Index: Ringtoets/HydraRing/src/Ringtoets.HydraRing.Calculation/Parsers/OvertoppingCalculationWaveHeightParser.cs
===================================================================
diff -u -rae5c94bea6f603eeafeed527190799ce2b049002 -r57c9aff5c1e30cb83c1cc2f33c7ce97dfe8d04fe
--- Ringtoets/HydraRing/src/Ringtoets.HydraRing.Calculation/Parsers/OvertoppingCalculationWaveHeightParser.cs	(.../OvertoppingCalculationWaveHeightParser.cs)	(revision ae5c94bea6f603eeafeed527190799ce2b049002)
+++ Ringtoets/HydraRing/src/Ringtoets.HydraRing.Calculation/Parsers/OvertoppingCalculationWaveHeightParser.cs	(.../OvertoppingCalculationWaveHeightParser.cs)	(revision 57c9aff5c1e30cb83c1cc2f33c7ce97dfe8d04fe)
@@ -83,7 +83,14 @@
         {
             try
             {
-                double waveHeight = Convert.ToDouble(result[waveHeightColumn]);
+                double waveHeight = double.NaN;
+                object waveHeightResult = result[waveHeightColumn];
+
+                if (waveHeightResult.GetType() != typeof(DBNull))   
+                {
+                    waveHeight = Convert.ToDouble(waveHeightResult);
+                }
+                
                 bool isOvertoppingDominant = Convert.ToBoolean(result[isOvertoppingDominantColumn]);
 
                 Output = new OvertoppingCalculationWaveHeightOutput(waveHeight,