Since VAInstall automatically detects previous installations of a named application on the end-users machine, building upgrade packages is very easy.

Suppose you shipped an app named "Hello", version "1.0", using VAInstall. You now want your customers to upgrade to version "1.1", without re-installing the whole app.

You just have to build a package with VAInstall, containing only the files necessary for the upgrade, and with the same app-name "Hello" and the new version "1.1".

On the end-users machine, the installer will detect version "1.0" and propose an upgrade to "1.1". If the user accepts, the new files will be stored in "Hello"'s main directory, replacing existing files, and the entries in the Windows registry and the uninstall information will be updated to the new version of "Hello".