Crawl Space Radon Mitigation

With 20 years of experience, Grand Junction Radon Mitigation installs sub-membrane depressurization (SMD) systems in crawl spaces throughout Mesa County. Our Colorado-licensed, NRPP-certified radon mitigation professionals seal the crawl space floor, exhausts radon above the roofline, and verifies performance through post-mitigation testing. Most radon-only installations take one day. Projects that include full encapsulation take longer.

Grand Junction Radon Mitigation is committed to improving indoor air quality for Western Colorado homes and businesses with reliable testing, mitigation, repairs, and customized solutions. Our team offers certified, dependable service, and provides quality workmanship.

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Why Radon Matters

Radon is an invisible, scentless radioactive gas, and testing is the only way to determine whether it is present in your home. In the U.S., it ranks as the second leading cause of lung cancer and is the top cause among people who have never smoked. In Colorado, radon is linked to roughly 500 lung cancer deaths each year, and around half of the state’s tested homes measure above the EPA’s action level.

The encouraging part is that radon exposure can be prevented. When a mitigation system is installed correctly, it blocks soil gas from entering your living area, and a follow-up test shows whether it was effective.

How Radon Gets Into Crawl Spaces

Radon is a naturally occurring radioactive gas produced when uranium and radium in soil and rock decay. Radon levels vary from home to home, even on the same street, but elevated readings are common across the Grand Valley, so every home should be tested.

Radon in a crawl space is common because the exposed soil floor gives soil gas a direct path into your home. Radon can enter through:

Exposed dirt floors without a vapor barrier
Foundation or stem wall cracks
Openings around pipes, wiring, and utility penetrations
Unsealed sump pits and loose access doors

After it enters, radon moves upward through floor joints and ductwork into the living area. The EPA recommends mitigation for any home measuring at or above 4.0 pCi/L and suggests considering it for levels between 2.0 and 4.0 pCi/L.

Radon in Grand Junction and the Grand Valley

Radon is a statewide issue in Colorado. About half of tested homes exceed the EPA action level, and the average indoor reading is well above the national norm, in part because of the state’s geology. Levels vary from county to county and from house to house, so testing is the only way to know.

Colorado’s health department offers free radon test kits periodically; check its website for availability. They also offer low-income radon mitigation assistance program for qualifying households.

Crawl Space Radon Mitigation Choices

Because crawl spaces expose the entire dirt floor to soil gas, they require a different strategy than slab foundations. We select the system according to the crawl space condition, access, and radon reading.

Sub-Membrane Depressurization Systems

For dirt or gravel crawl spaces, SMD is our primary solution. We install a heavy-duty membrane (also called a vapor barrier or liner) over the floor and place a perforated pipe beneath it. A fan then draws radon from under the membrane before it can reach the home.

Crawl Space Radon Fan and Ventilation Systems

An in-line radon fan installed in the attic, garage, or on an exterior wall removes soil gas and vents it above the roofline. Fan sizing is matched to the crawl space and soil conditions. A U-tube manometer allows you to verify operation at any time.

Vapor Barrier and Sealing: Blocking Soil Gas at the Floor

We use 10- to 20-mil reinforced polyethylene that meets ASTM E1745 requirements, chosen for how the space is used.

In crawl spaces that are rarely entered and have smooth, clear floors, 10- to 12-mil is our standard choice. We step up to 15- to 20-mil where there is regular foot traffic, stored items, mechanical equipment, or rough ground, because thicker reinforced liner resists tears and punctures.

We overlap seams by 12 inches, seal them with manufacturer-approved tape, and seal the liner to piers, pipes, and walls.

Crawl Space Depressurization (When a Full Membrane Isn’t Practical)

If low clearance or obstructions prevent full membrane installation, crawl-space depressurization may be used. A high-capacity fan vents air above the roofline, keeping the crawl space at lower pressure than the living area.

This approach requires sealing the crawl space and may raise energy costs. Because depressurization can cause fuel-burning appliances to backdraft, we test them before and after installation and recommend working CO alarms. We also verify suction and retest radon.

Sealed membrane systems generally perform more reliably, so we recommend crawl space depressurization only when a membrane can’t be installed.

Encapsulation: Controlling Radon and Moisture Together

Grand Junction crawl spaces face radon as well as moisture from spring snowmelt and irrigation runoff.

Sealing the crawl space helps address both concerns.

Full Crawl Space Encapsulation

We cover the floor with 12- to 20-mil reinforced liner and the walls and piers with [10- to 12-mil], tape all seams, and attach the liner to the foundation walls. Vents, rim joists, and other openings are sealed too. Because encapsulation by itself may not reliably reduce radon below 4.0 pCi/L, we combine it with SMD to manage radon and moisture in a single project. See our cost section below for how encapsulation affects the price of your radon system.

