Windows Terms & Definitions

Fully Welded Construction

The outside frame members and the sash frames have been fusion welded.  It is generally accepted that this is a superior manufacturing method, as opposed to a mechanically fastened frame where the frame members are attached with metal screws.

Sloping Sill Design

The bottom frame member (sill) is sloped to allow rain and condensation to drain away from the bottom of the window frame.

Weep System

An internal drainage system built into the window frame to allow moisture to pass downward through the frame and exit to the outside.

Security Locks

These locks limit the travel of the sashes on double hung or slider windows.  The locks are manually engaged from the inside, so that the window cannot be forced opened from outside the building.  They provide some deterrent to a break-in, while allowing one of the sashes to be opened slightly for ventilation.

Foam Filled Frames

Empty internal frame spaces are filled with an insulating material, generally foam, to increase the overall thermal efficiency of the window frame.

Balance System

On double hung windows the balance system regulates the force needed to open and close the sashes.  A spring steel balance system is generally regarded as superior to one using pulleys and cables.

Interlocking sashes

On double hung and slider units the windows may have an interlock system where the sash frames engage along their interface and pull tightly together to lessen air leakage.  This is a common feature in higher quality window designs.

Glass Unit

The heart of the window, consisting of two or three panes of glass sandwiched together and sealed with butyl rubber.  A spacer separates the individual panes of glass, forming an air tight, insulated, chamber(s).  There are a number of spacer options available.  Stainless steel and composite (super spacer) are more energy efficient than the older tin or aluminum types.

Low-Emissivity Coatings with Argon or Krypton Gas

A Low-E coating is a near invisible metallic layer applied directly to the glass surface.  This coating performs as a heat reflector.  Argon is an inert, clear gas that adds insulating value to the window.  (Krypton gas may also be used, typically in high end, triple pane units.)   When these two items are combined in a window unit, they work together to reflect heat and insulate.  During the winter, internal (furnace) heat will be reflected back into the living area, during the summer, the sun’s rays are reflected back to the environment helping to keep your house cooler.

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