diff --git a/src/blenderbim/blenderbim/bim/module/cost/data.py b/src/blenderbim/blenderbim/bim/module/cost/data.py
index 1c424cb1d6..09698a54be 100644
--- a/src/blenderbim/blenderbim/bim/module/cost/data.py
+++ b/src/blenderbim/blenderbim/bim/module/cost/data.py
@@ -198,8 +198,11 @@ class CostSchedulesData:
         #             data["DerivedUnitSymbol"] = "?"
         #         print("Total Cost", data["DerivedTotalCostQuantity"], cost_item.Name)
 
+    # TODO: dead code?
     @classmethod
-    def _get_object_quantities(cls, cost_item, element):
+    def _get_object_quantities(
+        cls, cost_item: ifcopenshell.entity_instance, element: ifcopenshell.entity_instance
+    ) -> list[int]:
         if not element.is_a("IfcObject"):
             return []
         cost_quantities = cost_item.CostQuantities
diff --git a/src/blenderbim/blenderbim/bim/module/geometry/operator.py b/src/blenderbim/blenderbim/bim/module/geometry/operator.py
index a26831bff1..385ca383c9 100644
--- a/src/blenderbim/blenderbim/bim/module/geometry/operator.py
+++ b/src/blenderbim/blenderbim/bim/module/geometry/operator.py
@@ -28,6 +28,7 @@ import ifcopenshell.util.element
 import ifcopenshell.util.representation
 import ifcopenshell.util.placement
 import ifcopenshell.api
+import blenderbim.core.geometry
 import blenderbim.core.geometry as core
 import blenderbim.core.aggregate
 import blenderbim.core.style
diff --git a/src/blenderbim/blenderbim/bim/module/style/operator.py b/src/blenderbim/blenderbim/bim/module/style/operator.py
index e8b0479f9c..cf36eee95e 100644
--- a/src/blenderbim/blenderbim/bim/module/style/operator.py
+++ b/src/blenderbim/blenderbim/bim/module/style/operator.py
@@ -22,6 +22,7 @@ import blenderbim.bim.helper
 import blenderbim.bim.handler
 import blenderbim.tool as tool
 import blenderbim.core.style as core
+import ifcopenshell.api
 import ifcopenshell.util.representation
 from blenderbim.bim.module.style.prop import switch_shading
 from pathlib import Path
diff --git a/src/blenderbim/blenderbim/core/aggregate.py b/src/blenderbim/blenderbim/core/aggregate.py
index 58d10814a7..44d4444f79 100644
--- a/src/blenderbim/blenderbim/core/aggregate.py
+++ b/src/blenderbim/blenderbim/core/aggregate.py
@@ -16,16 +16,30 @@
 # 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 typing import TYPE_CHECKING, Optional, Union
 
-def enable_editing_aggregate(aggregator, obj=None):
+if TYPE_CHECKING:
+    import bpy
+    import ifcopenshell
+    import blenderbim.tool as tool
+
+
+def enable_editing_aggregate(aggregator: tool.Aggregate, obj: bpy.types.Object) -> None:
     aggregator.enable_editing(obj)
 
 
-def disable_editing_aggregate(aggregator, obj=None):
+def disable_editing_aggregate(aggregator: tool.Aggregate, obj: bpy.types.Object) -> None:
     aggregator.disable_editing(obj)
 
 
-def assign_object(ifc, aggregator, collector, relating_obj=None, related_obj=None):
+def assign_object(
+    ifc: tool.Ifc,
+    aggregator: tool.Aggregate,
+    collector: tool.Collector,
+    relating_obj: Optional[bpy.types.Object] = None,
+    related_obj: Optional[bpy.types.Object] = None,
+) -> Union[ifcopenshell.entity_instance, None]:
     if not aggregator.can_aggregate(relating_obj, related_obj):
         return
     rel = ifc.run(
@@ -37,7 +51,13 @@ def assign_object(ifc, aggregator, collector, relating_obj=None, related_obj=Non
     return rel
 
 
-def unassign_object(ifc, aggregate, collector, relating_obj=None, related_obj=None):
+def unassign_object(
+    ifc: tool.Ifc,
+    aggregate: tool.Aggregate,
+    collector: tool.Collector,
+    relating_obj: Optional[bpy.types.Object] = None,
+    related_obj: Optional[bpy.types.Object] = None,
+) -> None:
     related_element = ifc.get_entity(related_obj)
     container = aggregate.get_container(related_element)
     if not relating_obj:
@@ -52,7 +72,15 @@ def unassign_object(ifc, aggregate, collector, relating_obj=None, related_obj=No
         collector.assign(related_obj)
 
 
-def add_part_to_object(ifc, aggregator, collector, blender, obj, part_class, part_name=None):
+def add_part_to_object(
+    ifc: tool.Ifc,
+    aggregator: tool.Aggregate,
+    collector: tool.Collector,
+    blender: tool.Blender,
+    obj: bpy.types.Object,
+    part_class: str,
+    part_name: Optional[str] = None,
+) -> None:
     part_obj = blender.create_ifc_object(ifc_class=part_class, name=part_name)
     assign_object(ifc, aggregator, collector, relating_obj=obj, related_obj=part_obj)
     blender.set_active_object(obj)
diff --git a/src/blenderbim/blenderbim/core/material.py b/src/blenderbim/blenderbim/core/material.py
index bd3eb87748..5a33704ead 100644
--- a/src/blenderbim/blenderbim/core/material.py
+++ b/src/blenderbim/blenderbim/core/material.py
@@ -16,15 +16,33 @@
 # 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 typing import TYPE_CHECKING, Optional, Union
 
-def unlink_material(ifc, obj=None):
+if TYPE_CHECKING:
+    import bpy
+    import ifcopenshell
+    import blenderbim.tool as tool
+
+
+def unlink_material(ifc: tool.Ifc, obj: bpy.types.Material) -> None:
     ifc.unlink(obj=obj)
 
 
-def add_material(ifc, material, style, obj=None, name=None, category=None, description=None):
+def add_material(
+    ifc: tool.Ifc,
+    material: tool.Material,
+    style: tool.Style,
+    obj: Optional[bpy.types.Material] = None,
+    name: Optional[str] = None,
+    category: Optional[str] = None,
+    description: Optional[str] = None,
+) -> ifcopenshell.entity_instance:
     if not obj:
         obj = material.add_default_material_object(name)
-    ifc_material = ifc.run("material.add_material", name=material.get_name(obj), category=category, description=description)
+    ifc_material = ifc.run(
+        "material.add_material", name=material.get_name(obj), category=category, description=description
+    )
     ifc.link(ifc_material, obj)
     ifc_style = style.get_style(obj)
     if ifc_style:
@@ -36,14 +54,16 @@ def add_material(ifc, material, style, obj=None, name=None, category=None, descr
     return ifc_material
 
 
-def add_material_set(ifc, material, set_type=None):
+def add_material_set(ifc: tool.Ifc, material: tool.Material, set_type: str) -> ifcopenshell.entity_instance:
     ifc_material = ifc.run("material.add_material_set", name="Unnamed", set_type=set_type)
     if material.is_editing_materials():
         material.import_material_definitions(material.get_active_material_type())
     return ifc_material
 
 
-def remove_material(ifc, material_tool, style, material=None) -> bool:
+def remove_material(
+    ifc: tool.Ifc, material_tool: tool.Material, style: tool.Style, material: ifcopenshell.entity_instance
+) -> bool:
     """returns True after deleting False,\n
     returns False if material used in material sets and cannot be removed"""
     if material_tool.is_material_used_in_sets(material):
@@ -58,31 +78,33 @@ def remove_material(ifc, material_tool, style, material=None) -> bool:
     return True
 
 
-def remove_material_set(ifc, material_tool, material=None):
+def remove_material_set(ifc: tool.Ifc, material_tool: tool.Material, material: ifcopenshell.entity_instance) -> None:
     ifc.run("material.remove_material_set", material=material)
     if material_tool.is_editing_materials():
         material_tool.import_material_definitions(material_tool.get_active_material_type())
 
 
-def load_materials(material, material_type=None):
+def load_materials(material: tool.Material, material_type: str) -> None:
     material.import_material_definitions(material_type)
     material.enable_editing_materials()
 
 
-def disable_editing_materials(material):
+def disable_editing_materials(material: tool.Material) -> None:
     material.disable_editing_materials()
 
 
-def select_by_material(material_tool, spatial, material=None):
+def select_by_material(
+    material_tool: tool.Material, spatial: tool.Spatial, material: ifcopenshell.entity_instance
+) -> None:
     spatial.select_products(material_tool.get_elements_by_material(material))
 
 
-def enable_editing_material(material_tool, material):
+def enable_editing_material(material_tool: tool.Material, material: ifcopenshell.entity_instance) -> None:
     material_tool.load_material_attributes(material)
     material_tool.enable_editing_material(material)
 
 
-def edit_material(ifc, material_tool, material):
+def edit_material(ifc: tool.Ifc, material_tool: tool.Material, material: ifcopenshell.entity_instance) -> None:
     attributes = material_tool.get_material_attributes()
     ifc.run("material.edit_material", material=material, attributes=attributes)
     material_tool.sync_blender_material_name(material)
@@ -92,11 +114,13 @@ def edit_material(ifc, material_tool, material):
     material_tool.enable_editing_materials()
 
 
-def disable_editing_material(material_tool):
+def disable_editing_material(material_tool: tool.Material) -> None:
     material_tool.disable_editing_material()
 
 
-def assign_material(ifc, material_tool, material_type, objects):
+def assign_material(
+    ifc: tool.Ifc, material_tool: tool.Material, material_type: Union[str, None], objects: list[bpy.types.Object]
+) -> None:
     material_type = material_type or material_tool.get_active_object_material()
     material = material_tool.get_active_material()
     for obj in objects:
@@ -109,7 +133,7 @@ def assign_material(ifc, material_tool, material_type, objects):
             material_tool.add_material_to_set(material_set=assigned_material, material=material)
 
 
-def unassign_material(ifc, material_tool, objects):
+def unassign_material(ifc: tool.Ifc, material_tool: tool.Material, objects: list[bpy.types.Object]) -> None:
     for obj in objects:
         element = ifc.get_entity(obj)
         if element:
@@ -125,7 +149,9 @@ def unassign_material(ifc, material_tool, objects):
                 ifc.run("material.unassign_material", products=[element])
 
 
-def patch_non_parametric_mep_segment(ifc, material_tool, profile_tool, obj):
+def patch_non_parametric_mep_segment(
+    ifc: tool.Ifc, material_tool: tool.Material, profile_tool: tool.Profile, obj: bpy.types.Object
+) -> None:
     element = ifc.get_entity(obj)
     if not element:
         return
diff --git a/src/blenderbim/blenderbim/core/style.py b/src/blenderbim/blenderbim/core/style.py
index 13576cb80f..f22b4b15d9 100644
--- a/src/blenderbim/blenderbim/core/style.py
+++ b/src/blenderbim/blenderbim/core/style.py
@@ -16,8 +16,16 @@
 # 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 typing import TYPE_CHECKING, Optional, Any
 
-def add_style(ifc, style, obj=None):
+if TYPE_CHECKING:
+    import bpy
+    import ifcopenshell
+    import blenderbim.tool as tool
+
+
+def add_style(ifc: tool.Ifc, style: tool.Style, obj: bpy.types.Material) -> ifcopenshell.entity_instance:
     element = ifc.run("style.add_style", name=style.get_name(obj))
     ifc.link(element, obj)
     if style.can_support_rendering_style(obj):
@@ -33,18 +41,26 @@ def add_style(ifc, style, obj=None):
     return element
 
 
-def add_external_style(ifc, style, obj, attributes):
+def add_external_style(ifc: tool.Ifc, style: tool.Style, obj: bpy.types.Material, attributes: dict[str, Any]) -> None:
     element = style.get_style(obj)
     ifc.run(
         "style.add_surface_style", style=element, ifc_class="IfcExternallyDefinedSurfaceStyle", attributes=attributes
     )
 
 
-def update_external_style(ifc, style, external_style, attributes):
+# TODO: unused `style` argument?
+def update_external_style(
+    ifc: tool.Ifc,
+    style: ifcopenshell.entity_instance,
+    external_style: ifcopenshell.entity_instance,
+    attributes: dict[str, Any],
+) -> None:
     ifc.run("style.edit_surface_style", style=external_style, attributes=attributes)
 
 
-def remove_style(ifc, material, style_tool, style=None):
+def remove_style(
+    ifc: tool.Ifc, material: tool.Material, style_tool: tool.Style, style: ifcopenshell.entity_instance
+) -> None:
     obj = ifc.get_object(style)
     ifc.unlink(obj=obj, element=style)
     ifc.run("style.remove_style", style=style)
@@ -54,7 +70,7 @@ def remove_style(ifc, material, style_tool, style=None):
         style_tool.import_presentation_styles(style_tool.get_active_style_type())
 
 
-def update_style_colours(ifc, style, obj=None, verbose=False):
+def update_style_colours(ifc: tool.Ifc, style: tool.Style, obj: bpy.types.Material, verbose: bool = False) -> None:
     element = style.get_style(obj)
 
     if style.can_support_rendering_style(obj):
@@ -91,7 +107,9 @@ def update_style_colours(ifc, style, obj=None, verbose=False):
     style.record_shading(obj)
 
 
-def update_style_textures(ifc, style, obj=None, representation=None):
+def update_style_textures(
+    ifc: tool.Ifc, style: tool.Style, obj: ifcopenshell.entity_instance, representation: ifcopenshell.entity_instance
+) -> None:
     element = style.get_style(obj)
 
     uv_maps = style.get_uv_maps(representation)
@@ -111,34 +129,34 @@ def update_style_textures(ifc, style, obj=None, representation=None):
         ifc.run("style.remove_surface_style", style=texture_style)
 
 
-def unlink_style(ifc, style=None):
+def unlink_style(ifc: tool.Ifc, style: ifcopenshell.entity_instance) -> None:
     obj = ifc.get_object(style)
     ifc.unlink(obj=obj, element=style)
 
 
-def enable_editing_style(style, obj=None):
+def enable_editing_style(style: tool.Style, obj: bpy.types.Material) -> None:
     style.enable_editing(obj)
     style.import_surface_attributes(style.get_style(obj), obj)
 
 
-def disable_editing_style(style, obj=None):
+def disable_editing_style(style: tool.Style, obj: bpy.types.Material) -> None:
     style.disable_editing(obj)
 
 
-def edit_style(ifc, style, obj=None):
+def edit_style(ifc: tool.Ifc, style: tool.Style, obj: bpy.types.Material) -> None:
     attributes = style.export_surface_attributes(obj)
     ifc.run("style.edit_presentation_style", style=style.get_style(obj), attributes=attributes)
     style.disable_editing(obj)
 
 
-def load_styles(style, style_type=None):
+def load_styles(style: tool.Style, style_type: str) -> None:
     style.import_presentation_styles(style_type)
     style.enable_editing_styles()
 
 
-def disable_editing_styles(style):
+def disable_editing_styles(style: tool.Style) -> None:
     style.disable_editing_styles()
 
 
-def select_by_style(style_tool, spatial, style=None):
+def select_by_style(style_tool: tool.Style, spatial: tool.Spatial, style: ifcopenshell.entity_instance) -> None:
     spatial.select_products(style_tool.get_elements_by_style(style))
diff --git a/src/blenderbim/blenderbim/tool/aggregate.py b/src/blenderbim/blenderbim/tool/aggregate.py
index 66e549f67d..9188e12a32 100644
--- a/src/blenderbim/blenderbim/tool/aggregate.py
+++ b/src/blenderbim/blenderbim/tool/aggregate.py
@@ -20,6 +20,7 @@ import bpy
 import blenderbim.core.tool
 import blenderbim.tool as tool
 import ifcopenshell.util.element
+from typing import Union
 
 
 class Aggregate(blenderbim.core.tool.Aggregate):
@@ -46,19 +47,21 @@ class Aggregate(blenderbim.core.tool.Aggregate):
         return False
 
     @classmethod
-    def disable_editing(cls, obj):
+    def disable_editing(cls, obj: bpy.types.Object) -> None:
         obj.BIMObjectAggregateProperties.is_editing = False
 
     @classmethod
-    def enable_editing(cls, obj):
+    def enable_editing(cls, obj: bpy.types.Object) -> None:
         obj.BIMObjectAggregateProperties.is_editing = True
 
     @classmethod
-    def get_container(cls, element):
+    def get_container(cls, element: ifcopenshell.entity_instance) -> Union[ifcopenshell.entity_instance, None]:
         return ifcopenshell.util.element.get_container(element)
 
     @classmethod
-    def get_relating_object(cls, related_element):
+    def get_relating_object(
+        cls, related_element: ifcopenshell.entity_instance
+    ) -> Union[ifcopenshell.entity_instance, None]:
         for rel in related_element.Decomposes:
             if rel.is_a("IfcRelAggregates"):
                 return rel.RelatingObject
diff --git a/src/blenderbim/blenderbim/tool/material.py b/src/blenderbim/blenderbim/tool/material.py
index a1bd4a51b8..4a72301f2f 100644
--- a/src/blenderbim/blenderbim/tool/material.py
+++ b/src/blenderbim/blenderbim/tool/material.py
@@ -19,43 +19,45 @@
 import bpy
 import ifcopenshell
 import blenderbim.core.tool
+import blenderbim.core.material
 import blenderbim.tool as tool
 import blenderbim.bim.helper
 import ifcopenshell.util.unit
 import ifcopenshell.util.element
+from typing import Union, Any
 
 
 class Material(blenderbim.core.tool.Material):
     @classmethod
-    def add_default_material_object(cls, name):
+    def add_default_material_object(cls, name: Union[str, None]) -> bpy.types.Material:
         return bpy.data.materials.new(name or "Default")
 
     @classmethod
-    def delete_object(cls, obj):
+    def delete_object(cls, obj: bpy.types.Material) -> None:
         bpy.data.materials.remove(obj)
 
     @classmethod
-    def disable_editing_materials(cls):
+    def disable_editing_materials(cls) -> None:
         bpy.context.scene.BIMMaterialProperties.is_editing = False
 
     @classmethod
-    def enable_editing_materials(cls):
+    def enable_editing_materials(cls) -> None:
         bpy.context.scene.BIMMaterialProperties.is_editing = True
 
     @classmethod
-    def get_active_material_type(cls):
+    def get_active_material_type(cls) -> str:
         return bpy.context.scene.BIMMaterialProperties.material_type
 
     @classmethod
-    def get_elements_by_material(cls, material):
+    def get_elements_by_material(cls, material: ifcopenshell.entity_instance) -> list[ifcopenshell.entity_instance]:
         return ifcopenshell.util.element.get_elements_by_material(tool.Ifc.get(), material)
 
     @classmethod
-    def get_name(cls, obj):
+    def get_name(cls, obj: bpy.types.Material) -> str:
         return obj.name
 
     @classmethod
-    def import_material_definitions(cls, material_type):
+    def import_material_definitions(cls, material_type: str) -> None:
         props = bpy.context.scene.BIMMaterialProperties
         expanded_categories = {m.name for m in props.materials if m.is_expanded}
         props.materials.clear()
@@ -89,11 +91,11 @@ class Material(blenderbim.core.tool.Material):
             new.total_elements = len(ifcopenshell.util.element.get_elements_by_material(tool.Ifc.get(), material))
 
     @classmethod
-    def is_editing_materials(cls):
+    def is_editing_materials(cls) -> bool:
         return bpy.context.scene.BIMMaterialProperties.is_editing
 
     @classmethod
-    def is_material_used_in_sets(cls, material):
+    def is_material_used_in_sets(cls, material: ifcopenshell.entity_instance) -> bool:
         for inverse in tool.Ifc.get().get_inverse(material):
             if inverse.is_a() in [
                 "IfcMaterialProfile",
@@ -105,48 +107,50 @@ class Material(blenderbim.core.tool.Material):
         return False
 
