Little more research behind Hart CO's answer
What's the best way to account for the depreciation of the original home value, the capital expenditures in 2011, and the capital expenditures in 2015?
The first question is to determine if it is a capital expenditure (not just any old home improvement).
According to 1.263(a)-3(d) of the Regs:
(1) Are for a betterment to the unit of property (see paragraph (j) of this section);
(2) Restore the unit of property (see paragraph (k) of this section); or
(3) Adapt the unit of property to a new or different use (see paragraph (l) of this section).
"Is what I'm doing a capital expenditure? Check here.
After determining "yes" to all three. We move to
how:
We refer to this article: for more info:
Replacement[s]... in your residential rental property: Is generally depreciated over a recovery period of 27.5 years using the straight line method of depreciation and a mid-month convention as residential rental property.
Is it best to have separate accounts for each capital expenditure to remember how much of which capital expenditure has been depreciated?
Yes and as the answers above state, it would be straight line and over the course of 27.5 years.
{Don't forget that you can write off some of these capitalization costs under Section 168.}
As always, good luck.