How Long Does Radon Mitigation Take?

The Short Answer

• Slab-on-grade home: 4–8 hours, one visit
• Finished basement with complex routing: 6–10 hours, one visit
• Crawl space with vapor barrier: 6–12 hours, sometimes two visits
• Multiple foundation types: 8–14 hours, usually one long day

Almost every residential radon mitigation job is completed in a single visit. It is not a multi-day project.

What Determines the Timeline

Foundation type

Slab-on-grade is the fastest. The contractor drills one core hole, installs a T-fitting, routes PVC pipe to the fan location, mounts and wires the fan, seals the core hole with hydraulic cement, and installs the warning device. On a clean job with good access to an attic or exterior wall, an experienced contractor can finish in 3–5 hours.

Finished basement takes longer because pipe routing through finished walls and ceilings is more involved. The contractor has to plan a route that's as invisible as possible — through closets, utility areas, or exterior walls — and that takes more time than running pipe through an open unfinished space. Add 2–4 hours over a slab job.

Crawl space is the longest. The vapor barrier has to go down before the suction point and pipe are installed. Prep work (debris removal, barrier layout, seaming, taping, wall lap-up) alone can take several hours. The actual fan installation is similar to a slab job, but total time including barrier work typically runs 6–12 hours. Some contractors split this into two visits: barrier installation one day, fan installation the next.

Number of suction points

Most homes need one suction point. Homes with isolated sub-slab zones, multiple foundation types (basement under part of the house, slab under another section), or poor sub-slab communication may need two or three. Each additional suction point adds 1–2 hours.

Pipe routing complexity

An interior pipe run through an unfinished utility room to the attic takes 30 minutes. Running pipe through a finished closet, around a tight corner in the mechanical room, and out through a brick exterior wall takes 3 hours. Complex routing is the single biggest variable in installation time.

Fan location

Attic mounting is cleanest but requires running pipe up through the house — often the longest pipe run. Exterior wall mounting is faster but exposes the fan to weather. An experienced contractor can usually quote the time impact after their initial walk-through.

How Long Until Levels Drop?

The fan starts working the moment it's turned on. Radon levels in the sub-slab space begin dropping within minutes; indoor air levels respond more slowly because the existing radon in the room takes time to be exchanged out.

Typical reduction timeline:

• 1–4 hours: Sub-slab pressure differential established, soil-gas entry point sealed
• 24 hours: Most homes see 50–75% reduction in indoor levels
• 48–72 hours: Levels approach their new stable baseline
• 30 days: The 30-day post-mitigation test captures the true ongoing average

Your contractor should provide (or sell you) a short-term test kit to run immediately after installation and another at 30 days. The 30-day reading is the one that matters for long-term planning.

How Long Does the System Last?

The pipe: Essentially permanent. Schedule 40 PVC lasts 50+ years under normal conditions. You will never replace the pipe.

The fan: 5–15 years depending on model and environment. Fans in attics (protected from UV and weather) last longer than those mounted on exterior walls in harsh climates. When a fan fails, it's a straightforward swap — same pipe, new fan, 1–2 hours of labor. Cost: $150–$350 for parts and labor.

How to know when the fan fails: The U-tube manometer (liquid warning device) equalizes when the fan stops creating negative pressure. Check it monthly — it takes 3 seconds and is the only maintenance the system needs.

Most homeowners retest every 2 years with a long-term alpha track kit to confirm the system is still performing. This catches fan wear before levels creep back up.

What to Expect on Installation Day

1. Contractor walk-through (30–60 min): They assess the sub-slab with a probe or small test hole, confirm communication, identify the suction point location, and plan the pipe route.
2. Core drilling (20–30 min): One or more 3" holes through the slab. Loud and dusty — expect the drill to run for 10–20 minutes.
3. Pipe installation (1–4 hrs): Highly variable based on routing complexity.
4. Fan mounting and wiring (30–60 min): Fan is mounted, electrical connection made.
5. Sealing and warning device (30 min): Core hole sealed with hydraulic cement, manometer installed.
6. System test and walkthrough (30 min): Contractor confirms the fan is running and creating negative pressure, shows you the manometer, and leaves test kit instructions.

You can be home during installation — most contractors prefer it so they can ask about access points and confirm routing preferences. You don't need to do anything except give them access to the attic or electrical panel if needed.

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