@maria Mendoza @Maria Mendoza what zip codes are you looking to buy the duplex in? 

If you intend to do upgrades, the second you open a wall or ceiling, that area is no longer grandfathered and must be brought to code.

They don't give you access but just about all the MLS info is there except agent to agent remarks, gate codes and commission amounts offered.  

You can search by your zip code to quickly gather a list of members in your local market. 

If you dont want a lot of people next time call the fire dept. and ask them what the occupancy codes are per bedroom and then put that in your lease. 

Zoning may make you take them down or possibly fine you for it, but it doesn't seem strictly enforced.  

I would tread carefully and NOT use the link you provided. you can find the code at this link it is longer and a little hard to translate.http://www.dgs.ca.gov/dsa/Programs/progAccess/acce...Also it is important to keep in mind that the parking requirements as far as quantity for accessible stalls is less for multi family than commercial (dimensions are the same)You may be interested in getting a CASp report for your property the report will tell you exactly what you need to bring your property into full compliance and certify it.

Keep in mind, if you do buy a strictly investment property 1st, your kids will not 'need' to be in the family home they're going to grow up in for another 5,6-7 years.

@Steve Vaughan  the best part is when I bought it in 04  ( a peak earning year for me) the tax code allowed me to write off 90% of purchase price year one>>>  saved me about 150k in income tax I would have paid to uncle sam that year...

My answers are based strictly on years of experience and "Facts".