Flush Sash Aluminium Windows
Clean, contemporary flush sash aluminium windows from Smarts. Trade-priced, PAS24 approved and delivered free across the UK.
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Alitherm 400 Aluminium Windows
Midland Aluminium is a trusted trade supplier of the Smarts Alitherm 400 aluminium window system. Designed for both residential and light commercial applications, the Alitherm 400 combines elegant aesthetics with outstanding security and thermal performance.
Available in fixed, side hung, top hung, tilt and turn and flush casement options, it is a system that works across virtually any project type. Get your quote within 24 hours.
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WER A+ Rated
Achieves a Window Energy Rating of A+, making it easy to meet current building regulation requirements.
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Multiple Opening Configurations
Available in fixed, side hung, top hung, tilt and turn and flush casement options, giving flexibility to specify for any project.
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Residential and Commercial Projects
Versatile enough to work across a wide range of project types — from homes to schools, colleges, hospitals, offices and public sector housing.
- Security
- Colours
- Downloads
Security You Can Rely On
The Smarts Alitherm 400 is approved to PAS24:2022, giving it full compliance with the UK's enhanced security standard for windows and doors. For installers and builders working on projects that require Part Q compliance or Secured by Design accreditation, that approval can be the difference between winning and losing a contract.
Colour Options
The Alitherm 400 is available in a huge range of powder coated colours, giving you and your customers virtually unlimited choice across every project. Single and dual colour configurations are available, allowing the inside and outside of the frame to be finished in different colours if required.
Black
Cream
Agate Grey
Pebble Grey
Dark Brown
White
Slate Grey
Anthracite Grey
Black
Cream
Agate Grey
Pebble Grey
Dark Brown
White
Slate Grey
Anthracite Grey
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Suitable for Far More Than Just Homes
The Alitherm 400 is not just a residential window system. Fully compliant with Part L of the Building Regulations, it is suitable for a wide range of commercial applications including schools, colleges, hospitals, offices and public sector housing.
If you work across both residential and commercial sectors, the Alitherm 400 is a single system that covers both — simplifying your product range and your supply chain.
Designed to Make Your Life Easier on Site
The Alitherm 400 features co-extruded gaskets in sashes, outer frames and Smart Quick-Glaze Beads, making fabrication straightforward and installation faster on site. Less time fitting means more jobs completed and more value from every working day.
A system designed with the installer in mind, from the factory floor to the finished installation. Speak with our team today to get a free quote within 24 hours.
Your Questions Answered
Not sure which product is right for your project, or want to know more about how we work? Here are the answers to the questions we get asked most often.
The Smarts Alitherm 400 is a high-performance aluminium window system designed for both residential and light commercial applications. It combines outstanding thermal performance, class-leading security and an unrivalled choice of colours, making it one of the most versatile aluminium window systems available in the UK market.
The Alitherm 400 is available in fixed, side hung, top hung, tilt and turn and flush casement configurations, giving you the flexibility to specify the right window for virtually any project or elevation requirement.
The Alitherm 400 achieves a WER A+ rating with u-values of 1.4W/m²K, making it fully compliant with current building regulation energy efficiency requirements and suitable for both new build and refurbishment projects.
Yes. The Alitherm 400 is approved to PAS24:2022 — the UK's enhanced security standard for windows and doors. This makes it suitable for new build projects, housing developments and any scheme where security performance is a requirement.
Yes. The Alitherm 400 is suitable for a wide range of residential and light commercial applications, including schools, colleges, hospitals, offices and public sector housing. Its versatility and compliance credentials make it a strong specification choice across both sectors.
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