How to Recognize a Good Vinyl Double Hung Window


Sash meeting rails showing structural interlock and K-Beam™ reinforcement.

Foam fill adds insulation to the multi-chambered construction.
Welded corners prevent air from leaking through the corners.
Insulated glass unit showing three panes of glass and two Super Spacers.

A well-designed vinyl double hung window is energy efficient, leaks very little air and is durable. Look for these six key components when window shopping.

  1. Interlocks: A well constructed window is designed so the sashes interlock with each other and the window frame. Good vinyl double hung window sashes do this by actually hooking into each other and the window frame. This generates a barrier that makes it more difficult for cold air to force its way past.
  2. Reinforced meeting rails: Reinforcement makes the window more durable and straight. This ensures longevity and keeps the sashes straight so they interlock nicely. The best reinforcement is non-metal. Soft-Lite’s non-metal K-Beam™, used in its Elements and Imperial LS windows, is five times stronger than steel and 700 times warmer than aluminum, greatly minimizing cold transfer. Soft-Lite also offers metal reinforcements for some of its window lines.
  3. Foam filled frame and sashes: Foam insulation greatly increases the energy efficiency of a window. Vinyl double hung windows have an advantage over wood and metal windows because of their multi-chambered construction. The most effective insulation, foam fill, can be injected into the chambers providing maximum insulation. Another product for insulating vinyl double hung windows is stick foam inserted into the chambers.
  4. Weather-stripping: The type of weather-stripping and the amount used greatly determines how much air the window will leak. The best weather-stripping holds its shape year after year. The best vinyl double hung window designs use multiple strips around the sashes which decreases air infiltration dramatically.
  5. Welded Corners: Air can leak through the corner joints of sashes and frames that are mechanically joined. Vinyl double hung windows by Soft-Lite are at an advantage because they have welded corner joints. The welded corners not only provide a clean finished look, they also provide total resistance against air infiltration through the corner joints.
  6. Insulated Glass: The number of glass panes, the type of spacer between the glass, the type of Low-e glass coating, and the type of gas fill all determine how energy efficient the glass unit will be. Soft-Lite vinyl double hung windows are offered in 23 different variations of insulated glass.

Learn more about Soft-Lite’s double hung window lines. Or, contact a vinyl window dealer near you.