diff --git a/data/json/mapgen/basecamps/expansion/modular_garage/version_2/modular_garage_common.json b/data/json/mapgen/basecamps/expansion/modular_garage/version_2/modular_garage_common.json
index 051a22bef9d42..70b6137b20160 100644
--- a/data/json/mapgen/basecamps/expansion/modular_garage/version_2/modular_garage_common.json
+++ b/data/json/mapgen/basecamps/expansion/modular_garage/version_2/modular_garage_common.json
@@ -74,16 +74,37 @@
       "palettes": [ "fbmg_2_common_palette" ]
     }
   },
+  {
+    "type": "mapgen",
+    "method": "json",
+    "nested_mapgen_id": "fbmg_2_3_roof",
+    "object": {
+      "mapgensize": [ 8, 8 ],
+      "rows": [
+        "rrrrrrrr",
+        "rrrrrrrr",
+        "rrrrrrrr",
+        "rrrrrrrr",
+        "rrrrrrrr",
+        "rrrrrrrr",
+        "        ",
+        "        "
+      ],
+      "palettes": [ "fbmg_2_common_palette" ]
+    }
+  },
   {
     "type": "mapgen",
     "update_mapgen_id": "fbmg_2_3",
     "method": "json",
-    "object": { "place_nested": [ { "chunks": [ "fbmg_2_3" ], "x": 6, "y": 16 } ] }
+    "object": {
+      "place_nested": [ { "chunks": [ "fbmg_2_3" ], "x": 6, "y": 16, "z": 0 }, { "chunks": [ "fbmg_2_3_roof" ], "x": 6, "y": 16, "z": 1 } ]
+    }
   },
   {
     "type": "mapgen",
     "method": "json",
-    "nested_mapgen_id": "fbmg_2_6",
+    "nested_mapgen_id": "fbmg_2_6_9",
     "object": {
       "mapgensize": [ 8, 8 ],
       "rows": [
@@ -100,11 +121,35 @@
       "palettes": [ "fbmg_2_common_palette" ]
     }
   },
+  {
+    "type": "mapgen",
+    "method": "json",
+    "nested_mapgen_id": "fbmg_2_6_9_roof",
+    "object": {
+      "mapgensize": [ 8, 8 ],
+      "rows": [
+        "rrrrrrrr",
+        "rrrrrrrr",
+        "rrrrrrrr",
+        "rrrrrrrr",
+        "rrrrrrrr",
+        "        ",
+        "        ",
+        "        "
+      ],
+      "palettes": [ "fbmg_2_common_palette" ]
+    }
+  },
   {
     "type": "mapgen",
     "update_mapgen_id": "fbmg_2_6",
     "method": "json",
-    "object": { "place_nested": [ { "chunks": [ "fbmg_2_6" ], "x": 6, "y": 11 } ] }
+    "object": {
+      "place_nested": [
+        { "chunks": [ "fbmg_2_6_9" ], "x": 6, "y": 11, "z": 0 },
+        { "chunks": [ "fbmg_2_6_9_roof" ], "x": 6, "y": 11, "z": 1 }
+      ]
+    }
   },
   {
     "type": "mapgen",
@@ -122,30 +167,12 @@
   },
   {
     "type": "mapgen",
+    "update_mapgen_id": "fbmg_2_9",
     "method": "json",
-    "nested_mapgen_id": "fbmg_2_9",
     "object": {
-      "mapgensize": [ 8, 8 ],
-      "rows": [
-        ",,,,,,,,",
-        ",,,,,,,,",
-        ",,,,,,,,",
-        ",,,,,,,,",
-        ",,,,,,,,",
-        "        ",
-        "        ",
-        "        "
-      ],
-      "flags": [ "ALLOW_TERRAIN_UNDER_OTHER_DATA" ],
-      "palettes": [ "fbmg_2_common_palette" ]
+      "place_nested": [ { "chunks": [ "fbmg_2_6_9" ], "x": 6, "y": 6, "z": 0 }, { "chunks": [ "fbmg_2_6_9_roof" ], "x": 6, "y": 6, "z": 1 } ]
