Why can’t I deduct the renovation costs for a rental apartment?

My spouse and I are privately employed and not in real estate business. We have a rental unit that almost breaks even every year after all costs and depreciation (e.g. +/- $3,000). We spent $12,000 for renovation costs last year installing new windows and doors. But, when I enter that in Turbotax under repairs it doesn’t make much difference to our bottomline taxes owed! What is the maximum amount allowed for renovations deduction every year, and what is the best way to deduct them?