When Apache writes new files (static content, like writing to the cache file) it creates this file without the proper permissions. There's no write permission for the group by default and this causes problems for us. Can we change the umask that apache starts with?
Apache inherits its umask from its parent, so simply set the umask in the script that starts Apache.
There's a similar question on StackOverflow that talks about this too, and they offer at least one OS-specific way of doing it, but the above is the general method.