Graf PVCu Welded Windows and Doors: The Ultimate Guide to uPVC Joint Types

Category: Technology / Innovation
Reading Time: 5 Minutes

For decades, uPVC windows have had a tell-tale sign that revealed they weren’t timber: the corner joint. If you look closely at a standard uPVC window, you will see a small groove running diagonally across the corner weld where excess plastic was “knifed” off. But technology has moved on. Enter the Graf Weld.

1. The Standard 45° Mitre Weld (The Old Way)

The ends are cut at 45° and melted together. Pushing molten plastic together creates a “sprue” (mess) that a machine then cuts away, leaving a shallow diagonal groove.

Standard Weld: Note the visible diagonal groove where dirt can collect.

2. The Seamless Graf Weld (The New Way)

Graf welding uses technology pioneered by Graf Synergy. Instead of letting the molten plastic spill out, the machine pushes it back inside the hollow chambers of the frame.

Comparison: Standard vs. Graf Weld

4. Seamless Bay Window Cills

Graf developed a “Seamless Sill Welder” which provides a high-precision finish to the cill—the part of the window you look at most often.

5. Mechanical Joints (The Heritage Alternative)

Mechanical joints are screwed and glued together, exactly like a traditional timber frame. This is most common on our Residence 9 (R9) collection.

Frequently Asked Questions