Moisture, Humidity, and Mold Prevention

Before suggesting a solution, we look for standing water, condensation, and musty smells. Based on the crawl space, we may install a dehumidifier, drainage mat, or sump pump to safeguard joists and subflooring from mold and rot.

Homes With a Basement, Slab, or Mixed Foundation

Many Grand Valley homes have more than one foundation type: a crawl space beside a basement, under an addition, or next to a slab-on-grade garage or family room. Radon can enter anywhere the home touches soil, so treating one area and ignoring another can leave a pathway open.

We match the method to each area:

Dirt or gravel crawl space: sub-membrane depressurization (SMD)
Concrete slab or basement floor: sub-slab depressurization, with suction through the slab
Sump pits, block walls, and floor-wall joints: sealing and suction as needed

Depending on the layout, one fan may serve more than one area, or separate suction points or fans may be needed. We decide this during your inspection using diagnostic testing and your radon results. Where a crawl space connects to a basement through a door or opening, we seal that connection. After installation, we retest the lowest livable level and any other areas of concern.

[Link: Learn more about basement and slab radon mitigation.]

Signs Your Crawl Space May Need Radon Mitigation

The most obvious indicator is a radon test result of 4.0 pCi/L or above. Additional warning signs include:

Exposed dirt floors or an unsealed vapor barrier
Foundation cracks or uncovered sump pits
Damp conditions, high humidity, or musty odors
Older crawl spaces that are not sealed

A home that has never been tested, or a real estate transaction that requires testing

How and Where to Test for Radon in a Home With a Crawl Space

If you’re planning a radon test in Grand Junction, test the home’s lowest livable level, rather than the crawl space itself. Since your family lives and breathes in the rooms above, that is the level that counts for the reading.

Pick an appropriate room: use a space that is regularly occupied, such as a bedroom or living room. Do not place the device in kitchens, bathrooms, laundry rooms, or closets.
Location: position it about 20 inches to 6 feet above the floor, and keep it clear of exterior doors, windows, vents, fans, and drafts. Use the directions that come with your kit.
Closed-house setup: for roughly 12 hours before a short-term test, and while the test is running, keep windows and exterior doors shut except for ordinary entry and exit, and do not operate whole-house or window fans.
Test length: a short-term test lasting 48 to 96 hours provides a fast snapshot.
Next step: because radon levels shift with weather, season, and how tightly sealed the home is, an elevated reading should be checked again with a second test before you make a decision.

If you hire someone to test it, Colorado law requires a licensed radon measurement professional. Once mitigation is in place, testing should be done at least 24 hours after the system starts running to verify that levels are under 4.0 pCi/L.

Our Crawl Space Radon Mitigation Process

Step 1: Inspection and Radon Assessment

We examine the soil, moisture, existing vapor barrier, and entry points, and we also review your radon test results.

Step 2: Custom System Design and Installation

We install the membrane, vent piping, and fan, seal all seams and penetrations, and label the system. Projects with full encapsulation or moisture work take longer, and your estimate will include a schedule.

Step 3: Verification and Post-Mitigation Testing

We verify suction at several points beneath the membrane, then test and confirm levels are below 4.0 pCi/L. We recommend retesting every two years.

What to Expect on Installation Day

Before we begin, we will review the plan with you and verify the locations for the suction pipe, fan, and outside vent.

Access: clear entry to the crawl space hatch and the pipe path is required. Please relocate stored items away from the access area and inform us about any pets. NAn adult needs to be home to give access o one needs to be home as long as we have access.
Installation: first we prep the crawl space floor, then we place and seal the membrane, fit the suction pipe and place the membrane over it, seal piers, penetrations, and sump covers, route the vent pipe above the roofline, install the fan, add the manometer, and label the system.
Power: the fan plugs into an existing outlet.
System testing: we confirm suction at multiple locations and, if fuel-burning appliances are present, check that they operate safely.
Finish: we explain how to read the manometer and leave your paperwork with you.

In most cases, radon-only installations are completed in one day. Some normal work noise should be expected during installation, although the fan itself runs quietly. Your follow-up radon test is performed at least 24 hours after the system begins operating.

After Installation: Living With Your Radon System

The U-tube manometer on the pipe shows whether the fan is working. Uneven liquid levels mean suction is on, and equal levels mean it isn’t.

Check the breaker, and call us if the manometer reads equal. Radon levels will rise if the fan stays off.

Our fans carry a 5-year manufacturer warranty when professionally installed and typically last 5-10 years or more. If a fan ever needs replacing, the cost is typically $300-$800 installed.

