diff --git a/source/model/modelutils.js b/source/model/modelutils.js
index d43c0c8..42bb5fa 100644
--- a/source/model/modelutils.js
+++ b/source/model/modelutils.js
@@ -236,16 +236,24 @@ OV.IsSolid = function (element)
         return null;
     }
 
-    // TODO: two cubes connecting in one edge is solid, but it detects it as not solid
     const topology = OV.GetTopology (element);
     for (let edgeIndex = 0; edgeIndex < topology.edges.length; edgeIndex++) {
         const edge = topology.edges[edgeIndex];
-        if (edge.triangles.length !== 2) {
+        let triCount = edge.triangles.length;
+        if (triCount === 0 || triCount % 2 !== 0) {
             return false;
         }
-        const edgeOrientation1 = GetEdgeOrientationInTriangle (topology, edge.triangles[0], edgeIndex);
-        const edgeOrientation2 = GetEdgeOrientationInTriangle (topology, edge.triangles[1], edgeIndex);
-        if (edgeOrientation1 === edgeOrientation2) {
+        let edgesDirection = 0;
+        for (let triIndex = 0; triIndex < edge.triangles.length; triIndex++) {
+            const triangleIndex = edge.triangles[triIndex];
+            const edgeOrientation = GetEdgeOrientationInTriangle (topology, triangleIndex, edgeIndex);
+            if (edgeOrientation) {
+                edgesDirection += 1;
+            } else {
+                edgesDirection -= 1;
+            }
+        }
+        if (edgesDirection !== 0) {
             return false;
         }
     }
diff --git a/test/tests/modelutils_test.js b/test/tests/modelutils_test.js
index eeb6f2b..f911d9d 100644
--- a/test/tests/modelutils_test.js
+++ b/test/tests/modelutils_test.js
@@ -178,6 +178,13 @@ describe ('Model Utils', function () {
         const model = testUtils.GetTwoCubesConnectingInOneEdgeModel ();
         let topology = OV.GetTopology (model);
         assert.strictEqual (topology.vertices.length, 14);
-        assert (!OV.IsSolid (model)); // TODO: should be identified as solid
-    });    
+        assert (OV.IsSolid (model));
+    });
+
+    it ('Two Cubes Connecting in One Face Topology Calculation', function () {
+        const model = testUtils.GetTwoCubesConnectingInOneFaceModel ();
+        let topology = OV.GetTopology (model);
+        assert.strictEqual (topology.vertices.length, 12);
+        assert (OV.IsSolid (model));
+    });     
 });
diff --git a/test/tests/quantities_test.js b/test/tests/quantities_test.js
index 726e886..07e5028 100644
--- a/test/tests/quantities_test.js
+++ b/test/tests/quantities_test.js
@@ -15,6 +15,21 @@ describe ('Quantities', function () {
         assert.strictEqual (OV.CalculateVolume (model), null);
     });
 
+    it ('Two Cubes Connecting in One Vertex Volume Calculation', function () {
+        const model = testUtils.GetTwoCubesConnectingInOneVertexModel ();
+        assert (OV.IsEqual (OV.CalculateVolume (model), 2.0));
+    });  
+
+    it ('Two Cubes Connecting in One Edge Volume Calculation', function () {
+        const model = testUtils.GetTwoCubesConnectingInOneEdgeModel ();
+        assert (OV.IsEqual (OV.CalculateVolume (model), 2.0));
+    });
+
+    it ('Two Cubes Connecting in One Face Volume Calculation', function () {
+        const model = testUtils.GetTwoCubesConnectingInOneFaceModel ();
+        assert (OV.IsEqual (OV.CalculateVolume (model), 2.0));
+    });  
+
     it ('Cube with Wrongly Oriented Triangle Volume Calculation', function () {
         var mesh = new OV.Mesh ();
         mesh.AddVertex (new OV.Coord3D (0.0, 0.0, 0.0));
diff --git a/test/utils/testutils.js b/test/utils/testutils.js
index 98ed01b..606ba6f 100644
--- a/test/utils/testutils.js
+++ b/test/utils/testutils.js
@@ -197,6 +197,24 @@ module.exports =
         return model;
     },
 
+
+    GetTwoCubesConnectingInOneFaceModel ()
+    {
+        let model = new OV.Model ();
+
+        let cube1 = this.GetCubeMesh ();
+        model.AddMesh (cube1);
+        
+        let cube2 = this.GetCubeMesh ();
+        let matrix = new OV.Matrix ().CreateTranslation (1.0, 0.0, 0.0);
+        let transformation = new OV.Transformation (matrix);
+        OV.TransformMesh (cube2, transformation);
+        model.AddMesh (cube2);
+
+        OV.FinalizeModel (model, function () { new OV.Material () });
+        return model;
+    },
+    
     GetCubeWithOneMissingFaceMesh ()
     {
         var cube = new OV.Mesh ();