diff --git a/src/ifcopenshell-python/ifcopenshell/express/schema_class.py b/src/ifcopenshell-python/ifcopenshell/express/schema_class.py
index f6be4e888e..ba38778175 100644
--- a/src/ifcopenshell-python/ifcopenshell/express/schema_class.py
+++ b/src/ifcopenshell-python/ifcopenshell/express/schema_class.py
@@ -283,10 +283,22 @@ __attribute__((optnone))
 
         self.statements.extend(
             (
-                "const schema_definition& %s::get_schema() {" % schema_name_title,
+                "static std::unique_ptr<schema_definition> schema;",
                 "",
-                "    static const schema_definition* s = %(schema_name)s_populate_schema();" % locals(),
-                "    return *s;",
+                "void %s::clear_schema() {" % schema_name_title,
+                "    schema.reset();",
+                "}",
+                "",
+            )
+        )
+
+        self.statements.extend(
+            (
+                "const schema_definition& %s::get_schema() {" % schema_name_title,
+                "    if (!schema) {",
+                "        schema.reset(%(schema_name)s_populate_schema());" % locals(),
+                "    }",
+                "    return *schema;",
                 "}",
                 "",
                 "",
diff --git a/src/ifcopenshell-python/ifcopenshell/express/templates.py b/src/ifcopenshell-python/ifcopenshell/express/templates.py
index af9ad4d1e9..f52580f516 100644
--- a/src/ifcopenshell-python/ifcopenshell/express/templates.py
+++ b/src/ifcopenshell-python/ifcopenshell/express/templates.py
@@ -38,6 +38,8 @@ struct %(schema_name)s {
 
 IFC_PARSE_API static const IfcParse::schema_definition& get_schema();
 
+IFC_PARSE_API static void clear_schema();
+
 static const char* const Identifier;
 
 // Forward definitions
diff --git a/src/ifcparse/Ifc2x3-schema.cpp b/src/ifcparse/Ifc2x3-schema.cpp
index 09168c89db..06ad4c3a2a 100644
--- a/src/ifcparse/Ifc2x3-schema.cpp
+++ b/src/ifcparse/Ifc2x3-schema.cpp
@@ -12533,9 +12533,16 @@ IfcParse::schema_definition* IFC2X3_populate_schema() {
 #pragma optimize("", on)
 #endif
         
-const schema_definition& Ifc2x3::get_schema() {
+static std::unique_ptr<schema_definition> schema;
 
-    static const schema_definition* s = IFC2X3_populate_schema();
-    return *s;
+void Ifc2x3::clear_schema() {
+    schema.reset();
+}
+
+const schema_definition& Ifc2x3::get_schema() {
+    if (!schema) {
+        schema.reset(IFC2X3_populate_schema());
+    }
+    return *schema;
 }
 
diff --git a/src/ifcparse/Ifc2x3.h b/src/ifcparse/Ifc2x3.h
index 0be1e861d7..a9ff0fbf90 100644
--- a/src/ifcparse/Ifc2x3.h
+++ b/src/ifcparse/Ifc2x3.h
@@ -44,6 +44,8 @@ struct Ifc2x3 {
 
 IFC_PARSE_API static const IfcParse::schema_definition& get_schema();
 
+IFC_PARSE_API static void clear_schema();
+
 static const char* const Identifier;
 
 // Forward definitions
diff --git a/src/ifcparse/Ifc4-schema.cpp b/src/ifcparse/Ifc4-schema.cpp
index 9263819618..5e8d1add16 100644
--- a/src/ifcparse/Ifc4-schema.cpp
+++ b/src/ifcparse/Ifc4-schema.cpp
@@ -15071,9 +15071,16 @@ IfcParse::schema_definition* IFC4_populate_schema() {
 #pragma optimize("", on)
 #endif
         
-const schema_definition& Ifc4::get_schema() {
+static std::unique_ptr<schema_definition> schema;
 
