Steel Build Purchase 100% for home Business, How do I Depreciate?

I Purchased and built a steel building on my property 100% for my home business?  I file schedule a C..  How do I depreciate the cost of the building?  I can't find any details on how to depreciate this purchase, as it seemingly doesn't fall under any of the categories for large purchases that I can find as explained in TT. (What Asset Category).  It is nonresidential real estate, even thought it is built in my residential back yard?

 

Thank  you!