Maybe this example will explain the idea better: Comparing owning 4 SFH and 1 4-family, in the first situation you have 4 roofs that can take damage in a bad storm, leaving you on the hook for suddenly dealing with substantial cap-ex expenses across 4 properties.

I find a combination of it being much easier to buy (30 settlements vs 1 settlement), manage (30 different addresses vs 1 building, 30 insurance policies vs 1 policy, 30 spring roof inspections vs 1 roof...), and yes, economies of scale ($850/yr insurance on my SFH vs $7k on the building) makes Multis more attractive to me than all SFHs.  

The hardwood floor of my whole unit needs to be replaced.It turns out the water is entering from my CMU wall due to the roof scuppers being overwhelmed and the gutters have significant bellies that are not allowing the water to flow freely.

(Boiler/furnace, hot water heater, windows, roof, siding)Why is it vacant????

4) What is the parallel to a real estate investor's surprise roof repair (deal buster)?

Comps in the area are upwards of $180k...Rubber roof in 2003HVAC's probably have 10 years left.What am I missing here?!

Asking $389,0008 unit Annual Rent Income = $54,840Annual Expenses - Gas/Electric = $5020- Insurance = $3500- Property Tax = $6396- Water/Sewer = $3535- Trash/ Lawn / Snow = $24008 year old roof, new water heater, old hot water boilerTenants pay their own electric Coin operated washer/dryerI will be purchasing with 20% downI have my own numbers and have included 5% each for vacancy/ capex in mine.

You costs are aggregated between several units and thus over the long term, are more likely to save money when you need to replace one roof instead of four.

30k could get you a property, but you have to consider capital expenditures (HVAC goes out, roof replacement).

In the past 8 years its had a new roof, two new furnaces​, two new ac units, updated electrical and plumbing​. the insides have nice laminate​ flooring​.