     @classmethod
-    def load_material_attributes(cls, material):
+    def load_material_attributes(cls, material: ifcopenshell.entity_instance) -> None:
         props = bpy.context.scene.BIMMaterialProperties
         props.material_attributes.clear()
         blenderbim.bim.helper.import_attributes2(material, props.material_attributes)
 
     @classmethod
-    def enable_editing_material(cls, material):
+    def enable_editing_material(cls, material: ifcopenshell.entity_instance) -> None:
         props = bpy.context.scene.BIMMaterialProperties
         props.active_material_id = material.id()
         props.editing_material_type = "ATTRIBUTES"
 
     @classmethod
-    def get_material_attributes(cls):
+    def get_material_attributes(cls) -> dict[str, Any]:
         return blenderbim.bim.helper.export_attributes(bpy.context.scene.BIMMaterialProperties.material_attributes)
 
     @classmethod
-    def disable_editing_material(cls):
+    def disable_editing_material(cls) -> None:
         props = bpy.context.scene.BIMMaterialProperties
         props.active_material_id = 0
         props.editing_material_type = ""
 
     @classmethod
-    def get_type(cls, element):
+    def get_type(cls, element: ifcopenshell.entity_instance) -> Union[ifcopenshell.entity_instance, None]:
         return ifcopenshell.util.element.get_type(element)
 
     @classmethod
-    def get_active_object_material(cls):
+    def get_active_object_material(cls) -> Union[str, None]:
         active_obj = bpy.context.active_object
         if not active_obj:
             return
         return active_obj.BIMObjectMaterialProperties.material_type
 
     @classmethod
-    def get_active_material(cls):
+    def get_active_material(cls) -> ifcopenshell.entity_instance:
         return tool.Ifc.get().by_id(int(bpy.context.active_object.BIMObjectMaterialProperties.material))
 
     @classmethod
-    def get_material(cls, element, should_inherit=False):
+    def get_material(
+        cls, element: ifcopenshell.entity_instance, should_inherit: bool = False
+    ) -> Union[ifcopenshell.entity_instance, None]:
         return ifcopenshell.util.element.get_material(element, should_inherit=should_inherit)
 
     @classmethod
-    def is_a_material_set(cls, material):
+    def is_a_material_set(cls, material: ifcopenshell.entity_instance) -> bool:
         return material.is_a() in [
             "IfcMaterialConstituentSet",
             "IfcMaterialLayerSet",
@@ -154,7 +158,9 @@ class Material(blenderbim.core.tool.Material):
         ]
 
     @classmethod
-    def add_material_to_set(cls, material_set, material):
+    def add_material_to_set(
+        cls, material_set: ifcopenshell.entity_instance, material: ifcopenshell.entity_instance
+    ) -> None:
         if material_set.is_a("IfcMaterialConstituentSet"):
             if not material_set.MaterialConstituents:
                 tool.Ifc.run(
@@ -195,7 +201,7 @@ class Material(blenderbim.core.tool.Material):
                     )
 
     @classmethod
-    def has_material_profile(cls, element):
+    def has_material_profile(cls, element: ifcopenshell.entity_instance) -> bool:
         material = cls.get_material(element, should_inherit=False)
         inherited_material = cls.get_material(element, should_inherit=True)
         if material and "Profile" in material.is_a():
@@ -205,11 +211,13 @@ class Material(blenderbim.core.tool.Material):
         return False
 
     @classmethod
-    def is_a_flow_segment(cls, element):
+    def is_a_flow_segment(cls, element: ifcopenshell.entity_instance) -> bool:
         return element.is_a("IfcFlowSegment")
 
     @classmethod
-    def replace_material_with_material_profile(cls, element):
+    def replace_material_with_material_profile(
+        cls, element: ifcopenshell.entity_instance
+    ) -> ifcopenshell.entity_instance:
         old_material = cls.get_material(element, should_inherit=False)
         old_inherited_material = cls.get_material(element, should_inherit=True)
         material = old_material if old_material and old_material.is_a("IfcMaterial") else None
@@ -225,14 +233,14 @@ class Material(blenderbim.core.tool.Material):
         return material_profile
 
     @classmethod
-    def update_elements_using_material(cls, material):
+    def update_elements_using_material(cls, material: ifcopenshell.entity_instance) -> None:
         # update elements that are using this material
         elements = ifcopenshell.util.element.get_elements_by_material(tool.Ifc.get(), material)
         objects = [tool.Ifc.get_object(e) for e in elements]
         tool.Geometry.reload_representation(objects)
 
     @classmethod
-    def sync_blender_material_name(cls, material):
+    def sync_blender_material_name(cls, material: ifcopenshell.entity_instance) -> None:
         name = material.Name or "Unnamed"
         obj = tool.Ifc.get_object(material)
         if obj:
@@ -245,7 +253,7 @@ class Material(blenderbim.core.tool.Material):
                 obj.name = name
 
     @classmethod
-    def get_style(cls, material):
+    def get_style(cls, material: ifcopenshell.entity_instance) -> Union[ifcopenshell.entity_instance, None]:
         for material_representation in material.HasRepresentation:
             for representation in material_representation.Representations:
                 for item in representation.Items:
diff --git a/src/blenderbim/blenderbim/tool/profile.py b/src/blenderbim/blenderbim/tool/profile.py
index c0295be0c7..10e8613694 100644
--- a/src/blenderbim/blenderbim/tool/profile.py
+++ b/src/blenderbim/blenderbim/tool/profile.py
@@ -17,18 +17,23 @@
 # along with BlenderBIM Add-on.  If not, see <http://www.gnu.org/licenses/>.
 
 import ifcopenshell
+import ifcopenshell.geom
 import ifcopenshell.util.element
 import ifcopenshell.util.unit
 import ifcopenshell.util.placement
 import ifcopenshell.util.representation
 import blenderbim.core.tool
 import blenderbim.tool as tool
+import PIL.ImageDraw
 from blenderbim.bim.module.model.decorator import ProfileDecorator
+from typing import Union
 
 
 class Profile(blenderbim.core.tool.Profile):
     @classmethod
-    def draw_image_for_ifc_profile(cls, draw, profile, size):
+    def draw_image_for_ifc_profile(
+        cls, draw: PIL.ImageDraw.ImageDraw, profile: ifcopenshell.entity_instance, size: float
+    ) -> None:
         """generates image based on `profile` using `PIL.ImageDraw`"""
         settings = ifcopenshell.geom.settings()
         settings.set(settings.INCLUDE_CURVES, True)
@@ -57,11 +62,11 @@ class Profile(blenderbim.core.tool.Profile):
             draw.line((tuple(grouped_verts[e[0]]), tuple(grouped_verts[e[1]])), fill="white", width=2)
 
     @classmethod
-    def is_editing_profile(cls):
-        return ProfileDecorator.installed
+    def is_editing_profile(cls) -> bool:
+        return bool(ProfileDecorator.installed)
 
