Permitting for an attached ADU

[Julien Weinrott]

Hi,

I'm in escrow on a triplex, less than 6000 sqft lot, zoned RD 1.5 in Los Angeles. It features (1) stand-alone and (2) apartments over three two-car garages (with plenty of public tran nearby).  Part of the stand-alone could be converted into a separate dwelling. The space is 400sqft with a separate entrance, full bath and kitchen. 

The problem I see:

I'm trying to digest these new ADU laws enacted October 2019 and my interpretation of the language is such that because this property is under LARD 1.5 zoning and the lot is less than 6,000 sqft, I would only be legally permitted 3 units. Therefore, the attached dwelling would be illegal if leased.

Is my interpretation of the law accurate or inaccurate?

Any help is much appreciated!