diff --git a/src/blenderbim/blenderbim/bim/module/cost/data.py b/src/blenderbim/blenderbim/bim/module/cost/data.py
index b1a7d6f365..61bf88ddc3 100644
--- a/src/blenderbim/blenderbim/bim/module/cost/data.py
+++ b/src/blenderbim/blenderbim/bim/module/cost/data.py
@@ -19,10 +19,13 @@
 import bpy
 import ifcopenshell
 import ifcopenshell.util.cost
+import ifcopenshell.util.date
 import ifcopenshell.util.element
+import ifcopenshell.util.unit
 import blenderbim.tool as tool
 import blenderbim.bim.schema
 from ifcopenshell.util.doc import get_entity_doc, get_predefined_type_doc
+from typing import Any
 
 
 def refresh():
@@ -34,6 +37,7 @@ def refresh():
 class CostSchedulesData:
     data = {}
     is_loaded = False
+    _cost_values: dict[int, dict[str, Any]]
 
     @classmethod
     def load(cls):
diff --git a/src/blenderbim/blenderbim/bim/module/model/opening.py b/src/blenderbim/blenderbim/bim/module/model/opening.py
index 1d55fb305d..5a7e517d71 100644
--- a/src/blenderbim/blenderbim/bim/module/model/opening.py
+++ b/src/blenderbim/blenderbim/bim/module/model/opening.py
@@ -44,6 +44,7 @@ from bpy.types import SpaceView3D
 from bpy.props import FloatProperty
 from bpy_extras.object_utils import AddObjectHelper, object_data_add
 from gpu_extras.batch import batch_for_shader
+from typing import Union, Optional, Any
 
 
 class AddFilledOpening(bpy.types.Operator, tool.Ifc.Operator):
@@ -59,7 +60,12 @@ class AddFilledOpening(bpy.types.Operator, tool.Ifc.Operator):
 
 
 class FilledOpeningGenerator:
-    def generate(self, filling_obj, voided_obj, target=None):
+    def generate(
+        self,
+        filling_obj: Union[bpy.types.Object, None],
+        voided_obj: Union[bpy.types.Object, None],
+        target: Optional[Vector] = None,
+    ) -> None:
         props = bpy.context.scene.BIMModelProperties
         unit_scale = ifcopenshell.util.unit.calculate_unit_scale(tool.Ifc.get())
 
@@ -187,7 +193,7 @@ class FilledOpeningGenerator:
                     should_sync_changes_first=False,
                 )
 
-    def regenerate_from_type(self, usecase_path, ifc_file, settings):
+    def regenerate_from_type(self, usecase_path: str, ifc_file: ifcopenshell.file, settings: dict[str, Any]) -> None:
         relating_type = settings["relating_type"]
 
         for related_object in settings["related_objects"]:
@@ -252,7 +258,9 @@ class FilledOpeningGenerator:
                 should_sync_changes_first=False,
             )
 
-    def generate_opening_from_filling(self, filling, filling_obj):
+    def generate_opening_from_filling(
+        self, filling: ifcopenshell.entity_instance, filling_obj: bpy.types.Object
+    ) -> ifcopenshell.entity_instance:
         # Since openings are reused later, we give a default thickness of 1.2m
         # which should cover the majority of curved, or super thick walls.
         thickness = 1.2
@@ -346,7 +354,9 @@ class FilledOpeningGenerator:
                 return True
         return False
 
-    def get_existing_opening_occurrence_if_any(self, filling):
+    def get_existing_opening_occurrence_if_any(
+        self, filling: ifcopenshell.entity_instance
+    ) -> Union[ifcopenshell.entity_instance, None]:
         filling_type = ifcopenshell.util.element.get_type(filling)
         if filling_type:
             filling_occurrences = ifcopenshell.util.element.get_types(filling_type)
diff --git a/src/blenderbim/blenderbim/bim/module/pset_template/data.py b/src/blenderbim/blenderbim/bim/module/pset_template/data.py
index 96c17cc712..77b6685a36 100644
--- a/src/blenderbim/blenderbim/bim/module/pset_template/data.py
+++ b/src/blenderbim/blenderbim/bim/module/pset_template/data.py
@@ -21,6 +21,7 @@ import bpy
 import pathlib
 import ifcopenshell
 import ifcopenshell.util.attribute
+import ifcopenshell.util.doc
 import blenderbim.tool as tool
 from blenderbim.bim.ifc import IfcStore
 
diff --git a/src/blenderbim/blenderbim/core/cost.py b/src/blenderbim/blenderbim/core/cost.py
index e703844b23..f23cb60a49 100644
--- a/src/blenderbim/blenderbim/core/cost.py
+++ b/src/blenderbim/blenderbim/core/cost.py
@@ -109,7 +109,9 @@ def edit_cost_item(ifc: tool.Ifc, cost: tool.Cost):
     cost.load_cost_schedule_tree()
 
 
-def assign_cost_item_type(ifc: tool.Ifc, cost: tool.Cost, spatial: tool.Spatial, cost_item, prop_name):
+def assign_cost_item_type(
+    ifc: tool.Ifc, cost: tool.Cost, spatial: tool.Spatial, cost_item: ifcopenshell.entity_instance, prop_name
+):
     product_types = spatial.get_selected_product_types()
     [
         ifc.run("control.assign_control", relating_control=cost_item, related_object=product_type)
@@ -118,7 +120,9 @@ def assign_cost_item_type(ifc: tool.Ifc, cost: tool.Cost, spatial: tool.Spatial,
     cost.load_cost_item_types(cost_item)
 
 
-def unassign_cost_item_type(ifc: tool.Ifc, cost: tool.Cost, spatial: tool.Spatial, cost_item, product_types):
+def unassign_cost_item_type(
+    ifc: tool.Ifc, cost: tool.Cost, spatial: tool.Spatial, cost_item: ifcopenshell.entity_instance, product_types
+):
     if not product_types:
         product_types = spatial.get_selected_product_types()
     [
@@ -133,7 +137,9 @@ def load_cost_item_types(cost: tool.Cost):
     cost.load_cost_item_types(cost_item)
 
 
-def assign_cost_item_quantity(ifc: tool.Ifc, cost: tool.Cost, cost_item, related_object_type, prop_name):
+def assign_cost_item_quantity(
+    ifc: tool.Ifc, cost: tool.Cost, cost_item: ifcopenshell.entity_instance, related_object_type, prop_name
+):
     products = cost.get_products(related_object_type)
     if products:
         ifc.run("cost.assign_cost_item_quantity", cost_item=cost_item, products=products, prop_name=prop_name)
@@ -159,7 +165,7 @@ def load_cost_item_resource_quantities(cost: tool.Cost):
     cost.load_cost_item_quantity_assignments(cost_item, related_object_type="RESOURCE")
 
 
-def assign_cost_value(ifc: tool.Ifc, cost_item, cost_rate):
+def assign_cost_value(ifc: tool.Ifc, cost_item: ifcopenshell.entity_instance, cost_rate):
     ifc.run("cost.assign_cost_value", cost_item=cost_item, cost_rate=cost_rate)
 
 
@@ -167,7 +173,7 @@ def load_schedule_of_rates(cost: tool.Cost, schedule_of_rates):
     cost.load_schedule_of_rates_tree(schedule_of_rates)
 
 
-def unassign_cost_item_quantity(ifc: tool.Ifc, cost: tool.Cost, cost_item, products):
+def unassign_cost_item_quantity(ifc: tool.Ifc, cost: tool.Cost, cost_item: ifcopenshell.entity_instance, products):
     ifc.run("cost.unassign_cost_item_quantity", cost_item=cost_item, products=products)
     cost.load_cost_item_quantities()
 
@@ -180,11 +186,11 @@ def enable_editing_cost_item_values(cost: tool.Cost, cost_item: ifcopenshell.ent
     cost.enable_editing_cost_item_values(cost_item)
 
 
-def add_cost_item_quantity(ifc: tool.Ifc, cost_item, ifc_class):
+def add_cost_item_quantity(ifc: tool.Ifc, cost_item: ifcopenshell.entity_instance, ifc_class):
     ifc.run("cost.add_cost_item_quantity", cost_item=cost_item, ifc_class=ifc_class)
 
 
-def remove_cost_item_quantity(ifc: tool.Ifc, cost_item, physical_quantity):
+def remove_cost_item_quantity(ifc: tool.Ifc, cost_item: ifcopenshell.entity_instance, physical_quantity):
     ifc.run("cost.remove_cost_item_quantity", cost_item=cost_item, physical_quantity=physical_quantity)
 
 
@@ -288,7 +294,9 @@ def export_cost_schedules(cost: tool.Cost, filepath, format, cost_schedule=None)
     return cost.export_cost_schedules(filepath, format, cost_schedule)
 
 
-def clear_cost_item_assignments(ifc: tool.Ifc, cost: tool.Cost, cost_item, related_object_type):
+def clear_cost_item_assignments(
+    ifc: tool.Ifc, cost: tool.Cost, cost_item: ifcopenshell.entity_instance, related_object_type
+):
     products = cost.get_cost_item_assignments(cost_item, filter_by_type=related_object_type)
     if products:
         ifc.run("cost.unassign_cost_item_quantity", cost_item=cost_item, products=products)
diff --git a/src/blenderbim/blenderbim/core/drawing.py b/src/blenderbim/blenderbim/core/drawing.py
index f52fc2e1c5..582a80551b 100644
--- a/src/blenderbim/blenderbim/core/drawing.py
+++ b/src/blenderbim/blenderbim/core/drawing.py
@@ -16,36 +16,44 @@
 # You should have received a copy of the GNU General Public License
 # along with BlenderBIM Add-on.  If not, see <http://www.gnu.org/licenses/>.
 
