How to Install New Windows

Before you pick up that measuring tape, you'll need to decide if new windows are in order. See more home construction pictures.
Before you pick up that measuring tape, you'll need to decide if new windows are in order. See more home construction pictures.
Geri Lavrov/Photographer's Choice/Getty Images

As far as home improvement projects go, a lot of experts will cheerfully tell you that installing windows is as easy as hammering a few nails. And in some ways, it's true; the actual installation of windows can be pretty much a matter of fitting a square peg in a square hole. But installing the windows turns out to be only a small part of the process. Consider, for instance, what goes into even deciding new windows are needed in the first place.

First, there's the almighty dollar. Replacement windows can run from around $150 to $300. You might think that, hey, as long as that window isn't broken and dim outlines can still be seen out of it, there's no reason for a replacement. But keep in mind that upgraded windows might actually save you money long-term.


For one, if you're buying the right window, you're saving money on energy. Windows are notorious for leaking heat out of a house at an alarming rate. To address this problem, the U.S. government has instituted an energy-performance rating system for windows. This rating tells you a few things: how much heat is collected or released depending on the season, how tight air leakage is and how it scores on overall energy efficiency [source: Energy Savers]. Check out guidelines on the Energy Savers Web site to see what numbers work for you, but you'll save yourself money in the long run by buying energy-efficient replacements.

Replacing those old, decrepit windows isn't just sparing you the embarrassment of looking like Boo Radley occupies your home. It's also a great way to increase the value of your place with a tiny home improvement project that can drastically change the outer appearance of a house. And then there's simply the fact that old windows are old: They crack more easily, they discolor, and you'll probably have to replace them anyway.

So now that we've discussed why those windows need replacing, let's peek through the glass to see what kind of windows we should be using as replacements.


A Window Into Windows

You probably recognize casement windows, which are hinged at the sides of the window frame.
You probably recognize casement windows, which are hinged at the sides of the window frame.
Dorling Kindersley RF/Thinkstock

Before you install your windows, you better be darn well sure you're going with the ones you both want and need. As we said before, windows are oftentimes the most inviting, interesting characteristics on your house's exterior. Don't choose something you won't find aesthetically pleasing to look out of or at for a whole lot of years.

But let's get into what kind of decisions you need to make when installing windows. When shopping for replacement windows, you'll find that you have several (seemingly thousands) to choose from, all of which have names that aren't entirely descriptive.


Casement, hopper, single- and double-hung: These are fancy names that list operating types and basically describe how the windows open or hinge. While the choices are mostly aesthetic, you'll want to make sure your choice fits in the frame you have. Keep in mind that some are better than others at energy savings; a window with any kind of sliding action will most likely be less tight against a frame, to account for the gliding motion [source: Energy Savers].

Another decision you'll have to make is whether you'd like vinyl or wood frames. And while it's a matter of taste, you'll also want to know the pros and cons. Vinyl windows don't require ongoing maintenance and are generally less expensive. Wood, on the other hand, can be painted or stained, and many prefer it to keep windows from looking mismatched to the house [source: American Vision].

You'll also need to determine what kind of windowpane you'll be staring out of (or into). Of course, we all picture glass when we think of windows in the home. But acrylic (or Plexiglas) has become a popular option. Acrylic windows are generally lighter and don't shatter as easily as glass. However, double-paned glass insulates just as well as acrylic and doesn't scratch nearly as easily.

Now that we have our windows ready to go, let's pull the blinds on the next page, where we'll learn how to get those suckers into place.


Windows for Home

Unless you're dealing with full-frame windows, replacing an old window with a new one is relatively straightforward.
Unless you're dealing with full-frame windows, replacing an old window with a new one is relatively straightforward.
Dorling Kindersley RF/Thinkstock

Before we go through our replacement steps, let's be clear that we're talking about an insert or pocket window; it's a fully assembled window that can fit in existing jambs (the vertical part of the window frame). There are a couple other options. Sash kits give an old frame new sashes (the frame that holds the pane in place) and jamb liners along with the window. And full-frame windows have a complete frame and new sashes, jambs, liners and sill.

Full-frame windows are their own beast. They're essentially the same as installing new construction windows, in the sense that you're removing everything down to the rough opening and replacing every part of the window -- frame, jambs and sills. It's the only option if the window frame is rotted or compromised.


The sash kits aren't much more difficult than the replacement, except instead of keeping old sashes and jambs intact, you'll be switching them out for new ones. That means that along with removing sashes and stops, you're taking out the jambs, installing new ones and then basically following the insert steps below to put in your new window:

  1. When you're installing a window, it's the measurements that will either make the project a snap or leave you in an angry stupor of home-improvement rage. From inside your house, measure from jamb to jamb at the bottom, middle and top of the window. Use the smallest measurement; that will be your width. Measure vertically from the sill to the head jamb (the horizontal part across the top) left, center and right. Use the shortest measurement for your length.
  2. Because you're replacing a window and not getting an entirely new frame, we're just removing the sashes. To do that, remove the inside stops; these are what we laypeople think of as the inside trim. Keep 'em in good shape; you'll be using them after you replace the window.
  3. Remove the lower sash; that means you're basically taking the lower part of the window out. You'll probably need to slide it up a little and then tilt it out. Now lower the upper sash a bit and tilt that one out as well. (Don't remove any of the outside stops.)
  4. Now you can tilt the bottom of the window into the jamb; secure it so it fits snugly. Some recommend putting a small beading of caulk around the inside stops on the jamb to create a nice seal. Either way, you can now screw the window into place through the existing holes. Replace the inside stops by hammering them in as they were before. Now go outside and apply a line of caulk between the stop and the window for a good seal.

And you've done it! Your replacement window is set.


Author's Note

Home improvement projects are tough enough; wading through the myriad ways they can be done to find the way they should be done is a challenge in itself. Remember that these are just rough guidelines; it's always a good idea to check with the window manufacturer's Web site to see if there's anything particular that will help the process of installation go smoothly. Ask a salesperson where you're buying your windows for any tips they know about particular brands or designs as well.

Related Articles


  • American Vision Windows. "Vinyl vs. Wood Windows." 2012. (May 3, 2012)
  • Energy Savers. "Window Operating Types." U.S. Department of Energy. Feb. 9, 2011. (May 3, 2012)
  • Fisher, Kathleen. "Window Shopping." Old House Journal. 2007. (May 3, 2012)
  • Fratzel, Todd. "How to Install Replacement Windows." Home Construction and Improvement. 2012. (May 3, 2012)
  • Hydrosight. "Comparison of Plexiglas and Mineral Glass." Dec. 31, 2011. (May 3, 2012)
  • Lowes. "How to Install a Replacement Window." 2012. (May 3, 2012)
  • "Top Ten Reasons to Buy Replacement Windows." May 24, 2011. (May 3, 2012)
  • Remodeling San Antonio. "Do I need new windows?" Oct. 15, 2010. (May 3, 2012)
  • Truini, Josepth. "How to Install Replacement Windows." This Old House Magazine. 2012. (May 3, 2012),,20171587,00.html