Why every homeowner should care about radon right now
Radon, a naturally occurring radioactive gas that leaks from soil and rock under houses, is the second leading cause of lung cancer in the United States, according to the U.S. Surgeon General. Because it has no odor, color, or taste, a house can test high even if the owner already lived there 20 years. The good news: if levels are below 4 pCi/L, the EPA says risk is low to moderate; if levels are above that, installation of a radon-reduction system typically lowers readings by 40 percent to 80 percent. With a weekend and about $250 in parts, most homeowners can install a straightforward DIY radon pipe system instead of paying $1,200 to $1,800 for a professional mitigator.
The $250 passive-to-active radon pipe system
There are two common DIY designs: a purely passive system and an active system that adds an inline fan. Passive systems work beautifully when a new slab is poured, but to bring down elevated levels in an existing house, an active system is almost always required. Here is the shopping list and game plan.
Shopping list (total before tax from any large home center):
- 150 cfm in-line radon fan – $110
- Royal pipe, 3-inch Schedule 40 PVC, 10 ft length – $16
- 5-ft Schedule 40 PVC pipe (cutoff of a longer stick) – $8
- PVC elbow 3-inch x2 – $6
- PVC clean out plug – $4
- PVC primer and cement – $13
- Roof flashing collar and vent cap – $24
- Plug-in lamp timer optional – $15
- Basic tools already on hand – drill, 1-inch spade bit, 3-inch hole saw, tape measure, utility knife, silicone caulk, caulk gun – $0
TOTAL: approximately $250
Step 1 – Test the house first
Before spending time or money, collect a two-day charcoal canister sample or mail-in alpha track test. Kits cost $15 to $30 at hardware stores and include prepaid return shipping. Try to run the test during cooler months when windows and doors stay closed. Record the exact pCi/L reading so you can celebrate the after-installation drop.
Step 2 – Pick the perfect pit
The ideal extraction point is:
- A poured concrete floor (basement or slab on grade)
- The floor with the least chance of plumbing or electrical lines underneath
- A spot beside an exterior wall (keeps later vent pipe run short)
Move any furniture and roll back rugs. Turn off HVAC for quiet so the drill battery lasts longer.
Step 3 – Core the 4-inch suction hole
Mark a 4-inch circle with a metal can. Drill a starter hole with a 1/4-inch masonry bit followed by a 3-inch starter spade bit to cut the circumference. The actual concrete hole ends up roughly 3.5 to 4 inches, plenty for the 3-inch PVC to sit inside. A cheap diamond grit hole saw from the hardware store makes the cut in about 10 minutes.
Step 4 – Clear soil out and wet-vac debris
Reach in with gloved hands or a bent metal spatula and rake a 4-inch deep cavity in the gravel or soil underneath the slab. Deepening the pit increases suction volume yet still leaves six inches of solid concrete around the edge for a solid seal later. Vacuum away crumbs so nothing falls back in.
Step 5 – Dry-fit all PVC
Slide the 3-inch PVC through the slab, attach a 3-inch sweep elbow directly above the hole, then route straight up an adjacent wall until the pipe reaches the chosen attic penetration. Keep elbows to a minimum – each adds static pressure. Use a torpedo level to ensure slight upward pitch so condensation runs back into the pit and not into the fan.
If the basement ceiling is finished, tack white PVC to the side of a closet wall, then trim drywall later to hide the line invisibly.
Step 6 – Cement pipe joints outdoors
Take the cut sections outside and glue them using primer then medium-set PVC cement. Inside, avoid solvents and fumes. Hold each joint for 30 seconds so the glue does not push apart. TIP: Give the entire stack an hour to cure before hauling back indoors.
Step 7 – Install fan correctly
Cut the straight riser about two feet above the floor and insert the in-line fan with the arrow pointing up (toward the roof). The fan manufacturer’s label usually announces flow direction to prevent backward installation. Seal the ends with rubber coupling joints that come in the fan box; hand-tighten with a screwdriver only.
Plugin installs: plug the cord into the nearest outlet and listen for a low hum. Power draw is roughly 50 watts, the same as an old incandescent light bulb. Turning the fan on a timer is unnecessary – EPA studies show systems are most effective when run 24/7.
