
Effect · every source
How to increase Building slot in CK3
6 sources raise Building slot and 0 lower it in the game files of patch 1.20.0.3.
building_slot_addThe biggest boosts
+2Tribal HoldBuilding · Province · government parameter government_is_wanua
+1MagistratesInnovation · Counties of this culture
+1WindmillsInnovation · Counties of this culture
What raises Building slot (6)
Innovations (4)

Counties of this culture
innovation_baliffs· game/common/culture/innovations/00_early_medieval_innovations.txt
Counties of this culture
innovation_windmills· game/common/culture/innovations/00_high_medieval_innovations.txt
Guilds+1
Counties of this culture
innovation_guilds· game/common/culture/innovations/00_high_medieval_innovations.txt
Ledger+1
Counties of this culture
innovation_ledger· game/common/culture/innovations/00_tribal_innovations.txt
Buildings (2)

Province · government parameter government_is_wanua
Levels 1–2: +2 to +2 (2 levels give it)
tribe· game/common/buildings/00_tribal_buildings.txt
Source: game/common/buildings/00_legendary_buildings.txt, game/common/buildings/00_tribal_buildings.txt, game/common/culture/innovations/00_early_medieval_innovations.txt, game/common/culture/innovations/00_high_medieval_innovations.txt, game/common/culture/innovations/00_tribal_innovations.txt and the English localisation, Crusader Kings III 1.20.0.3. Building chains are shown once, at their strongest level, with the range over their levels. Effects that come only from events or scale with a script value are not listed.