diff --git a/tests/domain/modelling/test_roof_recommendation.py b/tests/domain/modelling/test_roof_recommendation.py
index 63f28ce68..9e36b25f8 100644
--- a/tests/domain/modelling/test_roof_recommendation.py
+++ b/tests/domain/modelling/test_roof_recommendation.py
@@ -83,6 +83,34 @@ def test_room_in_roof_yields_no_recommendation_pending_a_dedicated_branch() -> N
     assert recommendation is None
 
 
+def test_vaulted_ceiling_with_nd_thickness_on_pre_1950_dwelling_yields_sloping_ceiling_insulation() -> None:
+    # Arrange — the 742265 shape (ADR-0047): a "Pitched (vaulted ceiling)" MAIN
+    # roof lodging the "ND" sentinel on an age-band-B dwelling. ND resolves to
+    # the age band's as-built state (A-D: uninsulated), and a vaulted ceiling
+    # has no loft void, so the one applicable Measure is rafter insulation.
+    baseline: EpcPropertyData = build_epc()
+    main: SapBuildingPart = _part(baseline, BuildingPartIdentifier.MAIN)
+    main.roof_construction_type = "Pitched (vaulted ceiling)"
+    main.roof_insulation_thickness = "ND"
+    main.construction_age_band = "B"
+
+    # Act
+    recommendation: Recommendation | None = recommend_roof_insulation(
+        baseline, _StubProducts()
+    )
+
+    # Assert
+    assert recommendation is not None
+    assert recommendation.surface == "Roof"
+    assert len(recommendation.options) == 1
+    option = recommendation.options[0]
+    assert option.measure_type == "sloping_ceiling_insulation"
+    simulated: EpcPropertyData = apply_simulations(baseline, [option.overlay])
+    assert (
+        _part(simulated, BuildingPartIdentifier.MAIN).roof_insulation_thickness == 100
+    )
+
+
 def test_loft_option_carries_cost_from_roof_area_and_product() -> None:
     # Arrange
     baseline: EpcPropertyData = build_epc()  # MAIN roof area 14.85 m^2