Playfelt's answer pretty much covers it, but I currently do home renovations, so speaking from experience, I thought I should answer in my own words as well.

There are 2 factors when doing reno work. Expenses and capital gains. Any major changes like adding a bathroom will be capital gain. Minor changes will depend if the change is necessary for daycare, like any minor changes done for safety issues. That can be declared a business expense. Smaller jobs, like repainting, would also be an expense, as long as there is some reason to do it for the business.

When you get into capital gains like a new bathroom, there is yearly depreciation, but that gets into an accountant or some studying.