     }
   },
-  {
-    "type": "mapgen",
-    "update_mapgen_id": "fbmg_2_9",
-    "method": "json",
-    "object": { "place_nested": [ { "chunks": [ "fbmg_2_9" ], "x": 6, "y": 6 } ] }
-  },
   {
     "type": "mapgen",
     "update_mapgen_id": "fbmg_2_gate_3",
@@ -180,11 +207,32 @@
       "palettes": [ "fbmg_2_common_palette" ]
     }
   },
+  {
+    "type": "mapgen",
+    "method": "json",
+    "nested_mapgen_id": "fbmg_2_12_roof",
+    "object": {
+      "mapgensize": [ 8, 8 ],
+      "rows": [
+        "rrrrrrrr",
+        "rrrrrrrr",
+        "rrrrrrrr",
+        "rrrrrrrr",
+        "        ",
+        "        ",
+        "        ",
+        "        "
+      ],
+      "palettes": [ "fbmg_2_common_palette" ]
+    }
+  },
   {
     "type": "mapgen",
     "update_mapgen_id": "fbmg_2_12",
     "method": "json",
-    "object": { "place_nested": [ { "chunks": [ "fbmg_2_12" ], "x": 6, "y": 2 } ] }
+    "object": {
+      "place_nested": [ { "chunks": [ "fbmg_2_12" ], "x": 6, "y": 2, "z": 0 }, { "chunks": [ "fbmg_2_12_roof" ], "x": 6, "y": 2, "z": 1 } ]
+    }
   },
   {
     "type": "mapgen",
diff --git a/data/json/mapgen/basecamps/expansion/modular_garage/version_2/modular_garage_construction.json b/data/json/mapgen/basecamps/expansion/modular_garage/version_2/modular_garage_construction.json
index 3d3ce8020b1f0..40a85f86d7720 100644
--- a/data/json/mapgen/basecamps/expansion/modular_garage/version_2/modular_garage_construction.json
+++ b/data/json/mapgen/basecamps/expansion/modular_garage/version_2/modular_garage_construction.json
@@ -36,11 +36,34 @@
       "palettes": [ { "param": "fbmg_2_construction_palette" } ]
     }
   },
+  {
+    "type": "mapgen",
+    "method": "json",
+    "nested_mapgen_id": "fbmg_2_1_roof_construction",
+    "object": {
+      "mapgensize": [ 7, 7 ],
+      "rows": [
+        "rrrrrr ",
+        "rrrrrr ",
+        "rrrrrr ",
+        "rrrrrr ",
+        "rrrrrr ",
+        "rrrrrr ",
+        "rr     "
+      ],
+      "palettes": [ "fbmg_2_common_palette" ]
+    }
+  },
   {
     "type": "mapgen",
     "update_mapgen_id": "fbmg_2_1_construction",
     "method": "json",
-    "object": { "place_nested": [ { "chunks": [ "fbmg_2_1_construction" ], "x": 0, "y": 16 } ] }
+    "object": {
+      "place_nested": [
+        { "chunks": [ "fbmg_2_1_construction" ], "x": 0, "y": 16, "z": 0 },
+        { "chunks": [ "fbmg_2_1_roof_construction" ], "x": 0, "y": 16, "z": 1 }
+      ]
+    }
   },
   {
     "type": "mapgen",
@@ -79,11 +102,34 @@
       "palettes": [ { "param": "fbmg_2_construction_palette" } ]
     }
   },
+  {
+    "type": "mapgen",
+    "method": "json",
+    "nested_mapgen_id": "fbmg_2_2_roof_construction",
+    "object": {
+      "mapgensize": [ 7, 7 ],
+      "rows": [
+        "rrrrrr ",
+        "rrrrrr ",
+        "rrrrrr ",
+        "rrrrrr ",
+        "rrrrrr ",
+        "rrrrrr ",
+        "    rr "
