diff --git a/tests/repositories/property/test_landlord_override_overlays.py b/tests/repositories/property/test_landlord_override_overlays.py
index ce86e78a..2b687656 100644
--- a/tests/repositories/property/test_landlord_override_overlays.py
+++ b/tests/repositories/property/test_landlord_override_overlays.py
@@ -77,6 +77,21 @@ def test_glazing_row_produces_a_glazing_overlay() -> None:
     assert overlays[0].glazing.glazing_type == 2
 
 
+def test_construction_age_band_row_produces_a_building_part_overlay() -> None:
+    # Arrange
+    overrides = ResolvedPropertyOverrides(
+        rows=(ResolvedPropertyOverride("construction_age_band", 0, "B"),)
+    )
+
+    # Act
+    overlays = overlays_from(overrides)
+
+    # Assert
+    assert len(overlays) == 1
+    main = overlays[0].building_parts[BuildingPartIdentifier.MAIN]
+    assert main.construction_age_band == "B"
+
+
 def test_unresolvable_rows_are_skipped() -> None:
     # Arrange — an "Unknown" property type and an unmapped wall material.
     overrides = ResolvedPropertyOverrides(