diff --git a/BuildVolume.py b/BuildVolume.py
index 1636cf9c00..f40f6df016 100644
--- a/BuildVolume.py
+++ b/BuildVolume.py
@@ -121,4 +121,4 @@ class BuildVolume(SceneNode):
         else:
             self._disallowed_area_mesh = None
 
-        self._aabb = AxisAlignedBox(minimum = Vector(minW, minH, minD), maximum = Vector(maxW, maxH, maxD))
+        self._aabb = AxisAlignedBox(minimum = Vector(minW, minH - 1.0, minD), maximum = Vector(maxW, maxH, maxD))