diff --git a/common/buildcraft/api/blueprints/Schematic.java b/common/buildcraft/api/blueprints/Schematic.java
index bfaff95f..a3825865 100755
--- a/common/buildcraft/api/blueprints/Schematic.java
+++ b/common/buildcraft/api/blueprints/Schematic.java
@@ -39,6 +39,15 @@ import net.minecraft.nbt.NBTTagCompound;
  */
 public class Schematic {
 
+	/**
+	 * Return true if the block on the world correspond to the block stored in
+	 * the blueprint at the location given by the slot. By default, this
+	 * subprogram is permissive and doesn't take into account metadata.
+	 */
+	public boolean isAlreadyBuilt(IBuilderContext context, int x, int y, int z) {
+		return true;
+	}
+
 	public final LinkedList<ItemStack> getRequirements(IBuilderContext context) {
 		LinkedList<ItemStack> res = new LinkedList<ItemStack>();
 
diff --git a/common/buildcraft/api/blueprints/SchematicBlock.java b/common/buildcraft/api/blueprints/SchematicBlock.java
index 8786107e..41cb9c0d 100755
--- a/common/buildcraft/api/blueprints/SchematicBlock.java
+++ b/common/buildcraft/api/blueprints/SchematicBlock.java
@@ -107,7 +107,7 @@ public class SchematicBlock extends SchematicBlockBase  implements Comparable<Sc
 	 * subprogram is permissive and doesn't take into account metadata.
 	 */
 	@Override
-	public boolean isValid(IBuilderContext context, int x, int y, int z) {
+	public boolean isAlreadyBuilt(IBuilderContext context, int x, int y, int z) {
 		return block == context.world().getBlock(x, y, z) && meta == context.world().getBlockMetadata(x, y, z);
 	}
 
diff --git a/common/buildcraft/api/blueprints/SchematicBlockBase.java b/common/buildcraft/api/blueprints/SchematicBlockBase.java
index 3ff1cf9d..d0327339 100755
--- a/common/buildcraft/api/blueprints/SchematicBlockBase.java
+++ b/common/buildcraft/api/blueprints/SchematicBlockBase.java
@@ -34,15 +34,6 @@ package buildcraft.api.blueprints;
  */
 public class SchematicBlockBase extends Schematic {
 
-	/**
-	 * Return true if the block on the world correspond to the block stored in
-	 * the blueprint at the location given by the slot. By default, this
-	 * subprogram is permissive and doesn't take into account metadata.
-	 */
-	public boolean isValid(IBuilderContext context, int x, int y, int z) {
-		return true;
-	}
-
 	public void writeCompleted(IBuilderContext context, int x, int y, int z, double completed) {
 
 	}
diff --git a/common/buildcraft/api/blueprints/SchematicEntity.java b/common/buildcraft/api/blueprints/SchematicEntity.java
index 8d6a2e6e..9471cf11 100755
--- a/common/buildcraft/api/blueprints/SchematicEntity.java
+++ b/common/buildcraft/api/blueprints/SchematicEntity.java
@@ -145,4 +145,24 @@ public class SchematicEntity extends Schematic {
 
 		return nbttaglist;
 	}
+
+	public boolean isAlreadyBuilt(IBuilderContext context, CoordTransformation transform) {
+		NBTTagList nbttaglist = cpt.getTagList("Pos", 6);
+		Position newPosition = new Position(nbttaglist.func_150309_d(0),
+				nbttaglist.func_150309_d(1), nbttaglist.func_150309_d(2));
+
+		newPosition = transform.translate(newPosition);
+
+		for (Object o : context.world().loadedEntityList) {
+			Entity e = (Entity) o;
+
+			Position existingPositon = new Position(e.posX, e.posY, e.posZ);
+
+			if (existingPositon.isClose (newPosition, 0.1F)) {
+				return true;
+			}
+		}
+
+		return false;
+	}
 }
diff --git a/common/buildcraft/api/blueprints/SchematicMask.java b/common/buildcraft/api/blueprints/SchematicMask.java
index 8f8ded16..46b52674 100755
--- a/common/buildcraft/api/blueprints/SchematicMask.java
+++ b/common/buildcraft/api/blueprints/SchematicMask.java
@@ -41,7 +41,7 @@ public class SchematicMask extends SchematicBlockBase {
 	}
 
