diff --git a/binaries/data/mods/public/gui/common/common_sprites.xml b/binaries/data/mods/public/gui/common/common_sprites.xml
index be8e08ea54..78b1098b1d 100644
--- a/binaries/data/mods/public/gui/common/common_sprites.xml
+++ b/binaries/data/mods/public/gui/common/common_sprites.xml
@@ -74,7 +74,17 @@
 		<image
 			backcolor="0 0 0 191"
 			size="0 0 100% 100%"
-			border="false"
+			border="true"
+			bordercolor="white"
+		/>
+	</sprite>
+
+	<sprite name="BackgroundErrorTooltip">
+		<image
+			backcolor="0 0 0 191"
+			size="0 0 100% 100%"
+			border="true"
+			bordercolor="red"
 		/>
 	</sprite>
 
diff --git a/binaries/data/mods/public/gui/session/input.js b/binaries/data/mods/public/gui/session/input.js
index 73de380b34..e4ae2c804d 100644
--- a/binaries/data/mods/public/gui/session/input.js
+++ b/binaries/data/mods/public/gui/session/input.js
@@ -82,16 +82,20 @@ function updateCursorAndTooltip()
 	if (!tooltipSet)
 		informationTooltip.hidden = true;
 	
-	var wallDragTooltip = getGUIObjectByName("wallDragTooltip");
-	if (placementSupport.wallDragTooltip)
+	var placementTooltip = getGUIObjectByName("placementTooltip");
+	if (placementSupport.tooltipMessage)
 	{
-		wallDragTooltip.caption = placementSupport.wallDragTooltip;
-		wallDragTooltip.hidden = false;
+		if (placementSupport.tooltipError)
+			placementTooltip.sprite = "BackgroundErrorTooltip";
+		else
+			placementTooltip.sprite = "BackgroundInformationTooltip";
+		placementTooltip.caption = placementSupport.tooltipMessage;
+		placementTooltip.hidden = false;
 	}
 	else
 	{
-		wallDragTooltip.caption = "";
-		wallDragTooltip.hidden = true;
+		placementTooltip.caption = "";
+		placementTooltip.hidden = true;
 	}
 }
 
@@ -105,13 +109,18 @@ function updateBuildingPlacementPreview()
 	{
 		if (placementSupport.template && placementSupport.position)
 		{
-			return Engine.GuiInterfaceCall("SetBuildingPlacementPreview", {
+			var result = Engine.GuiInterfaceCall("SetBuildingPlacementPreview", {
 				"template": placementSupport.template,
 				"x": placementSupport.position.x,
 				"z": placementSupport.position.z,
 				"angle": placementSupport.angle,
 				"actorSeed": placementSupport.actorSeed
 			});
+
+			// Show placement info tooltip if invalid position
+			placementSupport.tooltipError = !result.success;
+			placementSupport.tooltipMessage = result.success ? "" : result.message;
+			return result.success;
 		}
 	}
 	else if (placementSupport.mode === "wall")
@@ -862,10 +871,10 @@ function handleInputBeforeGui(ev, hoveredObject)
 				
 				if (result && result.cost)
 				{
-					placementSupport.wallDragTooltip = getEntityCostTooltip(result);
+					placementSupport.tooltipMessage = getEntityCostTooltip(result);
 					var neededResources = Engine.GuiInterfaceCall("GetNeededResources", result.cost);
 					if (neededResources)
-						placementSupport.wallDragTooltip += getNeededResourcesTooltip(neededResources);
+						placementSupport.tooltipMessage += getNeededResourcesTooltip(neededResources);
 				}
 				
 				break;
@@ -892,7 +901,7 @@ function handleInputBeforeGui(ev, hoveredObject)
 					}
 					else
 					{
-						placementSupport.wallDragTooltip = "Cannot build wall here!";
+						placementSupport.tooltipMessage = "Cannot build wall here!";
 					}
 					
 					updateBuildingPlacementPreview();
diff --git a/binaries/data/mods/public/gui/session/placement.js b/binaries/data/mods/public/gui/session/placement.js
index 0b429bcaf9..189d765d7e 100644
--- a/binaries/data/mods/public/gui/session/placement.js
+++ b/binaries/data/mods/public/gui/session/placement.js
@@ -13,11 +13,12 @@ PlacementSupport.prototype.Reset = function()
 	this.mode = null;
 	this.position = null;
 	this.template = null;
+	this.tooltipMessage = "";        // tooltip text to show while the user is placing a building
+	this.tooltipError = false;
 	this.wallSet = null;             // maps types of wall pieces ("tower", "long", "short", ...) to template names
 	this.wallSnapEntities = null;    // list of candidate entities to snap the starting and (!) ending positions to when building walls
 	this.wallEndPosition = null;
 	this.wallSnapEntitiesIncludeOffscreen = false; // should the next update of the snap candidate list include offscreen towers?
-	this.wallDragTooltip = null;     // tooltip text while the user is draggin the wall. Used to indicate the current cost to build the wall.
 	
 	this.SetDefaultAngle();
 	this.RandomizeActorSeed();
diff --git a/binaries/data/mods/public/gui/session/session.xml b/binaries/data/mods/public/gui/session/session.xml
index 243f620f47..92594b2c52 100644
--- a/binaries/data/mods/public/gui/session/session.xml
+++ b/binaries/data/mods/public/gui/session/session.xml
@@ -688,9 +688,9 @@
 	<object name="informationTooltip" type="tooltip" independent="true" style="informationTooltip"/>
 
