Vinyl windows are a popular option for most homeowners today. They’re durable, affordable, and easy to install. If you’re looking to install vinyl windows in your next building project, here are the key steps you need to know to get started.

Window Installation Glossary

Just in case you’re not familiar with the window installation process, here’s a quick guide to some of the technical terms we’ll use in this how-to:

  • Frame — The framework that surrounds and supports the entire window system. Nailing fins are attached to the frame of the window.
  • Sill — Bottom horizontal frame of the window.
  • Jamb — The vertical sides of a window.
  • Sash — Moveable part of the window (makes the window go up and down).
  • Nailing fin — An independent accessory that attaches to a window jamb to help ensure window is installed properly, and will resist bowing and warping over time. Also called nail fin.

How to Install a Vinyl Window with Integral Nailing Fin

One of the most important aspects of any window installation is ensuring that the window is plumb, flush, and square before you secure it to the window opening. Because vinyl expands and contracts as temperatures fluctuate, it’s imperative that the window and window opening are square, so that as the window shifts, you don’t end up with any gaps that can let water or cold air in. With that in mind, let’s get started:

1. Start with the window opening. Ensure that the window opening is level, house wrap extends all the way to the opening, and the sill pan flashing is installed. Each of these preliminary steps help ensure the window is adequately weatherproofed.

2. Caulk nailing fins. In this video, we’re installing a window that has an integral nail fin. This fin helps to ensure the window stays plumb, square, and level, and works to prevent bowing and warping over time.

  • When installing a window with integral nail fins, apply a bead of caulk to the back of each fin before setting the window into the opening.
  • This will add an additional layer of weather protection, and will help the window better adhere to the opening.

3. Lift window, and install sill (bottom of window) first. The rest of the window should slide into place.

4. Ensure that the window sill and jambs are level.

  • Open the bottom window sash and set level on the window sill. Install wood or horseshoe shims under the sill to level the window in the opening horizontally.
  • When the window is level horizontally, use a level to ensure that the jambs are also straight and not bowing. You may need to install shims where the sash meets the jambs in the middle of the window.

5. Secure window. When the window is plumb, level, and square, you may begin securing the window to the opening by nailing 1 ½” galvanized nails through the pre-punched holes in the nail fins.

  • Notice that the pre-punched holes are oblong – this is to allow the window to shift slightly as vinyl expands and contracts with temperature fluctuations.
  • Ensure that you have secured the window using every pre-punched hole in the nail fins.

6. Ensure window opens, closes, and locks. When the window is installed and secured, check for functionality by opening and closing both sashes, and ensure that the sash lock functions properly.

7. Your window is installed — now you simply need to install flashing over the nail fins, and you’re ready to move on to the next window!

We hope these instructions are a helpful companion to the step-by-step video we’ve included. For additional vinyl window installation instructions like cutting in a window with housewrap or flashing a vinyl window, head to the Zeeland Lumber & Supply YouTube channel for more in-depth video how-tos.

And if you’re ready to get started installing your vinyl windows, we’ve got the brands you’re looking for, and the accessories and materials you need to install them. Visit Zeeland Lumber & Supply to view our vast selection!

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