Once all the bricks have been restored to a building, you can also upgrade the door, windows, and chimney. Tapping on any building will bring up a bubble that shows the house’s level and what the reward will be when its next upgrade level is completed.
You’ll be asked to upgrade buildings in a particular order, and the current building will need to be fully upgraded before you can move on to the next.
The current building needing upgrades will have a bubble over it to show which items you have and which ones you still need to complete an upgraded part. Upgrade items are obtained as rewards from filling Hot Air Balloon requests. Items used to upgrade buildings include:
Once all parts have been obtained, the bubble will glow to let you know an upgrade can be finished! Tapping on one of the parts of a building and then dragging the upgraded version over onto it will complete the upgrade.