01205 311144

The Perfect Blend of Style and Performance

Our flush sash windows combine stunning aesthetics with exceptional performance. For a touch of heritage charm, choose uPVC profiles with a realistic woodgrain finish. Alternatively, aluminium offers a sleek and modern aesthetic, ideal for contemporary homes. No matter your style preference, our flush sash windows deliver superior thermal efficiency, enhanced weather resistance, and robust security, ensuring your windows perform flawlessly for years to come.

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large white kommerling flush windows

Key Features

Customisable colour options

Our flush sash windows come in a variety of colours, and you can even choose from a range of woodgrain finishes for a timber-effect look!

Fitted with care

If you’re a homeowner requiring installation, our expert team can fit your flush sash windows in your home.

Timeless appeal

This window style contains a sash that sits ‘flush’ with the window frame (hence the name!). This distinctive look can complement both modern and traditional homes!

Expert team 

Our expert family-run team is on hand to offer advice and answer any questions you may have throughout the entire process.

Material options

Our flush sash windows are available in both high performance uPVC and aluminium, both of which provide durability, security and weather resistance.

Thermal performance

Whether you choose uPVC or aluminium, our flush sash windows are designed to keep homes comfortable throughout the year and minimise energy costs.

  • Colour Options
  • Hardware Options
  • Downloads

    • Colour Options

    Find the perfect colour

    Explore Our Range of Colours

    Browse our extensive colour range! We offer timeless neutrals, bold colours and everything in between. We can even offer a range of wood-grain finishes that mimic timber.

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    Black Brown

    Black Brown

    Slate Grey

    Slate Grey

    Painswick

    Painswick

    Irish Oak

    Irish Oak

    Golden Oak

    Golden Oak

    Chartwell Green

    Chartwell Green

    White Ash

    White Ash

    Rosewood

    Rosewood

    Grained Anthracite Grey

    Grained Anthracite Grey

    Flat White

    Flat White

    Cream

    Cream

    Hardware Options

    Industry-leading hardware

    Complete the Look: Hardware Options

    To personalise your flush sash windows and achieve the perfect finishing touch, we offer a variety of high-quality hardware options.

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    Short Neck Handle

    Short Neck Handle

    Sliding Handle

    Sliding Handle

    With Key

    With Key

    Casement Handle

    Casement Handle

    Downloads

    Kommerling Window Brochure Kommerling Window & Door Brochure Kommerling 070 Window Brochure

    Our Order Process

    Request a free quote

    Let us know what you’re looking for and whether you need a trade supply or if you’re a homeowner needing installation.

    Speak to our experts within 24 hours

    Our team will aim to get back to you within 24 hours.

    Delivered within 2-4 weeks

    If you’re an installer, we can deliver your products within 2-4 weeks. If you’re a homeowner, we can aim to supply and fit within 6 weeks.

    Frequently Asked Questions

    Browse our FAQs below to find answers to commonly asked questions.

    01205 311144

    What makes flush sash windows different to casement windows?

    Unlike traditional casement windows where the sash protrudes above the frame, flush sash windows have a recessed sash that sits flush with the external frame when closed. This creates a smooth, seamless exterior.

    Do you offer installation services for flush sash windows?

    Yes! For trade professionals we can offer flush sash windows supply-only, or for homeowners we can fit your windows.

    Are flush sash windows suitable for my traditional-style home?

    Absolutely! Flush sash windows are similar to traditional timber window designs, especially when combined with wood-grain finishes for uPVC. If your home is in a conservation area, you’ll need to check with local planning authorities.

    How can I get a quote for new flush sash windows?

    Contact Boston Trade Frames today! We offer free consultations and quotes. Our friendly team will be happy to discuss your project requirements and recommend the perfect window for your needs.

    Can I customise my flush sash windows?

    Of course – we offer a range of customisation options including colours, finishes and hardware. You can even choose decorative glass!

    Compare Our Products

    Browse our window products to find the best solution.

    large white kommerling flush windows

    Flush Sash

    • Flush sash design - sash sits flush with the external frame
    • Choice of either uPVC or aluminium frames
    • Authentic woodgrain options for traditional heritage window style
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    Cream uPVC Liniar Windows

    Casement

    • Casement-style hinged at the sides or top, opening outwards
    • Insulating uPVC or thermally broken aluminium frames
    • Versatile style complements modern homes and traditional properties
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    Kommerling white tilt and turn windows

    Tilt & Turn

    • Tilt the sash inwards for ventilation or open outwards like a casement window
    • Made with strong and weatherproof aluminium
    • Slim profiles and maximum natural light thanks to strong aluminium frames
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    White sliding sash windows

    Sliding Sash

    • Sashes slide vertically up and down to open and close
    • Classic design that mimics traditional timber sash windows
    • Customisation options including glazing bars
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    kommerling french doors

    French Doors

    • Classic & elegant design that allows plenty of natural light in
    • Made with thermally efficient uPVC to minimise heat loss
    • Available in a range of colours and finishes
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    Cream uPVC Liniar Windows

    uPVC Windows

    • Strong, lightweight, and versatile plastic material
    • Wide range of styles available including casement and sliding sash
    • Supply-only uPVC windows available for installers
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    Sheerline grey aluminium windows

    Aluminium Windows

    • Made from strong, lightweight, and naturally corrosion-resistant aluminium
    • Thermally-broken profiles for energy efficiency
    • Various styles available including casement, flush sash and tilt & turn
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    kommerling flush profile
    white kommerling flush 70 windows

    Heritage Charm: Timber-Effect Flush Sash Windows

    For a touch of character and traditional charm, consider choosing our uPVC flush sash windows. Available in a variety of realistic woodgrain finishes, they perfectly replicate the classic look of traditional timber windows found in historic homes. However, if your home is located within a conservation area, it's important to check with your local planning authority before making any window replacements to ensure they meet specific requirements.

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    Contemporary & Sophisticated: Aluminium Flush Sash Windows

    The best part about flush sash windows is their versatility; in recent years, aluminium flush sash windows in darker colours such as deep grey or black have become increasingly popular among homeowners. The clean lines and minimalistic frames make flush sash windows a great choice for contemporary homes, and the inherent strength and slim sightlines of aluminium further enhance the modern look, allowing for plenty of natural light and uninterrupted views.

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    black kommerling flush windows

    What our customers say

    Don't just take our word for it. Read what our satisfied customers have to say about Boston Trade Frames.

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    Quotation Marks

    Quality products at a good price

    Dean Brotherton

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    Had Nigel do our double glazing on the front. Great price and great job.

    Richard Phillips

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    Good quality products at a good price helpful and quality customer service would definitely recommend

    Kevin Cook

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    Leave a review

    Get in touch with us

    If you would like any more information or a free quote, please get in touch with us! We’d be happy to answer any questions you may have.

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      The Brains

      Meet the Owner: Nigel

      Nigel Apps, owner and director of Boston Trade Frames, has dedicated his career to windows. He began in joinery, then transitioned to manufacturing high-quality uPVC windows.
      Nigel's unparalleled knowledge and expertise ensures that you get exceptional windows, doors and conservatories for every project.

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      Expertly Crafted Home Improvements in the Heart of Boston

      At our Boston factory, our close-knit team utilises cutting-edge machinery and years of experience to craft high-performance windows and doors. We manufacture systems from industry leaders such as Kömmerling and Solidor.

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      Established 1981