 	<!-- ================================  ================================ -->
-	<!-- Wall-dragging tooltip. Shows the total cost of building a wall while the player is dragging it. -->
+	<!-- Building placement info tooltip									-->
 	<!-- ================================  ================================ -->
-	<object name="wallDragTooltip" type="tooltip" independent="true" style="informationTooltip"/>
+	<object name="placementTooltip" type="tooltip" independent="true" style="informationTooltip"/>
 
 	<!-- ================================  ================================ -->
 	<!-- START of BOTTOM PANEL -->
diff --git a/binaries/data/mods/public/gui/session/styles.xml b/binaries/data/mods/public/gui/session/styles.xml
index 420e26efd4..ffa93185d5 100644
--- a/binaries/data/mods/public/gui/session/styles.xml
+++ b/binaries/data/mods/public/gui/session/styles.xml
@@ -206,7 +206,7 @@
 
     <style name="informationTooltip"
 	   anchor="top"
-	   buffer_zone="4"
+	   buffer_zone="6"
 	   font="serif-bold-14"
 	   maxwidth="300"
 	   offset="16 32"
diff --git a/binaries/data/mods/public/simulation/components/BuildRestrictions.js b/binaries/data/mods/public/simulation/components/BuildRestrictions.js
index 1ce4d6ee2e..2efbd6cf37 100644
--- a/binaries/data/mods/public/simulation/components/BuildRestrictions.js
+++ b/binaries/data/mods/public/simulation/components/BuildRestrictions.js
@@ -71,11 +71,50 @@ BuildRestrictions.prototype.Init = function()
 };
 
 /**
- * Returns true iff this entity can be built at its current position.
+ * Checks whether building placement is valid
+ *	1. Visibility is not hidden (may be fogged or visible)
+ *	2. Check foundation
+ *		a. Doesn't obstruct foundation-blocking entities
+ *		b. On valid terrain, based on passability class
+ *	3. Territory type is allowed
+ *	4. Dock is on shoreline and facing into water
+ *	5. Distance constraints satisfied
+ *
+ * Returns result object:
+ * 	{
+ *		"success":	true iff the placement is valid, else false
+ *		"message":	message to display in UI for invalid placement, else empty string
+ *  }
  */
 BuildRestrictions.prototype.CheckPlacement = function()
 {
-	// TODO: Return error code for invalid placement, which can be handled by the UI
+	var cmpIdentity = Engine.QueryInterface(this.entity, IID_Identity);
+	var name = cmpIdentity ? cmpIdentity.GetGenericName() : "Building";
+
+	var result = {
+		"success": false,
+		"message": name+" cannot be built due to unknown error",
+	};
+
+	// TODO: AI has no visibility info
+	var cmpPlayer = QueryOwnerInterface(this.entity, IID_Player);
+	if (!cmpPlayer.IsAI())
+	{
+		// Check whether it's in a visible or fogged region
+		// tell GetLosVisibility to force RetainInFog because preview entities set this to false,
+		// which would show them as hidden instead of fogged
+		var cmpRangeManager = Engine.QueryInterface(SYSTEM_ENTITY, IID_RangeManager);
+		var cmpOwnership = Engine.QueryInterface(this.entity, IID_Ownership);
+		if (!cmpRangeManager || !cmpOwnership)
+			return result; // Fail
+
+		var explored = (cmpRangeManager.GetLosVisibility(this.entity, cmpOwnership.GetOwner(), true) != "hidden");
+		if (!explored)
+		{
+			result.message = name+" cannot be built in unexplored area";
+			return result; // Fail
+		}
+	}
 
 	// Check obstructions and terrain passability
 	var passClassName = "";
@@ -91,20 +130,35 @@ BuildRestrictions.prototype.CheckPlacement = function()
 	}
 
 	var cmpObstruction = Engine.QueryInterface(this.entity, IID_Obstruction);
-	if (!cmpObstruction || !cmpObstruction.CheckFoundation(passClassName))
+	if (!cmpObstruction)
+		return result; // Fail
+
+	var ret = cmpObstruction.CheckFoundation(passClassName);
+	if (ret != "success")
 	{
-		return false;	// Fail
+		switch (ret)
+		{
+		case "fail_error":
+		case "fail_no_obstruction":
+			error("CheckPlacement: Error returned from CheckFoundation");
+			break;
+		case "fail_obstructs_foundation":
+			result.message = name+" cannot be built on another building or resource";
+			break;
+		case "fail_terrain_class":
+			// TODO: be more specific and/or list valid terrain?
+			result.message = name+" cannot be built on invalid terrain";
+		}
+		return result; // Fail
 	}
-	
+
 	// Check territory restrictions
 	var cmpTerritoryManager = Engine.QueryInterface(SYSTEM_ENTITY, IID_TerritoryManager);
 	var cmpPlayer = QueryOwnerInterface(this.entity, IID_Player);
 	var cmpPosition = Engine.QueryInterface(this.entity, IID_Position);
 	if (!(cmpTerritoryManager && cmpPlayer && cmpPosition && cmpPosition.IsInWorld()))
-	{
-		return false;	// Fail
-	}
-	
+		return result;	// Fail
+
 	var pos = cmpPosition.GetPosition2D();
 	var tileOwner = cmpTerritoryManager.GetOwner(pos.x, pos.y);
 	var isOwn = (tileOwner == cmpPlayer.GetPlayerID());
@@ -112,15 +166,26 @@ BuildRestrictions.prototype.CheckPlacement = function()
 	var isAlly = !isOwn && cmpPlayer.IsAlly(tileOwner);
 	// We count neutral players as enemies, so you can't build in their territory.
 	var isEnemy = !isNeutral && (cmpPlayer.IsEnemy(tileOwner) || cmpPlayer.IsNeutral(tileOwner));
-	
-	if ((isAlly && !this.HasTerritory("ally"))
-		|| (isOwn && !this.HasTerritory("own"))
-		|| (isNeutral && !this.HasTerritory("neutral"))
-		|| (isEnemy && !this.HasTerritory("enemy")))
+
+	var territoryFail = true;
+	var territoryType = "";
+	if (isAlly && !this.HasTerritory("ally"))
+		territoryType = "ally";
+	else if (isOwn && !this.HasTerritory("own"))
+		territoryType = "own";
+	else if (isNeutral && !this.HasTerritory("neutral"))
+		territoryType = "neutral";
+	else if (isEnemy && !this.HasTerritory("enemy"))
+		territoryType = "enemy";
+	else
+		territoryFail = false
+
+	if (territoryFail)
 	{
-		return false;	// Fail
+		result.message = name+" cannot be built in "+territoryType+" territory. Valid territories: " + this.GetTerritories().join(", ");
+		return result;	// Fail
 	}
-	
+
 	// Check special requirements
 	if (this.template.Category == "Dock")
 	{
@@ -130,39 +195,32 @@ BuildRestrictions.prototype.CheckPlacement = function()
 		//	so it's correct even if the criteria changes for these units
 		var cmpFootprint = Engine.QueryInterface(this.entity, IID_Footprint);
 		if (!cmpFootprint)
-		{
-			return false;	// Fail
-		}
-		
+			return result;	// Fail
+
 		// Get building's footprint
 		var shape = cmpFootprint.GetShape();
 		var halfSize = 0;
 		if (shape.type == "square")
-		{
 			halfSize = shape.depth/2;
-		}
 		else if (shape.type == "circle")
-		{
 			halfSize = shape.radius;
-		}
-		
+
 		var cmpTerrain = Engine.QueryInterface(SYSTEM_ENTITY, IID_Terrain);
 		var cmpWaterManager = Engine.QueryInterface(SYSTEM_ENTITY, IID_WaterManager);
 		if (!cmpTerrain || !cmpWaterManager)
-		{
-			return false;	// Fail
-		}
-		
+			return result;	// Fail
+
 		var ang = cmpPosition.GetRotation().y;
 		var sz = halfSize * Math.sin(ang);
 		var cz = halfSize * Math.cos(ang);
 		if ((cmpWaterManager.GetWaterLevel(pos.x + sz, pos.y + cz) - cmpTerrain.GetGroundLevel(pos.x + sz, pos.y + cz)) < 1.0 // front
 			|| (cmpWaterManager.GetWaterLevel(pos.x - sz, pos.y - cz) - cmpTerrain.GetGroundLevel(pos.x - sz, pos.y - cz)) > 2.0) // back
 		{
-			return false;	// Fail
+			result.message = name+" must be built on a valid shoreline";
+			return result;	// Fail
 		}
 	}
-	
+
 	// Check distance restriction
 	if (this.template.Distance)
 	{
@@ -189,16 +247,23 @@ BuildRestrictions.prototype.CheckPlacement = function()
 				}
 			}
 		}
-		
-		if ((this.template.Distance.MinDistance && nearest < this.template.Distance.MinDistance)
-			|| (this.template.Distance.MaxDistance && nearest > this.template.Distance.MaxDistance))
+
+		if (this.template.Distance.MinDistance && nearest < +this.template.Distance.MinDistance)
 		{
-			return false;	// Fail
+			result.message = name+" too close to a "+this.GetCategory()+", must be at least "+ +this.template.Distance.MinDistance+" units away";
+			return result;	// Fail
+		}
+		else if (this.template.Distance.MaxDistance && nearest > +this.template.Distance.MaxDistance)
+		{
+			result.message = name+" too far away from a "+this.GetCategory()+", must be within "+ +this.template.Distance.MaxDistance+" units";
+			return result;	// Fail
 		}
 	}
-	
+
 	// Success
-	return true;
+	result.success = true;
+	result.message = "";
+	return result;
 };
 
