diff --git a/src/bcf/bcf/v2/bcfxml.py b/src/bcf/bcf/v2/bcfxml.py
index fe1d482d61..c8782ac9ba 100644
--- a/src/bcf/bcf/v2/bcfxml.py
+++ b/src/bcf/bcf/v2/bcfxml.py
@@ -24,7 +24,7 @@ class BcfXml:
         self._xml_handler = xml_handler or XmlParserSerializer()
         self._version: Optional[mdl.Version] = None
         self._project_info: Optional[mdl.ProjectExtension] = None
-        self._topics: dict[str, TopicHandler] = {}
+        self._topics: Optional[dict[str, TopicHandler]] = None
         self._extension_schema: Optional[bytes] = None
         self._zip_file = self._load_zip_file()
 
@@ -88,21 +88,21 @@ class BcfXml:
     @property
     def topics(self) -> dict[str, TopicHandler]:
         """BCF topics."""
-        if not self._topics and self._zip_file:
-            self._topics = self._load_topics(self._zip_file, self._xml_handler)
+        if self._topics is None:
+            self._topics = self._load_topics()
         return self._topics
 
-    def _load_topics(
-        self, zip_file: zipfile.ZipFile, xml_handler: AbstractXmlParserSerializer
-    ) -> dict[str, TopicHandler]:
+    def _load_topics(self) -> dict[str, TopicHandler]:
         topics = {}
-        for topic_dir in zipfile.Path(zip_file).iterdir():
+        if self._zip_file is None:
+            return topics
+        for topic_dir in zipfile.Path(self._zip_file).iterdir():
             if not topic_dir.is_dir():
                 continue
             markup_path = topic_dir.joinpath("markup.bcf")
             if not markup_path.exists():
                 continue
-            topics[topic_dir.name] = TopicHandler(topic_dir, xml_handler)
+            topics[topic_dir.name] = TopicHandler(topic_dir, self._xml_handler)
         return topics
 
     @classmethod
diff --git a/src/bcf/bcf/v2/topic.py b/src/bcf/bcf/v2/topic.py
index 4d016449e2..4bcfaa7043 100644
--- a/src/bcf/bcf/v2/topic.py
+++ b/src/bcf/bcf/v2/topic.py
@@ -27,9 +27,9 @@ class TopicHandler:
         xml_handler: Optional[AbstractXmlParserSerializer] = None,
     ) -> None:
         self._markup: Optional[mdl.Markup] = None
-        self._viewpoints: dict[str, VisualizationInfoHandler] = {}
-        self._reference_files: dict[str, bytes] = {}
-        self._document_references: dict[str, bytes] = {}
+        self._viewpoints: Optional[dict[str, VisualizationInfoHandler]] = None
+        self._reference_files: Optional[dict[str, bytes]] = None
+        self._document_references: Optional[dict[str, bytes]] = None
         self._bim_snippet: Optional[bytes] = None
         self._xml_handler = xml_handler or XmlParserSerializer()
         self._topic_dir = topic_dir
@@ -80,14 +80,24 @@ class TopicHandler:
 
     @property
     def viewpoints(self) -> dict[str, VisualizationInfoHandler]:
-        if not self._viewpoints and self._topic_dir:
+        if self._viewpoints is None:
             self._viewpoints = self._load_viewpoints()
         return self._viewpoints
 
+    def _load_viewpoints(self) -> dict[str, VisualizationInfoHandler]:
+        if self._topic_dir and self.markup and (viewpoints := self.markup.viewpoints):
+            return VisualizationInfoHandler.from_topic_viewpoints(self._topic_dir, viewpoints)
+        return {}
+
     @property
     def reference_files(self) -> dict[str, bytes]:
-        if self._reference_files or not self.header:
+        if self._reference_files is not None:
             return self._reference_files
+
+        self._reference_files = {}
+        if not self.header:
+            return self._reference_files
+
         for ref in self.header.file:
             if ref.is_external:
                 continue
@@ -99,8 +109,13 @@ class TopicHandler:
 
     @property
     def document_references(self) -> dict[str, bytes]:
-        if self._document_references or not self.topic:
+        if self._document_references is not None:
             return self._document_references
+
+        self._document_references = {}
+        if not self.topic:
+            return self._document_references
+
         for doc in self.topic.document_reference:
             if doc.is_external or not doc.referenced_document:
                 continue
@@ -118,11 +133,6 @@ class TopicHandler:
                 return bim_snippet_path.read_bytes()
         return None
 
-    def _load_viewpoints(self) -> dict[str, VisualizationInfoHandler]:
-        if self.markup and (viewpoints := self.markup.viewpoints):
-            return VisualizationInfoHandler.from_topic_viewpoints(self._topic_dir, viewpoints)
-        return {}
-
     @classmethod
     def create_new(
         cls,
diff --git a/src/bcf/bcf/v3/bcfxml.py b/src/bcf/bcf/v3/bcfxml.py
index 3318264670..16d920737a 100644
--- a/src/bcf/bcf/v3/bcfxml.py
+++ b/src/bcf/bcf/v3/bcfxml.py
@@ -26,7 +26,7 @@ class BcfXml:
         self._version: Optional[mdl.Version] = None
         self._project_info: Optional[mdl.ProjectInfo] = None
         self._extensions: Optional[mdl.Extensions] = None
-        self._topics: dict[str, TopicHandler] = {}
+        self._topics: Optional[dict[str, TopicHandler]] = None
         self._documents: Optional[DocumentsHandler] = None
         self._zip_file = self._load_zip_file()
 
@@ -91,18 +91,22 @@ class BcfXml:
     @property
     def topics(self) -> dict[str, TopicHandler]:
         """BCF topics."""
-        if not self._topics and self._zip_file:
-            self._load_topics()
+        if self._topics is None:
+            self._topics = self._load_topics()
         return self._topics
 
-    def _load_topics(self) -> None:
+    def _load_topics(self) -> dict[str, TopicHandler]:
+        topics = {}
+        if self._zip_file is None:
+            return topics
         for topic_dir in zipfile.Path(self._zip_file).iterdir():
             if not topic_dir.is_dir():
                 continue
             markup_path = topic_dir.joinpath("markup.bcf")
             if not markup_path.exists():
                 continue
-            self._topics[topic_dir.name] = TopicHandler(topic_dir, self._xml_handler)
+            topics[topic_dir.name] = TopicHandler(topic_dir, self._xml_handler)
+        return topics
 
     @property
     def documents(self) -> Optional[DocumentsHandler]:
diff --git a/src/bcf/bcf/v3/topic.py b/src/bcf/bcf/v3/topic.py
index 2fd8db6fe4..b2f2bf4e22 100644
--- a/src/bcf/bcf/v3/topic.py
+++ b/src/bcf/bcf/v3/topic.py
@@ -26,7 +26,7 @@ class TopicHandler:
         xml_handler: Optional[AbstractXmlParserSerializer] = None,
     ) -> None:
         self._markup: Optional[mdl.Markup] = None
-        self._viewpoints: dict[str, VisualizationInfoHandler] = {}
+        self._viewpoints: Optional[dict[str, VisualizationInfoHandler]] = None
         self._bim_snippet: Optional[bytes] = None
         self._xml_handler = xml_handler or XmlParserSerializer()
         self._topic_dir = topic_dir
@@ -77,15 +77,15 @@ class TopicHandler:
 
     @property
     def viewpoints(self) -> dict[str, "VisualizationInfoHandler"]:
-        if (
-            not self._viewpoints
-            and self._topic_dir
-            and self.topic.viewpoints
-            and (viewpoints := self.topic.viewpoints.view_point)
-        ):
-            self._viewpoints = VisualizationInfoHandler.from_topic_viewpoints(self._topic_dir, viewpoints)
+        if self._viewpoints is None:
+            self._viewpoints = self._load_viewpoints()
         return self._viewpoints
 
+    def _load_viewpoints(self) -> dict[str, "VisualizationInfoHandler"]:
+        if self._topic_dir and self.topic.viewpoints and (viewpoints := self.topic.viewpoints.view_point):
+            return VisualizationInfoHandler.from_topic_viewpoints(self._topic_dir, viewpoints)
+        return {}
+
     def _load_bim_snippet(self) -> Optional[bytes]:
         bim_snippet_obj = self.topic.bim_snippet
         if bim_snippet_obj and not bim_snippet_obj.is_external and self._topic_dir: