Reuben's Home Inspection Blog

Radon Testing: Should You Rely on The Seller’s Test?

September 2nd, 2014 | No comments

We routinely get requests from past home inspection clients of ours asking us to re-send the radon gas test results from testing that we conducted many years ago. We get these requests because our past clients are now selling their home, and they’re performing their due diligence attempting to gather whatever information they can about their home to give to potential home buyers. In most cases, we still have the results and are happy to send them out. We recently received an email asking about this:

“Two months ago the seller had another buyer inspect the home.  The radon test came back at 1.8.  Does this need to be done again? Thanks!”

That’s a great question.  Here’s my generic advice on relying on the seller’s test results.

Over Two Years Old? Forget it.

How much value is there in old radon test results? If the test results are more than two years old, the EPA recommends conducting a new test. If the test results are less than two years old, there might be some value in those results.

Who Conducted the Previous Radon Test?

If the test results are less than two years old, find out who conducted the radon test before relying on the results. For obvious reasons, I don’t recommend relying on any type of DIY radon tests unless you Did It Yourself. If the radon test was professionally conducted, make sure the person / company conducting the test was qualified to do so. You’d hope that any home inspector charging money to conduct a radon test would be qualified to perform the test and would do it properly, but I’ve personally seen enough egregious testing errors to know that there are plenty of unqualified folks conducting radon tests in Minnesota. While there are no licensing requirements for radon testing companies in Minnesota, there are two large certifying bodies for radon measurement providers: the National Radon Proficiency Program (NRPP) and the National Radon Safety Board (NRSB). I’d feel fairly confident in relying on the radon gas test results from an NRPP or NRSB certified company. That’s not to say that you shouldn’t rely on the results from someone who isn’t certified, but you’d be right to at least ask a few questions about the qualifications and experience of the person / company doing the testing.

Has Anything Changed?

If there have been any major structural changes, HVAC changes, or there have been any significant projects that involved air sealing, which is most commonly done in the attic, don’t go with the old test results. Too much has changed that may have affected the radon levels. Have your own test conducted.

Where Was The Test Placed?

When a homeowner conducts a radon test on their own home, they’re supposed to test the lowest level of the home that is regularly used. If the home has an unfinished basement and nobody spends any time down there, the test should be placed on the first floor. When a radon test is conducted as part of a real estate transaction, the radon test should be placed in the lowest livable part of the home, whether it’s finished or not.  If a home buyer is going to rely on the seller’s radon test results, they should make sure the test was placed in the lowest livable area, not the lowest level that is regularly used.

In Conclusion

If a home buyer is going to rely on someone else’s radon test results instead of hiring their own company to conduct a radon test, they should make sure that the previous test was done within the last two years, the testing was done by a qualified person / company, no major changes happened at the home that could affect radon levels, and that the radon test was placed in the proper location.

Author: Reuben SaltzmanStructure Tech Home Inspections


Radon in New Minnesota Homes

September 3rd, 2013 | 1 comment

Starting in 2009, the Minnesota State Building Code adopted Appendix F of the International Residential Code. Since then, all new homes built to the standards of the Minnesota State Building Code have been built with at least a passive radon mitigation system, or in some cases, an active system. This was done to help deal with high levels of radon in Minnesota; approximately 40% of homes in Minnesota have elevated levels of radon gas.

There are four sections to the radon requirements for Minnesota that are publicly available online: 1322.2100 – Incorporation by reference1322.2101 – Scope1322.2102 – Definitions, and 1322.2103 – Requirements.  The last part is where most of the information is, and specifies exactly how a passive radon mitigation system is to be installed.

A passive radon mitigation system has a 4″ layer of rocks or sand underneath the basement slab and a soil gas retarder such as 6-mil poly laid on top of that, which is designed to prevent soil gases from coming into the home through cracks in the concrete.

Openings in the basement floor also need to be sealed, such as those around basement showers, the space between basement slabs and walls, and sump basket lids need to be made airtight as well.

Sump basket not sealed

To vent radon gases to the exterior of the home, a 3″ ABS or PVC pipe runs underneath the basement slab, where it can either connect to the drain tile system or to a “T” fitting that connects to a perforated section of piping running 10′ in both directions.  From there, the pipe runs up through the middle of the home and terminates 12″ above the surface of the roof, and is indistinguishable from a plumbing vent. To help prevent someone from accidentally connecting a plumbing drain or vent to the radon vent, the radon vent needs to be labeled “Radon Reduction System”.

Radon Reduction System label

The diagrams below, available at the “Incorporation by reference” page mentioned above, show a few examples of this system.

Radon mitigation diagrams

Effectiveness of Passive Radon Reduction Systems

Passive radon reduction systems have been installed in new Minnesota homes for the last four years and they’re doing good. While approximately 40% of homes in Minnesota have high radon levels (over 4.0 pCi/L), a recent study by the Minnesota Department of Health showed that only 21% of new homes with passive radon reduction systems had high radon levels.

If an elevated radon level is found at a new construction home, the fix is typically easy and inexpensive.  A radon fan can be installed at the radon vent in the attic, along with a simple monitor in the basement to show that the system is working.  This fan will suck soil gases out from underneath the house, and is extremely effective at minimizing radon levels.  An outlet will have already been installed in the attic for the fan, so the installation is a piece of cake.

Radon Fan

If you own a new home with a passive radon reduction system, it’s still important to have it tested for radon. Minnesota residents can purchase short-term DIY test kits for $7.95 here.  Long term tests are available for $21.95.

Author: Reuben Saltzman, Structure Tech Home Inspections


Why Test For Radon?

April 5th, 2011 | No comments

If you’re buying a home in Minnesota, get it tested for radon.  There are two reasons I give for having radon tested; lung cancer and money.

A few quick facts about radon

  • Radon is a gas formed by the breakdown of uranium and radium, both of which are found in high levels in Minnesota.
  • Every home is susceptible to radon, even new construction.
  • There are a large number of homes in Minnesota with high radon levels.  We’ve found that about one out of three houses have high levels of radon.
  • Radon is unpredictable.  Two houses built right next to each other, at the same time, with the same construction methods, may have very different radon levels.

Lung Cancer

Radon gas is the number one cause of lung cancer among non-smokers, and the second leading cause of cancer in America.  Radon testing is recommended by the EPA, the Surgeon General, the American Lung Association, and the Minnesota Department of Health.  The area most at risk in a home is the lowest level that gets lived in.


When we conduct a radon test and the test results come up high, the buyer typically asks the seller to pay for or install a radon mitigation system.  These systems are extremely effective at lowering radon levels, and they cost about $1500 on average.    If you buy a home and you decide not to test for radon as part of the home purchase, you can still test for radon after you own the home, but if a radon mitigation system needs to be installed, you won’t have the luxury of asking someone else to pay for it.  Well, I suppose you could always ask…

Picture this scenario: you buy a home, but don’t have it tested for radon.  Several years down the road, you sell your house.  The new buyers have a radon test performed, the radon test comes up high, so the buyers ask you to install or pay for a mitigation system.   You’ll probably wonder why you never tested for radon when you bought the house.  This happens a lot.

Objections to radon testing

We hear many objections to radon testing – some are valid, some aren’t.

The home doesn’t have a basement. Ok, that’s a good objection.  We’ve found that most homes without basements have very low levels of radon.  Basements with a walkout generally have lower levels, but we’ve still found our share of high radon tests at basements with walkouts.

It’s new construction. Minnesota requires a passive radon mitigation system installed in every new house; this doesn’t mean radon will be eliminated, it just means the chances for elevated radon levels will be reduced.

The home already has a mitigation system. If the system is working properly, the radon levels are probably very low.  We’ve never found high radon levels in a home with a working mitigation system.

I’m buying a bank owned property or short sale, so it doesn’t matter if the house has high radon levels.  The sellers won’t be paying to fix it, and I’ll still want the house either way. Fair enough.  It’s still a good idea to get a do-it-yourself test after you own the house though.

I’m going to do my own test. That’s fine, but it won’t be part of the real estate transaction.

Radon is a conspiracy of the government.  Oh boy.  I’ve heard this before, and I’m not going to get in to that discussion… but just for the sake of argument, let’s pretend radon is a conspiracy.  Who cares?  Even if radon was only a percieved health problem, it would still be a liability.

Reuben Saltzman, Structure Tech Home Inspections – EmailRadon Testing in Minnesota

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Could My Radon Monitor Be Broken?

October 19th, 2010 | 2 comments

One of the more awkward conversations that I had with a home seller this year dealt with a high radon test at his home in Minnesota.  We performed a radon test for the buyer, and the test came up high (over 4.0 pCi/L), so the buyer asked the seller to install a radon mitigation system.  The seller wasn’t happy about this, so he called us up to complain.

