diff --git a/LuaLibs/ProcessStepJointNotch.lua b/LuaLibs/ProcessStepJointNotch.lua
index 626b1d0..ab75dd6 100644
--- a/LuaLibs/ProcessStepJointNotch.lua
+++ b/LuaLibs/ProcessStepJointNotch.lua
@@ -1,4 +1,4 @@
--- ProcessStepJointNotch.lua by Egaltech s.r.l. 2019/10/22
+-- ProcessStepJointNotch.lua by Egaltech s.r.l. 2019/10/23
 -- Gestione calcolo tacca a gradino per Travi
 
 -- Tabella per definizione modulo
@@ -36,7 +36,12 @@ function ProcessStepJointNotch.Classify( Proc)
    local bDown = false
    for i = 1, nFacetCnt do
       local vtN = EgtSurfTmFacetNormVersor( Proc.Id, i-1, GDB_ID.ROOT)
-      if vtN:getZ() < -0.1 then
+      -- se faccia limite
+      if AreSameOrOppositeVectorApprox( vtN, Y_AX()) or AreSameOrOppositeVectorApprox( vtN, Z_AX()) then
+         -- attualmente non gestita
+         return false, false
+      -- altrimenti faccia principale
+      elseif vtN:getZ() < -0.1 then
          bDown = true
       end
    end