     @classmethod
-    def get_profile(cls, element):
+    def get_profile(cls, element: ifcopenshell.entity_instance) -> Union[ifcopenshell.entity_instance, None]:
         representations = element.Representation
         for representation in representations.Representations:
             if not representation.is_a("IfcShapeRepresentation"):
@@ -74,7 +79,7 @@ class Profile(blenderbim.core.tool.Profile):
         return None
 
     @classmethod
-    def get_model_profiles(cls):
+    def get_model_profiles(cls) -> list[ifcopenshell.entity_instance]:
         return tool.Ifc.get().by_type("IfcProfileDef")
 
     @classmethod
diff --git a/src/blenderbim/blenderbim/tool/root.py b/src/blenderbim/blenderbim/tool/root.py
index f1f36d6933..057644e9f5 100644
--- a/src/blenderbim/blenderbim/tool/root.py
+++ b/src/blenderbim/blenderbim/tool/root.py
@@ -21,6 +21,7 @@ import ifcopenshell
 import ifcopenshell.api
 import ifcopenshell.util.representation
 import ifcopenshell.util.element
+import ifcopenshell.util.placement
 import blenderbim.core.tool
 import blenderbim.core.aggregate
 import blenderbim.core.geometry
@@ -29,17 +30,17 @@ import blenderbim.core.style
 import blenderbim.tool as tool
 from mathutils import Vector
 from blenderbim.bim.module.model.opening import FilledOpeningGenerator
-from typing import Union, Optional
+from typing import Union, Optional, Any
 
 
 class Root(blenderbim.core.tool.Root):
     @classmethod
-    def add_tracked_opening(cls, obj):
+    def add_tracked_opening(cls, obj: bpy.types.Object) -> None:
         new = bpy.context.scene.BIMModelProperties.openings.add()
         new.obj = obj
 
     @classmethod
-    def assign_body_styles(cls, element, obj):
+    def assign_body_styles(cls, element: ifcopenshell.entity_instance, obj: bpy.types.Object) -> None:
         # Should this even be here? Should it be in the geometry tool?
         body = ifcopenshell.util.representation.get_representation(element, "Model", "Body", "MODEL_VIEW")
         if body:
@@ -56,7 +57,7 @@ class Root(blenderbim.core.tool.Root):
             )
 
     @classmethod
-    def copy_representation(cls, source, dest):
+    def copy_representation(cls, source: ifcopenshell.entity_instance, dest: ifcopenshell.entity_instance) -> None:
         def exclude_callback(attribute):
             return attribute.is_a("IfcProfileDef") and attribute.ProfileName
 
@@ -80,11 +81,13 @@ class Root(blenderbim.core.tool.Root):
             ]
 
     @classmethod
-    def does_type_have_representations(cls, element):
+    def does_type_have_representations(cls, element: ifcopenshell.entity_instance) -> bool:
         return bool(element.RepresentationMaps)
 
     @classmethod
-    def get_decomposition_relationships(cls, objs):
+    def get_decomposition_relationships(
+        cls, objs: list[bpy.types.Object]
+    ) -> dict[ifcopenshell.entity_instance, dict[str, Any]]:
         relationships = {}
         for obj in objs:
             element = tool.Ifc.get_entity(obj)
@@ -96,7 +99,9 @@ class Root(blenderbim.core.tool.Root):
         return relationships
 
     @classmethod
-    def get_connection_relationships(cls, objs):
+    def get_connection_relationships(
+        cls, objs: list[bpy.types.Object]
+    ) -> dict[ifcopenshell.entity_instance, dict[str, Any]]:
         relationships = {}
         for obj in objs:
             element = tool.Ifc.get_entity(obj)
@@ -119,7 +124,9 @@ class Root(blenderbim.core.tool.Root):
         return relationships
 
     @classmethod
-    def get_element_representation(cls, element, context):
+    def get_element_representation(
+        cls, element: ifcopenshell.entity_instance, context: ifcopenshell.entity_instance
+    ) -> Union[ifcopenshell.entity_instance, None]:
         if context.is_a("IfcGeometricRepresentationSubContext"):
             return ifcopenshell.util.representation.get_representation(
                 element,
@@ -134,13 +141,13 @@ class Root(blenderbim.core.tool.Root):
         return ifcopenshell.util.element.get_type(element)
 
     @classmethod
-    def get_object_name(cls, obj):
+    def get_object_name(cls, obj: bpy.types.Object) -> None:
         if "." in obj.name and obj.name.split(".")[-1].isnumeric():
             return ".".join(obj.name.split(".")[:-1])
         return obj.name
 
     @classmethod
-    def get_object_representation(cls, obj):
+    def get_object_representation(cls, obj: bpy.types.Object) -> Union[ifcopenshell.entity_instance, None]:
         if obj.data and obj.data.BIMMeshProperties.ifc_definition_id:
             return tool.Ifc.get().by_id(obj.data.BIMMeshProperties.ifc_definition_id)
         element = tool.Ifc.get_entity(obj)
@@ -152,19 +159,21 @@ class Root(blenderbim.core.tool.Root):
                 return element.Representation.Representations[0]
 
     @classmethod
-    def get_representation_context(cls, representation):
+    def get_representation_context(cls, representation: ifcopenshell.entity_instance) -> ifcopenshell.entity_instance:
         return representation.ContextOfItems
 
     @classmethod
-    def is_element_a(cls, element, ifc_class):
+    def is_element_a(cls, element: ifcopenshell.entity_instance, ifc_class: str) -> bool:
         return element.is_a(ifc_class)
 
     @classmethod
-    def link_object_data(cls, source_obj, destination_obj):
+    def link_object_data(cls, source_obj: bpy.types.Object, destination_obj: bpy.types.Object) -> None:
         destination_obj.data = source_obj.data
 
     @classmethod
-    def recreate_decompositions(cls, relationships, old_to_new):
+    def recreate_decompositions(
+        cls, relationships, old_to_new: dict[ifcopenshell.entity_instance, list[ifcopenshell.entity_instance]]
+    ) -> None:
         for subelement, data in relationships.items():
             new_subelements = old_to_new.get(subelement)
             new_elements = old_to_new.get(data["element"])
@@ -227,7 +236,11 @@ class Root(blenderbim.core.tool.Root):
                             )
 
     @classmethod
-    def recreate_connections(cls, relationship, old_to_new):
+    def recreate_connections(
+        cls,
+        relationship: dict[ifcopenshell.entity_instance, dict[str, Any]],
+        old_to_new: dict[ifcopenshell.entity_instance, list[ifcopenshell.entity_instance]],
+    ) -> None:
         for element, data in relationship.items():
             try:
                 new_relating_element = old_to_new.get(data["relating_element"])[0]
@@ -244,7 +257,9 @@ class Root(blenderbim.core.tool.Root):
             )
 
     @classmethod
-    def recreate_aggregate(cls, old_to_new):
+    def recreate_aggregate(
+        cls, old_to_new: dict[ifcopenshell.entity_instance, list[ifcopenshell.entity_instance]]
+    ) -> None:
         for old, new in old_to_new.items():
             old_aggregate = ifcopenshell.util.element.get_aggregate(old)
             if old_aggregate:
@@ -301,7 +316,7 @@ class Root(blenderbim.core.tool.Root):
         )
 
     @classmethod
-    def set_object_name(cls, obj, element):
+    def set_object_name(cls, obj: bpy.types.Object, element: ifcopenshell.entity_instance) -> None:
         # This disables the Blender name event handler
         obj.BIMObjectProperties.is_renaming = True
         name = getattr(element, "Name", getattr(element, "AxisTag", None))
@@ -309,7 +324,7 @@ class Root(blenderbim.core.tool.Root):
         obj.BIMObjectProperties.is_renaming = False
 
     @classmethod
-    def unlink_object(cls, obj):
+    def unlink_object(cls, obj: bpy.types.Object) -> None:
         tool.Ifc.unlink(obj=obj)
         if hasattr(obj.data, "BIMMeshProperties"):
             obj.data.BIMMeshProperties.ifc_definition_id = 0
diff --git a/src/blenderbim/blenderbim/tool/style.py b/src/blenderbim/blenderbim/tool/style.py
index 9ff8c9aa4c..ae99214599 100644
--- a/src/blenderbim/blenderbim/tool/style.py
+++ b/src/blenderbim/blenderbim/tool/style.py
@@ -20,11 +20,12 @@ import bpy
 import numpy as np
 import ifcopenshell
 import ifcopenshell.util.element
+import ifcopenshell.util.representation
 import blenderbim.core.tool
 import blenderbim.tool as tool
 import blenderbim.bim.helper
 from mathutils import Color
-from typing import Union
+from typing import Union, Any, Optional
 
 # fmt: off
 TEXTURE_MAPS_BY_METHODS = {
@@ -45,19 +46,19 @@ STYLE_PROPS_MAP = {
 
 class Style(blenderbim.core.tool.Style):
     @classmethod
-    def can_support_rendering_style(cls, obj):
+    def can_support_rendering_style(cls, obj: bpy.types.Material) -> bool:
         return obj.use_nodes and hasattr(obj.node_tree, "nodes")
 
     @classmethod
-    def disable_editing(cls, obj):
+    def disable_editing(cls, obj: bpy.types.Material) -> None:
         obj.BIMStyleProperties.is_editing = False
 
     @classmethod
-    def disable_editing_external_style(cls, obj):
+    def disable_editing_external_style(cls, obj: bpy.types.Material) -> None:
         obj.BIMStyleProperties.is_editing_external_style = False
 
     @classmethod
-    def disable_editing_styles(cls):
+    def disable_editing_styles(cls) -> None:
         bpy.context.scene.BIMStylesProperties.is_editing = False
 
     @classmethod
@@ -67,39 +68,40 @@ class Style(blenderbim.core.tool.Style):
         return new_style
 
     @classmethod
-    def enable_editing(cls, obj):
+    def enable_editing(cls, obj: bpy.types.Material) -> None:
         obj.BIMStyleProperties.is_editing = True
 
     @classmethod
-    def enable_editing_external_style(cls, obj):
+    def enable_editing_external_style(cls, obj: bpy.types.Material) -> None:
         obj.BIMStyleProperties.is_editing_external_style = True
 
     @classmethod
-    def enable_editing_styles(cls):
+    def enable_editing_styles(cls) -> None:
         bpy.context.scene.BIMStylesProperties.is_editing = True
 
     @classmethod
-    def export_surface_attributes(cls, obj):
+    def export_surface_attributes(cls, obj: bpy.types.Material) -> dict[str, Any]:
         return blenderbim.bim.helper.export_attributes(obj.BIMStyleProperties.attributes)
 
     @classmethod
-    def export_external_style_attributes(cls, obj):
+    def export_external_style_attributes(cls, obj: bpy.types.Material) -> dict[str, Any]:
         return blenderbim.bim.helper.export_attributes(obj.BIMStyleProperties.external_style_attributes)
 
     @classmethod
-    def get_active_style_type(cls):
+    def get_active_style_type(cls) -> str:
         return bpy.context.scene.BIMStylesProperties.style_type
 
+    # TODO: `obj` argument is unused?
     @classmethod
-    def get_context(cls, obj):
+    def get_context(cls, obj) -> Union[ifcopenshell.entity_instance, None]:
         return ifcopenshell.util.representation.get_context(tool.Ifc.get(), "Model", "Body", "MODEL_VIEW")
 
     @classmethod
-    def get_elements_by_style(cls, style):
+    def get_elements_by_style(cls, style: ifcopenshell.entity_instance) -> list[ifcopenshell.entity_instance]:
         return ifcopenshell.util.element.get_elements_by_style(tool.Ifc.get(), style)
 
     @classmethod
-    def get_name(cls, obj):
+    def get_name(cls, obj: bpy.types.Material) -> str:
         return obj.name
 
     @classmethod
@@ -126,7 +128,7 @@ class Style(blenderbim.core.tool.Style):
         return style_elements
 
     @classmethod
-    def get_shading_style_data_from_props(cls) -> dict:
+    def get_shading_style_data_from_props(cls) -> dict[str, Any]:
         """returns style data from blender props in similar way to `Loader.surface_style_to_dict`
         to be compatible with `Loader.create_surface_style_rendering`"""
         surface_style_data = dict()
@@ -154,7 +156,7 @@ class Style(blenderbim.core.tool.Style):
         return surface_style_data
 
     @classmethod
-    def get_texture_style_data_from_props(cls) -> list[dict]:
+    def get_texture_style_data_from_props(cls) -> list[dict[str, Any]]:
         """returns style data from blender props in similar way to `Loader.surface_texture_to_dict`
         to be compatible with `Loader.create_surface_style_with_textures`"""
         props = bpy.context.scene.BIMStylesProperties
@@ -174,7 +176,7 @@ class Style(blenderbim.core.tool.Style):
         return textures
 
     @classmethod
-    def set_surface_style_props(cls):
+    def set_surface_style_props(cls) -> None:
         """set blender style props based on currently edited IfcSurfaceStyle,
         reset unrelated props to default values"""
 
@@ -241,7 +243,7 @@ class Style(blenderbim.core.tool.Style):
         props["update_graph"] = prev_update_graph_value
 
     @classmethod
-    def get_surface_rendering_attributes(cls, obj, verbose=False):
+    def get_surface_rendering_attributes(cls, obj: bpy.types.Material, verbose: bool = False) -> dict[str, Any]:
         report = (lambda *x: print(*x)) if verbose else (lambda *x: None)
 
         def color_to_ifc_format(color):
@@ -403,22 +405,22 @@ class Style(blenderbim.core.tool.Style):
         return attributes
 
     @classmethod
-    def get_surface_rendering_style(cls, obj):
+    def get_surface_rendering_style(cls, obj: bpy.types.Material) -> Union[ifcopenshell.entity_instance, None]:
         style_elements = cls.get_style_elements(obj)
         return style_elements.get("IfcSurfaceStyleRendering", None)
 
     @classmethod
-    def get_texture_style(cls, obj):
+    def get_texture_style(cls, obj: bpy.types.Material) -> Union[ifcopenshell.entity_instance, None]:
         style_elements = cls.get_style_elements(obj)
         return style_elements.get("IfcSurfaceStyleWithTextures", None)
 
     @classmethod
-    def get_external_style(cls, obj):
+    def get_external_style(cls, obj: bpy.types.Material) -> Union[ifcopenshell.entity_instance, None]:
         style_elements = cls.get_style_elements(obj)
         return style_elements.get("IfcExternallyDefinedSurfaceStyle", None)
 
     @classmethod
-    def get_surface_shading_attributes(cls, obj):
+    def get_surface_shading_attributes(cls, obj: bpy.types.Material) -> dict[str, Any]:
         data = {
             "SurfaceColour": {
                 "Name": None,
@@ -433,7 +435,7 @@ class Style(blenderbim.core.tool.Style):
         return data
 
     @classmethod
-    def get_surface_shading_style(cls, obj):
+    def get_surface_shading_style(cls, obj: bpy.types.Material) -> Union[ifcopenshell.entity_instance, None]:
         if obj.BIMMaterialProperties.ifc_style_id:
             style = tool.Ifc.get().by_id(obj.BIMMaterialProperties.ifc_style_id)
             items = [s for s in style.Styles if s.is_a() == "IfcSurfaceStyleShading"]
@@ -441,7 +443,7 @@ class Style(blenderbim.core.tool.Style):
                 return items[0]
 
     @classmethod
-    def get_surface_texture_style(cls, obj):
+    def get_surface_texture_style(cls, obj: bpy.types.Material) -> Union[ifcopenshell.entity_instance, None]:
         if obj.BIMMaterialProperties.ifc_style_id:
             style = tool.Ifc.get().by_id(obj.BIMMaterialProperties.ifc_style_id)
             items = [s for s in style.Styles if s.is_a("IfcSurfaceStyleWithTextures")]
@@ -449,7 +451,7 @@ class Style(blenderbim.core.tool.Style):
                 return items[0]
 
     @classmethod
-    def get_uv_maps(cls, representation):
+    def get_uv_maps(cls, representation: ifcopenshell.entity_instance) -> list[ifcopenshell.entity_instance]:
         items = []
         for item in representation.Items:
             if item.is_a("IfcMappedItem"):
@@ -464,7 +466,7 @@ class Style(blenderbim.core.tool.Style):
         return results
 
     @classmethod
-    def get_style_ui_props_attributes(cls, style_type):
+    def get_style_ui_props_attributes(cls, style_type: str) -> Union[bpy.types.PropertyGroup, None]:
         props = bpy.context.scene.BIMStylesProperties
         if style_type == "IfcExternallyDefinedSurfaceStyle":
             return props.external_style_attributes
@@ -474,7 +476,7 @@ class Style(blenderbim.core.tool.Style):
             return props.lighting_style_colours
 
     @classmethod
-    def import_presentation_styles(cls, style_type):
+    def import_presentation_styles(cls, style_type: str) -> None:
         color_to_tuple = lambda x: (x.Red, x.Green, x.Blue)
         props = bpy.context.scene.BIMStylesProperties
         props.styles.clear()
@@ -497,13 +499,13 @@ class Style(blenderbim.core.tool.Style):
             new.total_elements = len(ifcopenshell.util.element.get_elements_by_style(tool.Ifc.get(), style))
 
     @classmethod
-    def import_surface_attributes(cls, style, obj):
+    def import_surface_attributes(cls, style: ifcopenshell.entity_instance, obj: bpy.types.Material) -> None:
         attributes = obj.BIMStyleProperties.attributes
         attributes.clear()
         blenderbim.bim.helper.import_attributes2(style, attributes)
 
     @classmethod
-    def import_external_style_attributes(cls, style, obj):
+    def import_external_style_attributes(cls, style: ifcopenshell.entity_instance, obj: bpy.types.Material) -> None:
         attributes = obj.BIMStyleProperties.external_style_attributes
         attributes.clear()
         blenderbim.bim.helper.import_attributes2(style, attributes)
@@ -514,26 +516,26 @@ class Style(blenderbim.core.tool.Style):
         return bool(external_style and external_style.Location and external_style.Location.endswith(".blend"))
 
     @classmethod
-    def is_editing_styles(cls):
+    def is_editing_styles(cls) -> bool:
         return bpy.context.scene.BIMStylesProperties.is_editing
 
     @classmethod
-    def record_shading(cls, obj):
+    def record_shading(cls, obj: bpy.types.Material) -> None:
         obj.BIMMaterialProperties.shading_checksum = repr(np.array(obj.diffuse_color).tobytes())
 
     @classmethod
-    def select_elements(cls, elements):
+    def select_elements(cls, elements: list[ifcopenshell.entity_instance]) -> None:
         for element in elements:
             obj = tool.Ifc.get_object(element)
             if obj:
                 obj.select_set(True)
 
     @classmethod
-    def change_current_style_type(cls, blender_material, style_type):
+    def change_current_style_type(cls, blender_material: bpy.types.Material, style_type: str) -> None:
         blender_material.BIMStyleProperties.active_style_type = style_type
 
     @classmethod
-    def get_styled_items(cls, style):
+    def get_styled_items(cls, style: ifcopenshell.entity_instance) -> list[ifcopenshell.entity_instance]:
         ifc_file = tool.Ifc.get()
 
         inverses = list(ifc_file.get_inverse(style))
@@ -554,13 +556,15 @@ class Style(blenderbim.core.tool.Style):
         return items
 
     @classmethod
-    def assign_style_to_object(cls, style, obj):
+    def assign_style_to_object(cls, style: ifcopenshell.entity_instance, obj: bpy.types.Object) -> None:
         """assigns `style` to `object` current representation"""
         representation = tool.Geometry.get_active_representation(obj)
         tool.Ifc.run("style.assign_representation_styles", shape_representation=representation, styles=[style])
 
     @classmethod
-    def assign_style_to_representation_item(cls, representation_item, style=None):
+    def assign_style_to_representation_item(
+        cls, representation_item: ifcopenshell.entity_instance, style: Optional[ifcopenshell.entity_instance] = None
+    ) -> None:
         ifc_file = tool.Ifc.get()
         if not representation_item.StyledByItem:
             if style is None:
@@ -574,12 +578,14 @@ class Style(blenderbim.core.tool.Style):
         styled_item.Styles = (style,)
 
