[gemy]

You are correct at 18months old, neutering will do nothing to stop marking - well at least not very likely.


Get an enclosed area for him, and yes continue working very frequently taking him out every 2hrs of so to go pee, and likely he will mark as well. You do know the difference between pee and marking? Yes.


The other thing you can do, and it can be a pain for you, is when he is free, you tether him to you and he goes where you go, this hopefully allows you to see and correct or interfere with him "marking" or peeing inside.


If all else fails you can diaper him when he is free in your home. Also the places he has marked needs a good cleaning with an enzymatic cleaner.