With a dozen properties over 25 years I have yet to spend a dollar on a roof or painting a house exterior.

It covers internet, water, trash, cable, and exterior (roof, siding, etc.).

It is important to find something that was properly maintained, with modern plumbing, electrical and roofing. 

we just see new investors in the forums blown away when they hit their fix big capex - a new roof, a new furnace, a driveway repair, a couple appliances going at once. 

Look up 'Margin vs Markup if you're curious.)So if my Plumbing Sub-Contractor gives me a bid of $20,000 for your project, I will not tell you that number, I will just have a price of $25,000 for plumbing on your Bid/Proposal.Note: It does come out close to even for you........my plumber gives me a steep discount because I give him $100k worth of work each year......

Eg roof and siding on one, all new paint and countops.

Its a steep learning curve but very rewarding if you stick with it.

I assume 15% of the rent for regular repairs and capital expenses (roof, furnace, windows etc.) and 5 % of the rent for vacancies.

Adding a 1/2 bath, new roof, central air or other typical improvements will increase the value of the property. 

Hey Denny - For rehab costs, a good place to start is breaking things down room by room and getting rough estimates for common repairs like the roof, HVAC, kitchen, light cosmetics, etc.