How to mitigate radon in Boston, MA
Radon is a measurement problem before it is a contracting problem. Test first, design the system to your foundation, and confirm with a post-mitigation test — anything else is guessing with a fan.
What to know about radon mitigation in Boston
Boston has some of the oldest housing stock in the country, including Beacon Hill brownstones, Back Bay row houses, South End bowfronts, and triple-deckers across Dorchester, Roxbury, and Jamaica Plain. Many properties are 100+ years old with lead paint, aging galvanized supply lines, knob-and-tube remnants, and historic preservation constraints.
Boston winters average ~49 inches of snowfall. Summer heat and humidity stress HVAC systems, and coastal storms, nor'easters, and bomb cyclones cause regular wind and water damage to exposed facades. Sea-level rise is making once-rare flood events routine in East Boston, the Seaport, and Charlestown.
How we price it
These are the factors that move a quote up or down. Knowing them helps you share the right context upfront so we can quote your specific situation accurately — and so you can compare bids on apples-to-apples scope.
Poured-concrete basement with good sub-slab aggregate is the simplest install — one suction point through the slab, sealed PVC riser, exterior fan. Slab-on-grade homes need careful suction-point siting because there is no basement to route through. Crawlspaces need a sealed membrane (encapsulation) tied into the suction system. Fieldstone or rubble foundations cannot be depressurized at the slab — they require a different approach, usually block-wall depressurization or full crawlspace encapsulation, and cost roughly 1.5–2x a standard install.
A single 4-inch suction point covers most homes up to about 2,000 sqft of slab if the sub-slab aggregate communicates well. Larger footprints, slabs poured in sections, or homes with interior footings that block airflow under the slab need additional suction points. Each additional point adds roughly $300–600 — pipe, coring, sealant, and labor.
Code (ANSI/AARST RMS-SF 2023) requires the fan to be outside the conditioned envelope — exterior wall, attic, or garage, never in a basement or living space. A clean exterior run up the side of the house is the cheapest and most accessible. Routing through an interior chase, up through closets, and out through the roof is more labor and looks better but adds $400–900. Aesthetics matter more on the front elevation than the back.
An open sump pit is a giant radon entry point. If you have one, it must be sealed with an airtight cover (gasketed, with grommets for the pump cord and discharge line) and tied into the mitigation system. Done right, your sump pit becomes a free second suction point. Done wrong, your sump pump fails because the cover blocks float-switch access. Confirm the mitigator uses a serviceable cover with a removable inspection port.
Short-term charcoal kits ($15–35) are cheap, mailed in, and adequate for a baseline screening — but they are vulnerable to "closed-house" violations and weather swings. Continuous radon monitors (CRMs) deployed for 48+ hours by a certified tester ($150–300) give you hour-by-hour readings, tamper detection, and a defensible result for real estate transactions. For any home where you are deciding whether to mitigate, the CRM test is worth it.
A legitimate install includes a post-mitigation short-term test 24 hours to 30 days after the fan is energized. EPA action level is 4 pCi/L; the practical mitigation target is below 2 pCi/L. If the post-test comes back at 3.5 pCi/L, technically you are "under the action level" but the system is underperforming and the mitigator should adjust (add a suction point, swap to a higher-static-pressure fan) at no charge.
RadonAway RP series and Festa AMG series are the industry standards. Fan model is sized to the suction needed (RP145 for tight slabs, RP265 for loose aggregate, larger for crawlspaces). A correctly sized and properly isolated fan is barely audible from inside. Vibration coming through the riser into the living space means the fan is rigidly coupled to the PVC — a soft rubber coupling at the fan inlet and outlet fixes it.
Project sizes we handle
Three scopes that cover almost everything in this trade. We'll help you place your project on the right tier based on the property, what you've already tried, and how long you plan to stay.
Single 4-inch suction point through the basement slab, 3-inch or 4-inch PVC riser up an interior wall and out through the rim joist, exterior-mounted RadonAway RP145 or RP265 fan, vertical discharge above the eave. U-tube manometer installed at the riser to confirm the fan is pulling vacuum. Post-mitigation short-term test included.
