diff --git a/tests/domain/epc/test_roof_party_ceiling_guard.py b/tests/domain/epc/test_roof_party_ceiling_guard.py
index 9152b655e..8ac91add4 100644
--- a/tests/domain/epc/test_roof_party_ceiling_guard.py
+++ b/tests/domain/epc/test_roof_party_ceiling_guard.py
@@ -40,3 +40,23 @@ def test_every_party_ceiling_marker_variant_resolves_to_its_member(
 
     # Assert
     assert result is expected
+
+
+@pytest.mark.parametrize(
+    "description",
+    [
+        "pitched, normal loft access: 100mm",
+        "flat: 150mm",
+        "pitched with sloping ceiling: unknown",
+        "roof room(s), insulated",
+    ],
+)
+def test_a_genuine_roof_description_is_left_to_the_llm(description: str) -> None:
+    # A non-party-ceiling roof must return None so the LLM classifier still
+    # resolves it — the guard only claims the markers it is certain about.
+
+    # Act
+    result = roof_party_ceiling_guard(description)
+
+    # Assert
+    assert result is None