Index: trunk/resources/data/validator/combinations.mapcss
===================================================================
--- trunk/resources/data/validator/combinations.mapcss	(revision 18674)
+++ trunk/resources/data/validator/combinations.mapcss	(revision 18731)
@@ -48,4 +48,6 @@
 way[canal                      ][!waterway],
 way[have_riverbank             ][!waterway],
+area[min_height                ][!height][/^(building|building:part)$/], /* #21286 */
+area[building:min_level        ][!building:levels][/^(building|building:part)$/], /* #21286 */
 *[border_type                  ][!boundary],
 *[piste:difficulty             ][!piste:type],
@@ -1077,2 +1079,10 @@
   group: tr("suspicious tag combination");
 }
+
+/* #21286 */
+area[/^(building|building:part)$/][height =~ /^[0-9]+(\.[0-9]+)?( m)?$/][min_height =~ /^[0-9]+(\.[0-9]+)?( m)?$/][get(split(" ", tag(height)), 0) <= get(split(" ", tag(min_height)), 0)],
+area[/^(building|building:part)$/][building:levels][building:min_level][tag("building:levels") <= tag("building:min_level")] {
+  throwWarning: tr("{0} is lower or equal to {1} on {2}", "{1.key}", "{2.key}", "{0.key}");
+  group: tr("suspicious tag combination");
+}
+