diff --git a/src/db/db/dbCellVariants.h b/src/db/db/dbCellVariants.h
index 11f2fde8d..8e6210ceb 100644
--- a/src/db/db/dbCellVariants.h
+++ b/src/db/db/dbCellVariants.h
@@ -28,6 +28,7 @@
 #include "dbLayout.h"
 #include "dbTrans.h"
 #include "tlTypeTraits.h"
+#include "tlUtils.h"
 
 namespace db
 {
@@ -354,6 +355,123 @@ public:
     }
   }
 
+  /**
+   *  @brief Commits the shapes for different variants to the current cell hierarchy
+   *
+   *  This is an alternative approach and will push the variant shapes into the parent hierarchy.
+   *  "to_commit" initially is a set of shapes to commit for the given cell and variant.
+   *  This map is modified during the algorithm and should be discarded later.
+   */
+  virtual void commit_shapes (db::Layout &layout, db::Cell &top_cell, unsigned int layer, std::map<db::cell_index_type, std::map<db::ICplxTrans, db::Shapes> > &to_commit)
+  {
+    if (to_commit.empty ()) {
+      return;
+    }
+
+    //  NOTE: this implementation suffers from accumulation of propagated shapes: we add more levels of propagated
+    //  shapes if required. We don't clean up, because we do not know when a shape collection stops being required.
+
+    db::LayoutLocker locker (&layout);
+
+    std::set<db::cell_index_type> called;
+    top_cell.collect_called_cells (called);
+    called.insert (top_cell.cell_index ());
+
+    for (db::Layout::bottom_up_const_iterator c = layout.begin_bottom_up (); c != layout.end_bottom_up (); ++c) {
+
+      if (called.find (*c) == called.end ()) {
+        continue;
+      }
+
+      db::Cell &cell = layout.cell (*c);
+
+      std::map<db::ICplxTrans, size_t> &vvc = m_variants [*c];
+      if (vvc.size () > 1) {
+
+        for (std::map<db::ICplxTrans, size_t>::const_iterator vc = vvc.begin (); vc != vvc.end (); ++vc) {
+
+          for (db::Cell::const_iterator i = cell.begin (); ! i.at_end (); ++i) {
+
+            std::map<db::cell_index_type, std::map<db::ICplxTrans, db::Shapes> >::const_iterator tc = to_commit.find (i->cell_index ());
+            if (tc != to_commit.end ()) {
+
+              const std::map<db::ICplxTrans, db::Shapes> &vt = tc->second;
+
+              //  NOTE: this will add one more commit slot for propagation ... but we don't clean up.
+              //  When would a cleanup happen?
+              std::map<db::ICplxTrans, db::Shapes> &propagated = to_commit [*c];
+
+              for (db::CellInstArray::iterator ia = i->begin (); ! ia.at_end (); ++ia) {
+
+                db::ICplxTrans t = i->complex_trans (*ia);
+                db::ICplxTrans rt = m_red (vc->first * t);
+                std::map<db::ICplxTrans, db::Shapes>::const_iterator v = vt.find (rt);
+                if (v != vt.end ()) {
+
+                  db::Shapes &ps = propagated [vc->first];
+                  tl::ident_map<db::Layout::properties_id_type> pm;
+
+                  for (db::Shapes::shape_iterator si = v->second.begin (db::ShapeIterator::All); ! si.at_end (); ++si) {
+                    ps.insert (*si, t, pm);
+                  }
+
+                }
+
+              }
+
+            }
+
+          }
+
+        }
+
+      } else {
+
+        //  single variant -> we can commit any shapes we have kept for this cell directly to the cell
+
+        std::map<db::cell_index_type, std::map<db::ICplxTrans, db::Shapes> >::iterator l = to_commit.find (*c);
+        if (l != to_commit.end ()) {
+          tl_assert (l->second.size () == 1);
+          cell.shapes (layer).insert (l->second.begin ()->second);
+          to_commit.erase (l);
+        }
+
+        //  for child cells, pull everything that needs to be committed to the parent
+
+        for (db::Cell::const_iterator i = cell.begin (); ! i.at_end (); ++i) {
+
+          std::map<db::cell_index_type, std::map<db::ICplxTrans, db::Shapes> >::const_iterator tc = to_commit.find (i->cell_index ());
+          if (tc != to_commit.end ()) {
+
+            const std::map<db::ICplxTrans, db::Shapes> &vt = tc->second;
+
+            for (db::CellInstArray::iterator ia = i->begin (); ! ia.at_end (); ++ia) {
+
+              db::ICplxTrans t = i->complex_trans (*ia);
+              db::ICplxTrans rt = m_red (vvc.begin ()->first * t);
+              std::map<db::ICplxTrans, db::Shapes>::const_iterator v = vt.find (rt);
+
+              if (v != vt.end ()) {
+
+                tl::ident_map<db::Layout::properties_id_type> pm;
+
+                for (db::Shapes::shape_iterator si = v->second.begin (db::ShapeIterator::All); ! si.at_end (); ++si) {
+                  cell.shapes (layer).insert (*si, t, pm);
+                }
+
+              }
+
+            }
+
+          }
+
+        }
+
+      }
+
+    }
+  }
+
   /**
    *  @brief Gets the variants for a given cell
    *
@@ -371,6 +489,19 @@ public:
     }
   }
 
