Many intact males mark territory. MOST neutered males don't. And, as expected, there are exceptions on both sides of the argument.

But NOT getting him neutered is a sure-fire way to guarrentee the marking WON'T stop.

So, get him neutered, and the odds will be in your favor that the marking will stop AND you will be helping his health, calming his desire to mate (which leads to attempted escape), and totally preventing an accidental litter from being born.