We had performed a radon test for the seller when he bought the home four years ago, and the test was below 4.0 pCi/L.

I could understand the seller’s frustration; I would have been frustrated too.  How could this be?  Was our electronic radon monitor broken?  No, it really just came down to timing.  Radon levels constantly fluctuate throughout the day, and even throughout the year.  There are many factors that affect radon test results – so many that you’ll never get the exact same results twice.  A few of the larger factors include:

  • Where the test was placed in the home.
  • Barometric pressure.  Rainy weather = lower pressure = higher radon levels
  • Ventilation systems.  An HRV running at full speed can cut radon levels in half.
  • Windows open vs closed.  Houses always act like chimneys; warm air rises.  This creates negative pressure in the basement and positive pressure at the upper levels.  When windows are open at the upper levels, the house will act even more like a chimney, which increases radon levels.  That’s right; opening windows on the upper levels can actually increase radon levels in the basement, which is where the test is placed.

With all of these factors, why even bother with a short term radon test? Because it helps to decide whether or not radon is a problem that needs to be dealt with.   The overall seasonal average typically won’t be too far off from the short term test.

I performed a radon test at my own house for 96 hours, and as you can see from the graph below, the levels didn’t vary all that much.  The overall average came out to 2.6 pCi/L.  If you were to only look at the highest levels in a 48 hour period for this test, the average would still only be 2.9 pCi/L.  I’ve performed many tests at my house throughout the year, and the average is consistently between 1 and 3.

Reuben's radon

For the record, we have every one of our electronic radon monitors calibrated annually.  While radon levels may be volatile, the accuracy of our tests isn’t.

Reuben Saltzman, Structure Tech Home Inspections – Email – Minneapolis Home Inspections

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Six Things To Consider Before Testing For Radon On The Home You’re Buying

October 5th, 2010 | No comments

If you’re buying a house in Minnesota and you want to have it tested for radon as part of your inspection contingency, here’s a list of six items that the EPA says you should consider before you have the test conducted.

Where the radon test will be located

The radon test should be placed in the lowest level of the home that could be used regularly, whether it’s finished or not.   I’ve said before that radon tests should never be placed in crawl spaces, but what if the basement ceiling height is 6′ 11″ ?  The Minnesota State Building Code defines a crawl space as “Areas or rooms with less than 7 feet ceiling height measured to the finished floor or grade below.” (MN Rules 1309.0202)    This is a grey area that should be discussed ahead of time.

Who should conduct the radon test

Smiley-winky-face Call Structure Tech, duh!  We’ve been testing radon in Minnesota for more than twenty years.

What type of radon test to do

A radon test performed with a continuous electronic monitor can be completed in as little as 48 hours.  The other type of test that is most commonly used for a real estate transaction is a charcoal canister test.  This type of test must remain in the home for minimum of 72 hours, and then the canisters must be sent to a lab for analysis.  Do you have time to get the testing completed?

When to do the radon test

The occupant of the home must maintain closed house conditions for 12 hours prior to, and throughout the duration of the radon test.  This means keeping windows and doors closed, except for normal traffic.  A few things that make this difficult would be if the seller is moving, if the home is under construction, if it’s new construction, or it’s a hot week in August and the home doesn’t have air conditioning.  Stuff to think about…

How the seller and the buyer will share the radon test results and test costs

The issue over the test costs is a no-brainer; if the buyer wants a test, they should pay for it.  If the seller doesn’t want to know about the test results, they should make that clear ahead of time.  Whywouldn’t the seller want to know?  If the test is high, this must now be disclosed to any future buyers if the deal falls apart for any reason.

When radon mitigation measures will be taken, and who will pay for them.

This is the big one.  Ideally this would be decided ahead of time, but I’ve never heard of this actually happening.  If the radon test comes up high, most home buyers will ask the seller to install a mitigation system, but will the seller be willing to do this?

While I’m certainly an advocate of radon testing, one of the few times that I don’t recommend testing for radon at the time of a home purchase is when the results aren’t going to make any difference. In other words, if the buyer has decided to purchase a home regardless of the radon levels and the seller is unwilling to mitigate high levels of radon, there’s no point in having a professional test performed ahead of time.  The buyers would be just as well off performing a long-term test on their own after they purchase the house.

Reuben Saltzman, Structure Tech Home Inspections – Email – Minneapolis Home Inspections

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