diff --git a/tests/domain/modelling/test_roof_recommendation.py b/tests/domain/modelling/test_roof_recommendation.py
index defc239cd..3acdbb86f 100644
--- a/tests/domain/modelling/test_roof_recommendation.py
+++ b/tests/domain/modelling/test_roof_recommendation.py
@@ -130,6 +130,43 @@ def test_vaulted_ceiling_with_nd_thickness_on_limited_insulation_age_band_yields
     assert recommendation is None
 
 
+def test_vaulted_ceiling_with_ni_thickness_yields_no_recommendation() -> None:
+    # Arrange — "NI" means insulation PRESENT at unknown thickness (RdSAP 10
+    # §5.11.4: score as 50 mm), never "no insulation" — even on an age band
+    # whose as-built state is uninsulated (ADR-0047, the ND ≠ NI distinction).
+    baseline: EpcPropertyData = build_epc()
+    main: SapBuildingPart = _part(baseline, BuildingPartIdentifier.MAIN)
+    main.roof_construction_type = "Pitched (vaulted ceiling)"
+    main.roof_insulation_thickness = "NI"
+    main.construction_age_band = "B"
+
+    # Act
+    recommendation: Recommendation | None = recommend_roof_insulation(
+        baseline, _StubProducts()
+    )
+
+    # Assert
+    assert recommendation is None
+
+
+def test_vaulted_ceiling_with_measured_thickness_yields_no_recommendation() -> None:
+    # Arrange — an explicitly-lodged depth means the rafters are already
+    # insulated; the sentinel-aware trigger must not loosen the numeric rule.
+    baseline: EpcPropertyData = build_epc()
+    main: SapBuildingPart = _part(baseline, BuildingPartIdentifier.MAIN)
+    main.roof_construction_type = "Pitched (vaulted ceiling)"
+    main.roof_insulation_thickness = 100
+    main.construction_age_band = "B"
+
+    # Act
+    recommendation: Recommendation | None = recommend_roof_insulation(
+        baseline, _StubProducts()
+    )
+
+    # Assert
+    assert recommendation is None
+
+
 def test_loft_option_carries_cost_from_roof_area_and_product() -> None:
     # Arrange
     baseline: EpcPropertyData = build_epc()  # MAIN roof area 14.85 m^2