By Gene and Katie Hamilton
Before You Begin
To measure the opening correctly decide how you want the storm window installed. One way is to mount the window to the blind stop, which is inside the window opening, the other is to overlap the window's flange to the trim board of the window. If you choose to use the overlapping method make sure you have the clearance necessary to bring the storm window sash through the interior after it is mounted. If that's not possible, you won't be able to remove the storms sash. Get specific measuring directions from the window supplier.
If necessary, make any repairs or paint the window frame and sashes before installing the storm window.
Step 1 : Prep the window jamb
Once you have measured the openings and have purchased your storm windows, you are ready to begin the actual installation. Start by cleaning off the blind stop. Then mount the new storm window using a screw at the top, center section. This will allow the window to actually center itself. Once the window is centered into the opening, you can fasten in the remainder of the screws.
Step 2 : Install the window
You can caulk the window either before placing it into the opening or after. However, be sure to caulk only the top and sides of the window - never caulk the bottom! This will allow any water that may get between the storm window and the window to weep to the outside and help with condensation between the units.
Finally adjust the sill expander (located at the bottom of the window) by sliding it down. Once the expander is in plane with the windowsill, insert a screw through the expander into the flange to hold it in place.