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Overview
Basements are a Build Mode feature in inZOI that allows underground floor construction, letting players build below ground level. It was scheduled for the Q4 2026 (October to December) timeframe in the 2026 Roadmap Part 1 letter, but shipped early in the v0.10.0 update on September 3, 2026.
Basements arrived ahead of that schedule. The v0.10.0 update of September 3, 2026 added basement construction for up to three basement floors on private residential properties, alongside the existing above-ground floors and adjustable foundation height.
Components
Component | Description |
|---|---|
Underground Floor Levels | Floors constructed below ground level. Private residential properties support up to three basement floors as of v0.10.0. |
Basement Construction | Walls, floors, ceilings, and fixtures placed in basement spaces. Compatible with existing furniture catalogs. |
Lighting and Visibility | Specific lighting model for basements (whether windows, lighting wells, or stair-down access provide visibility) has not been disclosed. |
Connection to the Other 2026 Build Mode Updates
Basements were announced as part of a Q4 2026 building expansion that also included the following, neither of which had shipped as of September 5, 2026:
Basements: This article.
Wall Decoration Modules: Interior and exterior wall decoration system.
Terrain Editing: Custom landscape sculpting (initial development).
Together these features were meant to complete the 2026 Build Mode roadmap. Basements arrived first and ahead of schedule; Curved Walls, originally a Q3 2026 item, had still not shipped as of September 5, 2026.
Use Cases
Basements enable:
Residential basement spaces (workshops, hobby rooms, home theaters, wine cellars).
Commercial basements for owned businesses (gym lower-level studio space, restaurant cellar storage, basement bars).
Storage and utility spaces that don't take above-ground square footage.
Themed basement environments (haunted house, prison cell, secret hideout) using existing decorative items.
Timeline
Date | Status |
|---|---|
December 26, 2025 | Announced in the 2026 Roadmap Part 1 letter as a Q4 2026 deliverable. |
March 26, 2026 | v0.7.0 anniversary update did not include Basements. Q4 schedule reaffirmed. |
May 29, 2026 | Underground building shown in the weekly developer video preview; the team said some previewed June-update systems will arrive with that patch and some later. |
Current target | Under active development as of late May 2026. May arrive with the June 2026 update or in a later patch; the original published roadmap window was Q4 2026. |
v0.10.0 Release (September 3, 2026)
Basement construction shipped in the v0.10.0 update, earlier than the Q4 window the roadmap letter had set. The released feature covers private residential properties and allows up to three floors below ground level.
The same update shipped three prebuilt properties that already use basement floors, one in each city: Mugunghwa Villa in Dowon, 1011 Willowtree Lane in Bliss Bay, and Bumi Indah House in Cahaya. Loading one of those lots is the quickest way to see how the underground floors connect to the ground floor.
Two related Build Mode changes landed in the same patch. Furniture categories now appear to the right of the item list, and the maximum number of floors allowed on public properties rose to 29, with some properties exempt from that limit.
Open Questions
Number of underground floor levels supported (one basement only, or multi-level basements).
Whether basements support windows, lighting wells, or only artificial lighting.
Whether existing properties can be retrofitted with basements or only new builds.
Whether basements affect property value calculations or appear separately on Edit City listings.
Whether weather and natural disasters affect basements differently from above-ground floors.
See Also
Build Mode covers the current building system. Foundations and Basements covers existing foundation system. Curved Walls is the Q3 2026 partner feature. Wall Decoration Modules is bundled in the same Q4 update. 2026 Roadmap tracks delivery status.