Hi. My first problem was that when I built light a mesh next to the destrucible one became complety dark. I solved the problem by Why does my object turn black when I build the lighting? - Rendering - Epic Developer Community Forums making lightmap resolution of that mesh to be 512, and changing the Light Map Coordinate Index to 1. I built light again, it became normal but my destructible one become extremely bright
UPD:
Now I covered the destructible mesh with a box and it became too dark