@mbr77 said in Peeing in the house. Please help!:
if I leave a package or something else there, he will pee on it, like he doesn't like there to be any clutter.
O.K. that gives you an opportunity to "set him up" so you are able to correct his behaviour. Deliberately leave something there, be nonchalant but keep an eye on him, and if possible catch him in the act. This sounds to me like some sort of territorial response.
For what it's worth, I have never bought into the theory that you actually do have to catch them in the act to correct behaviour. I base my opinion on having trained two farm dogs not to defecate or urinate in my barn, despite never having caught either of them "in the act". Expressing my disgust in no uncertain terms upon finding the evidence resulted in the behaviour ceasing in short order. One of my barn trained dogs went to a new home with my sister, where he never disgraced himself in the house, so the behaviour was generalized to indoors.