It is not being used for business purposes. More for storage, woodcrafting (not for resale), pet shelter since it also has a doggy door.
If there is no business use, then it's considered personal, and no deduction is allowed for personal items. The following also applies to separate structures on your property, in addition to your home.
To be able to deduct any expenses of your home or separate structures:
You must show that you use your home as your principal place of business. If you conduct business at a location outside of your home, but also use your home substantially and regularly to conduct business, you may qualify for a home office deduction. For example, if you have in-person meetings with patients, clients, or customers in your home in the normal course of your business, even though you also carry on business at another location, you can deduct your expenses for the part of your home used exclusively and regularly for business. You can deduct expenses for a separate free-standing structure, such as a studio, garage, or barn, if you use it exclusively and regularly for your business. The structure does not have to be your principal place of business or the only place where you meet patients, clients, or customers.
Generally, deductions for a home office are based on the percentage of your home devoted to business use. So, if you use a whole room or part of a room for conducting your business, you need to figure out the percentage of your home devoted to your business activities.
Additional tests for employee use. If you are an employee and you use a part of your home for business, you may qualify for a deduction for its business use. You must meet the tests discussed above plus:
If the use of the home office is merely appropriate and helpful, you cannot deduct expenses for the business use of your home.
For a full explanation of tax deductions for your home office refer to Publication 587, Business Use of Your Home.