diff --git a/datatypes/magicplan/domain/mapper.py b/datatypes/magicplan/domain/mapper.py
index 1342cc8b..71cb91c2 100644
--- a/datatypes/magicplan/domain/mapper.py
+++ b/datatypes/magicplan/domain/mapper.py
@@ -102,4 +102,21 @@ def _map_window_ventilation(
 
 
 def _map_door(wi: api.WallItem) -> Door:
-    return Door(width_mm=round(wi.size.x, 2))
+    return Door(
+        width_mm=round(wi.size.x, 2),
+        ventilation=_map_door_ventilation(wi.custom_displayable_fields),
+    )
+
+
+def _map_door_ventilation(
+    fields: list[api.SurveyField],
+) -> Optional[DoorVentilation]:
+    if not fields:
+        return None
+    by_label = {f.label: f for f in fields}
+    f = by_label.get("Door Undercut (mm)")
+    if f is None or not f.value.has_value:
+        return None
+    raw = f.value.value
+    undercut = float(raw[0] if isinstance(raw, list) else raw)
+    return DoorVentilation(undercut_mm=undercut)