+from __future__ import annotations
 from pathlib import Path
-import ifcopenshell
+from typing import TYPE_CHECKING, Optional
+
+if TYPE_CHECKING:
+    import bpy
+    import ifcopenshell
+    import blenderbim.tool as tool
 
 
-def enable_editing_text(drawing, obj=None):
+def enable_editing_text(drawing: tool.Drawing, obj: bpy.types.Object) -> None:
     drawing.enable_editing_text(obj)
     drawing.import_text_attributes(obj)
 
 
-def disable_editing_text(drawing, obj=None):
+def disable_editing_text(drawing: tool.Drawing, obj: bpy.types.Object) -> None:
     drawing.disable_editing_text(obj)
 
 
-def edit_text(drawing, obj=None):
+def edit_text(drawing: tool.Drawing, obj: bpy.types.Object) -> None:
     drawing.synchronise_ifc_and_text_attributes(obj)
     drawing.update_text_size_pset(obj)
     drawing.update_text_value(obj)
     drawing.disable_editing_text(obj)
 
 
-def enable_editing_assigned_product(drawing, obj=None):
+def enable_editing_assigned_product(drawing: tool.Drawing, obj: bpy.types.Object) -> None:
     drawing.enable_editing_assigned_product(obj)
     drawing.import_assigned_product(obj)
 
 
-def disable_editing_assigned_product(drawing, obj=None):
+def disable_editing_assigned_product(drawing: tool.Drawing, obj: bpy.types.Object) -> None:
     drawing.disable_editing_assigned_product(obj)
 
 
-def edit_assigned_product(ifc, drawing, obj=None, product=None):
+def edit_assigned_product(
+    ifc: tool.Ifc, drawing: tool.Drawing, obj: bpy.types.Object, product: Optional[ifcopenshell.entity_instance] = None
+) -> None:
     element = ifc.get_entity(obj)
     existing_product = drawing.get_assigned_product(element)
     if existing_product != product:
@@ -58,16 +66,16 @@ def edit_assigned_product(ifc, drawing, obj=None, product=None):
     drawing.disable_editing_assigned_product(obj)
 
 
-def load_sheets(drawing):
+def load_sheets(drawing: tool.Drawing) -> None:
     drawing.import_sheets()
     drawing.enable_editing_sheets()
 
 
-def disable_editing_sheets(drawing):
+def disable_editing_sheets(drawing: tool.Drawing) -> None:
     drawing.disable_editing_sheets()
 
 
-def add_sheet(ifc, drawing, titleblock: ifcopenshell.entity_instance):
+def add_sheet(ifc: tool.Ifc, drawing, titleblock: ifcopenshell.entity_instance) -> None:
     sheet = ifc.run("document.add_information")
     layout = ifc.run("document.add_reference", information=sheet)
     titleblock_reference = ifc.run("document.add_reference", information=sheet)
@@ -93,7 +101,7 @@ def add_sheet(ifc, drawing, titleblock: ifcopenshell.entity_instance):
     drawing.import_sheets()
 
 
-def regenerate_sheet(drawing, sheet=None):
+def regenerate_sheet(drawing: tool.Drawing, sheet: ifcopenshell.entity_instance) -> None:
     titleblock_uri = drawing.get_document_uri(sheet, "TITLEBLOCK")
     drawing.create_svg_sheet(sheet, drawing.sanitise_filename(Path(titleblock_uri).stem))
     try:
@@ -104,11 +112,11 @@ def regenerate_sheet(drawing, sheet=None):
             drawing.delete_file(path_layout)
 
 
-def open_sheet(drawing, sheet=None):
+def open_sheet(drawing: tool.Drawing, sheet: ifcopenshell.entity_instance) -> None:
     drawing.open_layout_svg(drawing.get_document_uri(sheet, "LAYOUT"))
 
 
-def remove_sheet(ifc, drawing, sheet=None):
+def remove_sheet(ifc: tool.Ifc, drawing: tool.Drawing, sheet: ifcopenshell.entity_instance) -> None:
     for reference in drawing.get_document_references(sheet):
         if drawing.get_reference_description(reference) in ("LAYOUT", "SHEET", "REVISION", "RASTER"):
             uri = ifc.resolve_uri(drawing.get_document_uri(reference))
@@ -118,7 +126,7 @@ def remove_sheet(ifc, drawing, sheet=None):
     drawing.import_sheets()
 
 
-def rename_sheet(ifc, drawing, sheet: ifcopenshell.entity_instance, identification: str, name: str) -> None:
+def rename_sheet(ifc: tool.Ifc, drawing, sheet: ifcopenshell.entity_instance, identification: str, name: str) -> None:
     if ifc.get_schema() == "IFC2X3":
         attributes = {"DocumentId": identification, "Name": name}
     else:
@@ -144,30 +152,32 @@ def rename_sheet(ifc, drawing, sheet: ifcopenshell.entity_instance, identificati
                     drawing.move_file(old_location, ifc.resolve_uri(new_location))
 
 
-def rename_reference(ifc, drawing, reference=None, identification=None):
+def rename_reference(
+    ifc: tool.Ifc, drawing: tool.Drawing, reference: ifcopenshell.entity_instance, identification: str
+) -> None:
     attributes = drawing.generate_reference_attributes(reference, Identification=identification)
     ifc.run("document.edit_reference", reference=reference, attributes=attributes)
 
 
-def load_schedules(drawing):
+def load_schedules(drawing: tool.Drawing) -> None:
     drawing.import_documents("SCHEDULE")
     drawing.enable_editing_schedules()
 
 
-def load_references(drawing):
+def load_references(drawing: tool.Drawing) -> None:
     drawing.import_documents("REFERENCE")
     drawing.enable_editing_references()
 
