Jim,

"Double hung" windows have two movable sashes. Each sash
moves vertically, traveling in its own track. For this reason, the
units are also referred to as "double track" windows. Both sashes
travel independent of one another and both should travel the entire
vertical length of the frame.

Generally, a single hung window will look very much like a
double hung window, but the top sash is stationary and just
the lower sash moves up and down.

It should be noted that many, many double hung windows are
accidentally "converted" into single hung units by inexperienced
amateur painters who paint the upper sashes shut. The previous
owners of my house did that to every window in the house.

If you have double hung windows which have been painted shut
on both the inside and the outside, figure on taking about one
hour per window to free the upper sash without damaging the sash,
the frame or the glass. Some spot priming and painting may
be necessary also. Small first floor windows may go quicker;
large and/or second floor windows may take longer, especially
if you keep dropping tools while up on the ladder.

Gideon

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JimL wrote in message ...
single hung vs double hung....

Please explain.