The robust and energy-efficient SOLID POLAR loft ladder has an 86 mm thick double-sealed hatch, which results in a heat transfer coefficient of 0.36 W/m2*K, guaranteeing the lowest heat loss and energy cost savings. To increase safety, the SOLID POLAR staircase has been equipped with a handrail to facilitate entry and with non-slip feet. The all-metal ladder allows for a maximum load of 210 kg. The ladder structure has been powder-coated, giving it a modern look and ensuring that it will last for many years. Ud - coefficient of the hatch centre.