Annex buildings in goalunited are additional expansions of the main building categories which offer extra benefits for various activities aimed at further enhancing the development of your club and players.
Once purchased, the annex buildings are available for a specific period of time, after which you need to re-purchase them to continue having access to the effect they offer.
To purchase or manage Annex buildings, go to Club -> Stadium and select “Annex” tab.

Here you will see the list of the available Annex buildings that you can purchase.
Each category has its own annex buildings.
For example, the Training building category has its own Annex training buildings which can be constructed.
The main Annex Buildings categories are:
Annex Training buildings (active)
Annex Club office buildings (planned for the future)
Annex Gastronomy buildings (planned for the future)
Annex Medical buildings (planned for the future)
While annex buildings are not upgradable to a higher level, you can own multiple of the same category of annex buildings
Annex buildings can sometimes have 1 or 2 sub-types of the building. In any case, you can purchase and own both and get the effect from both at the same time. You can choose which out of all available annex buildings from the specific category you want to show in your stadium complex Annex buildings do not need to be repaired over time as they have a predetermined specific duration.