diff --git a/src/p_3dfloors.cpp b/src/p_3dfloors.cpp
index 732866c5b8..5e8d05359c 100644
--- a/src/p_3dfloors.cpp
+++ b/src/p_3dfloors.cpp
@@ -426,10 +426,7 @@ void P_Recalculate3DFloors(sector_t * sector)
 	// Translucent and swimmable floors are split if they overlap with solid ones.
 	if (ffloors.Size()>1)
 	{
-		TArray<F3DFloor*> oldlist;
-		
-		oldlist = ffloors;
-		ffloors.Clear();
+		TArray<F3DFloor*> oldlist = std::move(ffloors);
 
 		// first delete the old dynamic stuff
 		for(i=0;i<oldlist.Size();i++)
@@ -653,6 +650,40 @@ void P_Recalculate3DFloors(sector_t * sector)
 	}
 }
 
+//==========================================================================
+//
+// removes all dynamic data. This needs to be done once before creating
+// the vertex buffer.
+//
+//==========================================================================
+
+void P_ClearDynamic3DFloorData()
+{
+	for (auto &sec : level.sectors)
+	{
+		TArray<F3DFloor*> & ffloors = sec.e->XFloor.ffloors;
+
+		// delete the dynamic stuff
+		for (unsigned i = 0; i < ffloors.Size(); i++)
+		{
+			F3DFloor * rover = ffloors[i];
+
+			if (rover->flags&FF_DYNAMIC)
+			{
+				delete rover;
+				ffloors.Delete(i);
+				i--;
+				continue;
+			}
+			if (rover->flags&FF_CLIPPED)
+			{
+				rover->flags &= ~FF_CLIPPED;
+				rover->flags |= FF_EXISTS;
+			}
+		}
+	}
+}
+
 //==========================================================================
 //
 // recalculates 3D floors for all attached sectors
@@ -891,6 +922,11 @@ void P_Spawn3DFloors (void)
 		line.special=0;
 		line.args[0] = line.args[1] = line.args[2] = line.args[3] = line.args[4] = 0;
 	}
+
+	for (auto &sec : level.sectors)
+	{
+		P_Recalculate3DFloors(&sec);
+	}
 }
 
 
diff --git a/src/p_3dfloors.h b/src/p_3dfloors.h
index e260f9f5f4..d0f4f500a5 100644
--- a/src/p_3dfloors.h
+++ b/src/p_3dfloors.h
@@ -123,6 +123,7 @@ void P_Recalculate3DFloors(sector_t *);
 void P_RecalculateAttached3DFloors(sector_t * sec);
 void P_RecalculateLights(sector_t *sector);
 void P_RecalculateAttachedLights(sector_t *sector);
+void P_ClearDynamic3DFloorData();
 
 lightlist_t * P_GetPlaneLight(sector_t * , secplane_t * plane, bool underside);
 void P_Spawn3DFloors( void );
diff --git a/src/p_setup.cpp b/src/p_setup.cpp
index 0cb8894da0..1dd094655d 100644
--- a/src/p_setup.cpp
+++ b/src/p_setup.cpp
@@ -3770,6 +3770,9 @@ void P_SetupLevel(const char *lumpname, int position, bool newGame)
 		node.len = (float)g_sqrt(fdx * fdx + fdy * fdy);
 	}
 
+	// CreateVBO must be run on the plain 3D floor data.
+	P_ClearDynamic3DFloorData();
+
 	// This must be done BEFORE the PolyObj Spawn!!!
 	InitRenderInfo();			// create hardware independent renderer resources for the level.
 	screen->mVertexData->CreateVBO();