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Alitherm 300
More about Alitherm 300 Casement Windows
Trusted manufacturers since 2000
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Made in the UK
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Bespoke Complex Products Fabricated
Alitherm 400 casement windows are a modern, energy-efficient upgrade to the trusted Alitherm 300 system—offering enhanced thermal performance and a more streamlined design. Ideal for residential and light commercial projects, Alitherm 400 windows feature a softline profile for a clean, contemporary appearance and are fully compliant with the latest UK Building Regulations, including Document L 2022. Manufactured in-house by Direct Trade Windows, these windows combine elegant aesthetics with long-lasting reliability.
Compared to Alitherm 300, the Alitherm 400 system offers improved thermal insulation and a more refined frame design for even slimmer sightlines. With side-hung and top-hung configurations, a wide range of colour options, and robust security features, it’s a premium choice for homeowners and architects who demand both performance and style. Our technical team is on hand to guide you through the specification process and ensure your windows are built to the highest standard.
Key Features:
- Improved thermal performance: Complies with Document L 2022 standards
- Softline frame design: More modern profile than Alitherm 300
- Slim sightlines: Maximises natural light while maintaining energy efficiency
- Flexible configurations: Available as side-hung or top-hung casement windows
- Custom finishes: Wide range of RAL colours, including dual-colour options
- Secure and durable: Multi-point locking with high-performance hardware
- In-house manufacturing: Tailored to order with expert support from our team
Technical Specification
Technical Specification – Alitherm 400 Casement Windows
- Material: Aluminium profiles extruded to BS EN 755-9 / EN 12020, alloy 6063 T6
- Thermal Break: Polyamide thermal break with extended insulation zones
- Glazing Options: 24mm to 40mm double or triple glazing, internally or externally beaded
- Opening Styles: Top-hung, side-hung, fixed lights, and French casement
- Max Sash Size: Side-hung: 600mm x 1400mm; Top-hung: 1400mm x 1400mm
- Max Sash Weight: 28kg (standard hinges), up to 40kg with egress hinges
- Locking: Multi-point espagnolette locking with stainless steel fixings
- Handles: Inline or cranked espagnolette handles in various finishes
- Weather Performance: Air: Class 4 | Water: Class 7A | Wind: Class AE2400
- U-Values: As low as 1.3 W/m²K when paired with appropriate glazing
- Compliance: PAS24 security tested, Document L compliant
- Finishes: Single and dual RAL colours, anodised, textured and special finishes available
Colours
White aluminium frame colour finish sample.
Matt white aluminium frame colour finish sample.
Matt brown aluminium frame colour finish sample.
Jet black aluminium frame colour finish sample
Grey aluminium frame colour finish sample.
Gloss white aluminium frame colour finish sample.
Gloss off white aluminium frame colour finish sample.
Dark red aluminium frame colour finish sample.
Dark grey aluminium frame colour finish sample.
Dark green aluminium frame colour finish sample.
Dark brown aluminium frame colour finish sample.
Dark blue aluminium frame colour finish sample.
Cream aluminium frame colour finish sample.
Black aluminium frame colour finish sample.
Anthracite grey aluminium frame colour finish sample.
Airforce grey aluminium frame colour finish sample.
Glass
Unglazed aluminium window frame with angled top.
Standard self-clean glass panel with clear finish.
Standard toughened glass panel with clear finish.
Clear solar control glass panel for improved comfort and energy efficiency.
Self-cleaning glass panel designed to break down dirt and reduce cleaning frequency.
Self Clean Solar Control panel combining dirt-repelling and heat-reducing technology.
Satin obscure glass panel with smooth frosted finish.
Laminated security glass panel with clear finish.
Hardware
Monkey Tail Handle
Pear Drop Handle
steel look window hardware
close up of steel look hardware
Brochure
Gallery
FAQs About Alitherm 400 Casement Windows at Direct Trade Windows
What are Alitherm 400 casement windows?
Alitherm 400 casement windows are slimline aluminium windows designed for modern performance, offering excellent thermal efficiency, durability, and sleek aesthetics.
Are Alitherm 400 windows energy efficient?
Yes. With U-values as low as 1.2 W/m²K when triple glazed, Alitherm 400 casement windows provide exceptional insulation and meet current UK Building Regulations.
Do Alitherm 400 casement windows meet security standards?
Absolutely. They are PAS 24:2016 accredited and feature robust multipoint locking systems for enhanced safety.
Can I customise the design of Alitherm 400 windows?
Yes. You can choose from casement, top-hung, and side-hung styles, a full range of RAL colours, and multiple glazing options.
Are Alitherm 400 casement windows suitable for commercial projects?
Yes. Their strength, weather resistance, and customisation options make them ideal for both residential and commercial applications.
What maintenance is required for Alitherm 400 windows?
Minimal. Aluminium is low-maintenance, requiring only occasional cleaning to maintain its appearance and performance.
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