diff --git a/recommendations/RoofRecommendations.py b/recommendations/RoofRecommendations.py
index ed087228..5ba7e82e 100644
--- a/recommendations/RoofRecommendations.py
+++ b/recommendations/RoofRecommendations.py
@@ -207,7 +207,7 @@ class RoofRecommendations:
                             floor_area=self.property.insulation_floor_area,
                             material=material
                         )
-                        is_override = "loft_insulation" in cost_result
+                        is_override = "loft_insulation" in self.property.override
                         if is_override:
                             cost_result = override_costs(cost_result)
                     elif material["type"] == "flat_roof_insulation":
@@ -216,7 +216,7 @@ class RoofRecommendations:
                             material=material,
                             non_insulation_materials=non_insulation_materials
                         )
-                        is_override = "flat_roof_insulation" in cost_result
+                        is_override = "flat_roof_insulation" in self.property.override
                         if is_override:
                             cost_result = override_costs(cost_result)
                     else:
diff --git a/recommendations/VentilationRecommendations.py b/recommendations/VentilationRecommendations.py
index 1657b759..aa6299e0 100644
--- a/recommendations/VentilationRecommendations.py
+++ b/recommendations/VentilationRecommendations.py
@@ -56,6 +56,10 @@ class VentilationRecommendations(Definitions):
         part[0]["quantity"] = n_units
         part[0]["quantity_unit"] = "part"
 
+        is_override = "cavity_wall_insulation" in cost_result
+        if is_override:
+            cost_result = override_costs(cost_result)
+
         # We recommend installing two mechanical ventilation systems
         self.recommendation = [
             {
diff --git a/recommendations/WallRecommendations.py b/recommendations/WallRecommendations.py
index 3acc17f0..471a62cb 100644
--- a/recommendations/WallRecommendations.py
+++ b/recommendations/WallRecommendations.py
@@ -221,7 +221,7 @@ class WallRecommendations(Definitions):
                     material=material.to_dict(),
                 )
 
-                is_override = "cavity_wall_insulation" in cost_result
+                is_override = "cavity_wall_insulation" in self.property.override
                 if is_override:
                     cost_result = override_costs(cost_result)
 
@@ -282,7 +282,7 @@ class WallRecommendations(Definitions):
                             material=material.to_dict(),
                             non_insulation_materials=non_insulation_materials
                         )
-                        is_override = "internal_wall_insulation" in cost_result
+                        is_override = "internal_wall_insulation" in self.property.override
                         if is_override:
                             cost_result = override_costs(cost_result)
 
@@ -292,7 +292,7 @@ class WallRecommendations(Definitions):
                             material=material.to_dict(),
                             non_insulation_materials=non_insulation_materials
                         )
-                        is_override = "external_wall_insulation" in cost_result
+                        is_override = "external_wall_insulation" in self.property.override
                         if is_override:
                             cost_result = override_costs(cost_result)
                     else: