diff --git a/include/xdg/constants.h b/include/xdg/constants.h
index b3d97ce5..e6e08354 100644
--- a/include/xdg/constants.h
+++ b/include/xdg/constants.h
@@ -77,12 +77,15 @@ constexpr int BVH_MAX_DEPTH = 64;
 // geometric property type (e.g. material assignment or boundary condition)
 // TODO: separate into VolumeProperty and SurfaceProperty
 enum class PropertyType {
+  NOT_FOUND = -2,
   BOUNDARY_CONDITION = -1,
   MATERIAL = 0,
   DENSITY = 1,
   TEMPERATURE = 2
 };
 
+static const Property PROPERTY_NOT_FOUND {PropertyType::NOT_FOUND, "NOT_FOUND"}; 
+
 static const std::map<PropertyType, std::string> PROP_TYPE_TO_STR =
 {
   {PropertyType::BOUNDARY_CONDITION, "BOUNDARY_CONDITION"},
diff --git a/src/mesh_manager_interface.cpp b/src/mesh_manager_interface.cpp
index a0f461f0..b59b9199 100644
--- a/src/mesh_manager_interface.cpp
+++ b/src/mesh_manager_interface.cpp
@@ -71,13 +71,15 @@ MeshManager::surface_has_property(MeshID surface, PropertyType type) const
 Property
 MeshManager::get_volume_property(MeshID volume, PropertyType type) const
 {
+  if (surface_metadata_.count({volume, type}) == 0) 
+    return PROPERTY_NOT_FOUND;
   return volume_metadata_.at({volume, type});
 }
 
 Property
 MeshManager::get_surface_property(MeshID surface, PropertyType type) const
 {
-  if (surface_metadata_.count({surface, type}) == 0)
+  if (surface_metadata_.count({surface, type}) == 0) 
     return {PropertyType::BOUNDARY_CONDITION, "transmission"};
   return surface_metadata_.at({surface, type});
 }