diff --git a/src/meshTools/directMapped/directMappedPolyPatch/directMappedPolyPatch.C b/src/meshTools/directMapped/directMappedPolyPatch/directMappedPolyPatch.C
index 5d54517f0b..e97377294c 100644
--- a/src/meshTools/directMapped/directMappedPolyPatch/directMappedPolyPatch.C
+++ b/src/meshTools/directMapped/directMappedPolyPatch/directMappedPolyPatch.C
@@ -209,7 +209,7 @@ void Foam::directMappedPolyPatch::findSamples
                 // patch faces
                 const labelList patchFaces(identity(pp.size()) + pp.start());
 
-                const treeBoundBox patchBb
+                treeBoundBox patchBb
                 (
                     treeBoundBox(pp.points(), pp.meshPoints()).extend
                     (
@@ -217,6 +217,8 @@ void Foam::directMappedPolyPatch::findSamples
                         1E-4
                     )
                 );
+                patchBb.min() -= point(ROOTVSMALL, ROOTVSMALL, ROOTVSMALL);
+                patchBb.max() += point(ROOTVSMALL, ROOTVSMALL, ROOTVSMALL);
 
                 autoPtr<indexedOctree<treeDataFace> > boundaryTree
                 (
diff --git a/src/meshTools/indexedOctree/indexedOctree.C b/src/meshTools/indexedOctree/indexedOctree.C
index 385fb2d314..9b065c36ac 100644
--- a/src/meshTools/indexedOctree/indexedOctree.C
+++ b/src/meshTools/indexedOctree/indexedOctree.C
@@ -26,7 +26,6 @@ License
 
 #include "indexedOctree.H"
 #include "linePointRef.H"
-// #include "triSurface.H"
 #include "meshTools.H"
 #include "OFstream.H"
 
diff --git a/src/meshTools/meshSearch/meshSearch.C b/src/meshTools/meshSearch/meshSearch.C
index 808da494b5..ef1aa46f67 100644
--- a/src/meshTools/meshSearch/meshSearch.C
+++ b/src/meshTools/meshSearch/meshSearch.C
@@ -460,8 +460,10 @@ const Foam::indexedOctree<Foam::treeDataFace>& Foam::meshSearch::boundaryTree()
         }
 
         treeBoundBox overallBb(mesh_.points());
-
         Random rndGen(123456);
+        overallBb.extend(rndGen, 1E-4);
+        overallBb.min() -= point(ROOTVSMALL, ROOTVSMALL, ROOTVSMALL);
+        overallBb.max() += point(ROOTVSMALL, ROOTVSMALL, ROOTVSMALL);
 
         boundaryTreePtr_ = new indexedOctree<treeDataFace>
         (
@@ -471,7 +473,7 @@ const Foam::indexedOctree<Foam::treeDataFace>& Foam::meshSearch::boundaryTree()
                 mesh_,
                 bndFaces                    // boundary faces only
             ),
-            overallBb.extend(rndGen, 1E-3), // overall search domain
+            overallBb,                      // overall search domain
             8,                              // maxLevel
             10,                             // leafsize
             3.0                             // duplicity
@@ -492,6 +494,10 @@ const Foam::indexedOctree<Foam::treeDataCell>& Foam::meshSearch::cellTree()
         //
 
         treeBoundBox overallBb(mesh_.points());
+        Random rndGen(123456);
+        overallBb.extend(rndGen, 1E-4);
+        overallBb.min() -= point(ROOTVSMALL, ROOTVSMALL, ROOTVSMALL);
+        overallBb.max() += point(ROOTVSMALL, ROOTVSMALL, ROOTVSMALL);
 
         cellTreePtr_ = new indexedOctree<treeDataCell>
         (
@@ -522,6 +528,10 @@ const Foam::indexedOctree<Foam::treeDataPoint>&
         //
 
         treeBoundBox overallBb(mesh_.cellCentres());
+        Random rndGen(123456);
+        overallBb.extend(rndGen, 1E-4);
+        overallBb.min() -= point(ROOTVSMALL, ROOTVSMALL, ROOTVSMALL);
+        overallBb.max() += point(ROOTVSMALL, ROOTVSMALL, ROOTVSMALL);
 
         cellCentreTreePtr_ = new indexedOctree<treeDataPoint>
         (
diff --git a/src/meshTools/searchableSurface/triSurfaceMesh.C b/src/meshTools/searchableSurface/triSurfaceMesh.C
index 9958afd1b1..4703d69201 100644
--- a/src/meshTools/searchableSurface/triSurfaceMesh.C
+++ b/src/meshTools/searchableSurface/triSurfaceMesh.C
@@ -352,17 +352,24 @@ const Foam::indexedOctree<Foam::treeDataTriSurface>&
 {
     if (tree_.empty())
     {
-        treeBoundBox bb(points(), meshPoints());
-
         // Random number generator. Bit dodgy since not exactly random ;-)
         Random rndGen(65431);
 
