Commercial Radon Mitigation Los Angeles

Three Reasons LA Property Owners Call Our Radon Contractors

We only do soil gas. No duct cleaning, no mold remediation, no general contracting bolted on. Radon, vapor intrusion, and methane systems are the entire business, and they have been since 2011. When a lender's environmental professional asks a technical question about pressure field extension or fan curve selection, the person answering has installed the system.

We tell you when you do not need us. Los Angeles is a low-radon county. A fair number of the calls we take end with us saying the building probably does not need mitigation, run the test, and if it comes back clean you are done. That costs us a sale and saves you an unnecessary capital expense, and it is why the same asset managers keep calling back.

One contractor for radon, VOCs and methane. A Fairfax District project can be in a methane zone under LADBS Division 71, in a DTSC vapor intrusion footprint, and carrying a lender radon requirement all at once. Most firms handle exactly one of those. We design the sub-slab system once so it satisfies all three, which is faster and considerably cheaper than three mobilizations.

Commercial Radon Services Across the Los Angeles Basin

Basin Radon & Soil Gas provides commercial radon testing and radon mitigation in Los Angeles and the surrounding basin, for multifamily portfolios, schools, offices, industrial buildings, and healthcare facilities. We measure the building, design the system, install it, verify it with a post-mitigation test, and hand you documentation that satisfies a lender, a district, or a regulator.

Our work covers commercial radon testing under the ANSI/AARST measurement protocols for large buildings, active sub-slab depressurization, sub-membrane systems over crawl spaces, HVAC-based pressure control in high-rise offices, vapor intrusion mitigation for VOC-impacted sites under DTSC oversight, LADBS methane mitigation systems, new construction soil gas design and installation, and the ongoing maintenance, monitoring, and fan replacement that keeps all of it working after the crew leaves. If it involves gas moving from soil into an occupied building, it is our lane.

Marcus started the company in 2011 after nine years doing vapor intrusion work for an environmental consulting firm, mostly on brownfield redevelopments. The shop is off Slauson in Vernon. The gray F-250 with the core rig on the back and the white Transit stacked with 4-inch PVC are ours.

Service areas include Los Angeles, Long Beach, Pasadena, Glendale, Burbank, Santa Monica, Torrance, Santa Clarita, Sherman Oaks, Culver City, Inglewood, El Segundo, Downey, Whittier, Carson, Gardena, Alhambra, Monterey Park, Van Nuys, Woodland Hills, Encino, Studio City, Northridge, Cerritos, Pomona, West Covina, Arcadia, and up into Thousand Oaks and Simi Valley, where radon levels run considerably higher than they do here. If your property is not on that list, call and ask. See our full service area.

Commercial Radon Mitigation Systems

A property manager in Koreatown called us last spring about a 44-unit building where two ground-floor units had tested at 6.1 and 7.8 pCi/L during a refinance. The rest of the building was fine. That is the pattern here more often than not: radon shows up in a slab section, not a whole property, and the fix follows the slab, not the address.

Commercial mitigation almost always means active sub-slab depressurization. We core through the slab, excavate a small pit under it, connect schedule 40 PVC, and put a fan on the line that holds the space beneath your building at a slightly lower pressure than the space above it. Soil gas takes the easy path up the pipe instead of the hard path through your expansion joints. Before we quote a suction point count we run a communication test, drilling test holes and measuring pressure field extension across the slab, because a slab poured over clean gravel might be served by two points where the same square footage over compacted native soil needs seven.

More on how commercial mitigation systems are designed and priced »

Commercial Radon Testing and Measurement

Testing a commercial building is not a hardware-store kit on a shelf. Device placement follows the ANSI/AARST protocols for large buildings and multifamily, which means ground-contact rooms, minimum device counts, documented closed-building conditions, and chain of custody. We deploy continuous radon monitors for anything on a deadline because they produce hour-by-hour data and a same-week report, and alpha track detectors when someone genuinely needs a long-term picture.

Where this gets interesting is occupied buildings. Tenants open windows. HVAC economizers cycle. A test that ignores those realities produces a number nobody can defend.