+  /**
+   *  @brief Returns true, if variants have been built
+   */
+  bool has_variants () const
+  {
+    for (std::map<db::cell_index_type, std::map<db::ICplxTrans, size_t> >::const_iterator i = m_variants.begin (); i != m_variants.end (); ++i) {
+      if (i->second.size () > 1) {
+        return true;
+      }
+    }
+    return false;
+  }
+
 private:
   std::map<db::cell_index_type, std::map<db::ICplxTrans, size_t> > m_variants;
   Reduce m_red;
diff --git a/src/db/db/dbDeepRegion.cc b/src/db/db/dbDeepRegion.cc
index 3fe83e3c6..7ad2960b7 100644
--- a/src/db/db/dbDeepRegion.cc
+++ b/src/db/db/dbDeepRegion.cc
@@ -713,11 +713,82 @@ DeepRegion::to_string (size_t nmax) const
   return db::AsIfFlatRegion::to_string (nmax);
 }
 
+static void produce_offgrid_markers (db::Shapes &markers, const db::Shapes &shapes, const db::ICplxTrans &tr, db::Coord g)
+{
+  for (db::Shapes::shape_iterator si = shapes.begin (db::ShapeIterator::All); ! si.at_end (); ++si) {
+
+    db::Polygon poly;
+    si->polygon (poly);
+
+    for (size_t i = 0; i < poly.holes () + 1; ++i) {
+
+      db::Polygon::polygon_contour_iterator b, e;
+
+      if (i == 0) {
+        b = poly.begin_hull ();
+        e = poly.end_hull ();
+      } else {
+        b = poly.begin_hole ((unsigned int) (i - 1));
+        e = poly.end_hole ((unsigned int)  (i - 1));
+      }
+
+      for (db::Polygon::polygon_contour_iterator p = b; p != e; ++p) {
+        db::Point pt = tr * *p;
+        if ((pt.x () % g) != 0 || (pt.y () % g) != 0) {
+          markers.insert (EdgePair (db::Edge (pt, pt), db::Edge (pt, pt)));
+        }
+      }
+
+    }
+
+  }
+
+}
+
 EdgePairs
 DeepRegion::grid_check (db::Coord gx, db::Coord gy) const
 {
-  //  TODO: snap be optimized by forming grid variants etc.
-  return db::AsIfFlatRegion::grid_check (gx, gy);
+  if (gx <= 0 || gy <= 0) {
+    throw tl::Exception (tl::to_string (tr ("Grid check requires a positive grid value")));
+  }
+
+  if (gx != gy) {
+    //  no way doing this hierarchically ?
+    return db::AsIfFlatRegion::grid_check (gx, gy);
+  }
+
+  ensure_merged_polygons_valid ();
+
+  db::Layout &layout = m_merged_polygons.layout ();
+
+  db::cell_variants_collector<db::GridReducer> vars (gx);
+  vars.collect (layout, m_merged_polygons.initial_cell ());
+
+  std::map<db::cell_index_type, std::map<db::ICplxTrans, db::Shapes> > to_commit;
+  std::auto_ptr<db::DeepEdgePairs> res (new db::DeepEdgePairs (m_merged_polygons.derived ()));
+
+  for (db::Layout::iterator c = layout.begin (); c != layout.end (); ++c) {
+
+    const std::map<db::ICplxTrans, size_t> &vv = vars.variants (c->cell_index ());
+    for (std::map<db::ICplxTrans, size_t>::const_iterator v = vv.begin (); v != vv.end (); ++v) {
+
+      db::Shapes *markers;
+      if (vv.size () == 1) {
+        markers = & c->shapes (res->deep_layer ().layer ());
+      } else {
+        markers = & to_commit [c->cell_index ()] [v->first];
+      }
+
+      produce_offgrid_markers (*markers, c->shapes (m_merged_polygons.layer ()), v->first, gx);
+
+    }
+
+  }
+
+  //  propagate the markers with a similar algorithm used for producing the variants
+  res->deep_layer ().commit_shapes (vars, to_commit);
+
+  return db::EdgePairs (res.release ());
 }
 
