The rules that size a Brentwood house
Los Angeles adopted the Baseline Mansionization Ordinance in 2008 and its hillside counterpart, the Baseline Hillside Ordinance, in 2011. City Planning wrote them to address out-of-scale development in single-family zones and the construction impacts that come with building in Hillside Areas. Together they set the size and bulk of a new home on a Brentwood lot.
Which set applies is a parcel question. Brentwood runs from level blocks to canyon streets, and LADBS determines whether the hillside rules apply to a given project. On a hillside lot the street counts as well: a new home on a lot fronting a Substandard Hillside Limited Street with a roadway narrower than 20 feet does not get a building or grading permit unless the project is approved under Los Angeles Municipal Code Section 12.24 X.21.
I read every lot on ZIMAS, the City's zoning map, before design starts, and I take the questions that matter to an LADBS preliminary plan check meeting with a plan check engineer when the lot is not simple.