 	@Override
-	public boolean isValid(IBuilderContext context, int x, int y, int z) {
+	public boolean isAlreadyBuilt(IBuilderContext context, int x, int y, int z) {
 		if (isConcrete) {
 			return !BlockUtil.isSoftBlock(context.world(), x, y, z);
 		} else {
diff --git a/common/buildcraft/api/core/Position.java b/common/buildcraft/api/core/Position.java
index a3646072..56091e95 100644
--- a/common/buildcraft/api/core/Position.java
+++ b/common/buildcraft/api/core/Position.java
@@ -148,4 +148,18 @@ public class Position {
 		return new Position(p.x < x ? x : p.x, p.y < y ? y : p.y, p.z < z ? z : p.z);
 	}
 
+	public boolean isClose(Position newPosition, float f) {
+		double dx = x - newPosition.x;
+		double dy = y - newPosition.y;
+		double dz = z - newPosition.z;
+
+		double sqrDis = dx * dx + dy * dy + dz * dz;
+
+		if (sqrDis > f * f) {
+			return false;
+		} else {
+			return true;
+		}
+	}
+
 }
diff --git a/common/buildcraft/builders/schematics/SchematicDirt.java b/common/buildcraft/builders/schematics/SchematicDirt.java
index 0ba68c0c..c270748e 100644
--- a/common/buildcraft/builders/schematics/SchematicDirt.java
+++ b/common/buildcraft/builders/schematics/SchematicDirt.java
@@ -29,7 +29,7 @@ public class SchematicDirt extends SchematicBlock {
 	}
 
 	@Override
-	public boolean isValid(IBuilderContext context, int x, int y, int z) {
+	public boolean isAlreadyBuilt(IBuilderContext context, int x, int y, int z) {
 		Block block = context.world().getBlock(x, y, z);
 
 		return block == Blocks.dirt || block == Blocks.grass || block == Blocks.farmland;
diff --git a/common/buildcraft/builders/schematics/SchematicFarmland.java b/common/buildcraft/builders/schematics/SchematicFarmland.java
index 8d94a692..4e684d44 100755
--- a/common/buildcraft/builders/schematics/SchematicFarmland.java
+++ b/common/buildcraft/builders/schematics/SchematicFarmland.java
@@ -29,7 +29,7 @@ public class SchematicFarmland extends SchematicBlock {
 	}
 
 	@Override
-	public boolean isValid(IBuilderContext context, int x, int y, int z) {
+	public boolean isAlreadyBuilt(IBuilderContext context, int x, int y, int z) {
 		Block block = context.world().getBlock(x, y, z);
 
 		return block == Blocks.farmland;
diff --git a/common/buildcraft/builders/schematics/SchematicFluid.java b/common/buildcraft/builders/schematics/SchematicFluid.java
index dd548d03..d24ab2c0 100644
--- a/common/buildcraft/builders/schematics/SchematicFluid.java
+++ b/common/buildcraft/builders/schematics/SchematicFluid.java
@@ -30,7 +30,7 @@ public class SchematicFluid extends SchematicBlock {
 	}
 
 	@Override
-	public boolean isValid(IBuilderContext context, int x, int y, int z) {
+	public boolean isAlreadyBuilt(IBuilderContext context, int x, int y, int z) {
 		if (meta == 0) {
 			return block == context.world().getBlock(x, y, z) && context.world().getBlockMetadata(x, y, z) == 0;
 		} else {
diff --git a/common/buildcraft/builders/schematics/SchematicGravel.java b/common/buildcraft/builders/schematics/SchematicGravel.java
index 2d23bc30..9c8028bb 100755
--- a/common/buildcraft/builders/schematics/SchematicGravel.java
+++ b/common/buildcraft/builders/schematics/SchematicGravel.java
@@ -29,7 +29,7 @@ public class SchematicGravel extends SchematicBlock {
 	}
 
