Index: Ringtoets/HeightStructures/src/Ringtoets.HeightStructures.Data/HeightStructuresFailureMechanismSectionResult.cs
===================================================================
diff -u -r673e35de0df920529e5dda63ea8b4dfb08ed65a8 -rd9c981f7b4c64d16e55fca0cb51eb9f4c9aec28f
--- Ringtoets/HeightStructures/src/Ringtoets.HeightStructures.Data/HeightStructuresFailureMechanismSectionResult.cs	(.../HeightStructuresFailureMechanismSectionResult.cs)	(revision 673e35de0df920529e5dda63ea8b4dfb08ed65a8)
+++ Ringtoets/HeightStructures/src/Ringtoets.HeightStructures.Data/HeightStructuresFailureMechanismSectionResult.cs	(.../HeightStructuresFailureMechanismSectionResult.cs)	(revision d9c981f7b4c64d16e55fca0cb51eb9f4c9aec28f)
@@ -30,17 +30,12 @@
     /// </summary>
     public class HeightStructuresFailureMechanismSectionResult : FailureMechanismSectionResult
     {
-        private readonly double assessmentLayerTwoA;
-
         /// <summary>
         /// Creates a new instance of <see cref="HeightStructuresFailureMechanismSectionResult"/>.
         /// </summary>
         /// <param name="section">The <see cref="FailureMechanismSection"/> to get the result from.</param>
         /// <exception cref="ArgumentNullException">Thrown when <paramref name="section"/> is <c>null</c>.</exception>
-        public HeightStructuresFailureMechanismSectionResult(FailureMechanismSection section) : base(section)
-        {
-            assessmentLayerTwoA = double.NaN;
-        }
+        public HeightStructuresFailureMechanismSectionResult(FailureMechanismSection section) : base(section) {}
 
         /// <summary>
         /// Gets the value of assessment layer two a.
@@ -49,7 +44,11 @@
         {
             get
             {
-                return assessmentLayerTwoA;
+                if (Calculation == null || !Calculation.HasOutput)
+                {
+                    return double.NaN;
+                }
+                return Calculation.Output.Probability;
             }
         }
 
Index: Ringtoets/HeightStructures/test/Ringtoets.HeightStructures.Data.Test/HeightStructuresFailureMechanismSectionResultTest.cs
===================================================================
diff -u -r73597729ce18d3ee00d8036bca8341e9c12f2953 -rd9c981f7b4c64d16e55fca0cb51eb9f4c9aec28f
--- Ringtoets/HeightStructures/test/Ringtoets.HeightStructures.Data.Test/HeightStructuresFailureMechanismSectionResultTest.cs	(.../HeightStructuresFailureMechanismSectionResultTest.cs)	(revision 73597729ce18d3ee00d8036bca8341e9c12f2953)
+++ Ringtoets/HeightStructures/test/Ringtoets.HeightStructures.Data.Test/HeightStructuresFailureMechanismSectionResultTest.cs	(.../HeightStructuresFailureMechanismSectionResultTest.cs)	(revision d9c981f7b4c64d16e55fca0cb51eb9f4c9aec28f)
@@ -22,6 +22,7 @@
 using Core.Common.Base.Geometry;
 using NUnit.Framework;
 using Ringtoets.Common.Data.FailureMechanism;
+using Ringtoets.Common.Data.Probability;
 
 namespace Ringtoets.HeightStructures.Data.Test
 {
@@ -46,5 +47,91 @@
             Assert.IsNaN(sectionResult.AssessmentLayerTwoA);
             Assert.IsNull(sectionResult.Calculation);
         }
+
+        [Test]
+        public void Calculation_SetNewValue_GetNewlySetValue()
+        {
+            // Setup
+            FailureMechanismSection section = CreateSection();
+
+            var result = new HeightStructuresFailureMechanismSectionResult(section);
+
+            var calculation = new HeightStructuresCalculation();
+
+            // Call
+            result.Calculation = calculation;
+
+            // Assert
+            Assert.AreSame(calculation, result.Calculation);
+        }
+
+        [Test]
+        public void AssessmentLayerTwoA_CalculationNull_ReturnNaN()
+        {
+            // Setup
+            FailureMechanismSection section = CreateSection();
+
+            var result = new HeightStructuresFailureMechanismSectionResult(section)
+            {
+                Calculation = null
+            };
+
+            // Call
+            double twoAValue = result.AssessmentLayerTwoA;
+
+            // Assert
+            Assert.IsNaN(twoAValue);
+        }
+
+        [Test]
+        public void AssessmentLayerTwoA_FailedCalculation_ReturnNaN()
+        {
+            // Setup
+            FailureMechanismSection section = CreateSection();
+
+            var result = new HeightStructuresFailureMechanismSectionResult(section)
+            {
+                Calculation = new HeightStructuresCalculation
+                {
+                    Output = new ProbabilityAssessmentOutput(1.0, 1.0, double.NaN, 1.0, 1.0)
+                }
+            };
+
+            // Call
+            double twoAValue = result.AssessmentLayerTwoA;
+
+            // Assert
+            Assert.IsNaN(twoAValue);
+        }
+
+        [Test]
+        public void AssessmentLayerTwoA_SuccessfulCalculation_ReturnProbability()
+        {
+            // Setup
+            FailureMechanismSection section = CreateSection();
+
+            double probability = 0.65;
+            var result = new HeightStructuresFailureMechanismSectionResult(section)
+            {
+                Calculation = new HeightStructuresCalculation
+                {
+                    Output = new ProbabilityAssessmentOutput(1.0, 1.0, probability, 1.0, 1.0)
+                }
+            };
+
+            // Call
+            double twoAValue = result.AssessmentLayerTwoA;
+
+            // Assert
+            Assert.AreEqual(probability, twoAValue);
+        }
+
+        private static FailureMechanismSection CreateSection()
+        {
+            return new FailureMechanismSection("Section", new[]
+            {
+                new Point2D(0, 0)
+            });
+        }
     }
 }
\ No newline at end of file