 BuildRestrictions.prototype.GetCategory = function()
diff --git a/binaries/data/mods/public/simulation/components/GuiInterface.js b/binaries/data/mods/public/simulation/components/GuiInterface.js
index 34429fe1f5..84b1e55120 100644
--- a/binaries/data/mods/public/simulation/components/GuiInterface.js
+++ b/binaries/data/mods/public/simulation/components/GuiInterface.js
@@ -798,10 +798,19 @@ GuiInterface.prototype.DisplayRallyPoint = function(player, cmd)
  * cmd.template is the name of the entity template, or "" to disable the preview.
  * cmd.x, cmd.z, cmd.angle give the location.
  * 
- * Returns true if the placement is okay (everything is valid and the entity is not obstructed by others).
+ * Returns result object from CheckPlacement:
+ * 	{
+ *		"success":	true iff the placement is valid, else false
+ *		"message":	message to display in UI for invalid placement, else empty string
+ *  }
  */
 GuiInterface.prototype.SetBuildingPlacementPreview = function(player, cmd)
 {
+	var result = {
+		"success": false,
+		"message": "",
+	}
+
 	// See if we're changing template
 	if (!this.placementEntity || this.placementEntity[0] != cmd.template)
 	{
@@ -832,26 +841,15 @@ GuiInterface.prototype.SetBuildingPlacementPreview = function(player, cmd)
 			pos.SetYRotation(cmd.angle);
 		}
 
-		// Check whether it's in a visible or fogged region
-		//	tell GetLosVisibility to force RetainInFog because preview entities set this to false,
-		//	which would show them as hidden instead of fogged
-		var cmpRangeManager = Engine.QueryInterface(SYSTEM_ENTITY, IID_RangeManager);
-		var visible = (cmpRangeManager && cmpRangeManager.GetLosVisibility(ent, player, true) != "hidden");
-		var validPlacement = false;
-
 		var cmpOwnership = Engine.QueryInterface(ent, IID_Ownership);
 		cmpOwnership.SetOwner(player);
 
-		if (visible)
-		{	// Check whether it's obstructed by other entities or invalid terrain
-			var cmpBuildRestrictions = Engine.QueryInterface(ent, IID_BuildRestrictions);
-			if (!cmpBuildRestrictions)
-				error("cmpBuildRestrictions not defined");
-
-			validPlacement = (cmpBuildRestrictions && cmpBuildRestrictions.CheckPlacement());
-		}
-
-		var ok = (visible && validPlacement);
+		// Check whether building placement is valid
+		var cmpBuildRestrictions = Engine.QueryInterface(ent, IID_BuildRestrictions);
+		if (!cmpBuildRestrictions)
+			error("cmpBuildRestrictions not defined");
+		else
+			result = cmpBuildRestrictions.CheckPlacement();
 
 		// Set it to a red shade if this is an invalid location
 		var cmpVisual = Engine.QueryInterface(ent, IID_Visual);
@@ -859,17 +857,15 @@ GuiInterface.prototype.SetBuildingPlacementPreview = function(player, cmd)
 		{
 			if (cmd.actorSeed !== undefined)
 				cmpVisual.SetActorSeed(cmd.actorSeed);
-		
-			if (!ok)
+
+			if (!result.success)
 				cmpVisual.SetShadingColour(1.4, 0.4, 0.4, 1);
 			else
 				cmpVisual.SetShadingColour(1, 1, 1, 1);
 		}
-
-		return ok;
 	}
 
-	return false;
+	return result;
 };
 
 /**
@@ -1317,7 +1313,8 @@ GuiInterface.prototype.SetWallPlacementPreview = function(player, cmd)
 				continue;
 			}
 			
-			validPlacement = (cmpBuildRestrictions && cmpBuildRestrictions.CheckPlacement());
+			// TODO: Handle results of CheckPlacement
+			validPlacement = (cmpBuildRestrictions && cmpBuildRestrictions.CheckPlacement().success);
 
 			// If a wall piece has two control groups, it's likely a segment that spans
 			// between two existing towers. To avoid placing a duplicate wall segment,
diff --git a/binaries/data/mods/public/simulation/components/Identity.js b/binaries/data/mods/public/simulation/components/Identity.js
index b2c905995a..65ec4d2da7 100644
--- a/binaries/data/mods/public/simulation/components/Identity.js
+++ b/binaries/data/mods/public/simulation/components/Identity.js
@@ -133,4 +133,9 @@ Identity.prototype.GetSelectionGroupName = function()
 	return (this.template.SelectionGroupName || "");
 };
 
+Identity.prototype.GetGenericName = function()
+{
+	return this.template.GenericName;
+};
+
 Engine.RegisterComponentType(IID_Identity, "Identity", Identity);
diff --git a/binaries/data/mods/public/simulation/helpers/Commands.js b/binaries/data/mods/public/simulation/helpers/Commands.js
index 58ee6e5672..513dc5cc98 100644
--- a/binaries/data/mods/public/simulation/helpers/Commands.js
+++ b/binaries/data/mods/public/simulation/helpers/Commands.js
@@ -601,22 +601,28 @@ function TryConstructBuilding(player, cmpPlayer, controlAllUnits, cmd)
 	var cmpOwnership = Engine.QueryInterface(ent, IID_Ownership);
 	cmpOwnership.SetOwner(player);
 	
