The Warehouse helps protect your resources from enemy raids. Upgrade to increase the amount of each resource protected.
The info sub-menu will show you the building Bonuses. The first number is the one based on the building level, and the second one (in green) is based on other bonuses (such as Research, Talent points, etc.) "More Info" will show you an expanded view of the below table, along with the Power generated by each level. Note that Wood is the same amounts as Food, Iron is 20% of the amount of Food, and Silver is 5%.
|Level||Food / Wood||Total at end of tier|
|1 to 10||+10,000||300,000|
|11 to 20||+20,000||500,000|
|21 to 40||+30,000||1,100,000|
|Level||Iron||Total at end of tier|
|1 to 10||+2,000||60,000|
|11 to 20||+4,000||100,000|
|21 to 40||+6,000||220,000|
|Level||Silver||Total at end of tier|
|1 to 10||+500||15,000|
|11 to 20||+1,000||25,000|
|21 to 40||+1,500||55,000|