You may want to replace a window if the glass has been damaged, you’re remodeling a room, or you want to upgrade your energy efficiency as well as your style by getting rid of those drafty single panes that are losing you money. When replacing a window, you can remove and replace the entire window down to the house frame. This method is best if the existing frame is damaged or deteriorating, but requires construction skills and know-how and will take more time and money. An easier and less expensive option is to install an insert replacement window into the existing frame. Insert replacements are only an option if your window frame is in good condition without rot or damage.

When replacing an entire window, first you’ll carefully remove the existing window with a pry bar and other tools. Next, you’ll make any repairs and adjustments needed to the existing frame or header and studs to ensure that the space is perfectly plumb and square, so the new window will sit perfectly within the space. Next, install the new window from the exterior, securing it into place. You’ll need to precisely wrap and insulate the window to ensure it doesn’t leak. Then, install the interior casing and exterior trim (as needed). If you prefer to hire a professional to install a window, consider replacing more than one window at a time, as the pro can work more efficiently.

To prepare your house for the installation of new replacement windows, start by clearing a path and the area around the window. Take down any window treatments like blinds or curtains, and cover your furniture to protect it from dust. And make sure the window replacement crew will have access to your house.

Before the window installation service arrives at your home, ask them if there are other preparation steps you should take.

It can take less than an hour to install a new window in a house, and you might be able to install all your windows in less than a day. However, this is assuming ideal conditions and that the previous window is already removed. Factors that may add to this timeframe include larger or more complex windows like bay windows or sidelights, as well as windows being installed in hard-to-reach places.

It is possible to install windows while it’s raining, and some professionals may perform the job in the rain. But keep in mind that if the rain is falling especially hard, it could cause moisture to enter the house. And, it’s not safe to work in strong winds or thunderstorms. Some technicians may also not install multi-story windows when it’s wet. Applying caulk can also become less effective if things are very wet.

The cost to replace a window can vary depending on factors such as window size, type of glass, brand of window, necessary trim repair, and any construction work required for installation. Labor rates and cost to do business in your region will also affect the cost. The national average window installation cost is $2,650 per project. Here are some examples of average trim repair and window replacement costs:

• Trim repair:
• Line and case a window frame with an MDF product: $400.
• Line and case a window frame with raw hemlock wood: $500.
• Approximate cost to install five windows at one time: $3,000.
• Approximate cost to install one double-hung, energy-efficient 3-foot by 4-foot window: $500-$550.
• For the same window size (3-foot by 4-foot) from a different manufacturer made with a specialty fiberglass exterior and all-wood interior, the cost could go up to $1,500.
• Pricing can go as high as $5,000 for a bay or bow window with specialty glass and framing.
• These examples include removal and disposal of old materials and window.

Choosing custom windows will increase your window installation cost but will provide you with exactly what you want. The average national cost for window installation is $2,650. Your custom window costs will vary based on several factors. The first factor is the type of frame you want. The four most common types of frames are vinyl, fiberglass, aluminum and wood. Wood is typically the most expensive option, followed by aluminum. The type of glass you select will also affect cost. There are single-, double- and triple-pane windows. Most double- and triple-pane windows have gas sealed between the panes that act as insulation. Windows typically cost more the more energy-efficient they are, though this efficiency can save you money on utility bills in the long run. The type of glass used can also affect cost. There are different grades of glass — high-performance glass, low-e coated glass, and more — which all provide you with better insulation. In addition, the number of unified inches (window height x window width) you need will affect cost. The cost of custom windows will also be affected by installation cost and whether any repair or construction work is required to properly fit the new window.