Multifamily and Apartment Radon Testing

This is the biggest single driver of commercial radon work in Los Angeles, and it comes almost entirely from lenders. Fannie Mae, Freddie Mac, and HUD all touch radon on multifamily loans, and the rules moved in 2025: FHFA rescinded the 2023 directive that had standardized a 25% testing threshold, Fannie now leaves scoping to the environmental professional, and Freddie reduced its minimum to 10% of ground-contact units with at least one test per building where testing is warranted. What that means practically is that your consultant's judgment now matters more than a fixed number, and the testing still has to be done right.

We test around tenants, not through them: 48-hour notice letters we will draft for you, deployment and retrieval scheduled in two passes, and units documented individually.

Multifamily radon testing and lender documentation »

Schools, Childcare and Campus Buildings

Schools are their own animal. ANSI/AARST RMS-LB, the mitigation standard for schools and large buildings, exists because a school's HVAC system is doing half the work already, for better or worse. Unit ventilators and rooftop packages change slab pressure every time they cycle, so a classroom can test clean in April and elevated in December for reasons that have nothing to do with the ground.

We schedule campus work around the calendar. Testing during regular session with closed-building conditions, core drilling over breaks, and results reported classroom by classroom so a facilities director can hand a board or a parent group a document instead of a summary.

Office Buildings and Medical Office

Got a subterranean parking structure with occupied space above it? That is the LA office building question, and it is usually answered with building pressurization rather than a sub-slab fan. Adjusting outdoor air and return balance on an existing air handler can hold the lowest occupied level slightly positive and shut radon entry down without a single core hole. When it cannot, we run sub-slab points in the garage where the pipe is out of everyone's way.

Office building radon and HVAC-based control »

Warehouse, Industrial and Tilt-Up

Big slabs, small problems, long pipe. An industrial building in Vernon or Torrance often needs only two or three suction points for 60,000 square feet because the slab was poured over an engineered aggregate base that moves air beautifully. The engineering challenge is routing: pipe has to clear forklift traffic, racking, and dock doors, which is why we sleeve or bollard every riser below 12 feet. Industrial sites also tend to be the ones where radon is not the only soil gas in play.

Vapor Intrusion and VOC Mitigation

Trichloroethylene does not care that it is not radon. Same pathway, same physics, different regulator: in Los Angeles, vapor intrusion sites usually sit under the Department of Toxic Substances Control rather than a building department, with screening levels, sub-slab and indoor air sampling, and long-term operation, maintenance and monitoring obligations that outlive the install. Old dry cleaners, plating shops, gas stations, and the industrial corridors around Torrance and the Del Amo and Montrose areas are where these show up.

Vapor intrusion mitigation under DTSC oversight »

LADBS Methane Mitigation Systems

Roughly a quarter of the City of Los Angeles sits in a methane zone or methane buffer zone, a legacy of the oil fields under the city and the 1985 Ross Dress for Less explosion in the Fairfax District that killed 23 people. Ordinance 175790 and Division 71 of the building code came out of that. If your project is in a zone, you get a soil gas test, a Site Design Level from I to V, a PE-stamped mitigation design, and, at Level II and above, a methane deputy inspector watching barrier coupons get cut and measured for 60-mil thickness roughly every 500 square feet.

Check your property on ZIMAS before you assume you are clear. Buffer zone counts.

New Construction Soil Gas Systems

Building it in costs a fraction of retrofitting it. Vent mat or perforated pipe in the gravel blanket, a sealed membrane, risers stubbed through the structure, and provisions for a fan if verification testing later says you need one. On a ground-up project we coordinate with the structural drawings during design so risers land inside walls instead of in the middle of a leasable floor plate.

Maintenance, Monitoring and Fan Replacement

Radon fans are simple machines that run continuously for years and then quietly stop. We keep RadonAway RP265 and GP501 units plus Fantech commercial inline fans in the shop so a replacement is usually same-week, not a special order. Service agreements cover annual manometer verification, fan checks, and retesting on whatever cycle your lender, district, or O&M plan requires. Telemetry monitoring is available where somebody needs an alert the day a fan fails rather than at the next inspection.

System maintenance, monitoring and fan replacement »

What Happens When You Call Us

1. A real conversation about the building. Age, foundation type, unit or square footage count, what triggered the question, and what deadline you are working against. Ten minutes on the phone tells us more than a form does.
2. Measurement first, always. Nobody should install a mitigation system on a building that has not been tested. We deploy devices per protocol and give you the data.
3. Diagnostics if a result comes back elevated. Communication testing on the slab tells us the suction point count, which is the single biggest line item in your quote.
4. A written scope and a fixed price. Fan model, pipe routing, penetration details, discharge location, expected disruption, and schedule.
5. Install, phased around your operations. Loud work happens when the building is empty.
6. Post-mitigation verification test and a signed report. If it does not read below 4.0 pCi/L, we come back and adjust the system. That part is not optional and not an extra.

