Alitherm 400 Aluminium French and Single Doors — Secure, Energy-Efficient & Made to Measure
Combining outstanding value and quality, with class-leading performance and security.
Explore Alitherm 400 aluminium French and single doors from Marlin Windows. Secure, energy-efficient, made-to-measure residential doors with slim sightlines, modern styling and a wide choice of colours.
Key Features
Optimum thermal efficiency
Incorporates innovative polyamide thermal break technology
Fully compliant with latest building regulations
PAS 24:2016 Approved
Dual colour possible
Unrivalled Choice of Colour
Alitherm 400 Doors
Alitherm 400 doors are a versatile aluminium door system designed for modern homes, extensions and renovation projects. Combining slim sightlines with strong thermal performance and reliable security, they are ideal for front, side and rear entrances.
Each door is manufactured to your exact size and specification, ensuring a precise fit and a high-quality finish. Whether you’re upgrading an existing entrance or completing a new build, Alitherm 400 offers a practical and stylish solution.
✔ Made to measure for any opening
✔ Slim, contemporary aluminium profiles
✔ High-security locking options (PAS 24 compliant)
✔ Thermally broken for improved energy efficiency
✔ Available as single or French doors
“Great quality products along with great customer service. Easy to recommend.”
Chris Hirst, Ilkley – Builder – VIEW PROJECT
Why Choose Alitherm 400 Doors?
Alitherm 400 is designed to deliver the right balance of style, performance and flexibility for residential properties.
Slim, modern design
Clean aluminium sightlines create a contemporary look that works well with both modern homes and traditional renovations.
Thermal efficiency
The system uses polyamide thermal break technology to help reduce heat loss and improve energy performance.
Flexible configurations
Choose from:
- Single doors
- French doors
- Open-in or open-out options
Enhanced security
Alitherm 400 doors are available with multi-point locking systems and PAS 24 compliant specifications for added peace of mind.
Weather performance
Designed to withstand the UK climate, these doors provide excellent resistance to wind and rain.
PM0009T Marlborough FR Frame 090818
PM0004P Sherbourne 4 FR+Frame 090818
PM0004T Sherbourne 4 FR+ Frame 090818
PM0007P Sherbourne 3 FR+ Frame 090818
PM0007T Sherbourne 3 FR Frame 090818
PM0008P Teddington FR+Frame 090818
PM0002P Bloomsbury FR+ Frame 090818.
PM0005P Kensington FR+Frame 090818
PM0005T Kensington FR+Frame 090818
PM0003P Broadstone FR+Frame 090818
PM0003T Broadstone FR+Frame 090818
PM0001P Amersham FRFrame 090818
PM0001T Amersham FR+Frame 090818.
PM0006P Oakham FR+Frame 090818
PM0006T Oakham FR+Frame 090818
Design Options
Colours
Available in a wide range of powder-coated finishes, including:
- Anthracite grey
- Black
- White
- Dual colour options (different inside and out)
Glazing
Choose from clear, obscure or decorative glazing options to suit your level of privacy and design preference.
Hardware
A variety of handles, hinges and accessories are available to complete your door
Technical Performance
Alitherm 400 doors are engineered to meet modern building standards.
- Thermal performance: Energy-efficient aluminium system
- Security: PAS 24 compliant options available
- Durability: Strong, low-maintenance aluminium construction
- Weather resistance: Tested for UK conditions
Why Choose Marlin Windows?
We combine quality manufacturing with a customer-focused approach to deliver doors you can rely on.
Made to measure
Every door is built to your exact requirements for a perfect fit.
Quality controlled
Our products go through structured quality checks throughout the manufacturing process.
Care from start to finish
From your initial enquiry to installation, we take care to ensure a smooth experience.
Expert guidance
We help you choose the right configuration, style and finish for your project.
REQUEST A QUOTE
Learn More
View our Alitherm 400 brochure
Ready to transform your home?
Get a made-to-measure quote for your Alitherm 400 door today. Our team will guide you through sizes, styles and glazing options to find the perfect fit for your home.
Or call us on 01535 603909 to speak with our team.
Frequently Asked Questions
If you require any support, please don’t hesitate to review our FAQs below or drop us a message on our contact form here
What is an Alitherm 400 door?
Alitherm 400 is a thermally broken aluminium door system designed for residential and light commercial use. It offers slim profiles, high strength, excellent weather resistance, and modern thermal performance, making it ideal for everyday access doors.
How secure are Alitherm 400 doors?
Aluminium is inherently strong, and Alitherm 400 doors can be fitted with high-security multi-point locking systems and robust hardware. PAS 24 compliant configurations are available for enhanced security performance.
Are Alitherm 400 doors suitable for front entrances?
Yes, they are ideal for front, side and rear doors thanks to their strength and security features.
What information must be provided in order to get an accurate quotation?
We will ask you to provide the following information:
- Approximate dimensions (width x height)
- Basic design/layout
- Project location
How long will my quotation take?
We aim to return all quotations within 24 hours however large projects may take longer.
Come and explore…
Aluminium Bi-fold Doors, Aluminium Heritage Windows and Traditional Steel Replacement Windows.
