diff --git a/tests/domain/modelling/test_floor_recommendation.py b/tests/domain/modelling/test_floor_recommendation.py
index 1ce5bd7f3..59ad21889 100644
--- a/tests/domain/modelling/test_floor_recommendation.py
+++ b/tests/domain/modelling/test_floor_recommendation.py
@@ -66,6 +66,28 @@ def test_uninsulated_solid_floor_yields_solid_insulation() -> None:
     assert recommendation.options[0].measure_type == "solid_floor_insulation"
 
 
+def test_at_regs_age_band_floor_yields_no_recommendation() -> None:
+    # Arrange — a solid ground floor lodged as-built at construction age band
+    # L (2012-2022). RdSAP's BS EN ISO 13370 cascade assigns it the at-regs
+    # U-value and 100 mm of added insulation resolves to the same (or a
+    # no-better) value — the measure cannot change the modelled floor, so
+    # offering it sells £3-4k of insulation for +0.00 SAP (portfolio 796:
+    # properties 709782/709790). The Floor U-Value Gate withholds it — the
+    # floor arm of ADR-0051's deferred follow-up.
+    baseline: EpcPropertyData = build_epc()
+    main: SapBuildingPart = _main(baseline)
+    main.floor_construction_type = "Solid"
+    main.construction_age_band = "L"
+
+    # Act
+    recommendation: Recommendation | None = recommend_floor_insulation(
+        baseline, _StubProducts()
+    )
+
+    # Assert
+    assert recommendation is None
+
+
 def test_already_insulated_floor_yields_no_recommendation() -> None:
     # Arrange
     baseline: EpcPropertyData = build_epc()