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A window sash is truly the sum of its parts.
If all of the pieces of a window sash were disassembled, it would probably be unrecognizable.
Older windows can be disassembled, but newer windows increasingly come with parts that are factory-built and sealed.
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PVC window frames are welded together.
Grilles are sealed behind glass.
What Is a Window Sash?
Glass
Two sheets of glass comprise a double-paned window.
Sometimes this is called glazing, as in double-glazed window or triple glazed window.
Single-paned windows are less common than in years past, with double-paned windows being more the norm.
Insulated Glass Unit (IGU)
The insulated glass unit is the heart of the modern window.
The window frame and peripheral items are not included with an IGU.
Older, single-pane windows may have true mullions, in which panes are separated by wood.
Newer double-pane windows may have a mullion look.
GBGs provide aesthetic appeal and allow for easier cleaning of the glass.
Gaskets
Glass must be sealed into the framework.
Gaskets made of rubber or TPVs (thermoplastic vulcanizates) serve this purpose.
Single-pane windows have no gas.
Seals allow for equalization of gas and outside pressure.
IGUs come with the gas already inside.
The lower window sash has the capacity toslide up and downuntil it is nearly parallel with the upper sash.
In this case, it may be referred to as a single-hung window.
Newer double-hung windows, though, tend to have upper sashes that move up and down.
However, modern single-hung windows are readily available.
An open upper sash is too high for most children to reach.
Care must be taken with casement windows when they are open.
A high wind can move casement window sashes and break them off.
Window Fogging and Leakage
Double-glazed IGUs often come with one problem: fogging.
Fogging is the result of improperly installed gaskets or gaskets that have deteriorated over the years.
Impaired seals allow gas to escape, greatly impacting the window’s insulating properties.
As condensation builds between the glass panes, light and views are obscured.
Window defogging is not a common practice, since the procedure often does not last for long.
This avoids the cost and mess of total window replacement.
