Commercial & Multifamily Radon Mitigation in Peoria, IL

Why Larger Buildings Usually Need Multiple Systems

A single-family home often achieves full-building depressurization from one or two suction points because the foundation is a relatively small, continuous footprint. A commercial building or apartment complex is a different animal: larger footprints, sections built or added at different times, interior structural footings that interrupt the aggregate layer beneath the slab, and sometimes a mix of foundation types within the same structure, slab in one wing, crawlspace in another. Any one of these factors can prevent a single suction point from achieving adequate negative pressure across the entire footprint, which is why most commercial and multifamily projects need multiple systems rather than one oversized one.

In apartment buildings specifically, individual units often have separate HVAC zoning, and radon entry can vary meaningfully unit to unit depending on which section of the building's foundation sits beneath each one. A unit directly above a section with poor sub-slab aggregate drainage, or above a shared mechanical room slab poured differently than the rest of the building, can read very differently than the unit next door, which is part of why per-unit or per-zone testing often matters more in multifamily settings than a single building-wide number would suggest.

Assessment: Understanding the Building Before Designing Anything

Commercial and multifamily projects start with a more involved assessment than a single-family home, because the stakes of an undersized or poorly placed system are higher and more expensive to correct after the fact. That means reviewing the foundation plans if available, walking the full footprint including any additions or renovated sections, checking for multiple slab pours or foundation types within the building, and testing to understand where radon levels are actually elevated rather than assuming uniformity across the whole property.

For occupied multifamily buildings, this often means coordinating testing across multiple units, at minimum a representative sample of ground-contact and lowest-level units, since those are the units most exposed to soil gas. Office and institutional buildings get a similar approach, focused on occupied ground-contact spaces rather than upper floors that have no direct soil contact.

Schools and daycare facilities deserve a specific mention here, since occupants spend concentrated hours in ground-contact classrooms and common areas, often at ages where lung development is still ongoing. Assessment for these buildings follows the same principles as any commercial property, full footprint review and representative testing, but scheduling around the academic calendar and minimizing disruption to classroom space are practical considerations that come up more in this setting than in a typical office building.

• •Full footprint assessment across additions and foundation types
• •Per-unit or per-zone testing rather than one building-wide number
• •Multi-system design matched to how the foundation is sectioned
• •Coordination around occupied space and tenant schedules

Designing and Installing Systems in Occupied Buildings

Working in an occupied apartment building or active commercial space adds logistics that a vacant single-family home does not have. Suction points and pipe runs need to be routed with tenant disruption and building aesthetics in mind, sometimes through shared mechanical spaces, sometimes requiring coordination with property management on scheduling to minimize impact on residents or business operations. Multiple fans across a larger property also mean more attention to electrical circuits, roof penetrations, and how discharge points are positioned relative to windows, balconies, and outdoor common areas that people actually use.

The installation itself follows the same underlying principles as a residential system, suction points into the sub-slab or sub-membrane space, connected to continuously running fans, discharging above the roofline, but scaled and multiplied to match a footprint that a single system was never going to adequately cover. Manometers or, in some larger installations, more robust monitoring get installed at each system so building maintenance staff have a straightforward way to confirm ongoing function across every zone.

Timeline, Cost Considerations, and Verification

Commercial and multifamily projects take meaningfully longer than single-family installs, often spanning multiple days to weeks depending on the number of systems required, building size, and how much coordination with occupied units the work requires. Cost scales with the number of systems and the complexity of routing pipe through larger, often more finished, structures, and a meaningful estimate can only come after the assessment phase has actually mapped out how many systems the building needs.

Verification matters even more at this scale. After installation, retesting across the same representative units or zones used in the initial assessment confirms that every section of the building, not just the areas nearest a suction point, has actually come down below the action level. For property owners, that documentation also matters for due diligence files, tenant communication, and demonstrating that the building has been properly addressed rather than partially treated.

Ongoing maintenance also looks different at commercial scale. A single-family home has one fan to monitor, while a larger property may have several systems spread across a footprint, each with its own manometer or monitoring point. We recommend property management build a periodic check of every system into routine building maintenance rather than treating radon mitigation as a one-time project that never needs revisiting, since a failed fan in a wing of a larger building is easy to miss without a deliberate check.

Frequently Asked Questions