diff --git a/schemas/HPXMLBaseElements.xsd b/schemas/HPXMLBaseElements.xsd
index 82eb2785..85572b9d 100644
--- a/schemas/HPXMLBaseElements.xsd
+++ b/schemas/HPXMLBaseElements.xsd
@@ -311,7 +311,7 @@
 				<xs:sequence>
 					<xs:element name="InsulationDepth" type="LengthMeasurement" minOccurs="0">
 						<xs:annotation>
-							<xs:documentation>[ft] Depth from grade to bottom of vertical slab perimeter insulation</xs:documentation>
+							<xs:documentation>[ft] Depth from top of slab to bottom of vertical slab perimeter insulation</xs:documentation>
 						</xs:annotation>
 					</xs:element>
 					<xs:element ref="extension" minOccurs="0"/>