 	@Override
-	public boolean isValid(IBuilderContext context, int x, int y, int z) {
+	public boolean isAlreadyBuilt(IBuilderContext context, int x, int y, int z) {
 		Block block = context.world().getBlock(x, y, z);
 
 		return block == Blocks.gravel;
diff --git a/common/buildcraft/builders/schematics/SchematicHanging.java b/common/buildcraft/builders/schematics/SchematicHanging.java
index c6264338..ad4288fd 100755
--- a/common/buildcraft/builders/schematics/SchematicHanging.java
+++ b/common/buildcraft/builders/schematics/SchematicHanging.java
@@ -9,6 +9,7 @@
 package buildcraft.builders.schematics;
 
 import net.minecraft.entity.Entity;
+import net.minecraft.entity.EntityHanging;
 import net.minecraft.init.Items;
 import net.minecraft.item.Item;
 import net.minecraft.item.ItemStack;
@@ -85,4 +86,30 @@ public class SchematicHanging extends SchematicEntity {
 			storedRequirements [0] = new ItemStack(baseItem);
 		}
 	}
+
+	@Override
+	public boolean isAlreadyBuilt(IBuilderContext context, CoordTransformation transform) {
+		Position newPosition = new Position (cpt.getInteger("TileX"), cpt.getInteger("TileY"), cpt.getInteger("TileZ"));
+		newPosition = transform.translate(newPosition);
+
+		int dir = cpt.getInteger("Direction");
+
+		for (Object o : context.world().loadedEntityList) {
+			Entity e = (Entity) o;
+
+			if (e instanceof EntityHanging) {
+				EntityHanging h = (EntityHanging) e;
+				Position existingPositon = new Position(h.field_146063_b, h.field_146064_c, h.field_146062_d);
+
+				System.out.println ("EXPECTED POS" + newPosition + ", found " + existingPositon);
+				System.out.println ("EXPECTED DIR" + dir + ", found " + ((EntityHanging) e).hangingDirection);
+
+				if (existingPositon.isClose(newPosition, 0.1F) && dir == ((EntityHanging) e).hangingDirection) {
+					return true;
+				}
+			}
+		}
+
+		return false;
+	}
 }
diff --git a/common/buildcraft/builders/schematics/SchematicIgnore.java b/common/buildcraft/builders/schematics/SchematicIgnore.java
index d4d274ba..eb04c73f 100644
--- a/common/buildcraft/builders/schematics/SchematicIgnore.java
+++ b/common/buildcraft/builders/schematics/SchematicIgnore.java
@@ -22,7 +22,7 @@ public class SchematicIgnore extends SchematicBlock {
 	}
 
 	@Override
-	public boolean isValid(IBuilderContext context, int x, int y, int z) {
+	public boolean isAlreadyBuilt(IBuilderContext context, int x, int y, int z) {
 		return true;
 	}
 
diff --git a/common/buildcraft/builders/schematics/SchematicIgnoreMeta.java b/common/buildcraft/builders/schematics/SchematicIgnoreMeta.java
index b61c85d9..b3014543 100644
--- a/common/buildcraft/builders/schematics/SchematicIgnoreMeta.java
+++ b/common/buildcraft/builders/schematics/SchematicIgnoreMeta.java
@@ -22,7 +22,7 @@ public class SchematicIgnoreMeta extends SchematicBlock {
 	}
 
 	@Override
-	public boolean isValid(IBuilderContext context, int x, int y, int z) {
+	public boolean isAlreadyBuilt(IBuilderContext context, int x, int y, int z) {
 		return block == context.world().getBlock(x, y, z);
 	}
 }
diff --git a/common/buildcraft/builders/schematics/SchematicMinecart.java b/common/buildcraft/builders/schematics/SchematicMinecart.java
index 2e609b38..a7797b36 100755
--- a/common/buildcraft/builders/schematics/SchematicMinecart.java
+++ b/common/buildcraft/builders/schematics/SchematicMinecart.java
@@ -9,6 +9,7 @@
 package buildcraft.builders.schematics;
 
 import net.minecraft.entity.Entity;
+import net.minecraft.entity.item.EntityMinecart;
 import net.minecraft.item.Item;
 import net.minecraft.item.ItemStack;
 import net.minecraft.nbt.NBTTagList;
@@ -51,4 +52,32 @@ public class SchematicMinecart extends SchematicEntity {
 		storedRequirements = new ItemStack [1];
 		storedRequirements [0] = new ItemStack(baseItem);
 	}
+
+	@Override
+	public boolean isAlreadyBuilt(IBuilderContext context, CoordTransformation transform) {
+		NBTTagList nbttaglist = cpt.getTagList("Pos", 6);
+		Position newPosition = new Position(nbttaglist.func_150309_d(0),
+				nbttaglist.func_150309_d(1), nbttaglist.func_150309_d(2));
+
+		newPosition.x += 0.5;
+		newPosition.z += 0.5;
+
+		newPosition = transform.translate(newPosition);
+
+		for (Object o : context.world().loadedEntityList) {
+			Entity e = (Entity) o;
+
+			Position existingPositon = new Position(e.posX, e.posY, e.posZ);
+
+			if (e instanceof EntityMinecart) {
+				System.out.println ("found " + existingPositon + ", should be " + newPosition);
+				if (existingPositon.isClose(newPosition, 0.1F)) {
+					return true;
+				}
+			}
+		}
+
+		return false;
+	}
+
 }
diff --git a/common/buildcraft/builders/schematics/SchematicPortal.java b/common/buildcraft/builders/schematics/SchematicPortal.java
index aa75ce49..77743114 100755
--- a/common/buildcraft/builders/schematics/SchematicPortal.java
+++ b/common/buildcraft/builders/schematics/SchematicPortal.java
@@ -27,7 +27,7 @@ public class SchematicPortal extends SchematicBlock {
 	}
 
 	@Override
-	public boolean isValid(IBuilderContext context, int x, int y, int z) {
+	public boolean isAlreadyBuilt(IBuilderContext context, int x, int y, int z) {
 		return true;
 	}
 
diff --git a/common/buildcraft/builders/schematics/SchematicPumpkin.java b/common/buildcraft/builders/schematics/SchematicPumpkin.java
index 48064c66..f5f06c18 100644
--- a/common/buildcraft/builders/schematics/SchematicPumpkin.java
+++ b/common/buildcraft/builders/schematics/SchematicPumpkin.java
@@ -22,7 +22,7 @@ public class SchematicPumpkin extends SchematicBlock {
 	}
 
 	@Override
-	public boolean isValid(IBuilderContext context, int x, int y, int z) {
+	public boolean isAlreadyBuilt(IBuilderContext context, int x, int y, int z) {
 		return block == context.world().getBlock(x, y, z);
 	}
 
diff --git a/common/buildcraft/builders/schematics/SchematicRail.java b/common/buildcraft/builders/schematics/SchematicRail.java
index 5f5bf76e..3530f9a0 100755
--- a/common/buildcraft/builders/schematics/SchematicRail.java
+++ b/common/buildcraft/builders/schematics/SchematicRail.java
@@ -60,7 +60,7 @@ public class SchematicRail extends SchematicBlock {
 	}
 
 	@Override
-	public boolean isValid(IBuilderContext context, int x, int y, int z) {
+	public boolean isAlreadyBuilt(IBuilderContext context, int x, int y, int z) {
 		return block == context.world().getBlock(x, y, z);
 	}
 
diff --git a/common/buildcraft/builders/schematics/SchematicRotateMeta.java b/common/buildcraft/builders/schematics/SchematicRotateMeta.java
index 07fafde2..1a4b3674 100644
--- a/common/buildcraft/builders/schematics/SchematicRotateMeta.java
+++ b/common/buildcraft/builders/schematics/SchematicRotateMeta.java
@@ -35,7 +35,7 @@ public class SchematicRotateMeta extends SchematicTile {
 	}
 