Professional note: Most residential codes require a radon system fan to be outside the building envelope (typically attic). For basements without attic access, install the fan at the exterior wall so the fan sits in a small sealed box vented to the outside. Many brands sell kits pre-made.
Step 8 – Roof penetration and sealing
Use a standard 3-inch roof jack, nail into roof decking, and slide the PVC through. Add aluminum cap on top to block rain and birds. Roof caulk around both the flashing lip and pipe neck with high-temp silicone.
Interior: once the pipe is in the right spot, load the slab gap with hydraulic cement or expanding foam to lock PVC and block air leaks. Lightly wet the concrete surface before inserting hydraulic cement; it grips instantly. Sand smooth for a paintable finish.
Step 9 – Retest and record the drop
Wait 24 hours for the system to equalize, then place a fresh two-day test canister one foot off the slab floor. Mail results. Most homeowners record 40 percent to 70 percent reduction, but any reading under 2 pCi/L passes. If levels stay elevated, enlarge the pit beneath the slab or consider adding a second suction point in a different corner.
Maintenance schedule that takes five minutes a year
- 12 months: Look at the pipe for spider webs or ice clogs in winter. Remove vent cap and poke a stiff wire through.
- 24 months: Plug in a cheap watt meter and confirm fan draws 40-60 watts. A drop to 20 watts means the bearings are dying; replacement motor costs $70 and twists out in 10 minutes.
- Whenever basement work is done: Inspect floor joints where concrete meets wall. Patch any new cracks with polyurethane caulk to keep soil gas from escaping.
Common mistakes that kill suction pressure
Too many elbows: Every 90-degree elbow removes as much pressure as 5 feet of straight pipe. Limit the system to two elbows.
Wrong fan size: A bathroom exhaust fan (rated at 70 CFM) is built for air movement, not pressure. It will spin fast but move almost no radon-laden air against a three-foot water column. Use only radon-approved fans labeled for soil suction.
Weak slab seal: The gap between PVC pipe and concrete should be airtight. Foam backer rod plus a top fillet of silicone prevent floor air from being sucked instead of radon from soil gas underneath.
Fan indoors: If the fan ever draws attic air down into the pipe and leaks into the house, you increase radon exposure, not reduce it. Mount fans outside or in an attic.
When calling a pro is the safer choice
A DIY solution works on 90 percent of homes that test over 4 pCi/L, but consider professional help if:
- Basement walls are crumbling or unsealed fieldstone (half the air below the slab is now open to living space)
- Tight crawl space makes vertical piping impossible without ductwork rearrangement
- Test results exceed 20 pCi/L, where EPA recommends hiring certified contractors (National Radon Proficiency Program list)
Bonus efficiency tip: combine with a dehumidifier
The same convection-driven airflow that pulls radon also pulls humid air into an unsealed basement. Once the suction point is sealed and piping is in place, a portable 35-pint dehumidifier often cycles 30 percent less because damp soil air now exhausts to the roof instead of pooling indoors. Lower humidity means shorter heat pump seasons – another utility bill win.
Quick fire FAQ
Q. Can radon pipe exit through a side wall instead of the roof?
Local codes vary, but many allow sidewall termination above the first floor window. Insulate the pipe in winter so condensation does not drip and stain siding.
Q. Is Schedule 20 PVC okay instead of Schedule 40?
No. Schedule 20 has thinner walls and flexes under suction. Always choose thick-wall Schedule 40 rated for soil gas pressure.
Q. Will radon system lower basement moisture too much and crack floors?
The system is strong enough to pull gas, but not strong enough to pull water vapor out of concrete. Humidity drops slightly yet never dangerously.
Q. Does this system work with a sump pit too?
Absolutely. Seal the sump lid with rubber gasket, add 3-inch PVC knockout, and tie into the main riser. Two suction points increase flow without adding another fan.
Take-away
A radon problem is serious but fix-in-a-weekend serious. Spend $20 on a test kit, follow the above nine steps, and rest easy knowing you cut lung-cancer risk while saving more than $1,000 in pro costs. Post-installation re-testing closes the loop, proving the fix worked and keeping your family safe for life.
Disclaimer
This article was generated by an AI tool for information purposes. Radon levels, building codes, and device specifications can vary; always verify local regulations and manufacturer instructions, and consult a licensed professional if results exceed 20 pCi/L.