Window and door installations vary greatly depending upon the age and style of the home as well as the products being installed. There are many ways of taking out an old window or door and installing a new one, but there are only a few ways that will hold up over time. It is critically important that the exterior integrity of the home is maintained throughout the installation process. The best products will perform poorly and fail over time without proper installation.

Generally speaking, if the old window has a nail fin then the new window should have one too. Installing the new window with the fin is just the beginning. The new window must be properly integrated into the wall structure utilizing multiple sealing layers. A weatherboard system of layering is used during the installation process, which ensures that the harsh winter rains will not be able to penetrate into the walls.

A few of the steps are illustrated below.

Siding is cut out around the old window exposing the nail fin.

Old window is removed completely and the opening is cleaned.

Interior surrounds are cut back to allow new window to fit properly
and sealant is applied behind the nail fin.

New window is installed level, plumb and square.
Flexible flashing is installed over the nail fin in a weatherboard fashion.

Exterior trim is installed prior to final finish caulking
and cleaning of the new window.

Many older homes with wood windows will be installed using the slope sill box frame method of installation. This method entails removing the movable sash of the old windows and installing the new window within the existing frame of the old window.

Removing the interior stop
to enable removal of bottom sash.

Removing bottom sash
after disconnecting weights.

Taking out parting bead which
allows top sash to be removed.

Back bed of caulking after sash
is removed and opening cleaned.

Installation of new window
working around obstacles.

Final finish caulking on interior and exterior.