If you apply the Folder Redirection GPO (Group Policy Object) to redirect the users My Documents folder to a server share and do not change the default Grant the user exclusive rights to <folder> policy, only the user who owns the folder can access it.

If you redirect folders for multiple users to the same location so they all can view the contents, you must pre-create the folder before applying the the Folder Redirection policy and you must disable the Grant the user exclusive rights to <folder> policy setting to prevent users from creating the folder and becoming the owner.

See the following tips:

2852 » An Administrator can not access a user's redirected My Documents Folder?

3471 » How can I insure that administrators have access to a user's redirected folder?

9520 » After insuring that Administrators have Full Control of newly redirected user folders, how do I 'fix' existing redirected folders?