 	@Override
-	public boolean isValid(IBuilderContext context, int x, int y, int z) {
+	public boolean isAlreadyBuilt(IBuilderContext context, int x, int y, int z) {
 		return block == context.world().getBlock(x, y, z);
 	}
 
diff --git a/common/buildcraft/builders/schematics/SchematicSeeds.java b/common/buildcraft/builders/schematics/SchematicSeeds.java
index 2a591c56..68b6c703 100755
--- a/common/buildcraft/builders/schematics/SchematicSeeds.java
+++ b/common/buildcraft/builders/schematics/SchematicSeeds.java
@@ -34,7 +34,7 @@ public class SchematicSeeds extends SchematicBlock {
 	}
 
 	@Override
-	public boolean isValid(IBuilderContext context, int x, int y, int z) {
+	public boolean isAlreadyBuilt(IBuilderContext context, int x, int y, int z) {
 		return context.world().getBlock(x, y, z) == block;
 	}
 }
diff --git a/common/buildcraft/builders/schematics/SchematicStairs.java b/common/buildcraft/builders/schematics/SchematicStairs.java
index e2f613e4..359a5a46 100644
--- a/common/buildcraft/builders/schematics/SchematicStairs.java
+++ b/common/buildcraft/builders/schematics/SchematicStairs.java
@@ -22,7 +22,7 @@ public class SchematicStairs extends SchematicBlock {
 	}
 
 	@Override
-	public boolean isValid(IBuilderContext context, int x, int y, int z) {
+	public boolean isAlreadyBuilt(IBuilderContext context, int x, int y, int z) {
 		return block == context.world().getBlock(x, y, z);
 	}
 
diff --git a/common/buildcraft/builders/schematics/SchematicStone.java b/common/buildcraft/builders/schematics/SchematicStone.java
index 7454664a..a0f29d6c 100755
--- a/common/buildcraft/builders/schematics/SchematicStone.java
+++ b/common/buildcraft/builders/schematics/SchematicStone.java
@@ -29,7 +29,7 @@ public class SchematicStone extends SchematicBlock {
 	}
 
 	@Override
-	public boolean isValid(IBuilderContext context, int x, int y, int z) {
+	public boolean isAlreadyBuilt(IBuilderContext context, int x, int y, int z) {
 		Block block = context.world().getBlock(x, y, z);
 
 		return block == Blocks.stone;
diff --git a/common/buildcraft/core/blueprints/BptBuilderBlueprint.java b/common/buildcraft/core/blueprints/BptBuilderBlueprint.java
index a902e691..7db7b96a 100644
--- a/common/buildcraft/core/blueprints/BptBuilderBlueprint.java
+++ b/common/buildcraft/core/blueprints/BptBuilderBlueprint.java
@@ -163,8 +163,7 @@ public class BptBuilderBlueprint extends BptBuilderBase {
 
 			try {
 				getNext = !slot.schematic.ignoreBuilding()
-						&& !slot.schematic.isValid(context, slot.x, slot.y,
-								slot.z);
+						&& !slot.isAlreadyBuilt(context);
 			} catch (Throwable t) {
 				// Defensive code against errors in implementers
 				t.printStackTrace();
@@ -207,15 +206,19 @@ public class BptBuilderBlueprint extends BptBuilderBase {
 			TileAbstractBuilder builder, LinkedList<BuildingSlotEntity> list) {
 		Iterator<BuildingSlotEntity> it = list.iterator();
 
-		while (iterator.hasNext()) {
+		while (it.hasNext()) {
 			BuildingSlotEntity slot = it.next();
 
-			if (checkRequirements(builder, slot.schematic)) {
-				useRequirements(builder, slot);
+			if (slot.isAlreadyBuilt(context)) {
+				it.remove();
+			} else {
+				if (checkRequirements(builder, slot.schematic)) {
+					useRequirements(builder, slot);
 