-	// Check whether it's obstructed by other entities or invalid terrain
+	// Check whether building placement is valid
 	var cmpBuildRestrictions = Engine.QueryInterface(ent, IID_BuildRestrictions);
-	if (!cmpBuildRestrictions || !cmpBuildRestrictions.CheckPlacement())
+	if (cmpBuildRestrictions)
 	{
-		if (g_DebugCommands)
+		var ret = cmpBuildRestrictions.CheckPlacement();
+		if (!ret.success)
 		{
-			warn("Invalid command: build restrictions check failed for player "+player+": "+uneval(cmd));
+			if (g_DebugCommands)
+			{
+				warn("Invalid command: build restrictions check failed for player "+player+": "+uneval(cmd));
+			}
+
+			var cmpGuiInterface = Engine.QueryInterface(SYSTEM_ENTITY, IID_GuiInterface);
+			cmpGuiInterface.PushNotification({ "player": player, "message": ret.message });
+			
+			// Remove the foundation because the construction was aborted
+			Engine.DestroyEntity(ent);
+			return false;
 		}
-		
-		var cmpGuiInterface = Engine.QueryInterface(SYSTEM_ENTITY, IID_GuiInterface);
-		cmpGuiInterface.PushNotification({ "player": player, "message": "Building site was obstructed" });
-		
-		// Remove the foundation because the construction was aborted
-		Engine.DestroyEntity(ent);
-		return false;
 	}
+	else
+		error("cmpBuildRestrictions not defined");
 	
 	// Check entity limits
 	var cmpEntityLimits = QueryPlayerIDInterface(player, IID_EntityLimits);
@@ -647,29 +653,6 @@ function TryConstructBuilding(player, cmpPlayer, controlAllUnits, cmd)
 		
 		// Remove the foundation because the construction was aborted 
 		Engine.DestroyEntity(ent); 
-	} 
-	
-	// TODO: AI has no visibility info
-	if (!cmpPlayer.IsAI())
-	{
-		// Check whether it's in a visible or fogged region
-		//	tell GetLosVisibility to force RetainInFog because preview entities set this to false,
-		//	which would show them as hidden instead of fogged
-		var cmpRangeManager = Engine.QueryInterface(SYSTEM_ENTITY, IID_RangeManager);
-		var visible = (cmpRangeManager && cmpRangeManager.GetLosVisibility(ent, player, true) != "hidden");
-		if (!visible)
-		{
-			if (g_DebugCommands)
-			{
-				warn("Invalid command: foundation visibility check failed for player "+player+": "+uneval(cmd));
-			}
-			
-			var cmpGuiInterface = Engine.QueryInterface(SYSTEM_ENTITY, IID_GuiInterface);
-			cmpGuiInterface.PushNotification({ "player": player, "message": "Building site was not visible" });
-			
-			Engine.DestroyEntity(ent);
-			return false;
-		}
 	}
 	
 	// We need the cost after tech modifications
diff --git a/source/simulation2/components/CCmpFootprint.cpp b/source/simulation2/components/CCmpFootprint.cpp
index 019aea33c7..301c456db4 100644
--- a/source/simulation2/components/CCmpFootprint.cpp
+++ b/source/simulation2/components/CCmpFootprint.cpp
@@ -1,4 +1,4 @@
-/* Copyright (C) 2012 Wildfire Games.
+/* Copyright (C) 2013 Wildfire Games.
  * This file is part of 0 A.D.
  *
  * 0 A.D. is free software: you can redistribute it and/or modify
@@ -186,7 +186,7 @@ public:
 					CFixedVector3D pos (initialPos.X + s.Multiply(radius), fixed::Zero(), initialPos.Y + c.Multiply(radius));
 
 					SkipTagObstructionFilter filter(spawnedTag); // ignore collisions with the spawned entity
-					if (cmpPathfinder->CheckUnitPlacement(filter, pos.X, pos.Z, spawnedRadius, spawnedPass))
+					if (cmpPathfinder->CheckUnitPlacement(filter, pos.X, pos.Z, spawnedRadius, spawnedPass) == ICmpObstruction::FOUNDATION_CHECK_SUCCESS)
 						return pos; // this position is okay, so return it
 				}
 			}
@@ -241,7 +241,7 @@ public:
 						CFixedVector2D pos (center + dir*i);
 
 						SkipTagObstructionFilter filter(spawnedTag); // ignore collisions with the spawned entity
-						if (cmpPathfinder->CheckUnitPlacement(filter, pos.X, pos.Y, spawnedRadius, spawnedPass))
+						if (cmpPathfinder->CheckUnitPlacement(filter, pos.X, pos.Y, spawnedRadius, spawnedPass) == ICmpObstruction::FOUNDATION_CHECK_SUCCESS)
 							return CFixedVector3D(pos.X, fixed::Zero(), pos.Y); // this position is okay, so return it
 					}
 				}
diff --git a/source/simulation2/components/CCmpObstruction.cpp b/source/simulation2/components/CCmpObstruction.cpp
index ccfe617dfd..4fa003378c 100644
--- a/source/simulation2/components/CCmpObstruction.cpp
+++ b/source/simulation2/components/CCmpObstruction.cpp
@@ -1,4 +1,4 @@
-/* Copyright (C) 2012 Wildfire Games.
+/* Copyright (C) 2013 Wildfire Games.
  * This file is part of 0 A.D.
  *
  * 0 A.D. is free software: you can redistribute it and/or modify
@@ -478,26 +478,26 @@ public:
 		return m_ControlPersist;
 	}
 
-	virtual bool CheckFoundation(std::string className)
+	virtual EFoundationCheck CheckFoundation(std::string className)
 	{
 		CmpPtr<ICmpPosition> cmpPosition(GetSimContext(), GetEntityId());
 		if (!cmpPosition)
-			return false; // error
+			return FOUNDATION_CHECK_FAIL_ERROR; // error
 
 		if (!cmpPosition->IsInWorld())
-			return false; // no obstruction
+			return FOUNDATION_CHECK_FAIL_NO_OBSTRUCTION; // no obstruction
 
