Index: /trunk/resources/data/validator/geometry.mapcss
===================================================================
--- /trunk/resources/data/validator/geometry.mapcss	(revision 16778)
+++ /trunk/resources/data/validator/geometry.mapcss	(revision 16779)
@@ -168,4 +168,5 @@
 
 /* Building overlapping building (spatial test) */
+area[building:part][building:part!~/no|entrance/] ⧉ area[building:part][building:part!~/no|entrance/],
 area[building][building!~/no|entrance/] ⧉ area[building][building!~/no|entrance/] {
   throwWarning: tr("Overlapping buildings");