The Decal Gallery manages building decals. It requires Base level 8 and lets you change the appearance of buildings using decals you own.
Decals and their stats
The gallery has separate views for collected decals, stat previews and bonus details. Bonuses include combat and development effects, so a decal is more than its building artwork.
Using or removing a decal is a different action from upgrading it. The interface shows its current level and the items needed for the next upgrade, including applicable decal components.
How upgrades work
Upgrades can consume one or more decals. The amount added cannot exceed what is required to reach the next star.
Some decals unlock an Upgrade Split feature at a particular level. Each specified decal used grants a partial stat increase, with another phase bonus after each third of the required amount. The total stats for the level remain the same; the feature changes how progress and bonuses arrive along the way.
The Base and other buildings still have their own upgrade levels. Decal progression is separate from constructing or leveling the building wearing the appearance.