 		CFixedVector2D pos = cmpPosition->GetPosition2D();
 
 		CmpPtr<ICmpPathfinder> cmpPathfinder(GetSimContext(), SYSTEM_ENTITY);
 		if (!cmpPathfinder)
-			return false; // error
+			return FOUNDATION_CHECK_FAIL_ERROR; // 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;
+			return FOUNDATION_CHECK_FAIL_ERROR;
 		}
 
 		// Get passability class
@@ -509,11 +509,9 @@ public:
 		SkipControlGroupsRequireFlagObstructionFilter filter(m_ControlGroup, m_ControlGroup2,
 			ICmpObstructionManager::FLAG_BLOCK_FOUNDATION);
 
-		if (m_Type == STATIC)
-			return cmpPathfinder->CheckBuildingPlacement(filter, pos.X, pos.Y, cmpPosition->GetRotation().Y, m_Size0, m_Size1, GetEntityId(), passClass);
-		else if (m_Type == UNIT)
+		if (m_Type == UNIT)
 			return cmpPathfinder->CheckUnitPlacement(filter, pos.X, pos.Y, m_Size0, passClass);
-		else 
+		else
 			return cmpPathfinder->CheckBuildingPlacement(filter, pos.X, pos.Y, cmpPosition->GetRotation().Y, m_Size0, m_Size1, GetEntityId(), passClass);
 	}
 
diff --git a/source/simulation2/components/CCmpPathfinder.cpp b/source/simulation2/components/CCmpPathfinder.cpp
index d91eb06e3f..0df667cde4 100644
--- a/source/simulation2/components/CCmpPathfinder.cpp
+++ b/source/simulation2/components/CCmpPathfinder.cpp
@@ -1,4 +1,4 @@
-/* Copyright (C) 2012 Wildfire Games.
+/* Copyright (C) 2013 Wildfire Games.
  * This file is part of 0 A.D.
  *
  * 0 A.D. is free software: you can redistribute it and/or modify
@@ -656,16 +656,16 @@ void CCmpPathfinder::ProcessSameTurnMoves()
 	}
 }
 
-bool CCmpPathfinder::CheckUnitPlacement(const IObstructionTestFilter& filter,
+ICmpObstruction::EFoundationCheck CCmpPathfinder::CheckUnitPlacement(const IObstructionTestFilter& filter,
 	entity_pos_t x, entity_pos_t z, entity_pos_t r,	pass_class_t passClass)
 {
 	// Check unit obstruction
 	CmpPtr<ICmpObstructionManager> cmpObstructionManager(GetSimContext(), SYSTEM_ENTITY);
 	if (!cmpObstructionManager)
-		return false;
+		return ICmpObstruction::FOUNDATION_CHECK_FAIL_ERROR;
 
 	if (cmpObstructionManager->TestUnitShape(filter, x, z, r, NULL))
-		return false;
+		return ICmpObstruction::FOUNDATION_CHECK_FAIL_OBSTRUCTS_FOUNDATION;
 
 	// Test against terrain:
 
@@ -680,36 +680,33 @@ bool CCmpPathfinder::CheckUnitPlacement(const IObstructionTestFilter& filter,
 		{
 			if (!IS_TERRAIN_PASSABLE(m_Grid->get(i,j), passClass))
 			{
-				return false;
+				return ICmpObstruction::FOUNDATION_CHECK_FAIL_TERRAIN_CLASS;
 			}
 		}
 	}
-	return true;
+	return ICmpObstruction::FOUNDATION_CHECK_SUCCESS;
 }
 
-bool CCmpPathfinder::CheckBuildingPlacement(const IObstructionTestFilter& filter,
+ICmpObstruction::EFoundationCheck CCmpPathfinder::CheckBuildingPlacement(const IObstructionTestFilter& filter,
 	entity_pos_t x, entity_pos_t z, entity_pos_t a, entity_pos_t w,
 	entity_pos_t h, entity_id_t id, pass_class_t passClass)
 {
 	// Check unit obstruction
 	CmpPtr<ICmpObstructionManager> cmpObstructionManager(GetSimContext(), SYSTEM_ENTITY);
 	if (!cmpObstructionManager)
-		return false;
+		return ICmpObstruction::FOUNDATION_CHECK_FAIL_ERROR;
 
 	if (cmpObstructionManager->TestStaticShape(filter, x, z, a, w, h, NULL))
-		return false;
+		return ICmpObstruction::FOUNDATION_CHECK_FAIL_OBSTRUCTS_FOUNDATION;
 
 	// Test against terrain:
 
 	UpdateGrid();
 
-	CmpPtr<ICmpObstruction> cmpObstruction(GetSimContext(), id);
-	if (!cmpObstruction)
-		return false;
-
 	ICmpObstructionManager::ObstructionSquare square;
-	if (!cmpObstruction->GetObstructionSquare(square))
-		return false;
+	CmpPtr<ICmpObstruction> cmpObstruction(GetSimContext(), id);
+	if (!cmpObstruction || !cmpObstruction->GetObstructionSquare(square))
+		return ICmpObstruction::FOUNDATION_CHECK_FAIL_NO_OBSTRUCTION;
 
