New barn to be used for farm activities

We built a new barn on our property last year, 1/2 of which is to be used for my wife's existing flower farm business that she's been running out of the house. I am familiar with listing business expenses based on home office use, and assume we can do that for the ongoing expenses. But I am not sure how or if the construction cost should be shown on my taxes. I realize I should have figured this out when we built it, but here we are. Thanks