Commercial Radon Mitigation in Santa Monica

Different City, Different Rulebook

Worth stating plainly because it confuses people constantly: Santa Monica is its own municipality and is not under the City of Los Angeles methane ordinance. LADBS Division 71, the methane zone requirements that govern projects in Fairfax, Beverly Grove, and much of central LA, stops at the city line. Santa Monica projects are reviewed by Santa Monica, and soil gas requirements here typically arrive through environmental case oversight rather than a prescriptive building code chapter.

What that means practically: a developer who has done three methane projects in LA and assumes the same process applies in Santa Monica will be surprised, in both directions. Some things are easier here. Some are less predictable because there is no published Site Design Level table to price against.

Deep Basements and Creative Office

Santa Monica's office stock, particularly the campuses around Colorado Avenue, Cloverfield, and the Bergamot area, tends toward two to four levels of subterranean parking under occupied space. That is protective for radon and complicating for everything else: below-grade walls have enormous ground contact area, waterproofing systems and soil gas barriers have to coexist, and any retrofit work happens in a garage that a tenant is parking in.

We have also found that the older creative-office conversions, warehouses and light industrial buildings turned into open office in the 1990s and 2000s, are the ones most likely to have an unsealed slab penetration nobody documented. Trench drains from a former manufacturing use, capped floor sinks, and abandoned pits under raised flooring.

Coastal Building Stock

The marine layer does something useful for us: buildings near the coast run their HVAC less aggressively and see more natural ventilation, which suppresses indoor soil gas concentrations relative to an identical building inland. Our Santa Monica radon results are among the lowest we record anywhere in the county.

The counterweight is that testing near the coast requires more attention to closed-building conditions, because an office two blocks from the beach in October has windows open, and any short-term test performed under those conditions understates the real number. We test coastal buildings in cooler months when we can, and use continuous monitors always so the data shows what actually happened.

Cost

Office testing $700 to $2,200. Sub-slab systems in creative office and low-rise commercial $7,500 to $16,000, with the higher end reflecting the garage coordination and after-hours work these properties usually require. Sealing-focused remediation on a specific identified pathway is far cheaper, often $2,000 to $6,000, and is frequently the right answer here.

Getting Started

Tenant asking for indoor air data before a lease renewal is our most common Santa Monica call. That is answered with a straightforward measurement program, usually cleanly, in about ten days. Development projects with soil gas conditions attached should call earlier than they think they need to.

Related: office building radon and new construction soil gas systems.

Santa Monica Questions

Does the LA methane ordinance apply in Santa Monica?

No. LADBS Division 71 applies within the City of Los Angeles only. Santa Monica is a separate jurisdiction with its own review process, and soil gas requirements here more typically arrive through environmental case oversight than through a prescriptive code chapter with assigned design levels.

Is radon a concern in coastal Santa Monica buildings?

Rarely. Our Santa Monica results are among the lowest we record in the county, helped by building stock that ventilates more naturally in a mild coastal climate. The caveat is that testing has to be done under genuinely closed conditions, which near the coast means cooler months and continuous monitors that can show when a window was opened.

Our building has three levels of subterranean parking. Is that good or bad?

Good for radon exposure in occupied space, since the garage takes the ground contact and is ventilated continuously. Complicating for retrofit work, because any system has to be installed in an operating garage and coordinated with the waterproofing.