diff --git a/core/src/io/anuke/mindustry/ai/WaveSpawner.java b/core/src/io/anuke/mindustry/ai/WaveSpawner.java
index 573edec198..ed25754b93 100644
--- a/core/src/io/anuke/mindustry/ai/WaveSpawner.java
+++ b/core/src/io/anuke/mindustry/ai/WaveSpawner.java
@@ -180,7 +180,13 @@ public class WaveSpawner{
     }
 
     private void setQuad(int quadx, int quady, boolean valid){
-        if(quadrants == null) quadrants = new GridBits(quadWidth(), quadHeight());
+        if(quadrants == null){
+            quadrants = new GridBits(quadWidth(), quadHeight());
+        }
+
+        if(!Mathf.inBounds(quadx, quady, quadWidth(), quadHeight())){
+            return;
+        }
 
         quadrants.set(quadx, quady, valid);
     }
diff --git a/core/src/io/anuke/mindustry/world/Build.java b/core/src/io/anuke/mindustry/world/Build.java
index 0beab97250..addaa507ea 100644
--- a/core/src/io/anuke/mindustry/world/Build.java
+++ b/core/src/io/anuke/mindustry/world/Build.java
@@ -1,5 +1,6 @@
 package io.anuke.mindustry.world;
 
+import com.badlogic.gdx.math.GridPoint2;
 import com.badlogic.gdx.math.Rectangle;
 import com.badlogic.gdx.math.Vector2;
 import io.anuke.mindustry.content.blocks.Blocks;
@@ -10,6 +11,7 @@ import io.anuke.mindustry.type.Recipe;
 import io.anuke.mindustry.world.blocks.BuildBlock.BuildEntity;
 import io.anuke.ucore.core.Events;
 import io.anuke.ucore.entities.Entities;
+import io.anuke.ucore.util.Geometry;
 
 import static io.anuke.mindustry.Vars.*;
 
@@ -154,6 +156,10 @@ public class Build{
                 return true;
             }
 
+            if(!contactsGround(tile.x, tile.y, type)){
+                return false;
+            }
+
             if(!type.canPlaceOn(tile)){
                 return false;
             }
@@ -173,6 +179,7 @@ public class Build{
             return true;
         }else{
             return (tile.getTeam() == Team.none || tile.getTeam() == team)
+                    && contactsGround(tile.x, tile.y, type)
                     && (!tile.floor().isLiquid || type.floating)
                     && tile.floor().placeableOn && !tile.hasCliffs()
                     && ((type.canReplace(tile.block())
@@ -181,6 +188,27 @@ public class Build{
         }
     }
 
+    private static boolean contactsGround(int x, int y, Block block){
+        if(block.isMultiblock()){
+            for(GridPoint2 point : Edges.getInsideEdges(block.size)){
+                Tile tile = world.tile(x + point.x, y + point.y);
+                if(tile != null && !tile.floor().isLiquid) return true;
+            }
+
+            for(GridPoint2 point : Edges.getEdges(block.size)){
+                Tile tile = world.tile(x + point.x, y + point.y);
+                if(tile != null && !tile.floor().isLiquid) return true;
+            }
+        }else{
+            for(GridPoint2 point : Geometry.d4){
+                Tile tile = world.tile(x + point.x, y + point.y);
+                if(tile != null && !tile.floor().isLiquid) return true;
+            }
+            return world.tile(x, y) != null && !world.tile(x, y).floor().isLiquid;
+        }
+        return false;
+    }
+
     /**Returns whether the tile at this position is breakable by this team*/
     public static boolean validBreak(Team team, int x, int y){
         Tile tile = world.tile(x, y);
diff --git a/core/src/io/anuke/mindustry/world/blocks/distribution/Conduit.java b/core/src/io/anuke/mindustry/world/blocks/distribution/Conduit.java
index 2061950eb1..826d9d52dd 100644
--- a/core/src/io/anuke/mindustry/world/blocks/distribution/Conduit.java
+++ b/core/src/io/anuke/mindustry/world/blocks/distribution/Conduit.java
@@ -23,6 +23,7 @@ public class Conduit extends LiquidBlock{
         super(name);
         rotate = true;
         solid = false;
+        floating = true;
     }
 
     @Override