diff --git a/source/simulation2/components/CCmpObstruction.cpp b/source/simulation2/components/CCmpObstruction.cpp
index ea6a621b95..c7f189d324 100644
--- a/source/simulation2/components/CCmpObstruction.cpp
+++ b/source/simulation2/components/CCmpObstruction.cpp
@@ -517,6 +517,38 @@ public:
 			return cmpPathfinder->CheckBuildingPlacement(filter, pos.X, pos.Y, cmpPosition->GetRotation().Y, m_Size0, m_Size1, GetEntityId(), passClass);
 	}
 
+	virtual bool CheckDuplicateFoundation()
+	{
+		CmpPtr<ICmpPosition> cmpPosition(GetSimContext(), GetEntityId());
+		if (!cmpPosition)
+			return false; // error
+
+		if (!cmpPosition->IsInWorld())
+			return false; // no obstruction
+
+		CFixedVector2D pos = cmpPosition->GetPosition2D();
+
+		CmpPtr<ICmpObstructionManager> cmpObstructionManager(GetSimContext(), SYSTEM_ENTITY);
+		if (!cmpObstructionManager)
+			return false; // error
+
+		// required precondition to use SkipControlGroupsRequireFlagObstructionFilter
+		if (m_ControlGroup == INVALID_ENTITY)
+		{
+			LOGERROR(L"[CmpObstruction] Cannot test for foundation obstructions; primary control group must be valid");
+			return false;
+		}
+
+		// Ignore collisions with entities unless they block foundations and match both control groups.
+		SkipTagRequireControlGroupsAndFlagObstructionFilter filter(m_Tag, m_ControlGroup, m_ControlGroup2,
+			ICmpObstructionManager::FLAG_BLOCK_FOUNDATION);
+
+		if (m_Type == UNIT)
+			return !cmpObstructionManager->TestUnitShape(filter, pos.X, pos.Y, m_Size0, NULL);
+		else
+			return !cmpObstructionManager->TestStaticShape(filter, pos.X, pos.Y, cmpPosition->GetRotation().Y, m_Size0, m_Size1, NULL);
+	} 
+
 	virtual std::vector<entity_id_t> GetConstructionCollisions()
 	{
 		std::vector<entity_id_t> ret;
diff --git a/source/simulation2/components/ICmpObstruction.cpp b/source/simulation2/components/ICmpObstruction.cpp
index 62780c381b..cad9d09f7b 100644
--- a/source/simulation2/components/ICmpObstruction.cpp
+++ b/source/simulation2/components/ICmpObstruction.cpp
@@ -24,6 +24,7 @@
 BEGIN_INTERFACE_WRAPPER(Obstruction)
 DEFINE_INTERFACE_METHOD_0("GetUnitRadius", entity_pos_t, ICmpObstruction, GetUnitRadius)
 DEFINE_INTERFACE_METHOD_1("CheckFoundation", bool, ICmpObstruction, CheckFoundation, std::string)
+DEFINE_INTERFACE_METHOD_0("CheckDuplicateFoundation", bool, ICmpObstruction, CheckDuplicateFoundation)
 DEFINE_INTERFACE_METHOD_0("GetConstructionCollisions", std::vector<entity_id_t>, ICmpObstruction, GetConstructionCollisions)
 DEFINE_INTERFACE_METHOD_1("SetActive", void, ICmpObstruction, SetActive, bool)
 DEFINE_INTERFACE_METHOD_3("SetDisableBlockMovementPathfinding", void, ICmpObstruction, SetDisableBlockMovementPathfinding, bool, bool, int32_t)
diff --git a/source/simulation2/components/ICmpObstruction.h b/source/simulation2/components/ICmpObstruction.h
index d97f2519c2..e08485eaef 100644
--- a/source/simulation2/components/ICmpObstruction.h
+++ b/source/simulation2/components/ICmpObstruction.h
@@ -51,6 +51,13 @@ public:
 	 */
 	virtual bool CheckFoundation(std::string className) = 0;
 
+	/**
+	 * Test whether this entity is colliding with any obstructions that share its
+	 * control groups and block the creation of foundations.
+	 * @return true if foundation is valid (not obstructed)
+	 */
+	virtual bool CheckDuplicateFoundation() = 0;
+
 	/**
 	 * Returns a list of entities that are colliding with this entity, and that
 	 * are set to block construction.
diff --git a/source/simulation2/components/ICmpObstructionManager.h b/source/simulation2/components/ICmpObstructionManager.h
index d2a30899a9..aa7d7922d1 100644
--- a/source/simulation2/components/ICmpObstructionManager.h
+++ b/source/simulation2/components/ICmpObstructionManager.h
@@ -397,6 +397,42 @@ public:
 	}
 };
 
+/**
+ * Obstruction test filter that will test only against shapes that:
+ *     - are part of both of the specified control groups
+ *     - AND have at least one of the specified flags set.
+ * 
+ * The first (primary) control group to include shapes from must be specified and valid.
+ * 
+ * This filter is useful for preventing entities with identical control groups
+ * from colliding e.g. building a new wall segment on top of an existing wall)
+ *
+ * @todo This filter needs test cases.
+ */
+class SkipTagRequireControlGroupsAndFlagObstructionFilter : public IObstructionTestFilter
+{
+	bool m_Exclude;
+	tag_t m_Tag;
+	entity_id_t m_Group;
+	entity_id_t m_Group2;
+	flags_t m_Mask;
+
+public:
+	SkipTagRequireControlGroupsAndFlagObstructionFilter(tag_t tag, entity_id_t group1, entity_id_t group2, flags_t mask) : 
+		m_Tag(tag), m_Group(group1), m_Group2(group2), m_Mask(mask)
+	{
+		ENSURE(m_Group != INVALID_ENTITY);
+	}
+
+	virtual bool TestShape(tag_t tag, flags_t flags, entity_id_t group, entity_id_t group2) const
+	{
+		// To be included in testing, a shape must not have the specified tag, and must
+		// match at least one of the flags in m_Mask, as well as both control groups.
+		return (tag.n != m_Tag.n && (flags & m_Mask) != 0 && ((group == m_Group
+			&& group2 == m_Group2) || (group2 == m_Group && group == m_Group2)));
+	}
+};
+
 /**
  * Obstruction test filter that will test only against shapes that do not have the specified tag set.
  */