Home Improvement Ideas Windows Window Repairs & How-To How to Install a Window Update your home's style or function and increase its energy efficiency with our tutorial for installing windows. By Kamron Sanders Published on June 5, 2023 Trending Videos Close this video player Photo: Cameron Sadeghpour Project Overview Working Time: 6 hours Total Time: 12 hours Skill Level: Intermediate Estimated Cost: $80 to $2,000 Whether you're looking to update your window's style and function or simply want to increase your home's energy efficiency, there are a number of reasons you may be looking to learn how to install a window. Like many home projects, window replacement can be done in a DIY capacity and doesn't necessarily require a contractor to be done right. Get to know the process of replacing a window below to see if it's a project for you. What You Need to Know About Window Replacement Costs Before You Begin Not all replacement windows are created equally, and the window installation process will differ depending on your chosen type. The two types of windows are new-construction windows and remodel windows. What Is a New-Construction Window? As the name suggests, new-construction windows are intended for use in new construction. They feature a flange for fastening the window to a framed rough opening that hasn't yet been covered by drywall, trim, or siding. What Is a Remodel Window? Remodel windows are designed to fit inside the hole left behind by a previously installed window. This design makes remodel windows much quicker and easier to install as replacements than new-construction windows, but the tradeoff is a smaller glass surface because the frame is designed to fit inside of the finished opening. How to Choose the Right Replacement Window When it comes time to decide between new-construction windows vs. remodel windows for your replacement window project, we suggest choosing remodel windows. Installing new-construction windows will likely require you to remove much more material, which will drastically increase the length of the project. While you may gain a slightly larger window, it simply isn't worth the added time. However, if your existing window frame is in poor shape, it may make more sense to reframe the entire window opening and install new-construction windows. What You Need to Know About Window Replacement Costs What You'll Need Equipment / Tools Measuring tape Pencil Flat bar Drill Drill bits Utility knife Level Caulk gun Painting supplies Oscillating multitool (optional) Materials Replacement window Shims Expanding foam for windows and doors Loose fiberglass insulation Window caulk Flashing tape Stop moulding Painter's caulk Interior paint Finish nails 3" Wood screws Instructions How to Install a Window Follow the steps below to replace old, dated windows with energy-efficient replacement windows. The process for removing windows will vary and you should adjust the steps below to suit your window. When in doubt, refer to the manufacturer's instructions for your specific replacement window for installation. Measure the Opening Measure the height of your window frame in multiple places including the edges and the middle and record the measurements. Repeat this process to measure the width. Make sure you measure the full height of the frame, past the stop moulding that surrounds the window. Purchase Replacement Window Purchase the replacement windows before tearing out the existing window to ensure you can promptly close up the opening. Use the shortest recorded measurement of both the width and height for your final dimensions when choosing a replacement window. To ensure your replacement window fits in your existing opening, choose a window that's 1/2 to 3/4 inch smaller than the dimensions of your opening. Remove Existing Window Follow this process to remove your existing window, breaking the seal of the paint and caulk with a utility knife to make removing trim easy. Start by removing the interior stop moulding, supporting the window as you go to ensure it doesn't fall out of the opening. If done so carefully, you'll likely be able to reuse it.Remove the sashes from the frame.Remove the fasteners holding the frame to the opening.Remove the frame from the opening.Remove any fasteners and shims left in the opening. Older windows may have additional hardware to hold the sashes and control their movement, including metal channels, weights, and balance lines. Carefully remove these and fill any voids left behind with loose fiber insulation. Prep the Window Frame To prepare the opening for the new window frame, clean the opening and replace any damaged or removed insulation. Fill any holes in the surface and replace any damaged materials. Inspect the exterior stop moulding, also called the blind stop, to ensure it isn't damaged. Replace if necessary. Apply flashing tape along the length of the sill, ensuring it extends up the inside of the lower exterior stop moulding. Dry-Fit the Window Place the new window inside the opening and hold it in the center using shims. Manipulate the shims to ensure the window sits level and plumb. Once the window is perfectly positioned, mark the placement of the shims by numbering the shims and writing corresponding numbers in each spot on the frame. If not installed both level and plumb, the window will not open and close properly after installation. Install the Window: Caulk and Place Follow the steps below to install the replacement window. Remove the window and apply a bead of exterior window caulk along the blind stop. Press the window tightly against the caulk to create a seal. Install the Window: Replace Shims Replace the shims, checking the window once more to ensure it sits level and plumb, centered in the opening. Adjust the shims if necessary. Drive screws through the pre-drilled holes in the window frame into the framed opening, installing shims at each pre-drilled hole to account for any gaps present. Cut off the excess shims with an oscillating multitool or utility knife. Install the Window: Check for Plumb Check the window for plumb and level once more and adjust if necessary. Install the Window: Add Insulation Stuff fiberglass insulation or spray expanding foam for windows and doors inside the cracks between the window frame and the framed opening and cut off the excess using a utility knife. Reinstall the interior stop moulding with finish nails. Install and Paint Window Trim Caulk around the window and the moulding, then allow the caulk to dry according to the manufacturer's instructions. Once dry, paint the moulding.