How Corner Welding Works — and Why It Matters

The corner joint is where a window frame is most likely to fail. It's where water first finds a way in, and where structural stress concentrates every time a window opens and closes.

In premium fabrication, corners are fusion-welded — the UPVC profile is heated and pressed together so it becomes one continuous, sealed piece. This creates a joint that is stronger than the profile itself and completely water-tight.

In cheap, manual fabrication, corners are often screwed or glued together instead. These joints work initially, but loosen over time with temperature changes, leading to gaps, leakage and eventual warping.

When comparing quotes, always ask how the corners are joined. It's a five-second question that reveals a lot about the fabricator's quality standards.