diff --git a/nix/build-all.py b/nix/build-all.py
index 1061994f75..dda92aff9e 100644
--- a/nix/build-all.py
+++ b/nix/build-all.py
@@ -63,7 +63,7 @@ PROJECT_NAME="IfcOpenShell"
 OCE_VERSION="0.18"
 # OCCT_VERSION="7.1.0"
 # OCCT_HASH="89aebde"
-PYTHON_VERSIONS=["2.7.12", "3.2.6", "3.3.6", "3.4.6", "3.5.3", "3.6.2"]
+PYTHON_VERSIONS=["2.7.16", "3.2.6", "3.3.6", "3.4.6", "3.5.3", "3.6.2"]
 # OCCT_VERSION="7.2.0"
 # OCCT_HASH="88af392"
 OCCT_VERSION="7.3.0"
diff --git a/src/ifcgeom_schema_agnostic/IfcGeomFilter.h b/src/ifcgeom_schema_agnostic/IfcGeomFilter.h
index c29a6c8f3d..8d4a1192e3 100644
--- a/src/ifcgeom_schema_agnostic/IfcGeomFilter.h
+++ b/src/ifcgeom_schema_agnostic/IfcGeomFilter.h
@@ -40,14 +40,17 @@ namespace IfcGeom {
     /// http://www.boost.org/doc/libs/1_62_0/doc/html/function/tutorial.html
 	typedef boost::function<bool(IfcUtil::IfcBaseEntity*)> filter_t;
 
-	struct filter {
-        filter() : include(false), traverse(false) {}
-        filter(bool incl, bool trav) : include(incl), traverse(trav) {}
+    struct filter
+    {
+        filter() : include(false), traverse(false), traverse_openings(false) {}
+        filter(bool incl, bool trav, bool trav_openings = false) : include(incl), traverse(trav), traverse_openings(trav_openings) {}
         /// Should the product be included (true) or excluded (false).
         bool include;
         /// If traversal requested, traverse to the parents to see if they satisfy the criteria. E.g. we might be looking for
         /// children of a storey named "Level 20", or children of entities that have no representation, e.g. IfcCurtainWall.
         bool traverse;
+		/// Include opening relationships as part of traversal.
+		bool traverse_openings;
         /// Optional description for the filtering criteria of this filter.
         std::string description;
 
@@ -59,9 +62,10 @@ namespace IfcGeom {
             return is_match == include;
         }
 
-		static bool traverse_match(IfcUtil::IfcBaseEntity* prod, const filter_t& pred) {
-			IfcUtil::IfcBaseEntity* parent, *current = prod;
-			while ((parent = IfcGeom::Kernel::get_decomposing_entity(current)) != nullptr) {
+        bool traverse_match(IfcUtil::IfcBaseEntity* prod, const filter_t& pred) const
+        {
+            IfcUtil::IfcBaseEntity* parent, *current = prod;
+            while ((parent = IfcGeom::Kernel::get_decomposing_entity(current, traverse_openings)) != nullptr) {
                 if (pred(parent)) {
                     return true;
                 }
diff --git a/src/ifcgeom_schema_agnostic/Kernel.cpp b/src/ifcgeom_schema_agnostic/Kernel.cpp
index e6def6a42a..28eb00a207 100644
--- a/src/ifcgeom_schema_agnostic/Kernel.cpp
+++ b/src/ifcgeom_schema_agnostic/Kernel.cpp
@@ -73,11 +73,11 @@ IfcGeom::Kernel* IfcGeom::impl::KernelFactoryImplementation::construct(const std
 
 #define CREATE_GET_DECOMPOSING_ENTITY(IfcSchema)                                                                 \
                                                                                                                  \
-IfcSchema::IfcObjectDefinition* get_decomposing_entity_impl(IfcSchema::IfcProduct* product) {                    \
+IfcSchema::IfcObjectDefinition* get_decomposing_entity_impl(IfcSchema::IfcProduct* product, bool include_openings) {\
 	IfcSchema::IfcObjectDefinition* parent = 0;                                                                  \
                                                                                                                  \
 	/* In case of an opening element, parent to the RelatingBuildingElement */                                   \
-	if (product->declaration().is(IfcSchema::IfcOpeningElement::Class())) {                                      \
+	if (include_openings && product->declaration().is(IfcSchema::IfcOpeningElement::Class())) {                  \
 		IfcSchema::IfcOpeningElement* opening = (IfcSchema::IfcOpeningElement*)product;                          \
 		IfcSchema::IfcRelVoidsElement::list::ptr voids = opening->VoidsElements();                               \
 		if (voids->size()) {                                                                                     \
@@ -88,7 +88,7 @@ IfcSchema::IfcObjectDefinition* get_decomposing_entity_impl(IfcSchema::IfcProduc
 		IfcSchema::IfcElement* element = (IfcSchema::IfcElement*)product;                                        \
 		IfcSchema::IfcRelFillsElement::list::ptr fills = element->FillsVoids();                                  \
 		/* In case of a RelatedBuildingElement parent to the opening element */                                  \
-		if (fills->size()) {                                                                                     \
+		if (fills->size() && include_openings) {                                                                 \
 			for (IfcSchema::IfcRelFillsElement::list::it it = fills->begin(); it != fills->end(); ++it) {        \
 				IfcSchema::IfcRelFillsElement* fill = *it;                                                       \
 				IfcSchema::IfcObjectDefinition* ifc_objectdef = fill->RelatingOpeningElement();                  \
@@ -140,11 +140,11 @@ namespace {
 	CREATE_GET_DECOMPOSING_ENTITY(Ifc4);
 }
 
-IfcUtil::IfcBaseEntity* IfcGeom::Kernel::get_decomposing_entity(IfcUtil::IfcBaseEntity* inst) {
+IfcUtil::IfcBaseEntity* IfcGeom::Kernel::get_decomposing_entity(IfcUtil::IfcBaseEntity* inst, bool include_openings) {
 	if (inst->as<Ifc2x3::IfcProduct>()) {
-		return get_decomposing_entity_impl(inst->as<Ifc2x3::IfcProduct>());
+		return get_decomposing_entity_impl(inst->as<Ifc2x3::IfcProduct>(), include_openings);
 	} else if (inst->as<Ifc4::IfcProduct>()) {
-		return get_decomposing_entity_impl(inst->as<Ifc4::IfcProduct>());
+		return get_decomposing_entity_impl(inst->as<Ifc4::IfcProduct>(), include_openings);
 	} else {
 		throw IfcParse::IfcException("Unexpected entity " + inst->declaration().name());
 	}
diff --git a/src/ifcgeom_schema_agnostic/Kernel.h b/src/ifcgeom_schema_agnostic/Kernel.h
index c924f8af6a..f41020889e 100644
--- a/src/ifcgeom_schema_agnostic/Kernel.h
+++ b/src/ifcgeom_schema_agnostic/Kernel.h
@@ -83,7 +83,7 @@ namespace IfcGeom {
 		static int surface_genus(const TopoDS_Shape&);
 
 		static bool is_manifold(const TopoDS_Shape& a);
-		static IfcUtil::IfcBaseEntity* get_decomposing_entity(IfcUtil::IfcBaseEntity*);
+		static IfcUtil::IfcBaseEntity* get_decomposing_entity(IfcUtil::IfcBaseEntity*, bool include_openings=true);
 		static std::map<std::string, IfcUtil::IfcBaseEntity*> get_layers(IfcUtil::IfcBaseEntity*);
 	};