How Is a Vinyl Window Made?

Mechanically Fastened Windows

• Brackets, screws and caulk hold together mechanically fastened windows. Even though these fasteners often result in sound, leak-proof windows from the manufacturer, if the windows are contorted, dropped or forced into racks during shipping or installation, the window seams may be compromised. This often makes the windows leak along the seams. Over-tightened screws can strip the connections and cause leaks, and caulk can be adversely affected by age or extremes in heat or cold temperatures.

Heat-Welded Windows

• Polyvinyl chloride (PVC), the type of vinyl used to make electrical, plumbing and other types of construction pipes, is used to make vinyl windows and is highly sensitive to heat welding. Sections of vinyl window frames connected with heat welding melt together to form one continuous piece of vinyl, which creates attractive, seamless corners. The drawback to heat-welded vinyl windows is hidden drainage chambers around the window perimeter that can let in air and water. The larger the area of the welded parts of the frame that touch each other, the tighter the seal.

PVC Quality and Size

• Although PVC is made from plasticizers, fillers, pigments and various other chemicals, the quality of each component affects its overall performance. Two ways to judge the excellence of the PVC ingredients is by comparing prices and researching the manufacturer’s reputation. Be sure the PVC is thick enough to adequately support the weight of the glass in the windowpanes.

Chamber and Color Considerations

• PVC vinyl is made up of chambers, and a higher number of chambers increases the strength of the weld. The number of square inches of chambers where the PVC frames connect at the corners is typically included on the label. The highest-quality PVC vinyl window frames are typically snow white, so be wary of those tinted blue, as that may be an indication of lower-quality PVC colored to hide the yellow color low-quality PVC takes on when exposed to light. Certain high-quality brands may be tinted blue for aesthetic purposes, so don’t automatically reject vinyl windows based solely on the tint.

Buying Tips

• Look for certification labels from the American Architectural Manufacturers Association (AAMA) and the Window and Door Manufacturer’s Association (WDMA) on the windows. Labels verifying the windows have been wind and weather tested are attached to high-quality vinyl windows, along with confirmations the windows have been tested for color stability.