Deductions & credits
From this IRS article on a home office deduction, the space must be used exclusively and regularly for administrative or management activities.
You could argue that the space is used regularly if you use it often to pull or deposit tools and equipment. You could also make the argument that one aspect of the management of the business is attending to the storage and maintenance of tools and equipment. While your use does not fit the typical definition of a home office, it seems you do have an argument to support your contention.
You enter the home office expense in the Business Expenses section of TurboTax, under Home Office Expense:
