diff --git a/src/Mod/Arch/ArchBuildingPart.py b/src/Mod/Arch/ArchBuildingPart.py
index 5dcad008d1..71c3d6101c 100644
--- a/src/Mod/Arch/ArchBuildingPart.py
+++ b/src/Mod/Arch/ArchBuildingPart.py
@@ -356,13 +356,16 @@ class BuildingPart:
             self.oldPlacement = FreeCAD.Placement(obj.Placement)
 
     def onChanged(self,obj,prop):
+
         ArchIFC.onChanged(obj, prop)
+
         if prop == "Height":
             for child in obj.Group:
                 if Draft.getType(child) in ["Wall","Structure"]:
                     if not child.Height.Value:
                         #print("Executing ",child.Label)
                         child.Proxy.execute(child)
+
         elif prop == "Placement":
             if hasattr(self,"oldPlacement"):
                 if self.oldPlacement:
@@ -391,6 +394,9 @@ class BuildingPart:
                             if deltap:
                                 child.Placement.move(deltap)
 
+        elif prop == "Group":
+            obj.Area = self.getArea(obj)
+
     def execute(self,obj):
 
         # gather all the child shapes into a compound
@@ -399,6 +405,19 @@ class BuildingPart:
             import Part
             obj.Shape = Part.makeCompound(shapes)
 
+    def getArea(self,obj):
+        
+        "computes the area of this floor by adding its inner spaces"
+        
+        area = 0
+        if hasattr(obj,"Group"):
+            for child in obj.Group:
+                if hasattr(child,"Area") and hasattr(child,"IfcType"):
+                    # only add arch objects that have an Area property
+                    # TODO only spaces? ATM only spaces and windows have an Area property
+                    area += child.Area.Value
+        return area
+
     def getShapes(self,obj):
 
         "recursively get the shapes of objects inside this BuildingPart"
diff --git a/src/Mod/Arch/ArchComponent.py b/src/Mod/Arch/ArchComponent.py
index f86c2b8704..60c8289d3c 100644
--- a/src/Mod/Arch/ArchComponent.py
+++ b/src/Mod/Arch/ArchComponent.py
@@ -326,11 +326,20 @@ class Component:
                         # if the final obj is rotated, this will screw all our IFC orientation. Better leave it like that then...
                         data = obj.Base.Proxy.getExtrusionData(obj.Base)
                         if data:
+                            return data
+                            # TODO above doesn't work if underlying shape is not at (0,0,0). But code below doesn't work well yet
                             # add the displacement of the final object
+                            disp = obj.Shape.CenterOfMass.sub(obj.Base.Shape.CenterOfMass)
                             if isinstance(data[2],(list,tuple)):
-                                return (data[0],data[1],[p.multiply(obj.Placement) for p in data[2]])
+                                ndata2 = []
+                                for p in data[2]:
+                                    p.move(disp)
+                                    ndata2.append(p)
+                                return (data[0],data[1],ndata2)
                             else:
-                                return (data[0],data[1],data[2].multiply(obj.Placement))
+                                ndata2 = data[2]
+                                ndata2.move(disp)
+                                return (data[0],data[1],ndata2)
             # the base is a Part Extrusion
             elif obj.Base.isDerivedFrom("Part::Extrusion"):
                 if obj.Base.Base: