diff --git a/domain/modelling/optimisation/optimiser.py b/domain/modelling/optimisation/optimiser.py
index 43a87dfce..4a5edd28e 100644
--- a/domain/modelling/optimisation/optimiser.py
+++ b/domain/modelling/optimisation/optimiser.py
@@ -271,13 +271,23 @@ def optimise_package_fabric_first(
     leftover_budget: Optional[float] = (
         None if budget is None else budget - _package_cost(fabric_package.selected)
     )
+    # A dependency phase 1 already injected (e.g. the wall's ventilation) is
+    # satisfied for the whole package: phase 2 must not force it in again.
+    fabric_types: set[MeasureType] = {
+        scored.option.measure_type for scored in fabric_package.selected
+    }
+    outstanding_dependencies: list[MeasureDependency] = [
+        dependency
+        for dependency in dependencies
+        if dependency.required.option.measure_type not in fabric_types
+    ]
     top_up: OptimisedPackage = optimise_package(
         groups=_rescored_groups(remaining_groups, post_fabric_scorer, baseline_epc),
         scorer=post_fabric_scorer,
         baseline_epc=baseline_epc,
         budget=leftover_budget,
         target_sap=target_sap,
-        dependencies=dependencies,
+        dependencies=outstanding_dependencies,
     )
     return OptimisedPackage(
         selected=[*fabric_package.selected, *top_up.selected],