Hi there.
Major improvements/renovations for your business property would be considered to be an increase to the value of your capital asset (building) rather than a current expense. You would then be able to depreciate (expense the use of the building) the asset by claiming capital cost allowance (CCA) as an expense.
For more information, see the CRA's webpage on CCA: https://www.canada.ca/en/revenue-agency/services/tax/businesses/topics/sole-proprietorships-partnerships/report-business-income-expenses/claiming-capital-cost-allowance.html
For information about how to enter this information in TurboTax, see our information page on Capital Cost Allowance here: https://turbotax.intuit.ca/tips/capital-cost-allowance-explained-3952
Hope this helps.
Fraser