+      ],
+      "palettes": [ "fbmg_2_common_palette" ]
+    }
+  },
   {
     "type": "mapgen",
     "update_mapgen_id": "fbmg_2_2_construction",
     "method": "json",
-    "object": { "place_nested": [ { "chunks": [ "fbmg_2_2_construction" ], "x": 14, "y": 16 } ] }
+    "object": {
+      "place_nested": [
+        { "chunks": [ "fbmg_2_2_construction" ], "x": 14, "y": 16, "z": 0 },
+        { "chunks": [ "fbmg_2_2_roof_construction" ], "x": 14, "y": 16, "z": 1 }
+      ]
+    }
   },
   {
     "type": "mapgen",
@@ -120,6 +166,22 @@
       "palettes": [ { "param": "fbmg_2_construction_palette" } ]
     }
   },
+  {
+    "type": "mapgen",
+    "method": "json",
+    "nested_mapgen_id": "fbmg_2_wall_1_3_roof_construction",
+    "object": {
+      "mapgensize": [ 5, 5 ],
+      "rows": [
+        "     ",
+        "     ",
+        "     ",
+        "     ",
+        "rrrrr"
+      ],
+      "palettes": [ "fbmg_2_common_palette" ]
+    }
+  },
   {
     "type": "mapgen",
     "method": "json",
@@ -156,6 +218,23 @@
       "palettes": [ { "param": "fbmg_2_construction_palette" } ]
     }
   },
+  {
+    "type": "mapgen",
+    "method": "json",
+    "nested_mapgen_id": "fbmg_2_wall_2_roof_construction",
+    "object": {
+      "mapgensize": [ 6, 6 ],
+      "rows": [
+        "      ",
+        "      ",
+        "      ",
+        "      ",
+        "      ",
+        "rrrrrr"
+      ],
+      "palettes": [ "fbmg_2_common_palette" ]
+    }
+  },
   {
     "type": "mapgen",
     "method": "json",
@@ -197,9 +276,12 @@
     "method": "json",
     "object": {
       "place_nested": [
-        { "chunks": [ "fbmg_2_wall_1_construction" ], "x": 2, "y": 18 },
-        { "chunks": [ "fbmg_2_wall_2_construction" ], "x": 7, "y": 17 },
-        { "chunks": [ "fbmg_2_wall_3_construction" ], "x": 13, "y": 18 }
+        { "chunks": [ "fbmg_2_wall_1_construction" ], "x": 2, "y": 18, "z": 0 },
+        { "chunks": [ "fbmg_2_wall_1_3_roof_construction" ], "x": 2, "y": 18, "z": 1 },
+        { "chunks": [ "fbmg_2_wall_2_construction" ], "x": 7, "y": 17, "z": 0 },
+        { "chunks": [ "fbmg_2_wall_2_roof_construction" ], "x": 7, "y": 17, "z": 1 },
+        { "chunks": [ "fbmg_2_wall_3_construction" ], "x": 13, "y": 18, "z": 0 },
+        { "chunks": [ "fbmg_2_wall_1_3_roof_construction" ], "x": 13, "y": 18, "z": 1 }
       ]
     }
   },
@@ -239,11 +321,33 @@
       "palettes": [ { "param": "fbmg_2_construction_palette" } ]
     }
   },
+  {
+    "type": "mapgen",
+    "method": "json",
+    "nested_mapgen_id": "fbmg_2_4_roof_construction",
+    "object": {
+      "mapgensize": [ 6, 6 ],
+      "rows": [
+        "r     ",
+        "rrrrrr",
+        "rrrrrr",
+        "rrrrrr",
+        "rrrrrr",
+        "rrrrrr"
+      ],
+      "palettes": [ "fbmg_2_common_palette" ]
+    }
+  },
   {
     "type": "mapgen",
     "update_mapgen_id": "fbmg_2_4_construction",
     "method": "json",
