Index: Ringtoets/Piping/src/Ringtoets.Piping.Forms/PropertyClasses/PipingSoilLayerProperties.cs
===================================================================
diff -u -rac96d7c315129af851634ed5a4a6800b59ede718 -r1d7fbceedb464d63908f3a1605b743d709b80301
--- Ringtoets/Piping/src/Ringtoets.Piping.Forms/PropertyClasses/PipingSoilLayerProperties.cs	(.../PipingSoilLayerProperties.cs)	(revision ac96d7c315129af851634ed5a4a6800b59ede718)
+++ Ringtoets/Piping/src/Ringtoets.Piping.Forms/PropertyClasses/PipingSoilLayerProperties.cs	(.../PipingSoilLayerProperties.cs)	(revision 1d7fbceedb464d63908f3a1605b743d709b80301)
@@ -21,7 +21,6 @@
 
 using System;
 using System.ComponentModel;
-using System.Globalization;
 using Core.Common.Base.Data;
 using Core.Common.Gui.Attributes;
 using Core.Common.Gui.PropertyBag;
@@ -70,11 +69,11 @@
         [ResourcesCategory(typeof(RingtoetsCommonFormsResources), nameof(RingtoetsCommonFormsResources.Categories_General))]
         [ResourcesDisplayName(typeof(RingtoetsCommonFormsResources), nameof(RingtoetsCommonFormsResources.SoilLayer_TopLevel_DisplayName))]
         [ResourcesDescription(typeof(RingtoetsCommonFormsResources), nameof(RingtoetsCommonFormsResources.SoilLayer_TopLevel_Description))]
-        public string TopLevel
+        public RoundedDouble TopLevel
         {
             get
             {
-                return new RoundedDouble(2, data.Top).Value.ToString(CultureInfo.CurrentCulture);
+                return new RoundedDouble(2, data.Top);
             }
         }
 
Index: Ringtoets/Piping/test/Ringtoets.Piping.Forms.Test/PropertyClasses/PipingSoilLayerPropertiesTest.cs
===================================================================
diff -u -r43b4218e6e71896eb4f3985555258caeb4c7f6f7 -r1d7fbceedb464d63908f3a1605b743d709b80301
--- Ringtoets/Piping/test/Ringtoets.Piping.Forms.Test/PropertyClasses/PipingSoilLayerPropertiesTest.cs	(.../PipingSoilLayerPropertiesTest.cs)	(revision 43b4218e6e71896eb4f3985555258caeb4c7f6f7)
+++ Ringtoets/Piping/test/Ringtoets.Piping.Forms.Test/PropertyClasses/PipingSoilLayerPropertiesTest.cs	(.../PipingSoilLayerPropertiesTest.cs)	(revision 1d7fbceedb464d63908f3a1605b743d709b80301)
@@ -21,10 +21,10 @@
 
 using System;
 using System.ComponentModel;
-using System.Globalization;
 using Core.Common.Gui.PropertyBag;
 using Core.Common.TestUtil;
 using NUnit.Framework;
+using Ringtoets.Common.Data.TestUtil;
 using Ringtoets.Piping.Forms.PropertyClasses;
 using Ringtoets.Piping.Primitives;
 
@@ -62,7 +62,9 @@
         public void GetProperties_WithData_ReturnExpectedValues()
         {
             // Setup
-            var layer = new PipingSoilLayer(-2.91)
+            const double topLevel = 5.4321;
+
+            var layer = new PipingSoilLayer(topLevel)
             {
                 MaterialName = "Test Name",
                 IsAquifer = true
@@ -74,7 +76,8 @@
             // Assert
             Assert.AreEqual(layer.MaterialName, properties.Name);
             Assert.AreEqual(layer.IsAquifer, properties.IsAquifer);
-            Assert.AreEqual(layer.Top.ToString(CultureInfo.CurrentCulture), properties.TopLevel);
+            Assert.AreEqual(2, properties.TopLevel.NumberOfDecimalPlaces);
+            Assert.AreEqual(topLevel, properties.TopLevel, properties.TopLevel.GetAccuracy());
         }
 
         [Test]