I need to be able to store more alloy to upgrade however even with both warehouses at level 10 I won..

Not sure what level you are at and how many resources you need. The first warehouse for Iron allow lets you store up to 1 Mil resources at level 10. The second one though has a max of 20 Mil so together you have a capacity of 21 Million + any other small increases from research etc.

You can also build a Warehouse 3 once warehouse 2 is maxed out.

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