Most residential radon fans draw about 15 to 75 watts, with larger models up to roughly 150. That typically costs about $20-$90 a year in electricity.

We discuss routing and color-matching with you at the estimate.

Don’t puncture it, keep stored items off it, and keep the access door closed.

Test again every two years and after major renovations or foundation work.

We provide documentation you can pass to buyers.

What Radon Mitigation Costs in Grand Junction

The radon mitigation cost in Grand Junction is determined largely by whether the job calls for only a radon system or for that system together with complete crawl space encapsulation.

Radon system only (sub-membrane depressurization): $2,000 to $4,500
Radon system with full encapsulation: $5,000–$15,000+, depending on crawl space size and condition
Moisture add-ons (dehumidifier, drainage mat, sump pump): quoted separately after inspection

Pricing depends on crawl space size and accessibility, vent pipe routing, fan type, existing moisture or debris, and the scope of any encapsulation work.

After an in-person inspection of your crawl space, we provide a written, itemized estimate. Buying or selling? Radon testing is common in Colorado home sales, and if a result comes back high, we can help with radon mitigation for a home sale and the documentation your buyer or lender may ask for. Check with your lender or agent about what applies to your transaction.

Help Paying for Mitigation

Assistance with mitigation costs is available through Colorado’s Department of Public Health and Environment. Its Low Income Radon Mitigation Assistance (LIRMA) program may pay for a radon system for homeowners who qualify. In general, applicants need to own and occupy the house, satisfy the program’s income criteria, and have a radon test result above 4.0 pCi/L. Income limits depend on county and household size, and applications are submitted online through CDPHE. In 2025, CDPHE helped mitigate more than 200 homes through the program, and it also provides free test kits to Colorado residents as long as supplies remain.

Our Standards, License, and Certifications

Colorado requires radon mitigation to be performed by a state-licensed professional, and licensed mitigators must follow ANSI/AARST radon mitigation standards. We install to ANSI/AARST SGM-SF, the soil gas mitigation standard for existing homes.

In practice, that means:

Membrane materials that meet ASTM E1745 where a membrane is used
Overlapped, sealed seams, sealed to piers, pipes, and walls
A labeled system, with documentation for you
A post-mitigation radon test to confirm results

Credentials: Insured · 20 years of experience

Schedule Crawl Space Radon Mitigation in Grand Junction

Give us a call or submit our online form. We’ll inspect your crawl space, go over your radon results, and schedule the installation, then verify the outcome with a follow-up test. If your post-mitigation test does not show the expected drop (below 4.0 pCi/L), we will return and adjust the system at no extra charge.

We provide radon mitigation across Mesa County, including Fruita, Palisade, Clifton, Orchard Mesa, Fruitvale and Redlands.

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Frequently Asked Questions

A radon system alone typically costs $2,000 to $4,500. If you also want full crawl space encapsulation, projects generally run 5,000–15,000 or more, depending on size, access, and moisture conditions. Combining the two in one project often costs less than doing them separately, because the membrane serves both purposes.

Sub-membrane depressurization. It pulls radon from beneath a sealed vapor barrier and vents it outdoors, addressing the issue at its source.

Radon forms naturally from the breakdown of uranium and radium in Colorado’s soil and rock. The gas seeps into homes through cracks, sump pits, crawl spaces, and other openings that touch the ground, and elevated levels are common across the state, including in the Grand Valley.

In Colorado, radon mitigation must be performed by a state-licensed professional, so start by confirming the contractor’s license on the state’s lookup. The listings also show any disciplinary actions. Then look for NRPP or NRSB certification, references from crawl space projects (not just basements), a written itemized estimate, and post-installation testing by a licensed measurement professional.

Before mitigation, use a 48 to 96 hour short-term test on the lowest livable level. After mitigation, we test at least 24 hours after the system begins operating to confirm levels are below 4.0 pCi/L.

A vapor barrier or encapsulation on its own usually isn’t enough. Radon can still pass through small gaps and foundation walls. A sealed membrane paired with an active suction fan is what reliably pulls radon out from under the floor, which is why we combine them.

A high result doesn’t have to derail a sale. Radon systems can be installed quickly, and a post-installation test documents the result for buyers and lenders. Ask your agent how your contract handles radon, since terms vary.

Yes. Colorado’s Department of Public Health and Environment runs the Low Income Radon Mitigation Assistance (LIRMA) program. You apply online through CDPHE, which will tell you which documents to submit. CDPHE also offers free radon test kits to Colorado residents periodically, which is a good first step. You can check its website for availability and eligibility.