Why Radon Mitigation Quotes Vary So Much

Two Colorado mitigation contractors come look at the same house. One quotes $1,500. The other quotes $4,200. You're standing there reading the two emails and wondering how that's even possible.

It usually is possible, and the answer is usually scope, not greed. This page walks through the real reasons radon mitigation quotes vary in Colorado — and the few cases where the spread is actually a red flag.

1. Foundation type

This is the biggest driver. A simple basement install runs $900–$1,900 in Colorado Springs. A crawlspace can hit $4,000 because of the heavy vapor barrier and the labor of sealing it. Multi-zone homes (tri-level, split-level, basement-plus-crawlspace) can push past $4,800.^[1] If one contractor priced a basement and the other priced a crawlspace, the quotes aren't comparable — even if they're for the same address.

2. Suction point count

One suction point is the most common. Multiple suction points are needed when the home has multiple foundation zones, or when a diagnostic test (pressure field extension, or PFE) shows the soil under the slab doesn't communicate well from one corner to the other. Each additional point adds labor, materials, and sometimes a second fan.

3. Fan sizing — and Colorado's altitude correction

This is where Colorado is genuinely different from a national average. Radon fans lose roughly 4% of their airflow capacity for every 1,000 feet of elevation.^[2] Colorado Springs sits at roughly 6,000 feet — meaning a fan that's perfectly sized for a sea-level install is significantly underpowered here. A contractor working off the national catalog spec without adjusting for altitude can quote less but install a system that doesn't bring your radon below 4.0 pCi/L. A contractor who specifies a larger fan or a second suction point isn't padding the quote — they're compensating for the altitude.

4. Sealing scope

Two contractors can both "seal the basement" and mean very different things. Slab cracks, sump pit lid, floor-wall joint, plumbing penetrations, sub-slab membrane in a crawlspace — each is a separate scope item. A quote that lists what's being sealed is more credible than one that just says "sealing included."

5. Pipe routing

Exterior routing (fan on the outside wall, pipe up the side of the house above the eave) is faster and cheaper than full interior routing (pipe through closets, the attic, and out the roof). Both can be AARST-compliant.^[3] Interior routing costs more for a reason — it looks cleaner from the outside and protects the pipe from weather and damage.

Before quoting a tight-soil or multi-zone home, a quality Colorado contractor will run a pressure field extension (PFE) test — drilling a small test hole through the slab, applying suction, and measuring how well the vacuum spreads through the sub-slab. If the field extends well, one suction point will work; if it doesn't, two or three may be needed.

Contractors who skip this step on a complex home are the contractors most likely to install a system that doesn't bring radon below the action level. If your home is anything other than a simple single-zone basement and your quote doesn't mention diagnostics, ask.

Sometimes the spread between quotes is real markup, not real scope. A handful of honest reasons for markup:

• Established contractor with overhead — full-time staff, marketing, insurance, warranty reserves. Their per-job overhead is higher; their failure rate is also typically lower.
• Premium fan model and longer warranty — a 7-year manufacturer warranty costs more than a 5-year.
• Same-day or guaranteed-completion scheduling — real estate deadline pressure usually carries a small premium.
• Better aesthetic finishing — paint match, pipe boxing, exterior alternative routing.

And the reasons that aren't fair:

• Quote doesn't list scope at all — just a price.
• "Required" upgrades that the contractor can't explain technically.
• Fear-based sales language ("your family is in danger if you don't act today").
• Refusal to put the post-mitigation test result threshold in writing.

When you have two quotes that look genuinely different, run them through this filter:

Compare	What you're checking
Foundation work	Same scope, same zones
Suction point count	Same number, same locations
Fan model	Both correctly sized for Colorado altitude
Sealing scope	Same items called out
Pipe routing	Interior vs exterior matches
Exhaust point	Above roof vs above eave
Manometer install	Included and accessible in both
Permits	Same contractor responsibility
Post-mitigation test	Included, with target pCi/L written
Workmanship warranty	Same length
DORA license + NRPP/NRSB	Both provided[4]

If all of those line up and one quote is still significantly higher, ask why. There's usually a defensible answer — or there isn't.

The cheaper quote is often the better choice when:

• The home is a simple single-zone basement with porous gravel soil
• The home already has a passive radon rough-in from new construction (post-2009 builds often do)
• The roof line favors exterior routing and the homeowner doesn't care about the aesthetic of an exterior pipe
• The contractor is established, licensed, and has 5+ year warranty on the fan

And when the cheap quote is the wrong call:

• The home is multi-zone or has a crawlspace and the cheap quote treats it as Scenario A
• The cheap quote omits the post-mitigation test
• No DORA license number or NRPP/NRSB certification on file
• The contractor can't or won't put scope details in writing