 
-def disable_editing_schedules(drawing):
+def disable_editing_schedules(drawing: tool.Drawing) -> None:
     drawing.disable_editing_schedules()
 
 
-def disable_editing_references(drawing):
+def disable_editing_references(drawing: tool.Drawing) -> None:
     drawing.disable_editing_references()
 
 
-def add_document(ifc, drawing, document_type, uri=None):
+def add_document(ifc: tool.Ifc, drawing: tool.Drawing, document_type: tool.Drawing.DOCUMENT_TYPE, uri: str) -> None:
     document = ifc.run("document.add_information")
     reference = ifc.run("document.add_reference", information=document)
     name = drawing.get_path_filename(uri)
@@ -180,34 +190,43 @@ def add_document(ifc, drawing, document_type, uri=None):
     drawing.import_documents(document_type)
 
 
-def remove_document(ifc, drawing, document_type, document=None):
+def remove_document(
+    ifc: tool.Ifc,
+    drawing: tool.Drawing,
+    document_type: tool.Drawing.DOCUMENT_TYPE,
+    document: ifcopenshell.entity_instance,
+) -> None:
     ifc.run("document.remove_information", information=document)
     drawing.import_documents(document_type)
 
 
-def open_schedule(drawing, schedule=None):
+def open_schedule(drawing: tool.Drawing, schedule: ifcopenshell.entity_instance) -> None:
     drawing.open_spreadsheet(drawing.get_document_uri(schedule))
 
 
-def open_reference(drawing, reference=None):
+def open_reference(drawing: tool.Drawing, reference: ifcopenshell.entity_instance) -> None:
     drawing.open_svg(drawing.get_document_uri(reference))
 
 
-def update_document_name(ifc, drawing, document=None, name=None):
+def update_document_name(
+    ifc: tool.Ifc, drawing: tool.Drawing, document: ifcopenshell.entity_instance, name=None
+) -> None:
     if drawing.get_name(document) != name:
         ifc.run("document.edit_information", information=document, attributes={"Name": name})
 
 
-def load_drawings(drawing):
+def load_drawings(drawing: tool.Drawing) -> None:
     drawing.import_drawings()
     drawing.enable_editing_drawings()
 
 
-def disable_editing_drawings(drawing):
+def disable_editing_drawings(drawing: tool.Drawing) -> None:
     drawing.disable_editing_drawings()
 
 
-def add_drawing(ifc, collector, drawing, target_view=None, location_hint=None):
+def add_drawing(
+    ifc: tool.Ifc, collector: tool.Collector, drawing: tool.Drawing, target_view=None, location_hint=None
+) -> None:
     drawing_name = drawing.ensure_unique_drawing_name(drawing.generate_drawing_name(target_view, location_hint))
     drawing_matrix = drawing.generate_drawing_matrix(target_view, location_hint)
     camera = drawing.create_camera(drawing_name, drawing_matrix, location_hint)
@@ -265,7 +284,12 @@ def add_drawing(ifc, collector, drawing, target_view=None, location_hint=None):
     drawing.import_drawings()
 
 
-def duplicate_drawing(ifc, drawing_tool, drawing=None, should_duplicate_annotations=False):
+def duplicate_drawing(
+    ifc: tool.Ifc,
+    drawing_tool: tool.Drawing,
+    drawing: ifcopenshell.entity_instance,
+    should_duplicate_annotations: bool = False,
+) -> ifcopenshell.entity_instance:
     drawing_name = drawing_tool.ensure_unique_drawing_name(drawing_tool.get_name(drawing))
     new_drawing = ifc.run("root.copy_class", product=drawing)
     drawing_tool.copy_representation(drawing, new_drawing)
@@ -302,7 +326,7 @@ def duplicate_drawing(ifc, drawing_tool, drawing=None, should_duplicate_annotati
     return new_drawing
 
 
-def remove_drawing(ifc, drawing_tool, drawing=None):
+def remove_drawing(ifc: tool.Ifc, drawing_tool: tool.Drawing, drawing: ifcopenshell.entity_instance) -> None:
     if drawing_tool.is_active_drawing(drawing):
         drawing_tool.run_drawing_activate_model()
 
@@ -330,7 +354,9 @@ def remove_drawing(ifc, drawing_tool, drawing=None):
     drawing_tool.import_drawings()
 
 
-def update_drawing_name(ifc, drawing_tool, drawing=None, name=None):
+def update_drawing_name(
+    ifc: tool.Ifc, drawing_tool: tool.Drawing, drawing: ifcopenshell.entity_instance, name=None
+) -> None:
     if drawing_tool.get_name(drawing) != name:
         ifc.run("attribute.edit_attributes", product=drawing, attributes={"Name": name})
     group = drawing_tool.get_drawing_group(drawing)
@@ -364,7 +390,13 @@ def update_drawing_name(ifc, drawing_tool, drawing=None, name=None):
             drawing_tool.import_sheets()
 
 
-def add_annotation(ifc, collector, drawing_tool, drawing=None, object_type=None):
+def add_annotation(
+    ifc: tool.Ifc,
+    collector: tool.Collector,
+    drawing_tool: tool.Drawing,
+    drawing: ifcopenshell.entity_instance,
+    object_type: str,
+) -> None:
     target_view = drawing_tool.get_drawing_target_view(drawing)
     context = drawing_tool.get_annotation_context(target_view, object_type)
     if not context:
@@ -387,12 +419,14 @@ def add_annotation(ifc, collector, drawing_tool, drawing=None, object_type=None)
     drawing_tool.enable_editing(obj)
 