+        // Slightly extended bb. Slightly off-centred just so on symmetric
+        // geometry there are less face/edge aligned items.
+        treeBoundBox bb
+        (
+            treeBoundBox(points(), meshPoints()).extend(rndGen, 1E-4)
+        );
+        bb.min() -= point(ROOTVSMALL, ROOTVSMALL, ROOTVSMALL);
+        bb.max() += point(ROOTVSMALL, ROOTVSMALL, ROOTVSMALL);
+
         tree_.reset
         (
             new indexedOctree<treeDataTriSurface>
             (
                 treeDataTriSurface(*this),
-                bb.extend(rndGen, 1E-4),    // slightly randomize bb
+                bb,
                 10,     // maxLevel
                 10,     // leafsize
                 3.0     // duplicity
@@ -375,12 +382,10 @@ const Foam::indexedOctree<Foam::treeDataTriSurface>&
 
 
 const Foam::indexedOctree<Foam::treeDataEdge>&
-    Foam::triSurfaceMesh::edgeTree() const
+ Foam::triSurfaceMesh::edgeTree() const
 {
     if (edgeTree_.empty())
     {
-        treeBoundBox bb(localPoints());
-
         // Boundary edges
         labelList bEdges
         (
@@ -395,6 +400,15 @@ const Foam::indexedOctree<Foam::treeDataEdge>&
         // Random number generator. Bit dodgy since not exactly random ;-)
         Random rndGen(65431);
 
+        // Slightly extended bb. Slightly off-centred just so on symmetric
+        // geometry there are less face/edge aligned items.
+        treeBoundBox bb
+        (
+            treeBoundBox(points(), meshPoints()).extend(rndGen, 1E-4)
+        );
+        bb.min() -= point(ROOTVSMALL, ROOTVSMALL, ROOTVSMALL);
+        bb.max() += point(ROOTVSMALL, ROOTVSMALL, ROOTVSMALL);
+
         edgeTree_.reset
         (
             new indexedOctree<treeDataEdge>
@@ -406,7 +420,7 @@ const Foam::indexedOctree<Foam::treeDataEdge>&
                     localPoints(),  // points
                     bEdges          // selected edges
                 ),
-                bb.extend(rndGen, 1E-4),    // slightly randomize bb
+                bb,     // bb
                 8,      // maxLevel
                 10,     // leafsize
                 3.0     // duplicity
@@ -463,8 +477,11 @@ void Foam::triSurfaceMesh::findNearest
 
     forAll(samples, i)
     {
-        static_cast<pointIndexHit&>(info[i]) =
-            octree.findNearest(samples[i], nearestDistSqr[i]);
+        static_cast<pointIndexHit&>(info[i]) = octree.findNearest
+        (
+            samples[i],
+            nearestDistSqr[i]
+        );
     }
 }
 
@@ -504,8 +521,11 @@ void Foam::triSurfaceMesh::findLineAny
 
     forAll(start, i)
     {
-        static_cast<pointIndexHit&>(info[i]) =
-            octree.findLineAny(start[i], end[i]);
+        static_cast<pointIndexHit&>(info[i]) = octree.findLineAny
+        (
+            start[i],
+            end[i]
+        );
     }
 }
 
diff --git a/src/meshTools/triSurface/triSurfaceSearch/triSurfaceSearch.C b/src/meshTools/triSurface/triSurfaceSearch/triSurfaceSearch.C
index 99f3a8eeaf..525126251f 100644
--- a/src/meshTools/triSurface/triSurfaceSearch/triSurfaceSearch.C
+++ b/src/meshTools/triSurface/triSurfaceSearch/triSurfaceSearch.C
@@ -50,19 +50,21 @@ triSurfaceSearch::triSurfaceSearch(const triSurface& surface)
     surface_(surface),
     treePtr_(NULL)
 {
-    treeBoundBox treeBb(surface_.points(), surface_.meshPoints());
+    // Random number generator. Bit dodgy since not exactly random ;-)
+    Random rndGen(65431);
 
-    scalar tol = 1E-6 * treeBb.avgDim();
-
-    point& bbMin = treeBb.min();
-    bbMin.x() -= tol;
-    bbMin.y() -= tol;
-    bbMin.z() -= tol;
-
-    point& bbMax = treeBb.max();
-    bbMax.x() += 2*tol;
-    bbMax.y() += 2*tol;
-    bbMax.z() += 2*tol;
+    // Slightly extended bb. Slightly off-centred just so on symmetric
+    // geometry there are less face/edge aligned items.
+    treeBoundBox treeBb
+    (
+        treeBoundBox(surface_.points(), surface_.meshPoints()).extend
+        (
+            rndGen,
+            1E-4
+        )
+    );
+    treeBb.min() -= point(ROOTVSMALL, ROOTVSMALL, ROOTVSMALL);
+    treeBb.max() += point(ROOTVSMALL, ROOTVSMALL, ROOTVSMALL);
 
     treePtr_.reset
     (