What This Costs, Plainly

Scope	Typical LA range	What moves the number
Commercial radon testing, small building	$650–$1,800	Device count, CRM vs long-term, turnaround
Multifamily testing, per unit tested	$45–$110	Unit count, access coordination, one vs two mobilizations
Single-slab mitigation system	$6,500–$12,000	Suction points, pipe run length, roof access
Multi-building or multi-slab property	$14,000–$28,000+	Number of separate slabs, each is effectively its own system
Affected multifamily unit (industry modeling)	$2,400–$4,000	AARST 2025 modeling; spreads to a few hundred per door portfolio-wide
Annual service and verification	$450–$1,600	System count, telemetry, retest frequency

Ranges reflect our own LA-area commercial work plus published industry modeling. Every commercial quote follows a site visit, because suction point count is the biggest variable and nobody can guess it from an address. Full breakdown in the commercial radon cost guide.

Questions We Get From Property Owners

Is radon actually a problem in Los Angeles buildings?

Mostly no, and that honesty is the point: Los Angeles County Public Health estimates only about 1% of buildings here test above the EPA action level of 4.0 pCi/L. But "about 1%" is not zero, and it is not spread evenly. The hillside zip codes along the south edge of the San Fernando Valley sit on marine sedimentary rock with above-background uranium, and the state's own testing database has produced readings in Studio City that averaged around 20 pCi/L. Ventura County, half an hour up the 101, is considered a high radon area outright. So the useful answer for a property owner is: your portfolio probably tests clean, one or two buildings might not, and you cannot tell which is which without measuring.

What triggers a commercial radon test in a low-radon market like ours?

Four things, in rough order of how often our phone rings for them. Agency and lender due diligence on multifamily acquisitions and refinances. School, childcare, and senior-living policy or parent pressure. A Phase I environmental site assessment where the consultant flags radon in scope. And a tenant, an employee, or a corporate EHS group who asked a question nobody at the property could answer.

How much does commercial radon mitigation cost in Los Angeles?

Most of our commercial systems land between $6,500 and $28,000, and the number is driven almost entirely by how many suction points the slab needs. A single-slab tilt-up warehouse can sometimes be handled with two points and a long run of pipe. A 1960s garden apartment complex with eleven separate slabs is eleven small jobs. For multifamily, industry modeling published through AARST in 2025 put affected-unit costs around $2,400 to $4,000 per unit, which on a large property spreads to a few hundred dollars per door across the whole asset. Our cost guide breaks all of it down.

Can you work while the building stays open?

Yes. Nearly all of our work is in occupied buildings, and the schedule is usually the harder problem than the engineering. Core drilling is loud for about twenty minutes per point, so we do that early, on weekends, or during school breaks. Pipe runs go in mechanical rooms, stairwells, and back-of-house corridors wherever we can keep them out of tenant space.

Who is legally allowed to do radon work in California?

Anyone providing professional radon measurement or mitigation in California has to appear on the California Department of Public Health certified list, which requires NRPP or NRSB certification and recertification every two years. Mitigators additionally have to hold a California contractor's license in classification B, C-20, C-36, or D-64. Ask any bidder for both. Plenty of general contractors will happily install a fan and a pipe without either one, and that install will not stand up when your lender's environmental professional reviews the file.

Is radon mitigation the same thing as methane mitigation?

The hardware rhymes; the rules do not. Both pull soil gas out from under a slab and vent it above the roofline. But methane work inside the City of Los Angeles falls under LADBS Division 71, which assigns your property a Site Design Level from I to V based on soil gas testing, requires a PE-stamped design, and brings in a methane deputy inspector at Level II and above. Radon work follows ANSI/AARST standards and has no deputy inspector. We do both, which is the whole reason we exist as one company: on a Fairfax or Santa Monica project you frequently need one system that satisfies both.

What happens if a test comes back over 4.0 pCi/L?

You mitigate the affected area and retest until it reads below 4.0. That is the standard every agency uses.