diff --git a/src/g_level.cpp b/src/g_level.cpp
index 48440baa90..2f631db98a 100644
--- a/src/g_level.cpp
+++ b/src/g_level.cpp
@@ -1483,6 +1483,7 @@ void G_InitLevelLocals ()
 	level.Music = info->Music;
 	level.musicorder = info->musicorder;
 	level.MusicVolume = 1.f;
+	level.HasHeightSecs = false;
 
 	level.LevelName = level.info->LookupLevelName();
 	level.NextMap = info->NextMap;
diff --git a/src/g_levellocals.h b/src/g_levellocals.h
index 183005c533..3d23fb0853 100644
--- a/src/g_levellocals.h
+++ b/src/g_levellocals.h
@@ -151,6 +151,7 @@ struct FLevelLocals
 	int8_t		WallHorizLight;
 
 	bool		FromSnapshot;			// The current map was restored from a snapshot
+	bool		HasHeightSecs;			// true if some Transfer_Heights effects are present in the map. If this is false, some checks in the renderer can be shortcut.
 
 	double		teamdamage;
 
diff --git a/src/gl/scene/gl_bsp.cpp b/src/gl/scene/gl_bsp.cpp
index 2295bebecc..83620cbb24 100644
--- a/src/gl/scene/gl_bsp.cpp
+++ b/src/gl/scene/gl_bsp.cpp
@@ -140,7 +140,7 @@ void GLSceneDrawer::AddLine (seg_t *seg, bool portalclip)
 		else
 		{
 			// clipping checks are only needed when the backsector is not the same as the front sector
-			in_area = hw_CheckViewArea(in_area, seg->v1, seg->v2, seg->frontsector, seg->backsector);
+			if (in_area == area_default) in_area = hw_CheckViewArea(seg->v1, seg->v2, seg->frontsector, seg->backsector);
 
 			backsector = hw_FakeFlat(seg->backsector, &bs, in_area, true);
 
diff --git a/src/gl/scene/gl_scene.cpp b/src/gl/scene/gl_scene.cpp
index e2823d9233..ef17b71282 100644
--- a/src/gl/scene/gl_scene.cpp
+++ b/src/gl/scene/gl_scene.cpp
@@ -111,7 +111,7 @@ void GLSceneDrawer::SetViewArea()
 	}
 	else
 	{
-		in_area = area_default;	// depends on exposed lower sectors
+		in_area = level.HasHeightSecs? area_default : area_normal;	// depends on exposed lower sectors, if map contains heightsecs.
 	}
 }
 
diff --git a/src/hwrenderer/scene/hw_fakeflat.cpp b/src/hwrenderer/scene/hw_fakeflat.cpp
index 994cd95fa6..6b535bdad9 100644
--- a/src/hwrenderer/scene/hw_fakeflat.cpp
+++ b/src/hwrenderer/scene/hw_fakeflat.cpp
@@ -153,13 +153,14 @@ bool hw_CheckClip(side_t * sidedef, sector_t * frontsector, sector_t * backsecto
 
 //==========================================================================
 //
-// check for levels with exposed lower areas
+// check for levels with exposed lower areas. May only be called if actual
+// state is not known yet!
 //
 //==========================================================================
 
-area_t hw_CheckViewArea(area_t in_area, vertex_t *v1, vertex_t *v2, sector_t *frontsector, sector_t *backsector)
+area_t hw_CheckViewArea(vertex_t *v1, vertex_t *v2, sector_t *frontsector, sector_t *backsector)
 {
-	if (in_area == area_default &&
+	if (
 		(backsector->heightsec && !(backsector->heightsec->MoreFlags & SECF_IGNOREHEIGHTSEC)) &&
 		(!frontsector->heightsec || frontsector->heightsec->MoreFlags & SECF_IGNOREHEIGHTSEC))
 	{
@@ -176,7 +177,7 @@ area_t hw_CheckViewArea(area_t in_area, vertex_t *v1, vertex_t *v2, sector_t *fr
 		else
 			return area_normal;
 	}
-	return in_area;
+	return area_default;
 }
 
 
diff --git a/src/hwrenderer/scene/hw_fakeflat.h b/src/hwrenderer/scene/hw_fakeflat.h
index e402627adb..8e5b9dfec9 100644
--- a/src/hwrenderer/scene/hw_fakeflat.h
+++ b/src/hwrenderer/scene/hw_fakeflat.h
@@ -12,5 +12,5 @@ enum area_t : int
 // Global functions. Make them members of GLRenderer later?
 bool hw_CheckClip(side_t * sidedef, sector_t * frontsector, sector_t * backsector);
 sector_t * hw_FakeFlat(sector_t * sec, sector_t * dest, area_t in_area, bool back);
-area_t hw_CheckViewArea(area_t in_area, vertex_t *v1, vertex_t *v2, sector_t *frontsector, sector_t *backsector);
+area_t hw_CheckViewArea(vertex_t *v1, vertex_t *v2, sector_t *frontsector, sector_t *backsector);
 
diff --git a/src/p_spec.cpp b/src/p_spec.cpp
index 5183324f99..da20dec4af 100644
--- a/src/p_spec.cpp
+++ b/src/p_spec.cpp
@@ -1343,6 +1343,7 @@ void P_SpawnSpecials (void)
 		case Transfer_Heights:
 			{
 				sec = line.frontsector;
+				
 				if (line.args[1] & 2)
 				{
 					sec->MoreFlags |= SECF_FAKEFLOORONLY;
@@ -1363,6 +1364,7 @@ void P_SpawnSpecials (void)
 				{
 					sec->MoreFlags |= SECF_IGNOREHEIGHTSEC;
 				}
+				else level.HasHeightSecs = true;
 				if (line.args[1] & 32)
 				{
 					sec->MoreFlags |= SECF_NOFAKELIGHT;