Stylish, Secure & Built to Last

Smartly Designed for Every Project

Alitherm 400 aluminium windows are engineered to meet the highest standards of security, energy efficiency, and versatility. From family homes to public buildings, these windows are tailored for both new builds and refurbishments, delivering consistent performance and sleek aesthetics across all applications.

With options including fixed, top hung, side hung, tilt & turn, and flush casement, the Alitherm 400 system provides unparalleled flexibility. A wide variety of sash styles — standard, slimline, flush, and heritage — makes it easy to match your windows to the style of any property. Plus, the system includes co-extruded gaskets and Smart Quick-Glaze Beads to speed up fabrication and installation.

Alitherm 400 is fully compliant with Document L of the Building Regulations and is PAS 24:2022 security approved, giving you peace of mind and full compliance for residential and commercial installations. With an unrivalled colour selection and exceptional thermal performance, it’s no surprise this is the go-to choice for installers and architects alike.

Key Features And Benefits

• Wide Style Range – Fixed, casement, tilt & turn, flush & more
• High Thermal Performance – Excellent insulation helps reduce energy bills
• PAS 24:2022 Approved – Enhanced security for peace of mind
• Quick & Easy Installation – Smart Quick-Glaze Beads and co-extruded gaskets
• Compliant with Document L – Fully up to date with building regulations
• Slim, Modern Profiles – Ideal for both heritage and contemporary projects
• Weather-Resistant – Durable aluminium design with excellent sealing
• Huge Colour Choice – Match any property with Smart’s aluminium colour range
• Residential & Light Commercial Use – Versatile enough for any project