Brick by Brick – Extra Buildings (Mod)
A mod for Brick by Brick: Tidy Up the Small Town! (Steam). It adds extra buildings to the game from a blueprint –
with real brick slots, holograms, construction sections, a blueprint board, a completion message and a build replay,
just like the original buildings. The main building is a simplified Notre-Dame with 26,462 bricks, with its own
walkable scaffold: 3D preview with brick list and construction sections.
Test buildings: a garage with 191 bricks and a round tower with 311 bricks.
Unofficial fan mod, not made by the game's developers. This repository contains no game files.
All mods and maps
Overview page: michel86ch-ui.github.io/brickbybrick-mod
| Map | More | Download |
|---|
| Notre-Dame: 26,462 bricks in five construction sites, with a walkable scaffold. The first design, with the teething troubles of a first attempt. World slot 4 | 3D preview · screenshots | Extra Buildings 1.2.0 |
| Test buildings: garage (191 bricks), round tower (311 bricks) | pictures below | in the same ZIP |
| Taj Mahal 1.0 — recommended: 40,262 bricks in seven construction sites, on a platform with four minarets. The better build of the two. World slot 3 | 3D preview · screenshot | Extra Buildings 1.2.0 |
Which one to build first
Start with the Taj Mahal. It is the newer map and the better one.
The Notre-Dame came first, and it carries what a first attempt carries. Its brickwork was frozen early, so the
bond is not as clean as it could be, and its scaffold stays standing once the building is done. The Taj Mahal was
generated afterwards with everything learned from it: the bond is laid course by course with a cost function, so
joints rarely sit on top of each other and the corners interlock; every brick is checked to be carried by the ones
below and to not overlap another; the inner scaffold is narrow and disappears the moment the building is
finished, leaving only the ramp; the stair up to the dome has full headroom.
And it plays that way too: a full run takes about 16 hours of laying bricks, and it goes well all the way through.
None of this makes the Notre-Dame a bad build — it is still 26,462 bricks and the showcase looks the part. It is
simply the older design, and it is the one that will show its age first.
Slots: the Taj Mahal is played in world slot 3, the Notre-Dame in world slot 4. Each building lives in its own slot;
start it with its button in the main menu and create a new save in that slot.
Every ZIP contains the same unmodified BepInEx 5.4.23.5, so the mods work together: unzip one after the other into the
game folder and overwrite.
Proof of concept for the Notre-Dame's round parts: the 311-brick round test tower, built to completion in the game.
Notre-Dame in the game
The simplified Notre-Dame with about 26,500 bricks, shown finished in the game with the mod's showcase mode (0.5.0): west
front with bell towers, round choir, spire over the crossing, and inside arcades of pointed arches that carry the upper
walls. More screenshots
Status (2026-10-27, version 1.2.0)
| Feature | Status |
|---|
| Brick slots, holograms, snapping into place | confirmed in game |
| Progress per section, blueprint board counts along | confirmed in game |
| Finished sections (final meshes), "Construction complete" message, build replay | confirmed in game |
| Plinth made of game bricks, own 3D model on the blueprint board (0.2.0) | confirmed in game |
| Mod map without the seven original buildings and their 18,485 bricks, garage in the town center (0.3.0) | confirmed in game |
| "Start Mod Map" / "Back to normal worlds" menu button with automatic restart (0.3.0) | confirmed in game |
| Saving and reloading the mod world | confirmed in game (an older test world reopened with its finished garage) |
| Round parts: 2x1 blocks along a circle (slightly overlapping), tilted pieces, a cone of roof-tile rings without flickering (0.3.1, round test tower with 311 bricks) | confirmed in game |
| Notre-Dame with about 26,500 bricks, 3D preview: loads as five construction sites (0.4.0), shown finished in showcase mode (0.5.0) | confirmed in game, screenshots |
| Notre-Dame: building it brick by brick: bricks snap in, sections finish, skill points are earned (0.5.0) | confirmed in game |
| Notre-Dame: start skill points for a new mod world (0.6.0) | confirmed in game |
| Notre-Dame: aluminium scaffold with landings at every stair corner, clerestory lanes, mobile scaffold unlocked and driving up ramps onto the plinth (1.0.0) | confirmed in game |
| Notre-Dame: a complete build | confirmed in game (26,462 of 26,462 bricks, all five sites) |
| Taj Mahal with about 40,000 bricks in seven construction sites, 3D preview: shown finished in showcase mode, scaffold that goes once the building is complete (1.1.0) | confirmed in game, screenshot |
Mod map: a separate world instead of the main world
An extra building changes the building list of a save; the game then no longer counts that world's run for the
leaderboard. That is why the mod only builds in a world of its own, the mod map (default: world slot 4).
The game loads the town scene once per game start and opens the worlds inside it. The mode therefore applies to the
whole game session:
| Mode | Behavior |
|---|
| normal (default) | The mod does nothing. The mod world is locked, because without the mod the game would drop the extra buildings' bricks when loading it. |
| mod map | The seven original buildings and their bricks are removed, the extra buildings are injected, every world choice in the menu opens the mod world, "MOD-MAP" is shown top left. |
The main menu has a button top left: Start Mod Map in a normal session, Back to normal worlds in a mod-map
session. It saves the mode and restarts the game through Steam.
Placed bricks are saved with their world position. Do not move a site (MoveKey, unbound by default, or X/Z in the config) in a mod world
that already has bricks on it: they would stay behind at the old place. Delete the mod world first.
Installation
- Download BrickByBrick-ExtraBuildings-1.2.0.zip
and unzip everything into the game folder, so that
winhttp.dll sits next to BrickByBrick.exe
(Steam: right-click the game > Manage > Browse local files).
- Start the game. Top left in the main menu: Start Taj Mahal (world 3) or Start Notre-Dame (world 4). The
game restarts.
- Important: the Taj Mahal is played in slot 3, the Notre-Dame in slot 4. Create a new save in that slot; it must
be empty (the mod never opens a slot that holds a normal save as a mod world).
Back to your own worlds: Back to normal worlds in the main menu. A new mod world starts with 20 skill points
(StartSkillPoints in BepInEx\config\michel.brickbybrick.extrabuildings.cfg, 0 = like the base game), and the
mobile scaffold is unlocked (UnlockScaffoldLift): in the base game it comes with the town's house, which the mod
map does not have. The settings file is created at the first game start. The ZIP contains BepInEx 5.4.23.5
(unmodified) and the mod with its blueprints; since 1.2.0 no settings file, so an update keeps yours.
Updating from 1.0.0, 1.1.x or the Taj Mahal beta: your worlds continue (1.0.0 only gains a stair tower inside the
Notre-Dame's scaffold; 1.1.1 only makes the Taj Mahal's ramp steeper; 1.2.0 changes the Taj Mahal's scaffold and
platform colour only). If "Start Taj Mahal" says that slot 3 holds a normal save although you built the Taj Mahal
there: the settings file of the 1.1.x ZIP replaced the list of your mod worlds. Add it in
BepInEx\config\michel.brickbybrick.extrabuildings.cfg: ModWorlds = singleplayer-4,singleplayer-3.
A Notre-Dame world built with 0.6.0 or earlier does not fit the blueprint: start a new save in slot 4.
Uninstall: delete winhttp.dll, doorstop_config.ini, .doorstop_version, changelog.txt,
ExtraBuildings-README.txt and the BepInEx folder in the game folder. The game itself is not modified.
Building
cd mods\ExtraBuildings
dotnet build -c Release -p:DeployToGame=true (copies the DLL + blueprints\*.json into the game)
py tools\gen_garage.py (regenerate the garage blueprint)
py tools\gen_roundtest.py (regenerate the round test tower)
py tools\gen_notredame.py 1.2 (Notre-Dame design, scale 1.2)
py tools\build_preview.py (3D preview page -> docs\notre-dame\index.html)
The project references the DLLs directly from the game folder (adjust GameDir in the .csproj if the game is
installed elsewhere).
How the game builds its buildings
Measured in the game code (Unity 6000.3.6, Mono) and in the scene data:
- Buildings are not in the code but in the scene: 7
ConstructionSites with 18,485 brick slots in total.
- Loose bricks: one
BrickWorldCatalog with exactly 18,485 bricks, GPU-instanced through BrickWorldSource.
- Scene start (
GameSceneInstaller.OnSceneEnterAsync): register the slots -> register the brick catalog ->
apply the save. After that, one ConstructionSceneInstaller per building initializes its site.
- A brick slot is a GameObject with
PlacementSlot + ConstructionSlot and a Hologram child. Slot ID and brick ID
are uint. A brick's pivot is its center, the grid is 0.21 m.
PlacementSlot.placeTrigger is the building's site area: a brick can only be placed while standing inside it.- Every site has a baked topology (
bakedSpecs) that GetBakedSpecs() checks strictly against the slots.
- Once a section is complete, the game shows a combined mesh (
finalVisualRoot) instead of the single bricks.
- The blueprint board shows a single pre-made mesh (
ConstructionBlueprintPreview.modelPrefab).
- Missing bricks or slots do not break loading: bricks from removed slots return to their start position,
unknown bricks are dropped.
- Saves are JSON (EasySave3), their sections Base64-encoded JSON.