 
-def build_schedule(drawing, schedule=None):
+def build_schedule(drawing: tool.Drawing, schedule: ifcopenshell.entity_instance) -> None:
     drawing.create_svg_schedule(schedule)
     drawing.open_svg(drawing.get_path_with_ext(drawing.get_document_uri(schedule), "svg"))
 
 
-def sync_references(ifc, collector, drawing_tool, drawing=None):
+def sync_references(
+    ifc: tool.Ifc, collector: tool.Collector, drawing_tool: tool.Drawing, drawing: ifcopenshell.entity_instance
+) -> None:
     if not drawing_tool.has_annotation(drawing):
         return
 
@@ -437,11 +471,13 @@ def sync_references(ifc, collector, drawing_tool, drawing=None):
             drawing_tool.sync_object_representation(reference_obj)
 
 
-def select_assigned_product(drawing, context):
+def select_assigned_product(drawing: tool.Drawing, context: bpy.types.Context) -> None:
     drawing.select_assigned_product(context)
 
 
-def activate_drawing_view(ifc, blender, drawing_tool, drawing):
+def activate_drawing_view(
+    ifc: tool.Ifc, blender: tool.Blender, drawing_tool: tool.Drawing, drawing: ifcopenshell.entity_instance
+) -> None:
     camera = ifc.get_object(drawing)
     if not camera:
         camera = drawing_tool.import_drawing(drawing)
diff --git a/src/blenderbim/blenderbim/tool/blender.py b/src/blenderbim/blenderbim/tool/blender.py
index d5055bf9bf..64fa9bf40f 100644
--- a/src/blenderbim/blenderbim/tool/blender.py
+++ b/src/blenderbim/blenderbim/tool/blender.py
@@ -468,7 +468,7 @@ class Blender(blenderbim.core.tool.Blender):
             active_object.select_set(True)
 
     @classmethod
-    def enum_property_has_valid_index(cls, props, prop_name: str, enum_items: tuple) -> bool:
+    def enum_property_has_valid_index(cls, props: bpy.types.PropertyGroup, prop_name: str, enum_items: tuple) -> bool:
         """method created for readibility and to avoid console warnings like
         `pyrna_enum_to_py: current value '17' matches no enum in 'BIMModelProperties', '', 'relating_type_id'`
         """
diff --git a/src/blenderbim/blenderbim/tool/cost.py b/src/blenderbim/blenderbim/tool/cost.py
index 01a392e727..2ce904b018 100644
--- a/src/blenderbim/blenderbim/tool/cost.py
+++ b/src/blenderbim/blenderbim/tool/cost.py
@@ -1,11 +1,13 @@
 import os
 import bpy
+import blenderbim.core.tool
 import blenderbim.tool as tool
 import ifcopenshell.util.date
 import ifcopenshell.util.cost
 import ifcopenshell.util.unit
 import blenderbim.bim.helper
 import json
+from typing import Optional
 
 
 class Cost(blenderbim.core.tool.Cost):
@@ -163,7 +165,7 @@ class Cost(blenderbim.core.tool.Cost):
         return
 
     @classmethod
-    def load_cost_item_types(cls, cost_item=None):
+    def load_cost_item_types(cls, cost_item: Optional[ifcopenshell.entity_instance] = None) -> None:
         if not cost_item:
             cost_item = cls.get_highlighted_cost_item()
             if not cost_item:
diff --git a/src/blenderbim/blenderbim/tool/drawing.py b/src/blenderbim/blenderbim/tool/drawing.py
index a223186670..d2a8f96aca 100644
--- a/src/blenderbim/blenderbim/tool/drawing.py
+++ b/src/blenderbim/blenderbim/tool/drawing.py
@@ -51,11 +51,14 @@ from blenderbim.bim.module.drawing.prop import get_diagram_scales, BOX_ALIGNMENT
 from lxml import etree
 from mathutils import Vector, Matrix
 from fractions import Fraction
-from typing import Optional, Union, Iterable, Any
+from typing import Optional, Union, Iterable, Any, Literal
 from pathlib import Path
 
 
 class Drawing(blenderbim.core.tool.Drawing):
+    ANNOTATION_DATA_TYPE = Literal["empty", "curve", "mesh"]
+    DOCUMENT_TYPE = Literal["SCHEDULE", "REFERENCE"]
+
     @classmethod
     def canonicalise_class_name(cls, name):
         return re.sub("[^0-9a-zA-Z]+", "", name)
@@ -68,11 +71,11 @@ class Drawing(blenderbim.core.tool.Drawing):
             )
 
     @classmethod
-    def get_annotation_data_type(cls, object_type):
+    def get_annotation_data_type(cls, object_type: str) -> ANNOTATION_DATA_TYPE:
         return ANNOTATION_TYPES_DATA[object_type][3]
 
