Grandfathered in generally comes from properties built like a century ago and the zoning or building codes changed through the decades but the city decided to allow the ones that have been in existence for decades to remain the same.  

That seems like the deal of the century.

Case shiller lists LA as the 2nd best in nation for buy n hold return for this century.   

It still on very rare occasions is done, and also on rare occasions for retrofit/modification work, you may still look for opportunities to support your structure/joist systems etc with the masonry - however sometime in the early 20th century pure masonry started going out of favor, for structures being built entirely with their wood/steel, and the masonry you saw was then basically an aesthetic detail that was 'tied' to the structure holding everything up. 

After spending years managing a very old (1870s built) high maintenance duplex, we decided it was time to re-position our equity gains into 2 easier-to-manage mid-century built single family rental properties in Class A areas.

I would like to hope that an STR since the last century is grandfathered, but it is definitely not guaranteed (the San Diego regulation had no grandfathering clause).The beach properties are already priced as though they are STRs. 

Amanda McClindon at Century 21 and Troy Wardlow at Bay Equity were an incredible team in helping us understand the home buying process, finding a home, and financing it.

Our company StoneBridge Groups, helped source this off market property, closed with StoneBridge Title Group, StoneBridge Construction Group did the renovation, and we listed it with our retail brokerage Century 21 StoneBridge Real Estate Group.

It is a mid-century modern building consisting of metal-framed structure which is enclosed in terra cotta hollow tile bricks.

A couple hundred dollars spent on an engineer to take a look is money very well spent and can save a fortune or at least buy peace of mind.I have a client finishing up a rehab on a mid century home in town where the county was wanting him to completely rip off about a third of the roof, after the new permitted re-roof.