UPVC windows are made from sections of profile, which are cut and joined together to for the shape of the window. These profiles are produced by forcing molten PVC through a precision die, the material is cooled almost immediately before being cut to length. The flatness, squareness, and straightness of the profile is maintained by the design characteristics of the profile and the tooling.
The windows are then fabricated from pieces of profile that have been cut to the correct size. These pieces of profiles are joined together using either heat-fusion welding or T-joint connectors. Steel or aluminium reinforcement sections are fixed inside the UPVC profiles to provide additional strength, where required.