diff --git a/applications/landlord_description_overrides/handler.py b/applications/landlord_description_overrides/handler.py
index 151fb7299..236b28894 100644
--- a/applications/landlord_description_overrides/handler.py
+++ b/applications/landlord_description_overrides/handler.py
@@ -18,9 +18,7 @@ from domain.epc.property_overrides.main_heating_guard import main_heating_guard
 from domain.epc.property_overrides.property_type import PropertyType
 from domain.epc.property_overrides.property_type_guard import property_type_guard
 from domain.epc.property_overrides.roof_type import RoofType
-from domain.epc.property_overrides.roof_party_ceiling_guard import (
-    roof_party_ceiling_guard,
-)
+from domain.epc.property_overrides.roof_guard import roof_guard
 from domain.data_transformation.guarded_column_classifier import (
     GuardedColumnClassifier,
 )
@@ -133,12 +131,13 @@ def _build_columns(
         "roof_type": lambda src: ClassifiableColumn(
             name="roof_type",
             source_column=src,
-            # A party ceiling ("another/same dwelling or premises above") has ~0
-            # heat loss and must never be classified as an external roof; the
-            # deterministic guard resolves those markers and the LLM handles the
-            # rest (#1376).
+            # Deterministic roof guards resolve the markers they are certain of
+            # ahead of the LLM: a party ceiling ("another/same dwelling or
+            # premises above", ~0 heat loss, #1376) and a slope-following ceiling
+            # ("PitchedWithSlopingCeiling", rafter/slope-line insulation, never
+            # the loft ladder, ADR-0066). The LLM handles the rest.
             classifier=GuardedColumnClassifier(
-                guard=roof_party_ceiling_guard,
+                guard=roof_guard,
                 fallback=ChatGptColumnClassifier(chat_gpt, RoofType, RoofType.UNKNOWN),
             ),
             repo=LandlordOverridesRepository[RoofType](
diff --git a/domain/epc/property_overrides/roof_guard.py b/domain/epc/property_overrides/roof_guard.py
index e3203e950..a45732324 100644
--- a/domain/epc/property_overrides/roof_guard.py
+++ b/domain/epc/property_overrides/roof_guard.py
@@ -2,8 +2,24 @@ from __future__ import annotations
 
 from typing import Optional
 
+from domain.epc.property_overrides.roof_party_ceiling_guard import (
+    roof_party_ceiling_guard,
+)
+from domain.epc.property_overrides.roof_sloping_ceiling_guard import (
+    roof_sloping_ceiling_guard,
+)
 from domain.epc.property_overrides.roof_type import RoofType
 
 
 def roof_guard(description: str) -> Optional[RoofType]:
-    raise NotImplementedError
+    """The deterministic roof guard for the roof `GuardedColumnClassifier`.
+
+    Composes the two roof guards that resolve a description with certainty, ahead
+    of the LLM fallback: a party ceiling (~0 heat loss, #1376) and a
+    slope-following ceiling (rafter/slope-line insulation, ADR-0066). The two
+    marker sets are disjoint, so precedence is immaterial; anything neither
+    recognises returns None and reaches the LLM classifier.
+    """
+    return roof_party_ceiling_guard(description) or roof_sloping_ceiling_guard(
+        description
+    )