Single Hung vs Double Hung
A very confusing term for some, and even more difficult choice for others. We should start with the definitions first. The majority of all functional windows have 2 sections. Traditionally (in the US), a top and bottom glass unit. A single hung is reference to the single sliding part of the window, (aka the sash) which is usually the bottom section of the window. The second part of the window is fixed, and does not possess any movement or operation. Operation of the sash, consists of unlocking and lifting; while the spring assist holds the section open until pushed close. Most vinyl windows will even have a tilt action to access the screen which also makes cleaning the exterior easier. Sliding windows also fit in this category, and have rollers instead of springs mechanics.
A double hung refers to windows in which both sections are operable sashes. These sashes work independently from each other, but both must be fully closed to lock the window. Double hung windows are not new, but they have recently been marketed heavily by companies looking to be creative and different. Lets do some comparisons of the benefits of each, to help make an informed decision in determining your preference.
What is the benefit to a homeowner for a double hung? According to the salesmen pushing them, they are easier to clean! This can be true, especially for upstairs windows, allowing you to tilt both sashes inward to clean without the need for a ladder. But, there are several exceptions to this, which we will discuss in a moment. Another selling point is the option to vent from the top or bottom utilizing the vent stops which is a handy feature for some.
What is the benefit to a homeowner for a single hung? Single hung windows are more efficient, in 2 different ways. The first is air penetration. The most efficient part of the window, will always be the fixed part that is sealed tight. The operational section relies on layers of weatherstripping to reduce the air, but more operational glass will equal more air penetration. The second is the insulation value of the window, which can be measured by U-factor rating. Most double hung windows will have a slightly higher U-factor than their single hung counterpart. Another important benefit to discuss is glass. Most window brands will have more glass on the top fixed section of a single hung, than the double hung counterpart. The extra thickness of the top sash actually takes away some of the glass.
So, are you still considering double hungs? Double check for some of these common issues you may not have been told.
1.They often don't work correctly with plantation shutters. The tilt function is often moot and unusable because the frame of your interior shutters are too thick.
2. Size matters. Big/ tall windows can make it very difficult, (if not impossible) to tilt the top sash. Its just not always practical, or safe!
3. Shapes. If you have any windows that are curved on top, they will need to be a separate window above a double hung. Not only will this cost more, but it will result in a bulky mullion that can be quite the eyesore.
So, what is the real benefit to a double hung, and why are they so popular? The easy answer is this; they are easier to install initially and then service for warranties. With the exception of triple panes, double hungs are not the one size fits all window option. They are a nice option when practical, but unless everything has been explained in detail, they could potentially be more of a hassle for the homeowner later.