diff --git a/domain/modelling/roof_recommendation.py b/domain/modelling/roof_recommendation.py
index 76c60241..aa09b620 100644
--- a/domain/modelling/roof_recommendation.py
+++ b/domain/modelling/roof_recommendation.py
@@ -20,8 +20,10 @@ from repositories.product.product_repository import ProductRepository
 _LOFT_MEASURE_TYPE = "loft_insulation"
 # RdSAP 10 Table 16: 0 mm lodged roof insulation is an uninsulated loft.
 _ROOF_UNINSULATED_MM = 0
-# Recommended loft-insulation depth (mm) — the building-regs standard top-up.
-_RECOMMENDED_LOFT_THICKNESS_MM = 270
+# Recommended loft-insulation depth (mm). Elmhurst re-lodges a loft-insulation
+# measure at 300 mm; pinning the before→after cascade (000490/001431) requires
+# the overlay to match that depth exactly (see test_elmhurst_cascade_pins).
+_RECOMMENDED_LOFT_THICKNESS_MM = 300
 
 
 def recommend_loft_insulation(
diff --git a/tests/domain/modelling/fixtures/loft_001431_after.pdf b/tests/domain/modelling/fixtures/loft_001431_after.pdf
new file mode 100644
index 00000000..1b76e032
Binary files /dev/null and b/tests/domain/modelling/fixtures/loft_001431_after.pdf differ
diff --git a/tests/domain/modelling/fixtures/loft_001431_before.pdf b/tests/domain/modelling/fixtures/loft_001431_before.pdf
new file mode 100644
index 00000000..6280eca5
Binary files /dev/null and b/tests/domain/modelling/fixtures/loft_001431_before.pdf differ
diff --git a/tests/domain/modelling/test_elmhurst_cascade_pins.py b/tests/domain/modelling/test_elmhurst_cascade_pins.py
index 8f7f5e83..bc2d6f32 100644
--- a/tests/domain/modelling/test_elmhurst_cascade_pins.py
+++ b/tests/domain/modelling/test_elmhurst_cascade_pins.py
@@ -20,6 +20,7 @@ from datatypes.epc.domain.epc_property_data import EpcPropertyData
 from domain.modelling.package_scorer import PackageScorer, Score
 from domain.modelling.product import Product
 from domain.modelling.recommendation import Recommendation
+from domain.modelling.roof_recommendation import recommend_loft_insulation
 from domain.modelling.simulation import EpcSimulation
 from domain.modelling.wall_recommendation import recommend_cavity_wall
 from domain.sap10_calculator.calculator import Sap10Calculator, SapResult
@@ -79,3 +80,22 @@ def test_cavity_wall_overlay_reproduces_the_relodged_after() -> None:
     _assert_overlay_reproduces_after(
         before, after, recommendation.options[0].overlay
     )
+
+
+def test_loft_overlay_reproduces_the_relodged_after() -> None:
+    # Arrange
+    before: EpcPropertyData = parse_recommendation_summary(
+        "loft_001431_before.pdf"
+    )
+    after: EpcPropertyData = parse_recommendation_summary(
+        "loft_001431_after.pdf"
+    )
+    recommendation: Recommendation | None = recommend_loft_insulation(
+        before, _AnyProduct()
+    )
+    assert recommendation is not None
+
+    # Act / Assert
+    _assert_overlay_reproduces_after(
+        before, after, recommendation.options[0].overlay
+    )
diff --git a/tests/domain/modelling/test_roof_recommendation.py b/tests/domain/modelling/test_roof_recommendation.py
index 8acfc5c6..f801ee7d 100644
--- a/tests/domain/modelling/test_roof_recommendation.py
+++ b/tests/domain/modelling/test_roof_recommendation.py
@@ -46,7 +46,7 @@ def test_uninsulated_loft_yields_a_loft_insulation_recommendation() -> None:
     option = recommendation.options[0]
     assert option.measure_type == "loft_insulation"
     simulated: EpcPropertyData = apply_simulations(baseline, [option.overlay])
-    assert _part(simulated, BuildingPartIdentifier.MAIN).roof_insulation_thickness == 270
+    assert _part(simulated, BuildingPartIdentifier.MAIN).roof_insulation_thickness == 300
 
 
 def test_already_insulated_loft_yields_no_recommendation() -> None: