Deck on an Owner-Occupied Multifamily

[Becky Watkins]

Last year I redid the stairs on my triplex. It was more than a small repair, so I am capitalizing it. My question is whether I can depreciate the whole thing or just 2/3 of the cost. The entrance to my unit is in the front and the other two are in the back. Even though it's a feature of the exterior, these stairs lead to the top unit and they are only used by/a benefit to the top unit.

A different yet related question: one time a tax professional told me it's okay to 2/3 everything, as long as I'm consistent. For example, I can deduct 2/3 improvements done to my own unit as long as I am only deducting 2/3 of the expenses to turn one of the rentals. Is that really the case?

Thanks in advance for any help!