Index: Ringtoets/Common/src/Ringtoets.Common.Forms/Views/FailureMechanismResultView.cs
===================================================================
diff -u -r602252658dcfe6cacca8ea7257323e560b9d1418 -r39fd57c75e24d3a6170b010861ed6ab47d1f2f42
--- Ringtoets/Common/src/Ringtoets.Common.Forms/Views/FailureMechanismResultView.cs	(.../FailureMechanismResultView.cs)	(revision 602252658dcfe6cacca8ea7257323e560b9d1418)
+++ Ringtoets/Common/src/Ringtoets.Common.Forms/Views/FailureMechanismResultView.cs	(.../FailureMechanismResultView.cs)	(revision 39fd57c75e24d3a6170b010861ed6ab47d1f2f42)
@@ -1,4 +1,4 @@
-// Copyright (C) Stichting Deltares 2017. All rights reserved.
+// Copyright (C) Stichting Deltares 2017. All rights reserved.
 //
 // This file is part of Ringtoets.
 //
@@ -167,6 +167,13 @@
         }
 
         /// <summary>
+        /// Determines if the failure mechanism has section assembly results that are manually overwritten.
+        /// </summary>
+        /// <returns><c>true</c> if the failure mechanism has section assembly results that are manually overwritten,
+        /// <c>false</c> otherwise.</returns>
+        protected abstract bool HasManualAssemblyResults();
+
+        /// <summary>
         /// Updates the data source of the data grid view with the current known failure mechanism section results.
         /// </summary>
         private void UpdateDataGridViewDataSource()
@@ -201,6 +208,11 @@
             {
                 FailureMechanismAssemblyResultControl.SetError(e.Message);
             }
+
+            if (HasManualAssemblyResults())
+            {
+                FailureMechanismAssemblyResultControl.SetWarning("Toetsoordeel is (deels) gebaseerd op handmatig overschreven toetsoordelen.");
+            }
         }
 
         private void InitializeFailureMechanismAssemblyResultPanel()
Index: Ringtoets/Common/test/Ringtoets.Common.Forms.Test/Views/FailureMechanismResultViewTest.cs
===================================================================
diff -u -r6db413e69ecbda9e1be48e269f8fa1a16fff1275 -r39fd57c75e24d3a6170b010861ed6ab47d1f2f42
--- Ringtoets/Common/test/Ringtoets.Common.Forms.Test/Views/FailureMechanismResultViewTest.cs	(.../FailureMechanismResultViewTest.cs)	(revision 6db413e69ecbda9e1be48e269f8fa1a16fff1275)
+++ Ringtoets/Common/test/Ringtoets.Common.Forms.Test/Views/FailureMechanismResultViewTest.cs	(.../FailureMechanismResultViewTest.cs)	(revision 39fd57c75e24d3a6170b010861ed6ab47d1f2f42)
@@ -353,6 +353,65 @@
         }
 
         [Test]
+        public void GivenFailureMechanismResultsView_WhenHasManualAssemblyResultsTrueDuringUpdate_ThenWarningSet()
+        {
+            // Given
+            TestFailureMechanismSectionResult sectionResult = FailureMechanismSectionResultTestFactory.CreateFailureMechanismSectionResult();
+
+            var sectionResults = new ObservableList<TestFailureMechanismSectionResult>
+            {
+                sectionResult
+            };
+
+            using (TestFailureMechanismResultView view = ShowFailureMechanismResultsView(sectionResults))
+            {
+                // Precondition
+                TestAssemblyResultControl resultControl = GetFailureMechanismAssemblyCategoryGroupControl();
+                ErrorProvider warningProvider = GetWarningProvider(resultControl);
+                Assert.IsEmpty(warningProvider.GetError(resultControl));
+
+                // When
+                view.HasManualSectionAssemblyResults = true;
+                sectionResult.NotifyObservers();
+
+                // Then
+                Assert.AreEqual("Toetsoordeel is (deels) gebaseerd op handmatig overschreven toetsoordelen.", warningProvider.GetError(resultControl));
+            }
+        }
+
+        [Test]
+        public void GivenFailureMechanismResultsView_WhenExceptionThrownAndHasManualAssemblyResultsTrueDuringUpdate_ThenMessagesSet()
+        {
+            // Given
+            TestFailureMechanismSectionResult sectionResult = FailureMechanismSectionResultTestFactory.CreateFailureMechanismSectionResult();
+
+            var sectionResults = new ObservableList<TestFailureMechanismSectionResult>
+            {
+                sectionResult
+            };
+
+            using (TestFailureMechanismResultView view = ShowFailureMechanismResultsView(sectionResults))
+            {
+                // Precondition
+                TestAssemblyResultControl resultControl = GetFailureMechanismAssemblyCategoryGroupControl();
+                ErrorProvider errorProvider = GetErrorProvider(resultControl);
+                Assert.IsEmpty(errorProvider.GetError(resultControl));
+
+                ErrorProvider warningProvider = GetWarningProvider(resultControl);
+                Assert.IsEmpty(warningProvider.GetError(resultControl));
+
+                // When
+                view.HasManualSectionAssemblyResults = true;
+                view.ThrowExceptionOnUpdate = true;
+                sectionResult.NotifyObservers();
+
+                // Then
+                Assert.AreEqual("Message", errorProvider.GetError(resultControl));
+                Assert.AreEqual("Toetsoordeel is (deels) gebaseerd op handmatig overschreven toetsoordelen.", warningProvider.GetError(resultControl));
+            }
+        }
+
+        [Test]
         public void GivenFailureMechanismResultsView_WhenFailureMechanismAssemblyControlUpdated_ThenDataCleared()
         {
             // Given
@@ -377,7 +436,7 @@
         }
 
