Thanks for answer heartlessphil. Yes I know BSP works opposite. I tried connecting meshes with BSPs in other project, but i didn’t like it cause the BSP was somehow more blueish, so now i do all visible parts in Blender. After difficulties with UV maps for lightmaps this time all the walls are separate meshes - with only one island per mesh. Tell me what should be the distance of isle to the border of UV map? I have used .3 in blender tho i don’t know is it enough but i thought that resolution of 512 would solve any issues. 
I’ll prepare UV maps screens now. Thanks again.