-				iterator.remove();
-				postProcessing.add(slot);
-				return slot;
+					it.remove();
+					postProcessing.add(slot);
+					return slot;
+				}
 			}
 		}
 
diff --git a/common/buildcraft/core/blueprints/BuildingSlot.java b/common/buildcraft/core/blueprints/BuildingSlot.java
index 74dcc448..fd141166 100755
--- a/common/buildcraft/core/blueprints/BuildingSlot.java
+++ b/common/buildcraft/core/blueprints/BuildingSlot.java
@@ -45,5 +45,7 @@ public abstract class BuildingSlot {
 		stackConsumed.add (stack);
 	}
 
+	public abstract boolean isAlreadyBuilt (IBuilderContext context);
+
 	public abstract Schematic getSchematic ();
 }
diff --git a/common/buildcraft/core/blueprints/BuildingSlotBlock.java b/common/buildcraft/core/blueprints/BuildingSlotBlock.java
index d92e2b9d..f1dcd748 100755
--- a/common/buildcraft/core/blueprints/BuildingSlotBlock.java
+++ b/common/buildcraft/core/blueprints/BuildingSlotBlock.java
@@ -40,7 +40,7 @@ public class BuildingSlotBlock extends BuildingSlot implements Comparable<Buildi
 	@Override
 	public void writeToWorld(IBuilderContext context) {
 		if (mode == Mode.ClearIfInvalid) {
-			if (!getSchematic().isValid(context, x, y, z)) {
+			if (!getSchematic().isAlreadyBuilt(context, x, y, z)) {
 				context.world().setBlockToAir(x, y, z);
 			}
 		} else {
@@ -119,4 +119,9 @@ public class BuildingSlotBlock extends BuildingSlot implements Comparable<Buildi
 	public void writeCompleted (IBuilderContext context, double complete) {
 		getSchematic().writeCompleted(context, x, y, z, complete);
 	}
+
+	@Override
+	public boolean isAlreadyBuilt(IBuilderContext context) {
+		return schematic.isAlreadyBuilt(context, x, y, z);
+	}
 }
diff --git a/common/buildcraft/core/blueprints/BuildingSlotEntity.java b/common/buildcraft/core/blueprints/BuildingSlotEntity.java
index 78763dbb..67852896 100755
--- a/common/buildcraft/core/blueprints/BuildingSlotEntity.java
+++ b/common/buildcraft/core/blueprints/BuildingSlotEntity.java
@@ -32,6 +32,7 @@ public class BuildingSlotEntity extends BuildingSlot {
 		NBTTagList nbttaglist = schematic.cpt.getTagList("Pos", 6);
 		Position pos = new Position(nbttaglist.func_150309_d(0),
 				nbttaglist.func_150309_d(1), nbttaglist.func_150309_d(2));
+
 		pos = transform.translate(pos);
 
 		return pos;
@@ -52,4 +53,9 @@ public class BuildingSlotEntity extends BuildingSlot {
 	public SchematicEntity getSchematic() {
 		return schematic;
 	}
+
+	@Override
+	public boolean isAlreadyBuilt(IBuilderContext context) {
+		return schematic.isAlreadyBuilt(context, transform);
+	}
 }
diff --git a/common/buildcraft/transport/blueprints/SchematicPipe.java b/common/buildcraft/transport/blueprints/SchematicPipe.java
index 1e6f4c65..25474d1f 100644
--- a/common/buildcraft/transport/blueprints/SchematicPipe.java
+++ b/common/buildcraft/transport/blueprints/SchematicPipe.java
@@ -28,7 +28,7 @@ import buildcraft.transport.TileGenericPipe.SideProperties;
 public class SchematicPipe extends SchematicTile {
 
 	@Override
-	public boolean isValid(IBuilderContext context, int x, int y, int z) {
+	public boolean isAlreadyBuilt(IBuilderContext context, int x, int y, int z) {
 		Pipe pipe = BlockGenericPipe.getPipe(context.world(), x, y, z);
 
 		if (BlockGenericPipe.isValid(pipe)) {