-    static const schema_definition* s = IFC4_populate_schema();
-    return *s;
+void Ifc4::clear_schema() {
+    schema.reset();
+}
+
+const schema_definition& Ifc4::get_schema() {
+    if (!schema) {
+        schema.reset(IFC4_populate_schema());
+    }
+    return *schema;
 }
 
diff --git a/src/ifcparse/Ifc4.h b/src/ifcparse/Ifc4.h
index 2a0652b192..8b80139d29 100644
--- a/src/ifcparse/Ifc4.h
+++ b/src/ifcparse/Ifc4.h
@@ -44,6 +44,8 @@ struct Ifc4 {
 
 IFC_PARSE_API static const IfcParse::schema_definition& get_schema();
 
+IFC_PARSE_API static void clear_schema();
+
 static const char* const Identifier;
 
 // Forward definitions
diff --git a/src/ifcparse/Ifc4x1-schema.cpp b/src/ifcparse/Ifc4x1-schema.cpp
index d442a761bf..277c319cc6 100644
--- a/src/ifcparse/Ifc4x1-schema.cpp
+++ b/src/ifcparse/Ifc4x1-schema.cpp
@@ -15472,9 +15472,16 @@ IfcParse::schema_definition* IFC4X1_populate_schema() {
 #pragma optimize("", on)
 #endif
         
-const schema_definition& Ifc4x1::get_schema() {
+static std::unique_ptr<schema_definition> schema;
 
-    static const schema_definition* s = IFC4X1_populate_schema();
-    return *s;
+void Ifc4x1::clear_schema() {
+    schema.reset();
+}
+
+const schema_definition& Ifc4x1::get_schema() {
+    if (!schema) {
+        schema.reset(IFC4X1_populate_schema());
+    }
+    return *schema;
 }
 
diff --git a/src/ifcparse/Ifc4x1.h b/src/ifcparse/Ifc4x1.h
index 72ddc03341..c2e6ba7490 100644
--- a/src/ifcparse/Ifc4x1.h
+++ b/src/ifcparse/Ifc4x1.h
@@ -44,6 +44,8 @@ struct Ifc4x1 {
 
 IFC_PARSE_API static const IfcParse::schema_definition& get_schema();
 
+IFC_PARSE_API static void clear_schema();
+
 static const char* const Identifier;
 
 // Forward definitions
diff --git a/src/ifcparse/Ifc4x2-schema.cpp b/src/ifcparse/Ifc4x2-schema.cpp
index 100ce7795f..0a9f35563f 100644
--- a/src/ifcparse/Ifc4x2-schema.cpp
+++ b/src/ifcparse/Ifc4x2-schema.cpp
@@ -15808,9 +15808,16 @@ IfcParse::schema_definition* IFC4X2_populate_schema() {
 #pragma optimize("", on)
 #endif
         
-const schema_definition& Ifc4x2::get_schema() {
+static std::unique_ptr<schema_definition> schema;
 
-    static const schema_definition* s = IFC4X2_populate_schema();
-    return *s;
+void Ifc4x2::clear_schema() {
+    schema.reset();
+}
+
+const schema_definition& Ifc4x2::get_schema() {
+    if (!schema) {
+        schema.reset(IFC4X2_populate_schema());
+    }
+    return *schema;
 }
 
diff --git a/src/ifcparse/Ifc4x2.h b/src/ifcparse/Ifc4x2.h
index 832b401d23..5be96d9c8c 100644
--- a/src/ifcparse/Ifc4x2.h
+++ b/src/ifcparse/Ifc4x2.h
@@ -44,6 +44,8 @@ struct Ifc4x2 {
 
 IFC_PARSE_API static const IfcParse::schema_definition& get_schema();
 
+IFC_PARSE_API static void clear_schema();
+
 static const char* const Identifier;
 
