Fully Mechanical Joints (just like Timber) a traditional mechanical jointed method, often used in timber joinery.
Timberweld® (a unique, patented method of joining PVCU windows together. The result is a perfect “wooden, butt-joint. Gives an ETL (External Timber Look) to the outside, but a diagonal weld internally.
Mitre weld - fuses joints together diagonally
Graf weld or Seamless weld (is the same as the mitre weld, just less visible)