New roof on SFR rental property - how to deduct?

I had the roof and gutters on one of my single family residential (SFR) rental properties completely replaced due to hail damage.  The entire cost to replace both was $17,830.  Insurance paid for $15,430 and I paid the $2,400 deductible out of pocket.  I understand a new roof qualifies as a separate asset and I will need to depreciate it over 27.5 years.  My question is what amount do I depreciate ($17,830 or $2,400)?  Thanks.