How to Install a Double Hung Sash Window

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Installing a double-hung sash window is a great way to spruce up the exterior look of your home while also improving its overall energy efficiency. Despite what many people would commonly think, there really isn’t much to installing one of these windows. All you’ll need to get started is the following tools and materials:

Remove the Old Window

To remove the old window you must first remove the interior molding to expose the framing of the rough opening. Using the pry bar and hammer, carefully remove the window and clean up any loose debris. Check to make sure the framing is secure, tight, and plumb which will be important when installing the new double-hung sash window.

Install the New Window

Before installing the double-hung sash window you’ll need to install a moisture barrier around the rough opening. Use a staple gun or tack hammer to fasten the material to the framing taking care not to leave any wrinkles or tears. Next, remove the inside stops of the window and place a couple of wood shims along the bottom sill of the framing to act as spacers. Then lift the window into place and use more shims as spacers for the jambs and header. Depending on the size of the window, you may need a hand to lift it into place. If the window is located on the ground level, it helps to have one set of hands on the inside and one set of hands-on on the outside.

Use a 2-foot level to check each jamb, header, and sill is plumb and level by adjusting and adding any of the shims as necessary. You’ll also want to keep the space between the window and the rough opening as even as possible all the way around the double-hung sash window. This will make it easier to install the window casing later. Once you’re satisfied everything looks level and even, use the cordless drill and 3-inch screws to fasten the window in place. Make sure you align the shims with the fasteners openings beneath the window stop to ensure a secure and sturdy installation. Once the window is securely fastened, replace the stops along the jamb to complete the installation.

Step 3 - Finish the New Window

Once the double-hung sash window is in place fill in the gap between the window and rough opening with an expandable foam material. This will prevent drafts along with the window frame while also helping to keep the window snug and in place.

Next, finish off the interior of the window by installing casing molding. You can cut any excess foam that protrudes past the finished wall with a utility knife. This will ensure a flat surface for installing the window casing.