diff --git a/tests/domain/epc/test_main_heating_system_overlay.py b/tests/domain/epc/test_main_heating_system_overlay.py
index 3ae8b07b7..5c1b680d2 100644
--- a/tests/domain/epc/test_main_heating_system_overlay.py
+++ b/tests/domain/epc/test_main_heating_system_overlay.py
@@ -285,6 +285,28 @@ def test_electric_underfloor_drags_the_conservative_group_7_control(
     assert simulation.heating.main_heating_control == 2701
 
 
+@pytest.mark.parametrize(
+    "main_heating_value",
+    [
+        "Electric underfloor, in concrete slab (off-peak)",
+        "Electric underfloor, integrated storage and direct-acting",
+        "Electric underfloor, in screed above insulation",
+    ],
+)
+def test_complete_underfloor_overlay_does_not_log_a_companion_gap(
+    main_heating_value: str, caplog: pytest.LogCaptureFixture
+) -> None:
+    # Electric underfloor now resolves a full companion set (category 8 +
+    # control 2701, ADR-0050), so the overlay must NOT log an
+    # incomplete-companion gap — guarding that the set stays complete.
+    # Act
+    with caplog.at_level(logging.ERROR):
+        main_heating_overlay_for(main_heating_value, 0)
+
+    # Assert
+    assert "incomplete companion set" not in caplog.text
+
+
 def test_screed_underfloor_defers_the_meter_to_the_cert() -> None:
     # "In screed above insulation (standard or off peak)" is tariff-ambiguous (81%
     # of the corpus lodge off-peak), so the archetype cannot know the meter — it