Welcome to your ultimate guide for building functional, immersive apartments in The Sims 3 using only Base Game and the Late Night expansion. Whether you’re after a classic townhouse setup or a modern elevator high-rise, this tutorial covers four different styles of apartment builds with everything you need to get them working perfectly for NPCs and your active Sim.

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Step 1: Build the Base Structure

Start with a flat, foundation-free building unless you’re doing the raised apartment type. Give each apartment a unique front door to reflect neighbor personality and make the space feel more lived in.

Create Boundaries:

• Use fencing to separate each apartment’s outdoor space.
• Add a gate so NPCs can access their designated area.

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Step 2: Designate NPC and Active Apartments

To distinguish between NPC apartments and your playable Sim’s apartment:

• Black out the NPC units with black flooring and walls (optional visual guide).
• Only furnish your playable Sim’s apartment.

Once the layouts are finalized:

Enable Cheats:

1. Press Ctrl + Shift + C to open the cheat console.
2. Type:
   • testingcheatsenabled true
   • buydebug on

Add Apartment Markers (found in BuyDebug):

• Hidden Room Marker: Place inside each NPC unit. This hides it completely during live gameplay.
• Public Room Marker: Place in all communal spaces—outdoor areas, fenced patios, or shared hallways.

⚠️ Don’t place any markers in your active Sim’s apartment.

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Step 3: Set Up NPC Doors

To convert doors into NPC-only:

• Ctrl + Shift + click the door > Make NPC Door
• Repeat this for each neighbor’s apartment.

Now only your Sim can access their unit, and NPC neighbors can use theirs.

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Editing After Marker Placement

Once apartment markers are placed, you’ll find that editing becomes restricted. To make changes:

Enable Advanced Building:

1. Open the cheat console again.
2. Type:
   • RestrictBuildBuyInBuildings off

This re-enables the build grid in hidden and public rooms for editing. Just be cautious:

• Avoid moving or deleting the room markers, or you’ll break functionality.

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Apartment Style 1: Townhouse Style

A row of side-by-side apartments with exterior-facing doors. Great for suburban settings.

• Each unit gets a front yard or patio.
• Use public markers for each yard.
• Add NPC doors for neighbor units.

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Apartment Style 2: Internal Hallway Layout

A structure with all apartments facing an enclosed indoor hallway.

• Create a shared staircase or lobby as the public zone.
• Place Public Room Markers in the lobby and hallways.
• Add Hidden Room Markers in all NPC apartments.

Note: Be mindful when placing these markers. Misplaced markers or forgotten public space can result in unusable doors or Sims getting stuck.

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Apartment Style 3: Elevator Building

A more vertical, city-style build using elevators from the Late Night expansion.

Required Additions:

• Wall Mailbox (from BuyDebug > Late Night filter) – Ensures all Sims access mail, even with elevators.
• Call Box (from Electronics in Buy Mode) – Enables visitors to buzz your Sim.

Additional Setup:

• Public markers go in elevator lobbies/hallways.
• Hidden markers in each NPC unit.
• Use Level Skip Markers (optional) for empty floors to save load time.

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Apartment Style 4: Raised Apartments with Foundation

These resemble starter homes with a porch or stair entry.

Key Setup:

• Ensure public markers are placed on the porch level right before the front door.
• Use fencing to clearly define each yard. Mark NPC yards as public to reduce property value.
• Do not place public markers outside fenced areas.

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Bonus Tips:

• Decorate each door differently to create more visual storytelling.
• Don’t add functional items (like grills or easels) to NPC yards—your Sim won’t be able to use them.
• Only furnish your active Sim’s space to keep costs low.
• Expect occasional glitches when switching between multiple custom apartment lots. Breaking them up with non-apartment builds in between can help.

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Final Words

Creating apartments in The Sims 3 takes patience, but once you’ve got it down, it opens up a more immersive and vibrant neighborhood life for your Sims. From public hallways to bustling elevator complexes, it’s all possible with a few cheats and careful setup.

Build smart, and give your Sims the neighbors (and memories) they deserve!

Happy building—and don’t forget to like and subscribe if this helped you out!