         [Test]
-        public void GivenFailureMechanismResultsViewWithFailureMechanismAssemblyError_WhenNoExceptionThrownDuringUpdate_ThenErrorCleared()
+        public void GivenFailureMechanismResultsViewWithMessages_WhenNoExceptionThrownAndManualSectionAssemblyResultsFalseDuringUpdate_ThenMessagesCleared()
         {
             // Given
             TestFailureMechanismSectionResult sectionResult = FailureMechanismSectionResultTestFactory.CreateFailureMechanismSectionResult();
@@ -390,19 +449,25 @@
             using (TestFailureMechanismResultView view = ShowFailureMechanismResultsView(sectionResults))
             {
                 view.ThrowExceptionOnUpdate = true;
+                view.HasManualSectionAssemblyResults = true;
                 sectionResult.NotifyObservers();
 
                 // Precondition
                 TestAssemblyResultControl resultControl = GetFailureMechanismAssemblyCategoryGroupControl();
                 ErrorProvider errorProvider = GetErrorProvider(resultControl);
                 Assert.AreEqual("Message", errorProvider.GetError(resultControl));
 
+                ErrorProvider warningProvider = GetWarningProvider(resultControl);
+                Assert.AreEqual("Toetsoordeel is (deels) gebaseerd op handmatig overschreven toetsoordelen.", warningProvider.GetError(resultControl));
+
                 // When
                 view.ThrowExceptionOnUpdate = false;
+                view.HasManualSectionAssemblyResults = false;
                 sectionResult.NotifyObservers();
 
                 // Then
                 Assert.IsEmpty(errorProvider.GetError(resultControl));
+                Assert.IsEmpty(warningProvider.GetError(resultControl));
             }
         }
 
@@ -490,6 +555,11 @@
             return TypeUtils.GetField<ErrorProvider>(resultControl, "errorProvider");
         }
 
+        private static ErrorProvider GetWarningProvider(TestAssemblyResultControl resultControl)
+        {
+            return TypeUtils.GetField<ErrorProvider>(resultControl, "warningProvider");
+        }
+
         private static TestAssemblyResultControl GetFailureMechanismAssemblyCategoryGroupControl()
         {
             return (TestAssemblyResultControl) new ControlTester("AssemblyResultControl").TheObject;
@@ -517,6 +587,8 @@
 
             public bool AssemblyResultControlUpdated { get; set; }
 
+            public bool HasManualSectionAssemblyResults { private get; set; }
+
             protected override FailureMechanismSectionResultRow<FailureMechanismSectionResult> CreateFailureMechanismSectionResultRow(
                 FailureMechanismSectionResult sectionResult)
             {
@@ -537,6 +609,11 @@
 
                 AssemblyResultControlUpdated = true;
             }
+
+            protected override bool HasManualAssemblyResults()
+            {
+                return HasManualSectionAssemblyResults;
+            }
         }
 
         private class TestAssemblyResultControl : AssemblyResultControl {}