How to stop squirrels from chewing on wood trim.

On my Allen home I replaced some wood trim that had been eaten by squirrels to find that they only came back to eat some more.  This time, our Mr. Fixit Fast Handyman suggested that we use cement board instead of wood to solve the problem.  It looks just like wood when painted and the squirrels stay away because they cannot bite it since it is so hard.  Problem solved!