You cannot claim the section 179 deduction for property held to produce rental income. This would include any rental assets along with capital improvements.
Per IRS Publication 946 How to Depreciate Property
, page 17: Property Acquired for Business Use
To qualify for the section 179 deduction, your property must have been acquired for use in your trade or business. Property you acquire only for the production of income, such as investment property, rental property (if renting property is not your trade or business), and property that produces royalties, does not qualify.
For more information regarding depreciation, please refer to the following publications: