I bought a rental home 5 years ago and installed a new roof ($4,000) 3 years ago. Since then, the roof is counted as a depreciated asset. Last year (2018) I sold my rental home.  Since this roof isn't recently installed, can I still add the original price of roof, $4,000 back to the cost basis of rental home to reduce capital gain? I will surely do the depreciation recapture.

If I cannot add the cost of roof to cost basis of rental home, the sales price of the roof will be a fair market value? or original price minus depreciation claimed over the years?

Thanks.