     @classmethod
-    def create_annotation_object(cls, drawing, object_type):
+    def create_annotation_object(cls, drawing: ifcopenshell.entity_instance, object_type: str) -> bpy.types.Object:
         data_type = cls.get_annotation_data_type(object_type)
         obj = annotation.Annotator.get_annotation_obj(drawing, object_type, data_type)
         if object_type == "FILL_AREA":
@@ -298,15 +301,15 @@ class Drawing(blenderbim.core.tool.Drawing):
         bpy.context.scene.DocProperties.is_editing_sheets = False
 
     @classmethod
-    def disable_editing_text(cls, obj):
+    def disable_editing_text(cls, obj: bpy.types.Object) -> None:
         obj.BIMTextProperties.is_editing = False
 
     @classmethod
-    def disable_editing_assigned_product(cls, obj):
+    def disable_editing_assigned_product(cls, obj: bpy.types.Object) -> None:
         obj.BIMAssignedProductProperties.is_editing_product = False
 
     @classmethod
-    def enable_editing(cls, obj):
+    def enable_editing(cls, obj: bpy.types.Object) -> None:
         bpy.ops.object.select_all(action="DESELECT")
         bpy.context.view_layer.objects.active = obj
         obj.select_set(True)
@@ -330,11 +333,11 @@ class Drawing(blenderbim.core.tool.Drawing):
         bpy.context.scene.DocProperties.is_editing_sheets = True
 
     @classmethod
-    def enable_editing_text(cls, obj):
+    def enable_editing_text(cls, obj: bpy.types.Object) -> None:
         obj.BIMTextProperties.is_editing = True
 
     @classmethod
-    def enable_editing_assigned_product(cls, obj):
+    def enable_editing_assigned_product(cls, obj: bpy.types.Object) -> None:
         obj.BIMAssignedProductProperties.is_editing_product = True
 
     @classmethod
@@ -428,7 +431,7 @@ class Drawing(blenderbim.core.tool.Drawing):
                     return location
 
     @classmethod
-    def get_path_filename(cls, path):
+    def get_path_filename(cls, path: str) -> str:
         return os.path.splitext(os.path.basename(path))[0]
 
     @classmethod
@@ -483,7 +486,7 @@ class Drawing(blenderbim.core.tool.Drawing):
         return ""
 
     @classmethod
-    def get_name(cls, element):
+    def get_name(cls, element: ifcopenshell.entity_instance) -> Union[str, None]:
         return element.Name
 
     @classmethod
@@ -563,7 +566,7 @@ class Drawing(blenderbim.core.tool.Drawing):
         ifcopenshell.util.element.remove_deep2(ifc_file, literal)
 
     @classmethod
-    def synchronise_ifc_and_text_attributes(cls, obj):
+    def synchronise_ifc_and_text_attributes(cls, obj: bpy.types.Object) -> None:
         literals = cls.get_text_literal(obj, return_list=True)
         literals_attributes = cls.export_text_literal_attributes(obj)
         defined_ifc_ids = [l.ifc_definition_id for l in obj.BIMTextProperties.literals]
@@ -784,7 +787,7 @@ class Drawing(blenderbim.core.tool.Drawing):
                 new.ifc_definition_id = drawing.id()  # Last, to prevent unnecessary prop callbacks
 
     @classmethod
-    def import_documents(cls, document_type):
+    def import_documents(cls, document_type: DOCUMENT_TYPE) -> None:
         dprops = bpy.context.scene.DocProperties
         if document_type == "SCHEDULE":
             documents_collection = dprops.schedules
@@ -845,7 +848,7 @@ class Drawing(blenderbim.core.tool.Drawing):
         return next(s for s in props.sheets[: props.active_sheet_index + 1][::-1] if s.is_sheet)
 
     @classmethod
-    def import_text_attributes(cls, obj):
+    def import_text_attributes(cls, obj: bpy.types.Object) -> None:
         props = obj.BIMTextProperties
         props.literals.clear()
 
@@ -863,7 +866,7 @@ class Drawing(blenderbim.core.tool.Drawing):
         props.font_size = str(text_data["FontSize"])
 
     @classmethod
-    def import_assigned_product(cls, obj):
+    def import_assigned_product(cls, obj: bpy.types.Object) -> None:
         element = tool.Ifc.get_entity(obj)
         product = cls.get_assigned_product(element)
         if product:
@@ -934,7 +937,7 @@ class Drawing(blenderbim.core.tool.Drawing):
         bpy.context.scene.DocProperties.should_draw_decorations = True
 
     @classmethod
-    def update_text_value(cls, obj):
+    def update_text_value(cls, obj: bpy.types.Object) -> None:
         props = obj.BIMTextProperties
         literals = cls.get_text_literal(obj, return_list=True)
         cls.import_text_attributes(obj)
@@ -943,7 +946,7 @@ class Drawing(blenderbim.core.tool.Drawing):
             props.literals[i].value = cls.replace_text_literal_variables(literal.Literal, product)
 
     @classmethod
-    def update_text_size_pset(cls, obj):
+    def update_text_size_pset(cls, obj: bpy.types.Object) -> None:
         """updates pset `EPset_Annotation.Classes` value
         based on current font size from `obj.BIMTextProperties.font_size`
         """
@@ -1522,7 +1525,7 @@ class Drawing(blenderbim.core.tool.Drawing):
         tool.Geometry.record_object_position(obj)
 
     @classmethod
-    def get_document_references(cls, document):
+    def get_document_references(cls, document: ifcopenshell.entity_instance) -> list[ifcopenshell.entity_instance]:
         if tool.Ifc.get_schema() == "IFC2X3":
             return document.DocumentReferences or []
         return document.HasDocumentReferences or []
@@ -1553,7 +1556,9 @@ class Drawing(blenderbim.core.tool.Drawing):
         return reference.Description
 
     @classmethod
-    def generate_reference_attributes(cls, reference: ifcopenshell.entity_instance, **attributes: Any) -> dict[str, Any]:
+    def generate_reference_attributes(
+        cls, reference: ifcopenshell.entity_instance, **attributes: Any
+    ) -> dict[str, Any]:
         """will automatically convert attributes below for IFC2X3 compatibility:
 
         - Identification -> ItemReference
@@ -1635,23 +1640,22 @@ class Drawing(blenderbim.core.tool.Drawing):
                 base_elements = set(ifc_file.by_type("IfcElement") + ifc_file.by_type("IfcSpatialElement"))
             elements = {e for e in (elements & base_elements) if e.is_a() != "IfcSpace"}
 
-        
         updated_set = set()
 
         for i in elements:
             # exclude annotations to avoid including annotations from other drawings
-            if not i.is_a("IfcAnnotation"): 
+            if not i.is_a("IfcAnnotation"):
                 updated_set.add(i)
-                #add aggregate too, if element is host by one
+                # add aggregate too, if element is host by one
                 if i.Decomposes:
                     aggregate = i.Decomposes[0].RelatingObject
-                    #remove IfcProject for class iterator. See https://github.com/IfcOpenShell/IfcOpenShell/issues/4361#issuecomment-2081223615
-                    if not aggregate.is_a("IfcProject"): 
+                    # remove IfcProject for class iterator. See https://github.com/IfcOpenShell/IfcOpenShell/issues/4361#issuecomment-2081223615
+                    if not aggregate.is_a("IfcProject"):
                         updated_set.add(aggregate)
 
-        # After the iteration is complete, update elements with updated set 
+        # After the iteration is complete, update elements with updated set
         elements.update(updated_set)
-            
+
         # add annotations from the current drawing
         annotations = tool.Drawing.get_group_elements(tool.Drawing.get_drawing_group(drawing))
         elements.update(annotations)
@@ -1694,7 +1698,7 @@ class Drawing(blenderbim.core.tool.Drawing):
         return reference.ReferencedDocument
 
     @classmethod
-    def select_assigned_product(cls, context):
+    def select_assigned_product(cls, context: bpy.types.Context) -> None:
         obj = context.active_object
         element = tool.Ifc.get_entity(obj)
         product = cls.get_assigned_product(element)
@@ -1713,7 +1717,7 @@ class Drawing(blenderbim.core.tool.Drawing):
         return True if (camera and camera.data.type == "ORTHO") else False
 
     @classmethod
-    def is_active_drawing(cls, drawing):
+    def is_active_drawing(cls, drawing: ifcopenshell.entity_instance) -> bool:
         return drawing.id() == bpy.context.scene.DocProperties.active_drawing_id
 
     @classmethod
diff --git a/src/blenderbim/blenderbim/tool/geometry.py b/src/blenderbim/blenderbim/tool/geometry.py
index 2d81ba415a..8031433e21 100644
--- a/src/blenderbim/blenderbim/tool/geometry.py
+++ b/src/blenderbim/blenderbim/tool/geometry.py
@@ -90,7 +90,7 @@ class Geometry(blenderbim.core.tool.Geometry):
         bpy.data.meshes.remove(data)
 
     @classmethod
-    def delete_ifc_object(cls, obj):
+    def delete_ifc_object(cls, obj: bpy.types.Object) -> None:
         element = tool.Ifc.get_entity(obj)
         if not element:
             return
diff --git a/src/blenderbim/blenderbim/tool/model.py b/src/blenderbim/blenderbim/tool/model.py
index 4025d37d39..d0c63912d4 100644
--- a/src/blenderbim/blenderbim/tool/model.py
+++ b/src/blenderbim/blenderbim/tool/model.py
@@ -23,6 +23,7 @@ import collections
 import collections.abc
 import numpy as np
 import ifcopenshell
+import ifcopenshell.util.element
 import ifcopenshell.util.unit
 import ifcopenshell.util.placement
 import ifcopenshell.util.representation
@@ -468,7 +469,7 @@ class Model(blenderbim.core.tool.Model):
                     has_deleted_opening = True
 
     @classmethod
-    def get_material_layer_parameters(cls, element):
+    def get_material_layer_parameters(cls, element: ifcopenshell.entity_instance) -> dict[str, Any]:
         unit_scale = ifcopenshell.util.unit.calculate_unit_scale(tool.Ifc.get())
         layer_set_direction = "AXIS2"
         offset = 0.0
diff --git a/src/blenderbim/blenderbim/tool/spatial.py b/src/blenderbim/blenderbim/tool/spatial.py
index 68c1d8c0e8..101d17e454 100644
--- a/src/blenderbim/blenderbim/tool/spatial.py
+++ b/src/blenderbim/blenderbim/tool/spatial.py
@@ -31,6 +31,7 @@ import json
 from math import pi
 from mathutils import Vector, Matrix
 from shapely import Polygon, MultiPolygon
+from typing import Generator
 
 
 class Spatial(blenderbim.core.tool.Spatial):
@@ -187,14 +188,14 @@ class Spatial(blenderbim.core.tool.Spatial):
         ]
 
