when you say local file, do you mean one local to the client PC, or on the actual server but not in the wwwroot ?
If you mean the latter you might want to try readfile('filepath'); (if the files aren't html, you would need to send the correct Content-Type headers , so for a word file use:
header('Content-Type: application/msword');
header('Content-Disposition: filename="'.$filename.'"');readfile($fullfilepath);