     @classmethod
-    def get_representation_item_style(cls, representation_item):
+    def get_representation_item_style(
+        cls, representation_item: ifcopenshell.entity_instance
+    ) -> Union[ifcopenshell.entity_instance, None]:
         for inverse in tool.Ifc.get().get_inverse(representation_item):
             if inverse.is_a("IfcStyledItem"):
                 for style in inverse.Styles:
                     return style
 
     @classmethod
-    def reload_material_from_ifc(cls, blender_material):
+    def reload_material_from_ifc(cls, blender_material: bpy.types.Material) -> None:
         blender_material.BIMStyleProperties.active_style_type = blender_material.BIMStyleProperties.active_style_type
diff --git a/src/ifc5d/ifc5d/ifc5Dspreadsheet.py b/src/ifc5d/ifc5d/ifc5Dspreadsheet.py
index b870329d20..31dd3e2d7a 100644
--- a/src/ifc5d/ifc5d/ifc5Dspreadsheet.py
+++ b/src/ifc5d/ifc5d/ifc5Dspreadsheet.py
@@ -26,7 +26,7 @@ import ifcopenshell
 import ifcopenshell.util.element
 import ifcopenshell.util.cost
 import ifcopenshell.util.date
-from typing import Union, Optional
+from typing import Union, Optional, Any
 
 
 class IfcDataGetter:
@@ -41,17 +41,17 @@ class IfcDataGetter:
         ]
 
     @staticmethod
-    def canonicalise_time(time):
+    def canonicalise_time(time: Union[datetime.datetime, None]) -> str:
         if not time:
             return "-"
         return time.strftime("%d/%m/%y")
 
     @staticmethod
-    def get_root_costs(cost_schedule):
+    def get_root_costs(cost_schedule: ifcopenshell.entity_instance) -> list[ifcopenshell.entity_instance]:
         return [obj for rel in cost_schedule.Controls or [] for obj in rel.RelatedObjects or []]
 
     @staticmethod
-    def get_cost_item_values(cost_item=None):
+    def get_cost_item_values(cost_item: Union[ifcopenshell.entity_instance, None]) -> Union[list[dict[str, Any]], None]:
         if not cost_item:
             return None
         values = []
@@ -71,14 +71,14 @@ class IfcDataGetter:
         return values
 
     @staticmethod
-    def process_categories(cost_item, categories):
+    def process_categories(cost_item: ifcopenshell.entity_instance, categories: set[str]) -> set[str]:
         for cost_value in cost_item.CostValues or []:
             if cost_value.Category:
                 categories.add("{}{}".format(cost_value.Category, " Cost"))
         return categories
 
     @staticmethod
-    def process_cost_item_categories(cost_item, categories):
+    def process_cost_item_categories(cost_item: ifcopenshell.entity_instance, categories: set[str]) -> set[str]:
         IfcDataGetter.process_categories(cost_item, categories)
         for rel in cost_item.IsNestedBy or []:
             for child in rel.RelatedObjects or []:
@@ -86,14 +86,20 @@ class IfcDataGetter:
         return categories
 
     @staticmethod
-    def get_cost_rates_categories(schedule):
+    def get_cost_rates_categories(schedule: ifcopenshell.entity_instance) -> set[str]:
         categories = set()
         for cost_item in IfcDataGetter.get_root_costs(schedule):
             IfcDataGetter.process_cost_item_categories(cost_item, categories)
         return categories
 
     @staticmethod
-    def process_cost_data(file, cost_item, cost_items_data, index, hierarchy="1"):
+    def process_cost_data(
+        file: ifcopenshell.file,
+        cost_item: ifcopenshell.entity_instance,
+        cost_items_data: list[dict[str, Any]],
+        index: int,
+        hierarchy: str = "1",
+    ) -> None:
         def listToString(s):
             return ", ".join([str(i) for i in s])
 
@@ -134,7 +140,7 @@ class IfcDataGetter:
             )
 
     @staticmethod
-    def get_cost_items_data(file, schedule):
+    def get_cost_items_data(file: ifcopenshell.file, schedule: ifcopenshell.entity_instance) -> list[dict[str, Any]]:
         cost_items_data = []
         index = 0
         for cost_item in IfcDataGetter.get_root_costs(schedule):
@@ -142,7 +148,7 @@ class IfcDataGetter:
         return cost_items_data
 
     @staticmethod
-    def format_unit(unit):
+    def format_unit(unit: ifcopenshell.entity_instance) -> str:
         if unit.is_a("IfcContextDependentUnit"):
             return f"{unit.UnitType} / {unit.Name}"
         else:
@@ -152,7 +158,7 @@ class IfcDataGetter:
             return f"{unit.UnitType} / {name}"
 
     @staticmethod
-    def get_cost_value_unit(cost_value=None):
+    def get_cost_value_unit(cost_value: Optional[ifcopenshell.entity_instance] = None) -> Union[str, None]:
         if not cost_value:
             return None
         unit = cost_value.UnitBasis
@@ -161,9 +167,9 @@ class IfcDataGetter:
         return IfcDataGetter.format_unit(unit.UnitComponent)
 
     @staticmethod
-    def get_cost_item_quantity(file, cost_item=None):
+    def get_cost_item_quantity(file: ifcopenshell.file, cost_item: ifcopenshell.entity_instance) -> dict[str, Any]:
         # TODO: handle multiple quantities, THOSE WHHICH ARE JUYST ASSIGNED TO THE COST ITEM DIRECTLY, NOT THROUGH OBJECTS.
-        def add_quantity(quantity, take_off_name):
+        def add_quantity(quantity: ifcopenshell.entity_instance, take_off_name: str) -> float:
             accounted_for.append(quantity)
             if take_off_name == "":
                 take_off_name = quantity[0]
diff --git a/src/ifcopenshell-python/ifcopenshell/util/element.py b/src/ifcopenshell-python/ifcopenshell/util/element.py
index 76366c2f0e..89999deb5b 100644
--- a/src/ifcopenshell-python/ifcopenshell/util/element.py
+++ b/src/ifcopenshell-python/ifcopenshell/util/element.py
@@ -833,7 +833,7 @@ def get_layers(
 
 def get_container(
     element: ifcopenshell.entity_instance, should_get_direct: bool = False, ifc_class: Optional[str] = None
-) -> ifcopenshell.entity_instance:
+) -> Union[ifcopenshell.entity_instance, None]:
     """
     Retrieves the spatial structure container of an element.
 
@@ -849,7 +849,7 @@ def get_container(
         example, you may be after the storey, not a space.
     :type ifc_class: str, optional
     :return: The direct or indirect container of the element or None.
-    :rtype: ifcopenshell.entity_instance
+    :rtype: Union[ifcopenshell.entity_instance, None]
 
     Example: