Problems with Decals, please help me

hey, I am working on my first ever environment(never used ue4 before this) and started getting these weird patterns on my (letf)wall when I look at the wall from that specific angle. When I hide my decals it disappears, I think it has something to do with the parent material because the pattern I get looks a little bit like that. I don't really know what it is, so if somebody knows please help me out that would be great  

Once again I am very very new to UE4(and polycount) so don't destroy me  

Thank You for your time