Since 2007, LEGO's modular building line has operated on a beautifully simple premise: every building occupies a 32x32-stud footprint, connects to its neighbors through a standardized sidewalk and Technic pin system, and separates into individual floors for display and play. This standard transformed LEGO city building from a freeform hobby into a structured discipline with real architectural constraints — and constraints, as any designer will tell you, are where creativity thrives.
Designing modular buildings in Stud.io gives you every advantage the physical standard offers plus several it does not. You can test floor separation without risking a collapse. You can clone repetitive elements across an entire facade in seconds. You can align six buildings side by side and check sight lines before committing a single real brick. And you can share your finished design with the global community as a downloadable file, complete with a parts list that anyone can order from BrickLink.
This guide walks through the entire process of building a modular in Stud.io, from setting up your first 32x32 baseplate template to rendering a finished street scene. If you are new to the software, start with the What Is Stud.io overview. If you already know your way around the interface, this is where the real building begins. For a deeper understanding of the physical modular standard and its history, the modular building standards guide covers everything from the original Cafe Corner to the current connection spec.
Every modular building begins with the same foundation: a 32x32-stud baseplate. In Stud.io, open a new project and search the parts palette for "baseplate 32x32" (part #3811). Place it at the origin point of your workspace. This baseplate is your entire building footprint — everything you construct will sit on or above this surface. Color it dark green if you want to match the standard LEGO modular aesthetic, or dark bluish gray if your building fronts directly onto a street without grass.
Before you place a single brick on top of that baseplate, set up your workspace for modular precision. Turn on the grid overlay (View > Grid) and set grid spacing to 1 stud. Enable snapping so every element locks to the grid automatically. This seems basic, but modular buildings demand absolute positional accuracy. A single stud of misalignment on the ground floor propagates upward through every subsequent floor, and when you try to connect your building to a neighbor, that error becomes a gap or an overlap that breaks the entire street.
Now establish the building boundary. The standard modular footprint uses the full 32x32 baseplate, but the actual building structure typically occupies roughly 24 studs deep by 32 studs wide, with the front 8 studs reserved for the sidewalk. Place temporary marker bricks — bright red 1x1 plates work well — at the corners of your building envelope: studs (0,0), (31,0), (31,23), and (0,23) for the building itself, with the remaining strip from row 24 to row 31 as your sidewalk zone. These markers will be removed later but serve as essential guides during construction. For a broader look at how baseplates and modular systems interact, that dedicated guide covers the MILS standard and other foundation approaches.
Save this empty baseplate with markers as a template file. Name it something clear like "Modular-Template-32x32.io" and keep it in a dedicated Stud.io projects folder. Every future modular you design starts from this file, which saves setup time and guarantees consistency across your entire street.
The physical connection between modular buildings uses Technic pins and bricks with holes, positioned at specific points along the shared wall. In Stud.io, replicating this connection system exactly is critical if you ever plan to build your design physically or share it with others who will. The connection points are located on the left and right edges of the baseplate, at standardized positions that have remained consistent across the entire modular line since 2007.
On each side wall of your building, place a 1x2 Technic brick (part #3700) at the baseplate level, positioned so the hole faces outward toward the neighboring building. The standard placement puts these connection bricks at rows 4 and 28 along each side edge — roughly one-eighth of the way in from front and back. A Technic half-pin (part #4274) inserted into the hole creates the male connector that slides into the corresponding hole on the adjacent building. In Stud.io, you can place the pin, rotate it to face outward, and verify alignment by duplicating your building and placing the copy alongside the original.
This is where Stud.io offers a massive advantage over physical building. In real life, testing the connection means building two structures and physically mating them, a process that can reveal alignment errors only after hours of work. In Stud.io, you duplicate the building, mirror it if needed, and slide it into position in seconds. If the Technic holes do not align perfectly, you see the problem immediately and fix it at the source. Test this connection early — do not wait until the building is finished. Place your Technic bricks on the ground floor, duplicate, test the fit, and only then proceed upward. The modular standards reference has the exact pin positions for every official modular set if you want to match a specific release.
The defining feature of modular buildings is floor separability — each story lifts off independently, revealing the interior below. In Stud.io, the way to achieve this cleanly is through submodels. Each floor of your building should be its own submodel within the master project file. This keeps the parts list organized, makes floor separation testing trivial, and allows you to hide individual floors while working on others.
To create a submodel in Stud.io, select all parts belonging to a single floor and choose Edit > Create Submodel (or right-click and select the option from the context menu). Name each submodel descriptively: "Ground Floor," "Second Floor," "Roof Section." The master model then contains references to each submodel, positioned at the correct vertical offset. You can click into any submodel to edit it independently, then return to the master view to see how all floors stack together.
The floor plate — the structural element that forms the ceiling of one floor and the floor of the next — is the most important element in the entire build. It needs to be rigid enough to lift without flexing, which means using overlapping plates in a grid pattern rather than a single layer. The standard approach is two layers of plates with their seams offset, creating a composite floor that resists bending. In Stud.io, build this floor plate as the base element of each submodel (except the ground floor, which sits directly on the baseplate). The floor plate's underside is the ceiling of the floor below, so plan any hanging light fixtures or ceiling details into the bottom of the upper submodel rather than the top of the lower one.
Start your ground floor submodel from the baseplate up. Build the exterior walls first, establishing the facade design, window placement, and doorway positions. Then fill in the interior. Move to the second floor submodel by duplicating the exterior wall structure (since upper floors often share the same footprint and wall positions) and modifying the facade as needed. Repeat for each additional floor. This building techniques guide for Stud.io covers the specific tools and shortcuts that make wall construction faster.
The front 8 studs of the 32x32 baseplate form the sidewalk zone, and this strip is where modular buildings transition from individual structures into a connected street. The sidewalk convention is one of the most important standards in the modular system because it is what creates visual continuity when buildings are placed side by side. Get the sidewalk wrong and even beautifully designed buildings look disconnected.
The standard sidewalk uses light bluish gray tiles (or plates with tiles on top) covering the full 32-stud width and 8-stud depth of the front zone. The surface should be flush — no exposed studs — to represent smooth pavement. Along the front edge (the curb), add a single row of dark bluish gray 1x1 tiles or plates, raised one plate height above the sidewalk surface, to create the curb step-down to the street. This curb line must be continuous across adjacent buildings, which means it must be positioned identically on every modular you design.
Street-level details transform a flat gray strip into a living sidewalk. Add a fire hydrant (built from a 1x1 round brick in red with a 1x1 round plate on top) near one corner. Place a mailbox, a newspaper stand, or a trash can at the curb. Use 1x2 tiles in a darker gray scattered across the sidewalk to suggest repaired sections or staining. A single 2x2 tile in tan near the building entrance implies a welcome mat. Street lamps built from bar elements with 1x1 round plates as lights anchor the sidewalk to the street. Every detail you add at ground level is amplified because this is the zone where the viewer's eye naturally enters the building. For inspiration on how official sets handle these details, the Assembly Square review breaks down one of the finest examples of modular street-level design LEGO has ever produced.
Physical modular buildings have interiors because the floors separate and people look inside. Digital modulars in Stud.io should have interiors for the same reason — they will be seen, either in section renders, in instruction documents, or when someone builds your design physically. An empty shell with detailed exterior walls and bare interior surfaces tells the viewer (and the builder) that the designer ran out of patience. The interior is half the building. Treat it accordingly.
Start each interior by establishing the floor finish. Reddish brown tiles create hardwood. White and black 1x1 tiles in a checkerboard make a classic diner or barbershop floor. Dark tan tiles suggest aged wood. Medium nougat plates with 1x1 round plates scattered on top read as a carpeted surface with furniture indentations. The floor finish sets the character of the room before a single piece of furniture is placed, so choose it deliberately.
Furniture and fixtures should be built at minifig scale, which means a table is 2-3 studs tall, a chair seat is 2 studs high, and a counter is 3 studs. Use SNOT techniques to place tiles on the sides of bricks for cabinet doors and appliance fronts. A kitchen needs a sink (1x2 tile recessed into a counter), a stove (printed or stickered 2x2 tile, or a plain dark gray tile with 1x1 round plates as burners), and shelving (1x4 plates mounted on brackets). A living room needs a couch (bracket-built with plates forming the seat and back), a table, and something on the walls — a 1x2 tile in a contrasting color works as a painting.
The key constraint is the 32-stud depth. With exterior walls consuming 2-3 studs on front and back, and a sidewalk eating 8 studs from the front, your usable interior depth is roughly 20-22 studs. Width is the full 32 studs minus wall thickness on each side, leaving about 28 studs. That is not a lot of space. Every piece of furniture must earn its place. Plan the room layout before building individual items, and do not be afraid to leave some open floor — a crowded room looks worse than a sparse one. If you want to study how much detail fits in a real modular interior, the modular buildings as investments guide discusses several sets whose interior design drove their aftermarket value.
One of Stud.io's most powerful advantages for modular design is the ability to test floor separation without physical risk. In real life, lifting a floor off a modular building is a two-handed operation that can dislodge parts, stress connections, and occasionally send a carefully built wall section tumbling. In Stud.io, you click a submodel, move it upward, and instantly see whether anything is still connected that should not be.
To test floor removal, switch to the master model view where all submodels are assembled. Click on the second-floor submodel and drag it straight up (hold the axis constraint to keep it vertical). If the floor lifts cleanly with all its parts and nothing from the ground floor comes with it, your separation is clean. If parts from the lower floor move with the upper floor, you have a connection that spans the floor boundary — a wall element that extends from one submodel into another, or a floor plate that is accidentally grouped with the wrong submodel.
The most common floor-separation failures are vertical elements that cross the boundary: staircase walls, elevator shafts, and columns that run through multiple floors. In physical builds, these are solved with clip-and-bar connections or simply by making the upper section rest on the lower section by gravity alone, without any interlocking studs. In Stud.io, replicate this by ensuring that vertical elements are split at the floor line and placed in the correct submodel. A column that runs from ground to second floor should be two separate elements: the lower half in the ground floor submodel, the upper half in the second floor submodel, with flat tiles on top of the lower section to allow clean separation.
Test every floor boundary before moving on. It takes seconds in Stud.io and saves hours of redesign later. If you are building a three-story modular with a roof section, you have three separation points to verify: ground-to-second, second-to-third, and third-to-roof. Do all four lifts, confirm clean separation, and only then consider the structure complete.
Modular buildings are full of repetition. A row of windows across a facade. Identical floor plates on every level. Matching balcony railings, repeating brick patterns, symmetric wall sections. Building each instance individually is tedious and error-prone. Stud.io's clone and copy tools turn this repetition from a chore into a strength.
The basic approach is straightforward: select a group of parts (a window assembly, a wall section, a decorative column), copy it (Ctrl+C / Cmd+C), and paste it (Ctrl+V / Cmd+V) into position. Stud.io places the pasted group at the same coordinates as the original, offset by a small amount, so you drag it into the correct position. For elements that repeat at regular intervals — windows across a facade, for example — paste the first copy, measure the offset in studs, then paste additional copies and move each one by the same offset. Precision matters here. A window that is one stud off from the pattern breaks the rhythm of the entire facade.
For more advanced repetition, use Stud.io's submodel system as a cloning mechanism. Build a single window assembly as a submodel, then insert multiple instances of that submodel into the parent model. The advantage is that any change you make to the submodel — swapping the window color, adding a flower box, changing the frame profile — automatically propagates to every instance. This is enormously powerful for facades where you want to experiment with window treatments across all floors simultaneously. Build one, clone many, edit once to update all.
The clone workflow is especially valuable for building techniques that involve complex assemblies. A decorative cornice built from twenty parts is painful to replicate manually but trivial to clone across a 32-stud facade. A baluster railing built from alternating 1x1 rounds and plates can be constructed once and duplicated for every balcony. Think of repetitive elements not as tedium but as efficiency opportunities. The clone tool makes your modular building more consistent and more detailed because it removes the cost of that detail from the building process.
A single modular building is a structure. A row of modular buildings is a street. The transition from one to the other is where the 32-stud standard proves its worth, and Stud.io is the ideal environment to test that transition before committing to physical bricks.
To align multiple modulars, open a new master project and import each building as a submodel. Position the first building with its baseplate origin at (0,0,0). Place the second building at (32,0,0) — exactly 32 studs to the right, with zero gap. The baseplates should touch edge to edge with no overlap. Check the Technic pin connections: the pins extending from Building A's right wall should align perfectly with the holes in Building B's left wall. If they do not, one of the buildings has its connection points at a non-standard position. Fix it in the source file before proceeding.
With two buildings aligned, check the sidewalk continuity. The curb line should flow unbroken from one building to the next. The sidewalk surface height should match exactly — a single plate of difference creates a visible step that breaks the illusion of a continuous street. The building facades do not need to align vertically (different architectural styles and setbacks are part of what makes a street interesting), but the ground-level infrastructure must be seamless.
Add a third building, then a fourth. As your street grows, start checking sight lines. Orbit the camera to street level and look down the block. Do the buildings read as a coherent neighborhood? Is there enough architectural variety? Too much? Are the rooflines varied enough to create an interesting skyline? These are questions you can only answer by seeing the full street assembled, and Stud.io lets you answer them without owning a single brick. For inspiration on modular street layouts, the Builds hub showcases community creations, and the first MOC guide can help if this is your first custom design project.
A finished modular building deserves a proper portrait, and Stud.io's built-in rendering engine — powered by Eyesight or the optional Photo Realistic renderer — produces images that rival professional LEGO photography. Rendering is the payoff for all the digital design work, the moment your building stops being a collection of colored shapes on screen and starts looking like a real LEGO model sitting on a real table.
For a single building render, position the camera at a three-quarter angle — roughly 30 degrees above horizontal and 45 degrees off the facade center line. This classic angle shows two faces of the building plus the roof, giving the viewer the most information in a single image. Set the background to a neutral gradient (dark gray to light gray works well) or a solid color that complements the building's palette. Enable shadows and ambient occlusion for depth.
For a street scene render, the camera angle changes. Pull back far enough to capture three or four buildings in frame. Lower the camera to near-street level for a dramatic perspective that emphasizes the height of the buildings and the depth of the street. Alternatively, use a high bird's-eye angle to show the rooftops and the overall layout. If you have detailed interiors, create a cutaway render by hiding the front facade submodel on one building, revealing the rooms inside while the rest of the street remains intact. This cross-section view is one of the most compelling images a modular designer can produce.
Export at the highest resolution your system can handle. For social media sharing, 2048x2048 pixels is a good baseline. For print or portfolio use, go to 4096x4096 or higher. Save the Stud.io camera position so you can re-render later if you make changes to the design. A well-rendered street scene is not just a pretty picture — it is the primary way your design communicates with the world. Take the time to get the lighting, angle, and composition right.
A modular building designed in Stud.io is not just a personal project — it is a shareable, buildable blueprint that anyone in the world can download, order parts for, and construct on their own table. The sharing ecosystem around Stud.io is one of its greatest strengths, and knowing how to use it effectively turns your design from a private file into a community contribution.
Start by generating a parts list. In Stud.io, go to File > Export > Export as BrickLink Wanted List. This creates an XML file that can be uploaded directly to BrickLink's Wanted List feature, where the buyer can find the cheapest combination of sellers for every part. Review the list for rare or expensive elements before sharing — if your design requires a part that only exists in one retired set, consider substituting a more available alternative. The goal is a design that anyone can actually build, not just admire on screen.
Next, generate building instructions. Stud.io includes an instruction maker that automatically creates step-by-step guides from your model. The quality of these auto-generated instructions depends heavily on how you structured your submodels. If each floor is a clean submodel with a logical build order, the instructions will be clear and followable. If your model is a single ungrouped mass of parts, the instruction generator will produce chaos. This is another reason to use submodels religiously from the start of the design process.
Share your finished design on BrickLink's Studio gallery, on Rebrickable (which has a dedicated Stud.io file section), and on community platforms like Reddit's r/lego and r/legoMOC. Include multiple render angles, the parts count, an estimated build difficulty, and a note about which modulars it was designed to sit next to. The modular community is collaborative and generous — sharing your design invites feedback, inspires others, and often leads to design improvements you never would have found on your own. For physical modular sets that might inspire your next digital design, the Reviews hub covers the official lineup, and the LEGO Shop is where you can pick up official modulars to study their construction firsthand.
A 32-stud baseplate is not a constraint. It is a contract between your building and every building that will ever stand beside it. Honor the standard, and your street will grow without limit.