A typical version of an overhead garage door used in the past would have been built as a one-piece panel.Newer versions of overhead garage doors are now generally built from several panels hinged together that roll along a system of tracks guided by rollers.[3] The history of the garage door could date back to 450 BC when chariots were stored in gatehouses, but in the United States, they arose around the start of the 20th century.Some manufacturers incorporate foamed-in-place polyurethane insulation within the monolithic panel and sectional garage doors.A typical single-car garage roller door has a preloaded spring inside the rolling mechanism.In the UK (and other parts of the EU), 'insulated' roller garage doors are available, using an aluminum lathe filled with polyurethane foam for thermal and acoustic insulation.However, it is essential to remember that if the garage door's weight is increased by adding glass, additional insulation, or even several coats of paint, the torsion spring's life may be significantly reduced.Additionally, springs in highly humid environments, such as coastal regions tend to have a significantly shorter cycle life, due to the corrosive cracking.Other factors like poor garage door maintenance, loose tracks, or components shorten torsion spring life.Maintenance of garage doors is described in the manufacturer's instructions and consists of periodic checks for correct operation, visual inspection of parts, and lubrication.The most common causes of injury from garage door systems include falling doors, pinch points, improperly adjusted opener force settings, and safety eyes, attempts at do-it-yourself repair without the proper knowledge or tools, and uncontrolled release of spring tension (on torsion spring systems).Force settings should cause a door to stop or reverse on encountering more than approximately 20 lb (10 kg) of resistance.
