So I tried to create a dome for my map, like gorge or process have them over the last point. When I compile my compilelog following problem occures: Spoiler: Interlopers zero area child patch Description: A solid in your level has a face with no area. My guess is that vrad.exe is trying to create a lightmap for a face that doesn't exist. Maybe you have an invalid brush? Solution: First check Hammers problemchecker (alt+p). If that doesn't solve your problems, you can either ignore the error, or try to find it anyway using cordon tools. You would be looking for brushes which might be too complex. I wouldn't recommend the second option. The article form Interlopers.net says you can ignore it and if I press alt+p there are no messages regarding this problem. Is this safe to ignore, or do I need to change something?