I recently wrote about this for BiggerPockets: https://www.biggerpockets.com/blog/dollar-cost-average-real-....

It is a common practice and comes at no cost to you.I would also recommend you require your tenants to get tenant's insurance and add you and your property manager as additional insured as well! 

Thoughts on the cost of this? 

You know, I always think that is very misleading when they charge thousands of dollars to newcomers base off marketing that boasts getting into real estate with no money down.These deals cost money. 

Leaks can be easy to fix or very costly to fix.  

Can try to reposition to Class B, but neighborhood may impede these efforts.Vacancy Est: Historically 10%, but 15-20% should be used to also cover tenant nonpayment, eviction costs & damages.Tenant Pool: majority will have FICO scores of 560-620, many blemishes, but should have no evictions in last 2 years.

All that does is cost you more money. 

Along with many others I'm sure, I read "The Book on Estimating Rehab Costs" by @J.

I'm afraid skylights might leak or increase the cost. 

Can try to reposition to Class B, but neighborhood may impede these efforts.Vacancy Est: Historically 10%, but 15-20% should be used to also cover tenant nonpayment, eviction costs & damages.Tenant Pool: majority will have FICO scores of 560-620, many blemishes, but should have no evictions in last 2 years.