     @classmethod
-    def get_selected_products(cls):
+    def get_selected_products(cls) -> Generator[ifcopenshell.entity_instance, None, None]:
         for obj in bpy.context.selected_objects:
             entity = tool.Ifc.get_entity(obj)
             if entity and entity.is_a("IfcProduct"):
                 yield entity
 
     @classmethod
-    def get_selected_product_types(cls):
+    def get_selected_product_types(cls) -> Generator[ifcopenshell.entity_instance, None, None]:
         for obj in bpy.context.selected_objects:
             entity = tool.Ifc.get_entity(obj)
             if entity and entity.is_a("IfcTypeProduct"):
diff --git a/src/ifcopenshell-python/ifcopenshell/util/cost.py b/src/ifcopenshell-python/ifcopenshell/util/cost.py
index 4d15ee8f33..44852b6e9c 100644
--- a/src/ifcopenshell-python/ifcopenshell/util/cost.py
+++ b/src/ifcopenshell-python/ifcopenshell/util/cost.py
@@ -17,13 +17,15 @@
 # along with IfcOpenShell.  If not, see <http://www.gnu.org/licenses/>.
 
 import lark
+import ifcopenshell
+from typing import Optional, Union
 
 
 arithmetic_operator_symbols = {"ADD": "+", "DIVIDE": "/", "MULTIPLY": "*", "SUBTRACT": "-"}
 symbol_arithmetic_operators = {"+": "ADD", "/": "DIVIDE", "*": "MULTIPLY", "-": "SUBTRACT"}
 
 
-def get_primitive_applied_value(applied_value):
+def get_primitive_applied_value(applied_value: Union[ifcopenshell.entity_instance, float, None]) -> float:
     if not applied_value:
         return 0.0
     elif isinstance(applied_value, float):
@@ -32,17 +34,21 @@ def get_primitive_applied_value(applied_value):
         return applied_value.wrappedValue
     elif applied_value.is_a("IfcMeasureWithUnit"):
         return applied_value.ValueComponent
-    assert False, "Applied value {applied_value} not implemented"
+    assert False, f"Applied value {applied_value} not implemented"
 
 
-def get_total_quantity(root_element):
+def get_total_quantity(root_element: ifcopenshell.entity_instance) -> Union[float, None]:
+    # 3 IfcPhysicalQuantity Value
     if root_element.is_a("IfcCostItem"):
         return sum([q[3] for q in root_element.CostQuantities or []]) or None
     elif root_element.is_a("IfcConstructionResource"):
-        return root_element.BaseQuantity[3] if root_element.BaseQuantity else 1.0
+        quantity = root_element.BaseQuantity
+        return quantity[3] if quantity else 1.0
 
 
-def calculate_applied_value(root_element, cost_value, category_filter=None):
+def calculate_applied_value(
+    root_element: ifcopenshell.entity_instance, cost_value: ifcopenshell.entity_instance, category_filter=None
+) -> float:
     if cost_value.ArithmeticOperator and cost_value.Components:
         component_values = []
         for component in cost_value.Components:
@@ -75,11 +81,11 @@ def calculate_applied_value(root_element, cost_value, category_filter=None):
             return sum_child_root_elements(root_element, category_filter=cost_value.Category)
         else:
             return get_primitive_applied_value(cost_value.AppliedValue)
-    return 0
+    return 0.0
 
 
-def sum_child_root_elements(root_element, category_filter=None):
-    result = 0
+def sum_child_root_elements(root_element: ifcopenshell.entity_instance, category_filter: Optional[str] = None) -> float:
+    result = 0.0
     for rel in root_element.IsNestedBy:
         for child_root_element in rel.RelatedObjects:
             if root_element.is_a("IfcCostItem"):
@@ -99,14 +105,14 @@ def sum_child_root_elements(root_element, category_filter=None):
     return result
 
 
-def serialise_cost_value(cost_value):
+def serialise_cost_value(cost_value: ifcopenshell.entity_instance) -> str:
     result = _serialise_cost_value(cost_value)
     if result and result[0] == "(" and result[-1] == ")":
         return result[1:-1]
     return result
 
 
-def _serialise_cost_value(cost_value):
+def _serialise_cost_value(cost_value: ifcopenshell.entity_instance) -> str:
     value = ""
     if cost_value.ArithmeticOperator and cost_value.Components:
         operator = arithmetic_operator_symbols[cost_value.ArithmeticOperator]
@@ -133,7 +139,7 @@ def _serialise_cost_value(cost_value):
     return value
 
 
-def serialise_applied_value(applied_value):
+def serialise_applied_value(applied_value: ifcopenshell.entity_instance) -> str:
     if applied_value.is_a("IfcMonetaryMeasure"):
         return str(applied_value.wrappedValue)
     return "?"