 	// Expand bounds by 1/sqrt(2) tile (multiply by TERRAIN_TILE_SIZE since we want world coordinates)
 	entity_pos_t expand = entity_pos_t::FromInt(2).Sqrt().Multiply(entity_pos_t::FromInt(TERRAIN_TILE_SIZE / 2));
@@ -728,10 +725,10 @@ bool CCmpPathfinder::CheckBuildingPlacement(const IObstructionTestFilter& filter
 			if (Geometry::PointIsInSquare(CFixedVector2D(x - square.x, z - square.z), square.u, square.v, halfSize)
 				&& !IS_TERRAIN_PASSABLE(m_Grid->get(i,j), passClass))
 			{
-				return false;
+				return ICmpObstruction::FOUNDATION_CHECK_FAIL_TERRAIN_CLASS;
 			}
 		}
 	}
 
-	return true;
+	return ICmpObstruction::FOUNDATION_CHECK_SUCCESS;
 }
diff --git a/source/simulation2/components/CCmpPathfinder_Common.h b/source/simulation2/components/CCmpPathfinder_Common.h
index f025ab963d..a5e4a74dd4 100644
--- a/source/simulation2/components/CCmpPathfinder_Common.h
+++ b/source/simulation2/components/CCmpPathfinder_Common.h
@@ -1,4 +1,4 @@
-/* Copyright (C) 2011 Wildfire Games.
+/* Copyright (C) 2013 Wildfire Games.
  * This file is part of 0 A.D.
  *
  * 0 A.D. is free software: you can redistribute it and/or modify
@@ -260,9 +260,9 @@ public:
 
 	virtual bool CheckMovement(const IObstructionTestFilter& filter, entity_pos_t x0, entity_pos_t z0, entity_pos_t x1, entity_pos_t z1, entity_pos_t r, pass_class_t passClass);
 
-	virtual bool CheckUnitPlacement(const IObstructionTestFilter& filter, entity_pos_t x, entity_pos_t z, entity_pos_t r, pass_class_t passClass);
+	virtual ICmpObstruction::EFoundationCheck CheckUnitPlacement(const IObstructionTestFilter& filter, entity_pos_t x, entity_pos_t z, entity_pos_t r, pass_class_t passClass);
 
-	virtual bool CheckBuildingPlacement(const IObstructionTestFilter& filter, entity_pos_t x, entity_pos_t z, entity_pos_t a, entity_pos_t w, entity_pos_t h, entity_id_t id, pass_class_t passClass);
+	virtual ICmpObstruction::EFoundationCheck CheckBuildingPlacement(const IObstructionTestFilter& filter, entity_pos_t x, entity_pos_t z, entity_pos_t a, entity_pos_t w, entity_pos_t h, entity_id_t id, pass_class_t passClass);
 
 	virtual void FinishAsyncRequests();
 
diff --git a/source/simulation2/components/CCmpTemplateManager.cpp b/source/simulation2/components/CCmpTemplateManager.cpp
index 65098cec46..e87e6a4430 100644
--- a/source/simulation2/components/CCmpTemplateManager.cpp
+++ b/source/simulation2/components/CCmpTemplateManager.cpp
@@ -501,6 +501,7 @@ void CCmpTemplateManager::CopyPreviewSubset(CParamNode& out, const CParamNode& i
 	// and safe (i.e. won't do anything that affects the synchronised simulation state), so additions
 	// to this list should be carefully considered
 	std::set<std::string> permittedComponentTypes;
+	permittedComponentTypes.insert("Identity");
 	permittedComponentTypes.insert("Ownership");
 	permittedComponentTypes.insert("Position");
 	permittedComponentTypes.insert("VisualActor");
diff --git a/source/simulation2/components/ICmpObstruction.cpp b/source/simulation2/components/ICmpObstruction.cpp
index 74ede56f02..fb5ce9d62d 100644
--- a/source/simulation2/components/ICmpObstruction.cpp
+++ b/source/simulation2/components/ICmpObstruction.cpp
@@ -1,4 +1,4 @@
-/* Copyright (C) 2012 Wildfire Games.
+/* Copyright (C) 2013 Wildfire Games.
  * This file is part of 0 A.D.
  *
  * 0 A.D. is free software: you can redistribute it and/or modify
@@ -21,9 +21,33 @@
 
 #include "simulation2/system/InterfaceScripted.h"
 
