Hi, i m working on an architectural project. I have imported my project from Belnder and i have no overlapping problem, everything s allright. All my meshes use the same material asets (a simple white) but they appear with different scale of grey. I mean my object faces are on the same plan, with the same material and they are on different grey nuances. Somebody can help me? 
On the pictures, the differences are visibles between the walls and the floors (floors is mesh1 and walls mesh2) !
Ok it s resolved. I begin my work on sketchup and the lightmaps weren t on the same scale and direction.