Things You'll Need
Phillips-head drill bit
Exterior grade caulking
Vinyl windows are a popular choice for home builders as well as for homeowners who wish to upgrade their windows. Vinyl windows are available for new construction and include a nailing fin along the perimeter of the window frame for quick and easy installation to the building's framework. Replacement vinyl windows are also available to upgrade existing windows and do not include a nailing fin. Replacement windows are installed by fastening them to the window opening framework through the inside of the window frame.
Place the window into the rough frame opening, making sure the interior of the window is facing inward. Have a helper hold the window into place while you place a level on vertical jambs on both sides of the window frame to make sure it is plumb. Make sure the bubble in the level is centered between to the two lines. Use wood shims placed in between the window frame and the rough frame opening to get the correct reading on the level, if necessary.
Place the level horizontally on the window sill to make sure it is level. Slide wood shims in between the sill and the bottom of the rough opening to make the window sill level, if necessary.
Measure the window diagonally with a measuring tape to make sure the window is square. Make sure the diagonal measurements are equal. Place shims between the window frame and the rough opening where needed.
Place the window in the rough opening once the window is plumb, level, and square, using the installation screws that came with your window. Place the screws at the pre-drilled holes on the inside of the window frame and drive them in with a Phillips-head bit installed in an electric drill in a clockwise direction. Do not overtighten the screws or the window frame could become deformed.
Test the window sash to make sure it is not binding. Use a level and recheck the window to make sure it is plumb, level and square. Caulk around the outside of the window frame with an exterior grade of caulking.
To measure your window opening for a new replacement window, measure across the opening at the top, center, and bottom of the opening. Use the smallest of these measurements to get the width of your new window. Measure the opening from top to bottom in the same fashion to get the height of your new window.