How to Install a Replacement Window

Installing windows is a task where "one size fits all" does not fit "at all." That isn't to say that there aren't some basic fundamental approaches, because certainly there are. Each window's applications, while not being entirely unique to the individual structure, do have their own characteristics. This article will therefore approach the project of installing replacement windows from a hypothetical point of view while sticking with the fundamental approaches mentioned above.

After you have measured your replacement window space and picked up a suitable replacement unit, you are ready to begin installation.

Some tools and equipment for the job:

Flat End Pry Bar
Reciprocating Saw with Hacksaw Blade (hand hack will also suffice)
Electric Screwdriver (hand screwdriver will also work)
Expanding Foam (aerosol product of your choice)
Wood Shims (packaged and available at any home improvement store)
Putty Knife
Razor Knife
Outdoor Weather Sealant (caulk gun and outdoor caulking compound of your choice)
Measuring Tape
Safety Goggles

Instructions for Installing Replacement Window:

1. Determine whether glass from old window will be saved. If it is desirable, use your razor knife and your putty knife to break away any old putty left on the window frame (this step would be encountered on older style windows only). Sometimes it is a good idea to perform this step to avoid any accidental cracking or breaking of glass during the removal process.

2. If the old window frame is to be completely replaced, remove outer trim using flat pry bar with care so as to not disturb wall areas surrounding window.

3. Once outer trim has been removed, remove the trim from the inside of the window.

4. With your reciprocating saw with hack blade (or hand hack), draw saw blade down from the top between the window frame and the wall stud. This serves to separate horizontal nailing that secures window to studs. Often it is difficult over the years to determine the location of all of these nails. Careful use of a hack saw gets the job done quickly, smoothly, and safely. It's always wise to provide support outside for the window frame. This is another good reason to have the glass removed prior to this step.

5. Once the old window frame has been removed and the inner support spars and studs have been cleaned, it is time to insert the new window. Prior to installing, be certain that an adequate amount of weather adhesive has been placed on the inside flange of the new window sill.

6. When window is in place and centered, take up any slack on either side with wood shims. Wedge the shims in tightly in several locations applying equal pressure from each side and top and bottom as necessary. Shims can be broken off at this point so that they protrude no further than the wall studs.

7. Using aerosol foam, fill any and all voids surrounding window frame between shims, top and bottom if necessary. This foam generally sets up in a short time, and when it does use your razor knife to trim dried foam so it, like the shims, does not protrude further out than the wall studs.

8. Having accomplished this and having anchored the new replacement window according to its specific directions (which will be included when the window is purchased; some window warranties require installers to use only their provided hardware), it's time for the inner trim.

9. Trimming the interior is basically installing window manufacturer's included sills. These should be weather-proofed as well. If walls have moisture barrier installed (many newer houses do) and if this barrier was compromised during window installation, be sure that it is repaired and sealed well around window.

I hope that this article has been helpful. It is, as mentioned, a basic approach. Your individual window installation experience may differ. A close assessment of size and the structure is imperative. Best of luck!