When the cheapest radon bid costs more
Nobody sets out to buy a system that does not work. It happens because the failure is invisible: the fan runs, the pipe is there, the invoice is paid, and nothing about the installation announces that the reading barely moved.
Three omissions account for nearly all of it, and all three are visible in the quote before you sign.
Omission one: one suction point where the slab needed two
This is the expensive one. If the sub-slab material will not carry suction across the footprint, a single point influences a fraction of the floor and the rest of the house keeps drawing soil gas as before.
Correcting it later means a second core, a second pit, more pipe, possibly a larger fan, and a second verification test. You have now paid for one and a half systems and lived with an elevated reading in between.
Omission two: no sealing on a slab that needed it
Sub-slab depressurization works by holding a small negative pressure beneath the floor. Every unsealed opening — floor-wall joint, an open sump, an abandoned floor drain, cracks, gaps around penetrations — bleeds that pressure away.
A system installed over an unsealed slab has to work harder to accomplish less, and on block foundations where soil gas travels up the wall cavity, sub-slab suction alone may miss the pathway entirely.
Omission three: no verification test
This is the omission that hides the other two. Without a post-mitigation measurement, nobody establishes whether the system worked — the homeowner assumes it did because equipment exists and a fan is audible.
Verification is a small fraction of the job cost. A contractor who prices it as standard is telling you they expect to pass it; one who treats it as optional has quietly transferred the risk of an underperforming design onto you.
What a lean bid looks like when it is legitimate
None of this means low bids are bad. A genuinely lean bid names the same suction point count as its competitors, includes the same sealing, specifies a comparable fan, and prices the verification test — it is simply cheaper because the operator has lower overhead or because your house is an easy job.
The test is not the number. It is whether the number is attached to a complete scope.
Cheapest isn't always best: common questions
How would I even know my system is underperforming?
Only by measuring. The manometer tells you the fan is moving air, which is not the same as telling you the concentration came down. If you have a system with no post-mitigation number on file, run a short-term test on the lowest lived-in level under closed-building conditions — it is inexpensive and it is the only way to find out.
If a system underperforms, who pays to fix it?
Whatever your written scope and warranty say — which is exactly why the remedy path belongs in the document before work starts. Contractors who stand behind their designs generally name the remedy: an additional suction point, further sealing, or a different fan. Without that language, you are negotiating after the fact with no agreed mechanism.
Can I add the verification test myself later?
Yes, and an independent measurement has the advantage that the person checking has no stake in the outcome. Budget for it separately, tell the installing contractor it is coming, and agree the remedy path in advance so an unfavourable result has somewhere to go.
Keep reading
- Cheapest vs best contractor — When the low bid is fine, and when it quietly costs more.
- Cost drivers — Seven variables that explain nearly every price difference.
- Red flags when hiring — Nine signals that a bid deserves more scrutiny than a signature.
- Post-mitigation testing — The measurement that proves the system worked — and what if it did not.
- All homeowner guides — every decision page in one place.
Count the suction points, find the sealing line, confirm the verification test. A bid with all three is safe to buy on price. A bid missing them is not cheaper — it is smaller.
Sources
- U.S. EPA — Radon
- U.S. EPA — A Citizen’s Guide to Radon
- U.S. EPA — Consumer’s Guide to Radon Reduction
Compare complete scopes, not headline numbers
Independent licensed contractors quote your house directly. Ask each for point count, sealing scope, and the verification test, then buy on price with confidence.