building project.

      Alexander O. · Reviews.io ·

    • ★★★★★

      The phase of architectural design and drawings was overseen with remarkable skill and meticulousness. After conducting a thorough property survey, excellent architectural drawings and suggested layouts were created. The team meticulously took into account every comment, producing design changes quickly and guaranteeing a smooth approval process all along the way. Thanks, Linx Owner Gary Pal and your all Guys!!!

      Michael B. · Reviews.io ·

    • ★★★★★

      LINX Design and Build completed our loft conversion to an exceptional standard and delivered everything on schedule. The team provided clear daily updates, maintained a clean and safe worksite, and demonstrated outstanding craftsmanship throughout the project. Our dedicated project manager ensured a smooth, stress-free experience. We highly recommend their renovation services.

      Robert P. · Reviews.io ·

    • ★★★★★

      Outstanding service from LINX Design and Build. From the initial consultation to the final handover, the team was professional, knowledgeable, and hardworking. Their commitment to quality, innovation, and customer satisfaction was evident throughout the project. Every aspect of the build was completed with care and precision, resulting in a finished home that exceeded our expectations. We highly recommend LINX Design and Build for anyone looking for a trustworthy and experienced building company.

      Joseph P. · Reviews.io ·

    • ★★★★★

      We are extremely happy with our kitchen infill extension and renovation. The team was professional, friendly, and reliable throughout. Their workmanship and attention to detail were excellent, transforming our space beautifully. Highly recommended for quality, service, and outstanding results!

      James K. · Reviews.io ·

    Our Trusted Partners

    AUTHORISED SUPPLIERS

    CHAS
    Constructionline
    NICEIC
    Federation of Master Builders
    TrustMark
    SafeContractor
    Gas Safe Register
    SMAS Worksafe
    IWA – Independent Warranty
    HomePro
    Freedom Homes Architects
    Extension Plans
    Trusted Partner
    RAMs

    Our team

    The People Behind LINX

    An in-house team delivering every project from first sketch to final handover — backed by 60+ tradesmen on site.

    • Gary Pal, Managing Director at LINX Design and Build

      Gary Pal

      Managing Director

    • Cristian Ghertan, Construction Director at LINX Design and Build

      Cristian Ghertan

      Construction Director

    • Ryan Anthony, Project Manager at LINX Design and Build

      Ryan Anthony

      Project Manager

    • Atul Singh, Project Manager at LINX Design and Build

      Atul Singh

      Project Manager

    • Steve McDermott, Project Consultant at LINX Design and Build

      Steve McDermott

      Project Consultant

    • Alexis Urbina, Business Development Manager at LINX Design and Build

      Alexis Urbina

      Business Development Manager

    • Vishal Gajjar, Business Growth Strategist at LINX Design and Build

      Vishal Gajjar

      Business Growth Strategist

    • Thomas Phillips, Head of Design at LINX Design and Build

      Thomas Phillips

      Head of Design

    • Manisha Silwal, Customer Service at LINX Design and Build

      Manisha Silwal

      Customer Service

    • Joseph Gomes, Tech / IT at LINX Design and Build

      Joseph Gomes

      Tech / IT

    FAQs

    Questions about basement conversions

    Ask us something else

    Basement conversions start from £28,000, and your price is fixed and guaranteed in writing.