 EdgePairs
diff --git a/src/db/db/dbDeepShapeStore.h b/src/db/db/dbDeepShapeStore.h
index 96dc17af3..b76d44510 100644
--- a/src/db/db/dbDeepShapeStore.h
+++ b/src/db/db/dbDeepShapeStore.h
@@ -159,6 +159,19 @@ public:
   template <class VarCollector>
   void separate_variants (VarCollector &collector);
 
+  /**
+   *  @brief Commits shapes for variants to the existing cell hierarchy
+   *
+   *  The "to_propagate" collection is a set of shapes per cell and variant. The
+   *  algorithm will put these shapes into the existing hierarchy putting the
+   *  shapes into the proper parent cells to resolve variants.
+   *
+   *  This map will be modified by the algorithm and should be discarded
+   *  later.
+   */
+  template <class VarCollector>
+  void commit_shapes (VarCollector &collector, std::map<db::cell_index_type, std::map<db::ICplxTrans, db::Shapes> > &to_propagate);
+
   /**
    *  @brief Gets the shape store object
    *  This is a pure const version to prevent manipulation of the store.
@@ -299,6 +312,21 @@ public:
     issue_variants (layout_index, var_map);
   }
 
+  /**
+   *  @brief Commits shapes for variants to the existing cell hierarchy
+   *
+   *  To use this method, first create a variant collector (db::cell_variant_collector) with the required
+   *  reducer and collect the variants. Then call this method on the desired layout index to commit the shapes for the
+   *  respective variants.
+   */
+  template <class VarCollector>
+  void commit_shapes (unsigned int layout_index, VarCollector &coll, unsigned int layer, std::map<db::cell_index_type, std::map<db::ICplxTrans, db::Shapes> > &to_commit)
+  {
+    tl_assert (is_valid_layout_index (layout_index));
+
+    coll.commit_shapes (layout (layout_index), initial_cell (layout_index), layer, to_commit);
+  }
+
   /**
    *  @brief For testing
    */
@@ -538,6 +566,13 @@ void DeepLayer::separate_variants (VarCollector &collector)
   mp_store->separate_variants (m_layout, collector);
 }
 
+template <class VarCollector>
+void DeepLayer::commit_shapes (VarCollector &collector, std::map<db::cell_index_type, std::map<db::ICplxTrans, db::Shapes> > &to_commit)
+{
+  check_dss ();
+  mp_store->commit_shapes (m_layout, collector, layer (), to_commit);
+}
+
 }
 
