diff --git a/src/blenderbim/blenderbim/bim/module/style/operator.py b/src/blenderbim/blenderbim/bim/module/style/operator.py
index 32a592b24c..8f22db9034 100644
--- a/src/blenderbim/blenderbim/bim/module/style/operator.py
+++ b/src/blenderbim/blenderbim/bim/module/style/operator.py
@@ -550,9 +550,19 @@ class EnableEditingSurfaceStyle(bpy.types.Operator, tool.Ifc.Operator):
                     props.is_specular_highlight_null = True
 
                 props.reflectance_method = surface_style.ReflectanceMethod
-        elif shading:
-            props.surface_colour = color_to_tuple(shading.SurfaceColour)
-            props.transparency = shading.Transparency or 0.0
+            elif self.ifc_class == "IfcExternallyDefinedSurfaceStyle":
+                attributes = props.external_style_attributes
+                attributes.clear()
+                blenderbim.bim.helper.import_attributes2(surface_style, attributes)
+        else:
+            if self.ifc_class == "IfcSurfaceStyleRendering":
+                if shading:
+                    props.surface_colour = color_to_tuple(shading.SurfaceColour)
+                    props.transparency = shading.Transparency or 0.0
+            elif self.ifc_class == "IfcExternallyDefinedSurfaceStyle":
+                attributes = props.external_style_attributes
+                attributes.clear()
+                blenderbim.bim.helper.import_attributes2(self.ifc_class, attributes)
 
         props.is_editing_style = self.style
         props.is_editing_class = self.ifc_class
@@ -607,6 +617,13 @@ class EditSurfaceStyle(bpy.types.Operator, tool.Ifc.Operator):
                 attributes=self.get_rendering_attributes(),
             )
             tool.Loader.create_surface_style_rendering(material, self.surface_style)
+        elif self.surface_style.is_a() == "IfcExternallyDefinedSurfaceStyle":
+            surface_style = ifcopenshell.api.run(
+                "style.edit_surface_style",
+                tool.Ifc.get(),
+                style=self.surface_style,
+                attributes=blenderbim.bim.helper.export_attributes(self.props.external_style_attributes),
+            )
 
     def add_new_style(self):
         material = tool.Ifc.get_object(self.style)
@@ -628,6 +645,14 @@ class EditSurfaceStyle(bpy.types.Operator, tool.Ifc.Operator):
                 attributes=self.get_rendering_attributes(),
             )
             tool.Loader.create_surface_style_rendering(material, surface_style)
+        elif self.props.is_editing_class == "IfcExternallyDefinedSurfaceStyle":
+            surface_style = ifcopenshell.api.run(
+                "style.add_surface_style",
+                tool.Ifc.get(),
+                style=self.style,
+                ifc_class="IfcExternallyDefinedSurfaceStyle",
+                attributes=blenderbim.bim.helper.export_attributes(self.props.external_style_attributes),
+            )
 
     def get_shading_attributes(self):
         return {
diff --git a/src/blenderbim/blenderbim/bim/module/style/prop.py b/src/blenderbim/blenderbim/bim/module/style/prop.py
index e399e0c3a2..c8af2e0bb9 100644
--- a/src/blenderbim/blenderbim/bim/module/style/prop.py
+++ b/src/blenderbim/blenderbim/bim/module/style/prop.py
@@ -80,6 +80,7 @@ class BIMStylesProperties(PropertyGroup):
     is_editing_style: IntProperty(name="Is Editing Style")
     is_editing_class: StringProperty(name="Is Editing Class")
     attributes: CollectionProperty(name="Attributes", type=Attribute)
+    external_style_attributes: CollectionProperty(name="External Style Attributes", type=Attribute)
     style_type: EnumProperty(items=get_style_types, default=2, name="Style Type")
     style_name: StringProperty(name="Style Name")
     surface_style_class: EnumProperty(
diff --git a/src/blenderbim/blenderbim/bim/module/style/ui.py b/src/blenderbim/blenderbim/bim/module/style/ui.py
index d3e97deb94..345dfc55f8 100644
--- a/src/blenderbim/blenderbim/bim/module/style/ui.py
+++ b/src/blenderbim/blenderbim/bim/module/style/ui.py
@@ -116,6 +116,8 @@ class BIM_PT_styles(Panel):
                 self.draw_surface_style_shading()
             elif self.props.is_editing_class == "IfcSurfaceStyleRendering":
                 self.draw_surface_style_rendering()
+            elif self.props.is_editing_class == "IfcExternallyDefinedSurfaceStyle":
+                self.draw_externally_defined_surface_style()
 
     def draw_surface_style_shading(self):
         row = self.layout.row()
@@ -184,6 +186,12 @@ class BIM_PT_styles(Panel):
         row.operator("bim.edit_surface_style", text="Save Rendering Style", icon="CHECKMARK")
         row.operator("bim.disable_editing_style", text="", icon="CANCEL")
 
+    def draw_externally_defined_surface_style(self):
+        blenderbim.bim.helper.draw_attributes(self.props.external_style_attributes, self.layout)
+        row = self.layout.row(align=True)
+        row.operator("bim.edit_surface_style", text="Save External Style", icon="CHECKMARK")
+        row.operator("bim.disable_editing_style", text="", icon="CANCEL")
+
 
 def draw_style_ui(self, context):
     mat = context.material