diff --git a/datatypes/epc/domain/mapper.py b/datatypes/epc/domain/mapper.py
index 80a650515..6c12b6e55 100644
--- a/datatypes/epc/domain/mapper.py
+++ b/datatypes/epc/domain/mapper.py
@@ -4445,6 +4445,9 @@ _API_ROOF_CONSTRUCTION_TO_STR: Dict[int, Optional[str]] = {
     6: None,
     7: None,
     8: "Pitched, sloping ceiling",
+    # "(another premises above)" per a live cert (uprn 10013320122) — same
+    # party-ceiling semantics as code 7, just "premises" not "dwelling".
+    9: None,
 }