+#include "simulation2/system/SimContext.h"
+
+std::string ICmpObstruction::CheckFoundation_wrapper(std::string className)
+{
+	EFoundationCheck check = CheckFoundation(className);
+
+	switch (check)
+	{
+	case FOUNDATION_CHECK_SUCCESS:
+		return "success";
+	case FOUNDATION_CHECK_FAIL_ERROR:
+		return "fail_error";
+	case FOUNDATION_CHECK_FAIL_NO_OBSTRUCTION:
+		return "fail_no_obstruction";
+	case FOUNDATION_CHECK_FAIL_OBSTRUCTS_FOUNDATION:
+		return "fail_obstructs_foundation";
+	case FOUNDATION_CHECK_FAIL_TERRAIN_CLASS:
+		return "fail_terrain_class";
+	default:
+		debug_warn(L"Unexpected result from CheckFoundation");
+		return "";
+	}
+}
+
 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_1("CheckFoundation", std::string, ICmpObstruction, CheckFoundation_wrapper, std::string)
 DEFINE_INTERFACE_METHOD_0("CheckDuplicateFoundation", bool, ICmpObstruction, CheckDuplicateFoundation)
 DEFINE_INTERFACE_METHOD_2("GetEntityCollisions", std::vector<entity_id_t>, ICmpObstruction, GetEntityCollisions, bool, bool)
 DEFINE_INTERFACE_METHOD_1("SetActive", void, ICmpObstruction, SetActive, bool)
diff --git a/source/simulation2/components/ICmpObstruction.h b/source/simulation2/components/ICmpObstruction.h
index d7a5f0970d..666680d891 100644
--- a/source/simulation2/components/ICmpObstruction.h
+++ b/source/simulation2/components/ICmpObstruction.h
@@ -1,4 +1,4 @@
-/* Copyright (C) 2012 Wildfire Games.
+/* Copyright (C) 2013 Wildfire Games.
  * This file is part of 0 A.D.
  *
  * 0 A.D. is free software: you can redistribute it and/or modify
@@ -30,6 +30,14 @@ class ICmpObstruction : public IComponent
 {
 public:
 
+	enum EFoundationCheck {
+		FOUNDATION_CHECK_SUCCESS,
+		FOUNDATION_CHECK_FAIL_ERROR,
+		FOUNDATION_CHECK_FAIL_NO_OBSTRUCTION,
+		FOUNDATION_CHECK_FAIL_OBSTRUCTS_FOUNDATION,
+		FOUNDATION_CHECK_FAIL_TERRAIN_CLASS
+	};
+
 	virtual ICmpObstructionManager::tag_t GetObstruction() = 0;
 
 	/**
@@ -47,9 +55,16 @@ public:
 	 * Test whether this entity is colliding with any obstruction that are set to
 	 * block the creation of foundations.
 	 * @param ignoredEntities List of entities to ignore during the test.
-	 * @return true if foundation is valid (not obstructed)
+	 * @return FOUNDATION_CHECK_SUCCESS if check passes, else an EFoundationCheck
+	 *	value describing the type of failure.
 	 */
-	virtual bool CheckFoundation(std::string className) = 0;
+	virtual EFoundationCheck CheckFoundation(std::string className) = 0;
+
+	/**
+	 * CheckFoundation wrapper for script calls, to return friendly strings instead of an EFoundationCheck.
+	 * @return "success" if check passes, else a string describing the type of failure.
+	 */
+	virtual std::string CheckFoundation_wrapper(std::string className);
 
 	/**
 	 * Test whether this entity is colliding with any obstructions that share its
diff --git a/source/simulation2/components/ICmpPathfinder.h b/source/simulation2/components/ICmpPathfinder.h
index ee7a3000aa..e75713addf 100644
--- a/source/simulation2/components/ICmpPathfinder.h
+++ b/source/simulation2/components/ICmpPathfinder.h
@@ -1,4 +1,4 @@
-/* Copyright (C) 2011 Wildfire Games.
+/* Copyright (C) 2013 Wildfire Games.
  * This file is part of 0 A.D.
  *
  * 0 A.D. is free software: you can redistribute it and/or modify
@@ -20,6 +20,7 @@
 
 #include "simulation2/system/Interface.h"
 
+#include "simulation2/components/ICmpObstruction.h"
 #include "simulation2/helpers/Position.h"
 
 #include "maths/FixedVector2D.h"
@@ -152,16 +153,18 @@ public:
 	/**
 	 * Check whether a unit placed here is valid and doesn't hit any obstructions
 	 * or impassable terrain.
-	 * Returns true if the placement is okay.
+	 * @return ICmpObstruction::FOUNDATION_CHECK_SUCCESS if the placement is okay, else
+	 *	a value describing the type of failure.
 	 */
-	virtual bool CheckUnitPlacement(const IObstructionTestFilter& filter, entity_pos_t x, entity_pos_t z, entity_pos_t r, pass_class_t passClass) = 0;
+	virtual ICmpObstruction::EFoundationCheck CheckUnitPlacement(const IObstructionTestFilter& filter, entity_pos_t x, entity_pos_t z, entity_pos_t r, pass_class_t passClass) = 0;
 
 	/**
 	 * Check whether a building placed here is valid and doesn't hit any obstructions
 	 * or impassable terrain.
-	 * Returns true if the placement is okay.
+	 * @return ICmpObstruction::FOUNDATION_CHECK_SUCCESS if the placement is okay, else
+	 *	a value describing the type of failure.
 	 */
-	virtual bool CheckBuildingPlacement(const IObstructionTestFilter& filter, entity_pos_t x, entity_pos_t z, entity_pos_t a, entity_pos_t w, entity_pos_t h, entity_id_t id, pass_class_t passClass) = 0;
+	virtual ICmpObstruction::EFoundationCheck CheckBuildingPlacement(const IObstructionTestFilter& filter, entity_pos_t x, entity_pos_t z, entity_pos_t a, entity_pos_t w, entity_pos_t h, entity_id_t id, pass_class_t passClass) = 0;
 
 	/**
 	 * Toggle the storage and rendering of debug info.