BMO (Baseline Mansionization Ordinance)
City of LA rules limiting the size of single-family homes in non-hillside R1 zones.
The Baseline Mansionization Ordinance caps the size of single-family homes in flat-lot R1 zones to prevent oversized 'McMansions.' It works through a tighter FAR (typically 0.45 plus a 20% bonus for green-building features) and stricter side-yard setbacks for second stories.
Whole-home remodels and second-story additions on R1 lots in Beverlywood, Cheviot Hills, Carthay, and similar flat neighborhoods almost always trigger BMO review.
Related terms
- FAR (Floor Area Ratio)The ratio of total building floor area to lot size — caps how much you can build.
- BHO (Baseline Hillside Ordinance)City of LA rules governing residential construction on hillside lots — height, grading, haul routes.
- LA City PlanningThe City of LA agency that handles zoning, entitlements, and HPOZ review.
People also ask
FAQ — BMO (Baseline Mansionization Ordinance)
What does "BMO (Baseline Mansionization Ordinance)" mean in plain English?
City of LA rules limiting the size of single-family homes in non-hillside R1 zones.
Why does BMO (Baseline Mansionization Ordinance) matter for a California ADU or remodel?
BMO (Baseline Mansionization Ordinance) comes up in the zoning and land-use side of nearly every Greater LA and Bay Area project we touch. The Baseline Mansionization Ordinance caps the size of single-family homes in flat-lot R1 zones to prevent oversized 'McMansions.' It works through a tighter FAR (typically 0.45 plus a 20% bonus for green-building features) and stricter side-yard setbacks for second stories. Getting it right at design saves rework later — getting it wrong is one of the most common reasons permits stall.
Where will I see BMO (Baseline Mansionization Ordinance) on my own project?
Most owners run into BMO (Baseline Mansionization Ordinance) during the design or plan-check phase. Your project manager flags it on the schedule, walks you through what the city expects, and confirms documentation is in place before the inspection that depends on it.
Does BMO (Baseline Mansionization Ordinance) cost extra?
Sometimes — depends on whether it adds scope (a report, a structural detail, a fee) or just a paperwork step. Anything cost-impacting is itemized in your contract or change order, never buried in the invoice.
Who at Alpha Dream handles BMO (Baseline Mansionization Ordinance)?
The project architect owns design-level decisions; the permit runner owns city interactions; the project manager owns field execution. You always know who to ask.