For 15 years, the GL250 has redefined airtight loft access. Discover why housebuilders still trust the original market‑leading design for outstanding performance.
Fifteen years after launch, the Manthorpe GL250 Loft Access Door remains the benchmark for airtight, thermally efficient loft entry solutions. When air‑tightness testing became mandatory, traditional drop‑down doors began failing under negative pressure, bowing along their length and breaking their seals. Housebuilders needed a solution that didn’t just pass tests but solved the structural weakness behind those failures.
Manthorpe responded by reimagining the loft door from the ground up. Instead of refining an older design, the team engineered a completely new approach built around airtightness, insulation coverage, accessibility and modern styling.
A key breakthrough was moving the hinge outward into the frame edge. This allowed a larger opening and created space for an unbroken airtight seal. It also enabled full removability of the door during installation, making fitting quicker and preventing insulation damage later.
From this innovation came the GL250’s defining feature: the sliding catch surround. Originally created to conceal the new hinge geometry, it evolved into a full‑perimeter locking system. Instead of relying on a single catch, the GL250 locks into twelve anchor points, distributing pressure evenly to prevent bowing and eliminating secondary air‑leakage paths. All catch and hinge mechanics sit outside the air‑seal line, allowing maximum insulation coverage with minimal cold bridging.
Installation is just as straightforward. The frame screws directly upward into the ceiling for consistent seal compression, and the door snaps securely back into place through simple hinge blockers.
Independent BRE testing confirmed the GL250’s performance, achieving 0.19 m³/h/m² at 50Pa and 0.05 m³/h at 2Pa, far exceeding the standards for both Part L and BS 5250. It also outperformed the nearest competitor by over 300 times under −50Pa pressure testing.
Today, with every new home requiring air‑tightness testing, the GL250 remains the No.1 specified loft door for builders seeking proven reliability, exceptional airtightness and modern aesthetics.
Explore the full performance data and product details below: