diff --git a/engines/ultima/ultima8/world/sort_item.h b/engines/ultima/ultima8/world/sort_item.h
index 76e95e55ffa..7eda5e1a888 100644
--- a/engines/ultima/ultima8/world/sort_item.h
+++ b/engines/ultima/ultima8/world/sort_item.h
@@ -22,6 +22,7 @@
 #ifndef ULTIMA8_WORLD_SORTITEM_H
 #define ULTIMA8_WORLD_SORTITEM_H
 
+#include "common/str.h"
 #include "ultima/ultima8/misc/common_types.h"
 
 namespace Ultima {
@@ -341,8 +342,8 @@ inline bool SortItem::below(const SortItem &si2) const {
 	// Specialist z flat handling
 	if (si1._flat && si2._flat) {
 		// Differing z is easy for flats
-		if (si1._zTop != si2._zTop)
-			return si1._zTop < si2._zTop;
+		if (si1._z != si2._z)
+			return si1._z < si2._z;
 
 		// Equal z
 
@@ -381,22 +382,32 @@ inline bool SortItem::below(const SortItem &si2) const {
 		}
 
 		// Clearly in z
-		if (si1._zTop <= si2._z)
+		if (si1._z < si2._z && si1._zTop <= si2._z)
 			return true;
 
-		if (si1._z >= si2._zTop)
+		if (si1._z > si2._z && si1._z >= si2._zTop)
 			return false;
+
+		// Overlapping z-bottom check
+		// If an object's base (z-bottom) is higher another's, it should be rendered after.
+		// This check must be on the z-bottom and not the z-top because two objects with the
+		// same z-position may have different heights (think of a mouse sorting vs the Avatar).
+		if (si1._z != si2._z)
+			return si1._z < si2._z;
+
+		// Equal z
+
+		// Flat always gets drawn before
+		if (si1._flat != si2._flat)
+			return si1._flat > si2._flat;
+
+		// Trans always gets drawn after
+		if (si1._trans != si2._trans)
+			return si1._trans < si2._trans;
 	}
 
 	// Are overlapping in all 3 dimentions if we come here
 
-	// Overlapping z-bottom check
-	// If an object's base (z-bottom) is higher another's, it should be rendered after.
-	// This check must be on the z-bottom and not the z-top because two objects with the
-	// same z-position may have different heights (think of a mouse sorting vs the Avatar).
-	if (si1._z != si2._z)
-		return si1._z < si2._z;
-
 	// Land always gets drawn first
 	if (si1._land != si2._land)
 		return si1._land > si2._land;
diff --git a/test/engines/ultima/ultima8/world/sort_item.h b/test/engines/ultima/ultima8/world/sort_item.h
index 4c4d02e8ed5..fd205a24e4c 100644
--- a/test/engines/ultima/ultima8/world/sort_item.h
+++ b/test/engines/ultima/ultima8/world/sort_item.h
@@ -155,6 +155,37 @@ class U8SortItemTestSuite : public CxxTest::TestSuite {
 		TS_ASSERT(!si2.below(si1));
 	}
 
+	/**
+	 * Overlapping non-flat items draw transparent after
+	 * Test case for rendering issue at MainActor::teleport 41 17627 16339 48
+	 * Wall with window should render after non-window wall
+	 */
+	void test_nonflat_tranparent_sort() {
+		Ultima::Ultima8::SortItem si1(nullptr);
+		Ultima::Ultima8::SortItem si2(nullptr);
+
+		si1._x = 32;
+		si1._y = 96;
+		si1._z = 0;
+		si1._xLeft = 0;
+		si1._yFar = 0;
+		si1._zTop = 40;
+		si1._solid = true;
+
+		si2._x = 32;
+		si2._y = 160;
+		si2._z = 0;
+		si2._xLeft = 0;
+		si2._yFar = 32;
+		si2._zTop = 40;
+		si2._trans = true;
+		si2._solid = true;
+		si2._land = true;
+
+		TS_ASSERT(si1.below(si2));
+		TS_ASSERT(!si2.below(si1));
+	}
+
 	/* Overlapping non-flat occludes flat */
 	void test_basic_occludes() {
 		Ultima::Ultima8::SortItem si1(nullptr);
@@ -173,4 +204,40 @@ class U8SortItemTestSuite : public CxxTest::TestSuite {
 		TS_ASSERT(si1.occludes(si2));
 		TS_ASSERT(!si2.occludes(si1));
 	}
+
+	/**
+	 * Overlapping non-flat does occlude flat due to frame offset
+	 * Test case for rendering issue at MainActor::teleport 49 19167 17582 48
+	 */
+	void test_frame_offset_occludes() {
+		Ultima::Ultima8::SortItem si1(nullptr);
+		Ultima::Ultima8::SortItem si2(nullptr);
+
+		si1._xLeft = si2._xLeft = 0;
+		si1._yFar = si2._yFar = 0;
+		si1._z = si2._z = 0;
+		si1._y = si2._y = 128;
+		si1._x = si2._x = 128;
+		si1._zTop = 16;
+		si2._zTop = 0;
+
+		si1.calculateBoxBounds(0, 0);
+		si2.calculateBoxBounds(0, 0);
+
+		// ShapeFrame (240:1)
+		si1._sx = si1._sxBot - 32;
+		si1._sy = si1._syBot - 48;
+		si1._sx2 = si1._sx + 65;
+		si1._sy2 = si1._sy + 48;
+
+		// ShapeFrame (301:1)
+		si2._sx = si2._sxBot - 31;
+		si2._sy = si2._syBot - 31;
+		si2._sx2 = si2._sx + 62;
+		si2._sy2 = si2._sy + 32;
+
+		// FIXME: This case fails here currently
+		//TS_ASSERT(!si1.occludes(si2));
+		TS_ASSERT(!si2.occludes(si1));
+	}
 };