-    "object": { "place_nested": [ { "chunks": [ "fbmg_2_4_construction" ], "x": 0, "y": 10 } ] }
+    "object": {
+      "place_nested": [
+        { "chunks": [ "fbmg_2_4_construction" ], "x": 0, "y": 10, "z": 0 },
+        { "chunks": [ "fbmg_2_4_roof_construction" ], "x": 0, "y": 10, "z": 1 }
+      ]
+    }
   },
   {
     "type": "mapgen",
@@ -281,11 +385,33 @@
       "palettes": [ { "param": "fbmg_2_construction_palette" } ]
     }
   },
+  {
+    "type": "mapgen",
+    "method": "json",
+    "nested_mapgen_id": "fbmg_2_5_roof_construction",
+    "object": {
+      "mapgensize": [ 6, 6 ],
+      "rows": [
+        "     r",
+        "rrrrrr",
+        "rrrrrr",
+        "rrrrrr",
+        "rrrrrr",
+        "rrrrrr"
+      ],
+      "palettes": [ "fbmg_2_common_palette" ]
+    }
+  },
   {
     "type": "mapgen",
     "update_mapgen_id": "fbmg_2_5_construction",
     "method": "json",
-    "object": { "place_nested": [ { "chunks": [ "fbmg_2_5_construction" ], "x": 14, "y": 10 } ] }
+    "object": {
+      "place_nested": [
+        { "chunks": [ "fbmg_2_5_construction" ], "x": 14, "y": 10, "z": 0 },
+        { "chunks": [ "fbmg_2_5_roof_construction" ], "x": 14, "y": 10, "z": 1 }
+      ]
+    }
   },
   {
     "type": "mapgen",
@@ -323,11 +449,33 @@
       "palettes": [ { "param": "fbmg_2_construction_palette" } ]
     }
   },
+  {
+    "type": "mapgen",
+    "method": "json",
+    "nested_mapgen_id": "fbmg_2_7_roof_construction",
+    "object": {
+      "mapgensize": [ 6, 6 ],
+      "rows": [
+        "r     ",
+        "rrrrrr",
+        "rrrrrr",
+        "rrrrrr",
+        "rrrrrr",
+        " rrrrr"
+      ],
+      "palettes": [ "fbmg_2_common_palette" ]
+    }
+  },
   {
     "type": "mapgen",
     "update_mapgen_id": "fbmg_2_7_construction",
     "method": "json",
-    "object": { "place_nested": [ { "chunks": [ "fbmg_2_7_construction" ], "x": 0, "y": 5 } ] }
+    "object": {
+      "place_nested": [
+        { "chunks": [ "fbmg_2_7_construction" ], "x": 0, "y": 5, "z": 0 },
+        { "chunks": [ "fbmg_2_7_roof_construction" ], "x": 0, "y": 5, "z": 1 }
+      ]
+    }
   },
   {
     "type": "mapgen",
@@ -365,11 +513,33 @@
       "palettes": [ { "param": "fbmg_2_construction_palette" } ]
     }
   },
+  {
+    "type": "mapgen",
+    "method": "json",
+    "nested_mapgen_id": "fbmg_2_8_roof_construction",
+    "object": {
+      "mapgensize": [ 6, 6 ],
+      "rows": [
+        "     r",
+        "rrrrrr",
+        "rrrrrr",
+        "rrrrrr",
+        "rrrrrr",
+        "rrrrr "
+      ],
+      "palettes": [ "fbmg_2_common_palette" ]
+    }
+  },
   {
     "type": "mapgen",
     "update_mapgen_id": "fbmg_2_8_construction",
     "method": "json",
-    "object": { "place_nested": [ { "chunks": [ "fbmg_2_8_construction" ], "x": 14, "y": 5 } ] }
+    "object": {
+      "place_nested": [
+        { "chunks": [ "fbmg_2_8_construction" ], "x": 14, "y": 5, "z": 0 },
+        { "chunks": [ "fbmg_2_8_roof_construction" ], "x": 14, "y": 5, "z": 1 }
+      ]
+    }
   },
   {
     "type": "mapgen",
@@ -407,11 +577,33 @@
       "palettes": [ { "param": "fbmg_2_construction_palette" } ]
     }
   },
+  {
+    "type": "mapgen",
+    "method": "json",
+    "nested_mapgen_id": "fbmg_2_10_roof_construction",
+    "object": {
+      "mapgensize": [ 6, 6 ],
+      "rows": [
+        "r     ",
+        "rrrrrr",
+        "rrrrrr",
+        "rrrrrr",
+        " rrrrr",
+        "      "
+      ],
+      "palettes": [ "fbmg_2_common_palette" ]
+    }
+  },
   {
     "type": "mapgen",
     "update_mapgen_id": "fbmg_2_10_construction",
     "method": "json",
-    "object": { "place_nested": [ { "chunks": [ "fbmg_2_10_construction" ], "x": 0, "y": 1 } ] }
+    "object": {
+      "place_nested": [
+        { "chunks": [ "fbmg_2_10_construction" ], "x": 0, "y": 1, "z": 0 },
+        { "chunks": [ "fbmg_2_10_roof_construction" ], "x": 0, "y": 1, "z": 1 }
+      ]
+    }
   },
   {
     "type": "mapgen",
@@ -449,10 +641,32 @@
       "palettes": [ { "param": "fbmg_2_construction_palette" } ]
     }
   },
+  {
+    "type": "mapgen",
+    "method": "json",
+    "nested_mapgen_id": "fbmg_2_11_roof_construction",
+    "object": {
+      "mapgensize": [ 6, 6 ],
+      "rows": [
+        "     r",
+        "rrrrrr",
+        "rrrrrr",
+        "rrrrrr",
+        "rrrrr ",
+        "      "
+      ],
+      "palettes": [ "fbmg_2_common_palette" ]
+    }
+  },
   {
     "type": "mapgen",
     "update_mapgen_id": "fbmg_2_11_construction",
     "method": "json",
-    "object": { "place_nested": [ { "chunks": [ "fbmg_2_11_construction" ], "x": 14, "y": 1 } ] }
+    "object": {
+      "place_nested": [
+        { "chunks": [ "fbmg_2_11_construction" ], "x": 14, "y": 1, "z": 0 },
+        { "chunks": [ "fbmg_2_11_roof_construction" ], "x": 14, "y": 1, "z": 1 }
+      ]
+    }
   }
 ]
diff --git a/data/json/mapgen/basecamps/expansion/modular_garage/version_2/modular_garage_palettes.json b/data/json/mapgen/basecamps/expansion/modular_garage/version_2/modular_garage_palettes.json
index 274a13e0f2fb0..1dfa97a1ed351 100644
--- a/data/json/mapgen/basecamps/expansion/modular_garage/version_2/modular_garage_palettes.json
+++ b/data/json/mapgen/basecamps/expansion/modular_garage/version_2/modular_garage_palettes.json
@@ -2,8 +2,15 @@
   {
     "type": "palette",
     "id": "fbmg_2_common_palette",
-    "terrain": { "p": "t_palisade", "P": "t_palisade_pulley", "G": "t_palisade_gate", ";": "t_dirt", ",": "t_dirtfloor" },
-    "furniture": { "c": "f_counter", "I": "f_rack", ";": "f_clear" }
+    "terrain": {
+      ",": "t_dirtfloor",
+      ";": "t_dirt",
+      "G": "t_palisade_gate",
+      "p": "t_palisade",
+      "P": "t_palisade_pulley",
+      "r": "t_shingle_flat_roof"
+    },
+    "furniture": { ";": "f_clear", "c": "f_counter", "I": "f_rack" }
   },
   {
     "type": "palette",