When installing and deploying Office Web Apps 2013 to a security hardened drive, Office Web Apps may not work correctly if there are permissions missing from the security hardened drive, including (but not limited to) Office Web Apps cache locations (for locations see https://technet.microsoft.com/en-us/library/jj219442.aspx). The default location on most systems is the C drive, but some customers may install to non-system drives (such as a D drive, E drive, etc) and permissions may be stripped from those drives.
The Office Web Apps 2013 installer allows you to choose a path where the code will be installed, and non-system drives are supported. Also some of our configuration settings (such as CacheLocation) default to using the system drive, those can be overridden using the New-OfficeWebAppsFarm or Set-OfficeWebAppsFarm cmdlets. The Office Web Apps installation will still need to put a few small files in the %PROGRAMDATA% folder, which is typically on the system drive.
When deploying Office Web Apps 2013 to a hard drive that is security hardened (permissions are removed), the following permissions need to be present on the installation folders:
The “CREATOR OWNER” & “SERVERNAME\users” need permissions to the install location on the non-system drive:
Deploy Office Web Apps Server