Index: Riskeer/Common/src/Riskeer.Common.Data/FailurePath/FailurePathAssemblyResult.cs
===================================================================
diff -u -rf5bd7e0b6014f6f2026ea36d4ee53183cbb8a6a4 -rf021c1bffb41b07a8f60f9d96dcf2a08f9fc03cf
--- Riskeer/Common/src/Riskeer.Common.Data/FailurePath/FailurePathAssemblyResult.cs	(.../FailurePathAssemblyResult.cs)	(revision f5bd7e0b6014f6f2026ea36d4ee53183cbb8a6a4)
+++ Riskeer/Common/src/Riskeer.Common.Data/FailurePath/FailurePathAssemblyResult.cs	(.../FailurePathAssemblyResult.cs)	(revision f021c1bffb41b07a8f60f9d96dcf2a08f9fc03cf)
@@ -19,13 +19,18 @@
 // Stichting Deltares and remain full property of Stichting Deltares at all times.
 // All rights reserved.
 
+using Riskeer.Common.Data.Probability;
+using RiskeerCommonDataResources = Riskeer.Common.Data.Properties.Resources;
+
 namespace Riskeer.Common.Data.FailurePath
 {
     /// <summary>
     /// Class containing the assembly result of an entire failure path.
     /// </summary>
     public class FailurePathAssemblyResult
     {
+        private double manualFailurePathAssemblyProbability;
+
         /// <summary>
         /// Creates a new instance of <see cref="FailurePathAssemblyResult"/>
         /// </summary>
@@ -43,6 +48,16 @@
         /// <summary>
         /// Gets or sets the probability of a failure path assembly.
         /// </summary>
-        public double ManualFailurePathAssemblyProbability { get; set; }
+        public double ManualFailurePathAssemblyProbability
+        {
+            get => manualFailurePathAssemblyProbability;
+            set
+            {
+                ProbabilityHelper.ValidateProbability(value, null,
+                                                      RiskeerCommonDataResources.ArbitraryProbabilityFailureMechanismSectionResult_AssessmentProbability_Value_needs_to_be_in_Range_0_,
+                                                      true);
+                manualFailurePathAssemblyProbability = value;
+            }
+        }
     }
 }
\ No newline at end of file
Index: Riskeer/Common/test/Riskeer.Common.Data.Test/FailurePath/FailurePathAssemblyResultTest.cs
===================================================================
diff -u -rf5bd7e0b6014f6f2026ea36d4ee53183cbb8a6a4 -rf021c1bffb41b07a8f60f9d96dcf2a08f9fc03cf
--- Riskeer/Common/test/Riskeer.Common.Data.Test/FailurePath/FailurePathAssemblyResultTest.cs	(.../FailurePathAssemblyResultTest.cs)	(revision f5bd7e0b6014f6f2026ea36d4ee53183cbb8a6a4)
+++ Riskeer/Common/test/Riskeer.Common.Data.Test/FailurePath/FailurePathAssemblyResultTest.cs	(.../FailurePathAssemblyResultTest.cs)	(revision f021c1bffb41b07a8f60f9d96dcf2a08f9fc03cf)
@@ -19,6 +19,8 @@
 // Stichting Deltares and remain full property of Stichting Deltares at all times.
 // All rights reserved.
 
+using System;
+using Core.Common.TestUtil;
 using NUnit.Framework;
 using Riskeer.Common.Data.FailurePath;
 
@@ -37,5 +39,43 @@
             Assert.AreEqual(FailurePathAssemblyProbabilityResultType.Automatic, result.ProbabilityResultType);
             Assert.IsNaN(result.ManualFailurePathAssemblyProbability);
         }
+
+        [Test]
+        [SetCulture("nl-NL")]
+        [TestCase(-20)]
+        [TestCase(-1e-6)]
+        [TestCase(1 + 1e-6)]
+        [TestCase(12)]
+        public void ManualInitialFailureMechanismResultProfileProbability_InvalidValue_ThrowsArgumentOutOfRangeException(double newValue)
+        {
+            // Setup
+            var result = new FailurePathAssemblyResult();
+
+            // Call
+            void Call() => result.ManualFailurePathAssemblyProbability = newValue;
+
+            // Assert
+            const string message = "De waarde voor de faalkans moet in het bereik [0,0, 1,0] liggen.";
+            TestHelper.AssertThrowsArgumentExceptionAndTestMessage<ArgumentOutOfRangeException>(Call, message);
+        }
+
+        [Test]
+        [TestCase(0)]
+        [TestCase(1e-6)]
+        [TestCase(0.5)]
+        [TestCase(1 - 1e-6)]
+        [TestCase(1)]
+        [TestCase(double.NaN)]
+        public void ManualInitialFailureMechanismResultProfileProbability_ValidValue_NewValueSet(double newValue)
+        {
+            // Setup
+            var result = new FailurePathAssemblyResult();
+
+            // Call
+            result.ManualFailurePathAssemblyProbability = newValue;
+
+            // Assert
+            Assert.AreEqual(newValue, result.ManualFailurePathAssemblyProbability);
+        }
     }
 }
\ No newline at end of file