Window Installation Process

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Whether you are installing a replacement window or installing a window into a new construction, the window installation process can be a DIY project that requires a little labor (1 day) and some of the following tools: hammer, drill, caulk, measuring tape, shims, pry bar, utility knife, chisel, square, screwdriver, a level, and the new window.

In replacing a window, first take the measurements of the existing window and frame so that you can buy a new window to fit properly.  The frame that actually holds the window pane is called the sash.  The frame or sash opening should be about ¼ to 3/8 larger than the exterior dimensions.

Properly fitted windows allow a homeowner to save on utility bills, throughout the four seasons.

Windows help to protect us from harmful UV rays, they keep heat in, add value to a home, and provide a nicer living experience.

A sash or frame can be made of metal, plastic, or wood. The top and bottom part of the sash are referred to as the rails, and its sides are called stiles.

Installing a window will require at least two people, protective goggles and gloves. Begin by taking the right measurements of the inside jambs, the top, bottom, and middle of the window.

If you are removing an old window, remove the sashes, followed by removing the interior and exterior casing.  Remove the nails that hold the old window to the jamb, then carefully remove the window so that the glass does not break.  Scrape off any loose paint, fill in holes or cracks with putty, then sand the jambs and paint the surface.

Simply replacing a window is easier, because an existing frame is available.  But if you are installing a new window, then you must find the wall studs to frame the window for a perfect fit.

Inspect the frame to ensure that the condition of the jamb is good because if it isn’t, then you must replace or repair the damaged areas. If there are any gaps between the original window and the wall studs, this is an excellent time to place fiberglass or foam insulation into the gaps.

You are almost ready to place the new window into place, but first you must apply some caulk, preferably “elastomeric or silicon.” Apply two beads of caulk to the inner face of the exterior casing, or to the top and sides of the frame to prevent moisture from seeping in.

You are now working on the interior of the building, where you will take the window and press it tightly against the exterior casings or blind stops. While holding the window in place, drive one 2” screw through the upper side jamb and the frame. Drive the screw in loosely so that the window can open and close properly.

Plumb and level the window from corner to corner because both corners should measure up the same. Screw the window in place with the nails; it should take at least three nails along the vertical sides of the window.  

The final step is to re-install the stops or if needed, add new stops. Use a primer with paint and paint the exterior frame and the interior of the window sash and frame.