- Schedule 40 PVC, 3" or 4"
- RadonAway RP145 / RP265 fan
- U-tube manometer
- Polyurethane sealant at slab penetration
Best for: Most poured-concrete basements in single-family homes up to ~2,500 sqft footprint, with a single accessible exterior wall for the riser.
Two or more suction points (or one suction point plus an airtight, integrated sump cover), interior PVC routing up through a closet chase to an attic-mounted fan and roof penetration, balanced for even airflow. Includes pre-install sub-slab communication test to verify suction-point siting. Sealed sump pit with serviceable inspection port. Post-mitigation CRM test (48-hour) instead of short-term charcoal.
- RadonAway RP265 or Festa AMG500
- Schedule 40 PVC with sweep elbows
- Gasketed sump cover with pump-cord grommet
- Pre-install smoke test for sub-slab communication
Best for: Homes with 2,500+ sqft slabs, interior footings that segment the sub-slab area, finished basements where exterior routing is undesirable, or homes with an existing sump.
For crawlspaces: 12+ mil reinforced vapor barrier (e.g. Stego Wrap, Viper CS) covering the entire floor and partway up walls, all seams taped and sealed, perforated suction line under the membrane, tied into a dedicated fan. For fieldstone or rubble foundations: block-wall depressurization or perimeter sub-membrane system, often with multiple suction points. Includes long-term alpha-track confirmation (90 days) in addition to the short-term post test.
- 12-mil+ reinforced poly vapor barrier
- Sealing tape rated for vapor barriers (e.g. PolyShield)
- Perforated sub-membrane suction piping
- Block-wall depressurization piping for fieldstone
- Long-term alpha-track detector for verification
Best for: Crawlspaces, fieldstone or rubble foundations, homes with mixed foundation types (e.g. partial basement + crawlspace), or homes that tested above 10 pCi/L where you want maximum reduction.
What we reach for and why
The materials and techniques behind a job that lasts — so you know what's in the quote and why it's there.
The dominant method for basements and slab-on-grade homes. A fan pulls a slight negative pressure under the slab, intercepting radon-laden soil gas before it enters the home and venting it above the roofline. When the foundation supports it, SSD reduces indoor radon by 90%+ — typically from 10–20 pCi/L down to below 2.
A reinforced 12+ mil vapor barrier sealed at the perimeter and at every seam, with perforated suction piping run beneath it, tied to a dedicated mitigation fan. The membrane is both the radon barrier and a moisture barrier — pulling double duty against rot and mold. Cheap polyethylene (6-mil construction plastic) is not adequate; specify a reinforced cross-laminated product like Stego Wrap or Viper CS.
Used on hollow concrete-block (CMU) or fieldstone foundations where you cannot effectively depressurize under the slab. Suction is pulled from inside the hollow block cores or the wall cavity, intercepting radon before it enters the basement air. Often paired with SSD on the slab and capping the top course of block.
The default mitigation fan in the US. RP145 for tight, low-permeability slabs (high static pressure, lower airflow). RP265 for typical residential. RP380 for crawlspaces or loose aggregate. Listed lifespan is 8–12 years; most fail in the 10-year range and should be replaced before they stop pulling vacuum (the manometer will show the drift before you smell anything).
A simple water-filled gauge installed at the PVC riser that shows the fan is pulling vacuum. The two water columns should be at unequal heights whenever the fan is running. If they level out, the fan has failed or the system is leaking — check before you assume the system is working. Every code-compliant install requires one.
Schedule 40 PVC (3" or 4") with sweep elbows for airflow, not standard plumbing 90s. Slab penetration sealed with polyurethane sealant (not silicone — it does not bond to concrete reliably). Discharge must be at least 10 feet above grade, 10 feet from any window or air intake, and terminate above the eaveline. Codes vary on horizontal vs. vertical discharge — RI and MA both require vertical termination above the roof or eave.
Polycarbonate or polyethylene cover with a foam gasket, sealed to the rim of the sump pit with polyurethane sealant or butyl tape. Grommeted penetrations for the sump-pump power cord and discharge line, plus a removable inspection port so the pump can still be serviced. Done right, it doubles as a second suction point and adds zero ongoing maintenance.
What to watch for
A short list of the things that actually matter for safety, code, and your peace of mind. Worth confirming with any pro before you sign — we expect these questions and we're happy you ask.
What else might come up
Most projects touch more than one trade. Here's where this one usually overlaps with others — so you can plan ahead instead of scrambling.
Radon testing is a standard inspection add-on ($150–300) and one of the most common deal items in southern New England. If you are buying, get a 48-hour CRM test during the inspection window. If you are selling, pre-testing and remediating before listing avoids price negotiations later.
A sealed sump cover is part of the radon system. If you are replacing the pump, do it before the radon install so the mitigator can integrate a serviceable cover. If you are installing a new sump in a home that might need mitigation, scope it with a sealed-cover-ready design.
Encapsulation is both the moisture fix and the radon barrier. Combining the jobs saves $500–1,000 versus doing them separately, and the radon piping has to go under the membrane — so it has to be installed at the same time as the encapsulation.
The fan runs 24/7 and should be on its own switched circuit (or a dedicated, labeled breaker) so the homeowner can de-energize it for service without killing other loads. Some installs use an existing exterior outlet, but a dedicated circuit is the cleaner solution and adds $250–450.
Water and radon enter through the same cracks and joints. Sealing the cove joint, repairing foundation cracks, and routing groundwater (interior drain tile, exterior waterproofing) reduces both. Done together, the radon system has less infiltration to fight and the basement is dry.
A standard sub-slab depressurization (SSD) system on a poured-concrete basement runs $1,200–2,500. Short-term test kits run $15–35 mail-in; a professional continuous-monitor test is $150–300. Fieldstone foundations, crawlspaces, and multi-suction-point installs push the system into the $2,500–4,500 range.
The dominant cost drivers are foundation type, the number of suction points needed, the fan routing path through the house, and whether your existing sump pit needs to be sealed and integrated.
See what drives priceWhat we show up with
The equipment we bring is part of what separates a real job from a shortcut. Here's what to expect on a typical visit.
Hour-by-hour radon readings with tamper detection. Used for pre-install testing, post-mitigation verification, and real estate transactions. Sun Nuclear 1028 and Femtotech RDS-30 are the workhorses.
Passive 2–7 day exposure cartridge mailed to a lab. The standard baseline screening tool for homeowners. Cheap, broadly accurate, vulnerable to closed-house violations.
Water-filled differential pressure gauge installed at the PVC riser. Confirms the fan is pulling vacuum at a glance. Required by ANSI/AARST code on every install.
Tests sub-slab communication during the design phase. Smoke at a test hole should be drawn toward the planned suction point when the fan runs — confirms one point will pull from the whole slab.
Cuts the suction-point hole through 4–6 inches of concrete slab cleanly without cracking. Wet drilling controls dust. A hammer drill and chisel is not an acceptable substitute on a finished basement.
The fan that actually does the work. Sized to the foundation: RP145 for tight slabs, RP265 for typical residential, RP380 for crawlspaces. 8–12 year service life.
Seals the slab penetration around the suction-point pipe and seals the cove joint and any visible slab cracks. Bonds to concrete, stays flexible — silicone does not work here.
How a job goes
Pre-mitigation test & diagnostic visit
Confirm the radon level with a 48-hour CRM test if not already done. On the diagnostic visit, the mitigator walks the foundation, identifies the slab type, locates the cove joint, finds the optimal suction-point location, and runs a sub-slab communication test (smoke pencil at a test hole) to confirm one suction point will pull from the whole slab. Identifies whether an additional suction point or sump integration will be needed.
What you see: The pro inspecting the basement perimeter, drilling a small test hole in the slab, running a brief vacuum-pressure test, walking the exterior to plan the riser route.
System design & quote
Quote based on what was found, not a template. Specifies suction-point count and location, fan model, routing path (exterior wall vs. interior chase), sump integration if applicable, sealing of cove joint and visible slab cracks, and the post-mitigation test method. Includes the 5-year warranty terms and the target post-mitigation level (<2 pCi/L).
What you see: A written scope with diagrams or photos showing where the suction point, riser, and fan will be installed. No surprises after this point.
Core drilling & suction point
Wet-core a 4" hole through the slab at the planned location, excavate 3–5 gallons of soil under the slab to create a suction void, drop in the PVC stub, seal around the penetration with polyurethane. Seal the cove joint and any visible slab cracks as part of the same visit.
What you see: Some water from wet drilling, a contained pile of slab dust, the suction-point pipe protruding 6–8 inches above the slab. The cove joint sealed with a visible bead of polyurethane.
Riser, fan & exterior penetration
Run Schedule 40 PVC from the suction point up the wall and out through the rim joist (or up through an interior chase to the attic). Mount the fan outside the conditioned space — exterior wall, garage, or attic. Vertical discharge above the eave or roof. Install the U-tube manometer at the riser. Wire the fan to a dedicated circuit or switched outlet.
What you see: PVC piping up the wall, fan housing mounted with rubber isolation, manometer mounted at eye level on the riser, exterior discharge pipe extending above the eave.
Energize & post-mitigation test
Power on the fan, confirm the manometer shows differential pressure (water columns unequal), check for any audible vibration and add isolation if needed. Deploy a 48-hour CRM or short-term charcoal kit. Read the results 24 hours to 30 days later. Target is below 2 pCi/L. If above, mitigator returns to add a suction point or swap to a higher-static-pressure fan at no charge.
What you see: Manometer reading confirmed (photo it for your records), fan running quietly outside, a test device sitting in the basement for 48 hours, a written report with the post-mitigation pCi/L number when it comes back.
Documentation & warranty handoff
Written package: pre- and post-mitigation test results, system diagram, fan model and install date, manometer baseline photo, warranty terms (5-year system, 5-year manufacturer fan), and maintenance schedule (visual manometer check monthly, retest every 2 years). Keep this with your home closing documents — it transfers to the next owner.
What you see: A folder or PDF with everything you need to prove the system exists, works, and is under warranty.
- Most recent radon test result (pCi/L) and the test type (short-term charcoal, CRM, long-term alpha-track)
- Foundation type (poured basement, block basement, fieldstone, crawlspace, slab-on-grade, or mixed)
- Approximate square footage of the slab or crawlspace footprint
- Whether you have an existing sump pit and where it is located
- Year the home was built
- Photos of the basement walls, slab, and any exposed footings or interior support walls
- Photo of the exterior elevation where the riser might run
- Photo of the rim joist area where the pipe would penetrate the wall
- Whether the basement is finished, partially finished, or unfinished
- Any history of moisture, efflorescence, or visible cracks in the slab or walls
- Test result above 10 pCi/L (priority install — EPA recommends action within months, not years)
- Fieldstone or rubble foundation (specialty mitigation, not a standard SSD)
- Mixed foundation (e.g. basement plus crawlspace) — almost always requires a multi-zone approach
- Existing sump pit with an open or loosely covered top (significant entry point that changes the system design)
- Visible cracks in the slab wider than 1/8 inch or a separated cove joint (entry points that need sealing as part of the install)
Permits, timing, and what's local to Boston
Permits & regulations
Boston's Inspectional Services Department oversees building, electrical, plumbing, and gas permits. The city has strict zoning, historic district overlays (Back Bay, Beacon Hill, South End, Bay Village, Mission Hill Triangle), state energy code plus the Boston stretch code, and BERDO emissions reporting for larger buildings.
Permit authority: Boston Inspectional Services Department (https://www.boston.gov/departments/inspectional-services)
What's local to Boston
Mass Save rebates (heat pumps, weatherization, induction) apply citywide and stack with BERDO compliance work — worth raising on any HVAC or envelope project.
What homeowners ask us
Where else we serve
Ready to Get Started?
Call or text us for a free consultation about Radon Mitigation in Boston. Our experts are ready to help.
Call or Text
401.407.5678Available 7 days a week • Response within minutes
Get a Free Text Estimate: