Help with white lines between ceiling and walls

[skainet]

Any idea why i am getting these white lines (see attachment) between the ceiling and walls?.The main light source for the scene is the coronaskymap.

i am using 3dsmax2016 with corona 5

thanks

[romullus]

You need to add thickness to the walls. Shell modifier will do.

[skainet]

That was it.

Thanks a lot¡