Alitherm 400 aluminium windows, fabricated by BM Bi-Folding Doors using Smart Systems profiles, provide a high-performance, trade-focused solution that meets the latest UK Building Regulations, including 2022 Part L insulation standards. Designed for ease of fabrication and installation, this system combines slim sightlines with excellent thermal performance and security.

Available in multiple configurations — fixed, side-hung, top-hung, tilt & turn, flush sash, and steel-look variants — the Alitherm 400 suite delivers versatility across residential and light-commercial projects. Each unit is made to order for accuracy and consistency, offering clean aesthetics, reliable operation, and compatibility with complementary Smart Systems door ranges. Backed by BM’s quality assurance and technical support, it’s a window system trusted by trade professionals for both performance and value.