Depending on the part of the country you live in and the style house you own you may have either double-hung windows or single-hung windows. Theses two types of windows can look very similar if you don’t know what to look for, but knowing which you have is important.
The operation of the bottom sash is almost always guaranteed in sash windows, but in a single-hung window the top sash is stationary. It can be removed easily, but it is not designed to be operable like the bottom sash. In double-hungs both sash are operable.
You can read a little more on the history and working of a double-hung window in “Why Are There Double-Hung Windows”
Single-hung windows are more common in older homes (pre-1850s) and colder climates. While the double-hung was the king of the windows in warmer climates, the single-hung was a simple and effective option in northern portions of the country.
In a single-hung window the bottom sash functions much the same as a double-hung window, sliding up and down vertically in the jamb. Sometimes there is a rope and pulley balance system but more often single-hung windows use some different balance systems like spring bolts, sash hooks, tape balances, or other simple regional solutions to hold the sash in place when open.
Historic single-hung windows, while simpler than their double-hung cousins are more varied in their design and mechanics. They may look the same from the street, but often the working of the window will vary by age and region.
The easiest way to tell if you have a single-hung window is to look below the top sash on the exterior of the window. Double-hung windows will have a small space between the sash and the jamb allowing it to slide up and down. Sometimes that space is caulked or painted over making it difficult to see though.
Single-hung windows usually do not have that small space. They are supported by an, often removable, piece of wood trim set into the jamb below the sash to help hold it in place. Sometimes this piece of trim is not as easily removable and it is an integrated part of the jamb. You can see both options in the photos above.
Also, there is often no parting bead on single-hung windows.
Working With Single-Hung Windows
Single-hung windows are much the same as double-hung windows when it comes to repair, removal, and restoration. The bottom sash is held in place by a small piece of trim on the interior side called a stop.
Once the stop is removed the bottom sash can be raised above the stool and swung inward. Depending on the type of hardware being used to balance the bottom sash you may have to remove the hardware first if it is in the way or disconnect it from the side of the sash.
Once the bottom sash is out then often the top sash can be removed very simply (unless an overzealous painter has made you job more difficult).
In certain cases, you may see a simple stop block attached underneath the top sash. Don’t be fooled, this is usually a modification done to a double-hung window when the ropes on the top sash have broken and someone didn’t have the time or knowledge to replace the ropes. It’s a quick fix to keep the top sash from sagging down, NOT a sign that you have single-hung windows.
The repair and restoration of single-hung windows is exactly the same as with double-hung windows. The only real difference is the mechanics that you are dealing with. While they may be different and often times unique they are usually much simpler.
You can learn more about how to restore your windows on my resource page How To: Repair Old Windows.