 namespace tl
diff --git a/src/db/unit_tests/dbCellVariantsTests.cc b/src/db/unit_tests/dbCellVariantsTests.cc
index 8b207a252..f43cd7f1e 100644
--- a/src/db/unit_tests/dbCellVariantsTests.cc
+++ b/src/db/unit_tests/dbCellVariantsTests.cc
@@ -392,3 +392,47 @@ TEST(100_OrientationVariantsWithLayout)
   CHECKPOINT();
   db::compare_layouts (_this, ly, tl::testsrc () + "/testdata/algo/cell_variants_au1.gds");
 }
+
+TEST(101_Propagation)
+{
+  db::Layout ly;
+  {
+    std::string fn (tl::testsrc ());
+    fn += "/testdata/algo/cell_variants_l1.gds";
+    tl::InputStream stream (fn);
+    db::Reader reader (stream);
+    reader.read (ly);
+  }
+
+  std::map<db::cell_index_type, std::map<db::ICplxTrans, db::Shapes> > to_commit;
+
+  db::cell_index_type top_cell_index = *ly.begin_top_down ();
+  db::Cell &top_cell = ly.cell (top_cell_index);
+
+  unsigned int l1 = ly.get_layer (db::LayerProperties (1, 0));
+  unsigned int l2 = ly.insert_layer (db::LayerProperties (2, 0));
+
+  db::cell_variants_collector<db::MagnificationAndOrientationReducer> vb;
+  vb.collect (ly, top_cell);
+
+  for (db::Layout::const_iterator c = ly.begin (); c != ly.end (); ++c) {
+
+    const std::map<db::ICplxTrans, size_t> &vv = vb.variants (c->cell_index ());
+    for (std::map<db::ICplxTrans, size_t>::const_iterator v = vv.begin (); v != vv.end (); ++v) {
+
+      db::Shapes &out = to_commit [c->cell_index ()][v->first];
+      for (db::Shapes::shape_iterator s = c->shapes (l1).begin (db::ShapeIterator::All); ! s.at_end (); ++s) {
+        db::Box b = s->bbox ().transformed (v->first);
+        b.enlarge (db::Vector (-100, 0));
+        out.insert (b.transformed (v->first.inverted ()));
+      }
+
+    }
+
+  }
+
+  vb.commit_shapes (ly, top_cell, l2, to_commit);
+
+  CHECKPOINT();
+  db::compare_layouts (_this, ly, tl::testsrc () + "/testdata/algo/cell_variants_au2.gds");
+}
diff --git a/src/db/unit_tests/dbDeepRegionTests.cc b/src/db/unit_tests/dbDeepRegionTests.cc
index 7597be1b2..16bb37458 100644
--- a/src/db/unit_tests/dbDeepRegionTests.cc
+++ b/src/db/unit_tests/dbDeepRegionTests.cc
@@ -969,7 +969,7 @@ TEST(17_SinglePolygonChecks)
   }
 }
 
-TEST(18_Checks)
+TEST(18_MultiPolygonChecks)
 {
   db::Layout ly;
   {
@@ -1013,6 +1013,41 @@ TEST(18_Checks)
   }
 }
 
+TEST(19_GridCheck)
+{
+  db::Layout ly;
+  {
+    std::string fn (tl::testsrc ());
+    fn += "/testdata/algo/deep_region_l1.gds";
+    tl::InputStream stream (fn);
+    db::Reader reader (stream);
+    reader.read (ly);
+  }
+
+  db::cell_index_type top_cell_index = *ly.begin_top_down ();
+  db::Cell &top_cell = ly.cell (top_cell_index);
+
+  db::DeepShapeStore dss;
+
+  unsigned int l3 = ly.get_layer (db::LayerProperties (3, 0));
+
+  db::Region r3 (db::RecursiveShapeIterator (ly, top_cell, l3), dss);
+  db::Region r3_gc1;
+  r3.grid_check (25, 25).polygons (r3_gc1, 100);
+  db::Region r3_gc2;
+  r3.grid_check (40, 40).polygons (r3_gc2, 100);
+
+  db::Layout target;
+  unsigned int target_top_cell_index = target.add_cell (ly.cell_name (top_cell_index));
+
+  target.insert (target_top_cell_index, target.get_layer (db::LayerProperties (10, 0)), r3);
+  target.insert (target_top_cell_index, target.get_layer (db::LayerProperties (11, 0)), r3_gc1);
+  target.insert (target_top_cell_index, target.get_layer (db::LayerProperties (12, 0)), r3_gc2);
+
+  CHECKPOINT();
+  db::compare_layouts (_this, target, tl::testsrc () + "/testdata/algo/deep_region_au19.gds");
+}
+
 TEST(100_Integration)
 {
   db::Layout ly;
diff --git a/testdata/algo/cell_variants_au2.gds b/testdata/algo/cell_variants_au2.gds
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index 000000000..c30651bb0
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new file mode 100644
index 000000000..56c817fbc
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index 000000000..85b83f54e
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diff --git a/testdata/algo/deep_region_au17.gds b/testdata/algo/deep_region_au17.gds
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index 000000000..df3ab0872
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diff --git a/testdata/algo/deep_region_au18.gds b/testdata/algo/deep_region_au18.gds
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index 000000000..35edb6a15
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diff --git a/testdata/algo/deep_region_au19.gds b/testdata/algo/deep_region_au19.gds
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