 // Forward definitions
diff --git a/src/ifcparse/Ifc4x3_rc1-schema.cpp b/src/ifcparse/Ifc4x3_rc1-schema.cpp
index 643f2101bf..01fc5d876b 100644
--- a/src/ifcparse/Ifc4x3_rc1-schema.cpp
+++ b/src/ifcparse/Ifc4x3_rc1-schema.cpp
@@ -17143,9 +17143,16 @@ IfcParse::schema_definition* IFC4X3_RC1_populate_schema() {
 #pragma optimize("", on)
 #endif
         
-const schema_definition& Ifc4x3_rc1::get_schema() {
+static std::unique_ptr<schema_definition> schema;
 
-    static const schema_definition* s = IFC4X3_RC1_populate_schema();
-    return *s;
+void Ifc4x3_rc1::clear_schema() {
+    schema.reset();
+}
+
+const schema_definition& Ifc4x3_rc1::get_schema() {
+    if (!schema) {
+        schema.reset(IFC4X3_RC1_populate_schema());
+    }
+    return *schema;
 }
 
diff --git a/src/ifcparse/Ifc4x3_rc1.h b/src/ifcparse/Ifc4x3_rc1.h
index 970c7d88cf..0d49d07989 100644
--- a/src/ifcparse/Ifc4x3_rc1.h
+++ b/src/ifcparse/Ifc4x3_rc1.h
@@ -44,6 +44,8 @@ struct Ifc4x3_rc1 {
 
 IFC_PARSE_API static const IfcParse::schema_definition& get_schema();
 
+IFC_PARSE_API static void clear_schema();
+
 static const char* const Identifier;
 
 // Forward definitions
diff --git a/src/ifcparse/Ifc4x3_rc2-schema.cpp b/src/ifcparse/Ifc4x3_rc2-schema.cpp
index 944de6b57a..bc307a9205 100644
--- a/src/ifcparse/Ifc4x3_rc2-schema.cpp
+++ b/src/ifcparse/Ifc4x3_rc2-schema.cpp
@@ -17245,9 +17245,16 @@ IfcParse::schema_definition* IFC4X3_RC2_populate_schema() {
 #pragma optimize("", on)
 #endif
         
-const schema_definition& Ifc4x3_rc2::get_schema() {
+static std::unique_ptr<schema_definition> schema;
 
-    static const schema_definition* s = IFC4X3_RC2_populate_schema();
-    return *s;
+void Ifc4x3_rc2::clear_schema() {
+    schema.reset();
+}
+
+const schema_definition& Ifc4x3_rc2::get_schema() {
+    if (!schema) {
+        schema.reset(IFC4X3_RC2_populate_schema());
+    }
+    return *schema;
 }
 
diff --git a/src/ifcparse/Ifc4x3_rc2.h b/src/ifcparse/Ifc4x3_rc2.h
index 9648cad06e..473b69a065 100644
--- a/src/ifcparse/Ifc4x3_rc2.h
+++ b/src/ifcparse/Ifc4x3_rc2.h
@@ -44,6 +44,8 @@ struct Ifc4x3_rc2 {
 
 IFC_PARSE_API static const IfcParse::schema_definition& get_schema();
 
+IFC_PARSE_API static void clear_schema();
+
 static const char* const Identifier;
 
 // Forward definitions
diff --git a/src/ifcparse/Ifc4x3_rc3-schema.cpp b/src/ifcparse/Ifc4x3_rc3-schema.cpp
index eac792db0a..68b4918a47 100644
--- a/src/ifcparse/Ifc4x3_rc3-schema.cpp
+++ b/src/ifcparse/Ifc4x3_rc3-schema.cpp
@@ -17122,9 +17122,16 @@ IfcParse::schema_definition* IFC4X3_RC3_populate_schema() {
 #pragma optimize("", on)
 #endif
         
-const schema_definition& Ifc4x3_rc3::get_schema() {
+static std::unique_ptr<schema_definition> schema;
 
-    static const schema_definition* s = IFC4X3_RC3_populate_schema();
-    return *s;
+void Ifc4x3_rc3::clear_schema() {
+    schema.reset();
+}
+
+const schema_definition& Ifc4x3_rc3::get_schema() {
+    if (!schema) {
+        schema.reset(IFC4X3_RC3_populate_schema());
+    }
+    return *schema;
 }
 
diff --git a/src/ifcparse/Ifc4x3_rc3.h b/src/ifcparse/Ifc4x3_rc3.h
index 1cc2ffcd4a..0ba741a6e1 100644
--- a/src/ifcparse/Ifc4x3_rc3.h
+++ b/src/ifcparse/Ifc4x3_rc3.h
@@ -44,6 +44,8 @@ struct Ifc4x3_rc3 {
 
 IFC_PARSE_API static const IfcParse::schema_definition& get_schema();
 
+IFC_PARSE_API static void clear_schema();
+
 static const char* const Identifier;
 
 // Forward definitions
diff --git a/src/ifcparse/Ifc4x3_rc4-schema.cpp b/src/ifcparse/Ifc4x3_rc4-schema.cpp
index edab421d43..0c875db269 100644
--- a/src/ifcparse/Ifc4x3_rc4-schema.cpp
+++ b/src/ifcparse/Ifc4x3_rc4-schema.cpp
@@ -17136,9 +17136,16 @@ IfcParse::schema_definition* IFC4X3_RC4_populate_schema() {
 #pragma optimize("", on)
 #endif
         
-const schema_definition& Ifc4x3_rc4::get_schema() {
+static std::unique_ptr<schema_definition> schema;
 
-    static const schema_definition* s = IFC4X3_RC4_populate_schema();
-    return *s;
+void Ifc4x3_rc4::clear_schema() {
+    schema.reset();
+}
+
+const schema_definition& Ifc4x3_rc4::get_schema() {
+    if (!schema) {
+        schema.reset(IFC4X3_RC4_populate_schema());
+    }
+    return *schema;
 }
 
diff --git a/src/ifcparse/Ifc4x3_rc4.h b/src/ifcparse/Ifc4x3_rc4.h
index 2a35062a95..e27ef42f96 100644
--- a/src/ifcparse/Ifc4x3_rc4.h
+++ b/src/ifcparse/Ifc4x3_rc4.h
@@ -44,6 +44,8 @@ struct Ifc4x3_rc4 {
 
 IFC_PARSE_API static const IfcParse::schema_definition& get_schema();
 
+IFC_PARSE_API static void clear_schema();
+
 static const char* const Identifier;
 
 // Forward definitions
diff --git a/src/ifcparse/IfcSchema.cpp b/src/ifcparse/IfcSchema.cpp
index e9b479aae6..9f4fcf6c02 100644
--- a/src/ifcparse/IfcSchema.cpp
+++ b/src/ifcparse/IfcSchema.cpp
@@ -37,6 +37,14 @@ bool IfcParse::named_type::is(const IfcParse::declaration& decl) const {
 	return declared_type()->is(decl);
 }
 
+IfcParse::entity::~entity() {
+	for (auto attribute : attributes_) {
+		delete attribute;
+	}
+	for (auto inverse_attribute : inverse_attributes_) {
+		delete inverse_attribute;
+	}
+}
 static std::map<std::string, const IfcParse::schema_definition*> schemas;
 
 IfcParse::schema_definition::schema_definition(const std::string& name, const std::vector<const declaration*>& declarations, instance_factory* factory)
@@ -61,6 +69,7 @@ IfcParse::schema_definition::~schema_definition() {
 	for (std::vector<const declaration*>::const_iterator it = declarations_.begin(); it != declarations_.end(); ++it) {
 		delete *it;
 	}
+	delete factory_;
 }
 
 IfcUtil::IfcBaseClass* IfcParse::schema_definition::instantiate(IfcEntityInstanceData * data) const {
@@ -149,3 +158,36 @@ std::vector<std::string> IfcParse::schema_names() {
 
 	return return_value;
 }
+
+void IfcParse::clear_schemas() {
+#ifdef HAS_SCHEMA_2x3
+	Ifc2x3::clear_schema();
+#endif
+#ifdef HAS_SCHEMA_4
+	Ifc4::clear_schema();
+#endif
+#ifdef HAS_SCHEMA_4x1
+	Ifc4x1::clear_schema();
+#endif
+#ifdef HAS_SCHEMA_4x2
+	Ifc4x2::clear_schema();
+#endif
+#ifdef HAS_SCHEMA_4x3_rc1
+	Ifc4x3_rc1::clear_schema();
+#endif
+#ifdef HAS_SCHEMA_4x3_rc2
+	Ifc4x3_rc2::clear_schema();
+#endif
+#ifdef HAS_SCHEMA_4x3_rc3
+	Ifc4x3_rc3::clear_schema();
+#endif
+#ifdef HAS_SCHEMA_4x3_rc4
+	Ifc4x3_rc4::clear_schema();
+#endif
+
+	// clear any remaining registered schemas
+	// we pop schemas until map is empty, because map iteration is invalidated after each erasure
+	while (!schemas.empty()) {
+		delete schemas.begin()->second;
+	}
+}
diff --git a/src/ifcparse/IfcSchema.h b/src/ifcparse/IfcSchema.h
index 5b7c805429..b11a115982 100644
--- a/src/ifcparse/IfcSchema.h
+++ b/src/ifcparse/IfcSchema.h
@@ -55,6 +55,8 @@ namespace IfcParse {
 
 	class IFC_PARSE_API parameter_type {
 	public:
+		virtual ~parameter_type() {}
+
 		virtual const named_type* as_named_type() const { return static_cast<named_type*>(0); }
 		virtual const simple_type* as_simple_type() const { return static_cast<simple_type*>(0); }
 		virtual const aggregation_type* as_aggregation_type() const { return static_cast<aggregation_type*>(0); }
@@ -107,6 +109,8 @@ namespace IfcParse {
 			, type_of_element_(type_of_element)
 		{}
 
+		virtual ~aggregation_type() { delete type_of_element_; }
+
 		aggregate_type type_of_aggregation() const { return type_of_aggregation_; }
 		int bound1() const { return bound1_; }
 		int bound2() const { return bound2_; }
@@ -160,6 +164,8 @@ namespace IfcParse {
 			: declaration(name, index_in_schema)
 			, declared_type_(declared_type)	{}
 
+		virtual ~type_declaration() { delete declared_type_; }
+
 		const parameter_type* declared_type() const { return declared_type_; }
 
 		virtual const type_declaration* as_type_declaration() const { return this; }
@@ -203,6 +209,8 @@ namespace IfcParse {
 			, type_of_attribute_(type_of_attribute)
 			, optional_(optional) {}
 
+		~attribute() { delete type_of_attribute_; }
+
 		const std::string& name() const { return name_; }
 		const parameter_type* type_of_attribute() const { return type_of_attribute_; }
 		bool optional() const { return optional_; }
@@ -277,6 +285,8 @@ namespace IfcParse {
 			, supertype_(supertype)
 		{}
 
+		virtual ~entity();
+
 		bool is(const std::string& name) const {
 			if (name == name_) return true;
 			else if (supertype_) return supertype_->is(name);
@@ -387,6 +397,8 @@ namespace IfcParse {
 
 	class IFC_PARSE_API instance_factory {
 	public:
+		virtual ~instance_factory() {}
+
 		virtual IfcUtil::IfcBaseClass* operator()(IfcEntityInstanceData* data) const = 0;
 	};
 
@@ -453,6 +465,8 @@ namespace IfcParse {
 	IFC_PARSE_API std::vector<std::string> schema_names();
 
 	IFC_PARSE_API void register_schema(schema_definition*);
+
+	IFC_PARSE_API void clear_schemas();
 }
 
 #endif