Strange artifacts in the floor

Good morning to all.
Can someone tell me what are the strange artifacts that appear in the corners and the right side on the floor of this room?
Thank you


Can you attach the blend file? I think this would help to figure out the problem.

It looks like a normal problem… just with the image it’s impossible to chek it, but it looks that you have other faces that make the smoothness of your floor to bend at the sides…
Try to change the smooth to flat, or to remove the faces you have in the sides.

Thank’s for the response. I manage to solve this by joining the mesh of the floor with the walls and remove doubles.
Normaly i like to have diferent materials separated, but in this case i had to join them.
Thank you again.