How to Install Replacement Windows

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Window Replacement Options

You have two choices for vinyl replacement windows: full-frame windows and insert windows.

Full-Frame Replacement Windows

  • Replace the entire existing window down to the house frame
  • Necessary when existing window frames are old and deteriorating
  • More advanced project because you have to remove interior and exterior trims and sometimes the siding

Insert or Pocket Replacement Windows

  • Replace only the existing sashes with smaller windows that fit inside the existing frames
  • Existing frames must be in good condition
  • More DIY-friendly than full-frame replacements because your current trims and siding aren’t removed

This project gives you step-by-step instructions for how to replace a window insert or pocket window from the exterior of a house. Some replacement windows can be installed from the interior or exterior. Check the manufacturer’s documentation to get specific instructions for your windows.

How to Measure for Replacement Windows

  • Determine the height and width of the pocket opening using a tape measure.
  • Measure inside the existing frame rather than between the stops that hold the sashes in place (you’ll have to open the lower sash to get the measurement).
  • Measure the height at the left, middle and right of the window.
  • Measure the width at the top, middle and bottom.
  • Use the smallest height and width measurements when ordering your windows.
  • Don’t proceed until you have your new windows and have measured them all to make sure they’ll fit.

How to Remove the Old Window

There are different window designs, so the steps needed to remove yours may vary. Sometimes it’s best to remove the sashes from the inside, but for this project, it’ll be easier to remove the existing windows from the outside.


How to Install the New Window

Follow these detailed instructions on how to install replacement windows.


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