The Thermafold 1000 insulated folding door combines energy saving qualities with a high aesthetic appearance. It is designed for use in openings up to 6000mm wide and 6000mm high and is particularly suitable for applications where a bottom track needs to be avoided such as railway depots. Its ease of operation allows the door to be manually operated, unlike upward moving doors such as sectional overhead and rolling shutters, particularly on larger openings. The operation is simple and avoids the need for cables, springs etc., thus avoiding high maintenance after installation, and the fact that the door is sideways opening means that the leading edge is in constant vision and less prone to damage from vehicles passing through the opening.