the houses in the first screen shot have gaps between the polygons. if those are level blocks i don't think there can be much you can do to fix it, except there's a variable in the manual that you set to choose how much the engine tries to fill these gaps. sorry, i can't remember what it is. if they are MDL model's, some welding and merging can be done to pull them together.

i'm on my parent's computer right now so i'm unable to download the demo, but it looks like you're going quite well.

julz