diff --git a/src/Mod/BIM/importers/exportIFC.py b/src/Mod/BIM/importers/exportIFC.py
index 74208443f6..a12fbda457 100644
--- a/src/Mod/BIM/importers/exportIFC.py
+++ b/src/Mod/BIM/importers/exportIFC.py
@@ -2346,6 +2346,7 @@ def getRepresentation(
                     if hasattr(obj,"Material"):
                         if obj.Material:
                             m = obj.Material.Label
+                            rgbt[i] = (rgbt[i][0], rgbt[i][1], rgbt[i][2], obj.Material.Transparency/100.0)
                     psa = ifcbin.createIfcPresentationStyleAssignment(m,rgbt[i][0],rgbt[i][1],rgbt[i][2],rgbt[i][3])
                     surfstyles[key] = psa
                 isi = ifcfile.createIfcStyledItem(shape,[psa],None)
diff --git a/src/Mod/BIM/importers/exportIFCHelper.py b/src/Mod/BIM/importers/exportIFCHelper.py
index d4e6feb2b3..d044269850 100644
--- a/src/Mod/BIM/importers/exportIFCHelper.py
+++ b/src/Mod/BIM/importers/exportIFCHelper.py
@@ -381,13 +381,13 @@ class recycler:
                 self.rgbs[key] = c
             return c
 
-    def createIfcSurfaceStyleRendering(self,col,trans=0):
+    def createIfcSurfaceStyleRendering(self,col,trans=1):
         key = (col.Red,col.Green,col.Blue,trans)
         if self.compress and key in self.ssrenderings:
             self.spared += 1
             return self.ssrenderings[key]
         else:
-            if trans == 0:
+            if trans == 1:
                 trans = None
             c = self.ifcfile.createIfcSurfaceStyleRendering(col,trans,None,None,None,None,None,None,"FLAT")
             if self.compress:
@@ -405,7 +405,7 @@ class recycler:
                 self.transformationoperators[key] = c
             return c
 
-    def createIfcSurfaceStyle(self,name,r,g,b,t=0):
+    def createIfcSurfaceStyle(self,name,r,g,b,a=1):
         if name:
             key = name + str((r,g,b))
         else:
@@ -415,22 +415,22 @@ class recycler:
             return self.sstyles[key]
         else:
             col = self.createIfcColourRgb(r,g,b)
-            ssr = self.createIfcSurfaceStyleRendering(col,t)
+            ssr = self.createIfcSurfaceStyleRendering(col,a)
             c = self.ifcfile.createIfcSurfaceStyle(name,"BOTH",[ssr])
             if self.compress:
                 self.sstyles[key] = c
             return c
 
-    def createIfcPresentationStyleAssignment(self,name,r,g,b,t=0,ifc4=False):
+    def createIfcPresentationStyleAssignment(self,name,r,g,b,a=1,ifc4=False):
         if name:
-            key = name+str((r,g,b,t))
+            key = name+str((r,g,b,a))
         else:
-            key = str((r,g,b,t))
+            key = str((r,g,b,a))
         if self.compress and key in self.psas:
             self.spared += 1
             return self.psas[key]
         else:
-            iss = self.createIfcSurfaceStyle(name,r,g,b,t)
+            iss = self.createIfcSurfaceStyle(name,r,g,b,a)
             if ifc4:
                 c = iss
             else: