Barn and storage on the main farm
The Barn is a building you'll only find on the main farm, and it stores the products and farm supplies you make. How much fits inside depends on the level you upgrade it to and on whether you build the basic version for Dollars or the Gold-priced Spacious barn. Without enough capacity your storage fills up fast and production, such as grinding feed in the Windmill, stops on its own.
The Barn is a basic building worth investing in as you go, because with no free capacity your feed production in the Windmill grinds to a halt - and if you have Gold to spare, build the Spacious barn right away, since at the top level it holds over three and a half times more than the classic Dollar version.
The Barn stores products and supplies on the main farm only

The Barn is a building you'll only find on the main farm - you can't build it on the side farms, where storage is handled differently. It takes up 7x6 tiles and stores the products and farm supplies you make, so everything the Windmill turns out, everything you harvest from your animals and anything else you produce.
Only a limited number of barns can stand on your farm, which is a clear sign that upgrading the ones you already have beats counting on building more. What's special about the Barn is that it needs no worker to build or upgrade - with both versions, the regular one and the Gold one, the worker count is zero at the first level and at the top level alike.
A higher level means more capacity and higher costs
The Barn can be upgraded from its basic level all the way to level 12. Every upgraded level raises storage capacity, the price of the next level and the build time - the difference between the first and the last level is noticeable.
At the first level you build the Barn for 1000 Dollars and construction takes 12 minutes. At the highest, 12th level, the price jumps to 45000 Diamonds and construction takes 5 days and 10 hours. On top of that, you'll only reach that top level once your farmer hits level 139 - before that the Barn won't offer it for upgrade at all.
The Spacious barn is the Gold version with more capacity
Alongside the classic Barn you build for Dollars there's also a Gold variant - the Spacious barn. It works exactly the same way, just with a higher starting and maximum capacity, and logically with a higher price in Gold.
| Barn | Spacious barn | |
|---|---|---|
| Level 1 price | 1000 Dollars | 450 Gold |
| Level 1 build time | 12 minutes | 15 minutes |
| Max level price | 45000 Diamonds | 127600 Gold |
| Max level build time | 5 days 10 hours | 6 days 6 hours |
| Level 1 capacity | 200 | 300 |
| Max level capacity | 2000 | 7000 |
The capacity gap at the top level is huge - the Spacious barn holds over three and a half times more than the classic one. If you have Gold to spare, it's worth going straight for this variant, because it catches up on capacity faster and doesn't eat up any extra space on your farm.
The storage overview has tabs for every farm and for the cooperative

The storage overview in the game is split into tabs based on where you use the items - you'll find the Main farm, Farm supplies, Fishing area, Gourmet farm and Flower farm listed separately. On top of that there's a Cooperative village tab and an Extended view that shows more information at once.
According to the texts in the game interface you can also drag some production buildings from your farm into the cooperative village - the Barn, Cowshed, Duck coop, Windmill, Water mill, Spinning factory or the Dye factory and Clothing factory, for example - and store them there as a community building.
A full Barn stops feed production in the Windmill

Here's one thing players often forget - if the Barn is full of a particular type of feed, the Windmill stops making it until you free up space. Production shuts itself down even when you have the raw materials for another batch.
That's why it pays to watch which feed piles up fastest and either use it up on your animals or keep raising your Barn capacity. Otherwise you lose Windmill time while it stands idle instead of grinding.
The warehouse covers the same job on the obsidian farm

On the obsidian farm a different building covers the same need - the Warehouse, or rather its Gold variant, the Spacious warehouse. The principle is identical to the Barn on the main farm - the higher you upgrade the warehouse, the more products and supplies it holds, and the spacious version fits more than the regular one.
Buildings and products mentioned in the text
BarnMain farm · 7 × 6
Spacious barnMain farm · 7 × 6
WindmillMain farm · 6 × 4
WarehouseCooperative village · 7 × 7
Spacious warehouseObsidian farm · from level 114 · 7 × 6
Spinning factoryGourmet farm · from level 19 · 7 × 6
Clothing factoryGourmet farm · from level 19 · 7 × 6
Fishing areaFishing area · 1 × 1