I would also target COA’s with newly replaced roofs, and negotiate to have the seller pay any outstanding special assessments at closing.

A builder may not know all of the overlapping aspects that affect the build and design - setbacks and buffers for example.

The second one needed a full roof.

Its ALL about doing the reno correctly, Roof, and furnace/HW tank if older then 10yearsish, replace, all new cosmetics including LVP through entire, ect.

or “Is it legal to build a treehouse on a duplex roof?”

The disposition of SFH's in markets that fail to turn is one of the most overlooked and grueling aspects of this strategy.   10 Years ago when I first began investing I grew a 30+ SFH portfolio in a neighborhood in Northwest Philadelphia and it pains me to say I fell into category 2.

Anything above that needs to be justified - roof replacement, parking lot repaving, etc. 

You kind of have to separate out the asset protection aspect from the banking aspect when you think about it.

I saw an ad for EverSeal offering a 50-year warranty for their flat roof system.

There are some good things mentioned here about other aspects to look at such as appreciation or tax benefits, but I totally understand wanting to cash-flow out the gate.