Doug Kladder

Doug Kladder

Director of Center for Environmental Research & Technology, Inc. (CERTI).

At CERTI, we are frequently called on for advice by students. More and more, we have been receiving calls from measurement professionals who have been asked to do a radon survey in a large building, such as a school, or an apartment complex with several apartments distributed throughout several buildings. This is happening more often as owners of large buildings are taking recommended action or are being required to do so by lenders or state requirements. Those requirements typically state testing be performed by certified or licensed individuals. Hence, phone calls are made to certified individuals who are likely more familiar with performing tests on individual homes. So, let's dig a little into this.

Question 1: What is the type of structure and purpose of the survey?

The answer to this question defines what protocol you may be following. If it is a full survey on a school, the School and Large Building Standard is to be followed. If it is an apartment complex, the Multi-Family Testing protocol would be the basis. Both standards can be read at or purchased for local use.

If the purpose of the survey is to assess the entire campus or complex, that typically will mean 100% of ground contact and occupied locations and 10% of upper floor units in a multi-story complex. In an apartment situation, at a minimum, this involves one test location per living unit meeting the previous criteria. In a school, it would typically mean every occupied, ground contact room (including small offices, music practice rooms, classrooms, teacher lounges, etc.).

One can imagine there could be a lot of test locations and hence a lot of test devices -- like hundreds! So sequentially placing your CRM is not feasible. Since all locations should be tested at the same time you will likely need to use passive devices like Activated Charcoal, Electret Ion Chambers or Liquid Scintillation.

Also, the protocols lay out two basic timing strategies:

  • Extended: where one places individual devices in each test location (plus 10% duplicates and 5% blanks) and retests locations exhibiting elevated levels. If it is likely you will have some elevated results, this could lead to a second mobilization and testing campaign.
  • Time Sensitive: Where two devices are deployed in each test location (plus 5% Blanks) and no follow-up testing is required even if the average of collocated devices yields an elevated reading. So just one campaign-but more devices.

The answer to the question as to why the survey is needed is important as it will help decide which approach you will take. If it is for closing out a multi-family, new construction project, the developer is not likely to want to extend the testing period and hence delay financing. If it is a school often the extended approach is more feasible.

Question 2: How much should I charge per test?

First, it is inadvisable to quote a per test cost. Large surveys are a lot different than a test for a single-family house sale. Our suggestion is to step back and estimate your time for each of the elements that are needed, plus the cost of the devices and base your quote on a fixed bid or time and material basis. Most clients will prefer a fixed bid basis but be sure to include all of your assumptions.

If you propose a per test price you could get burned if the actual number of device locations is less than you estimated which would not allow you to recover your allocated overhead costs. This can certainly happen when testing an apartment complex and a tenant refuses access, has changed a lock or the apartment is too dangerous to enter.

Here are a few elements you should consider in addition to the cost of your measurement devices:

  • Communication Plan: You should develop notices that are to be distributed by your client’s agent in advance of the survey. This typically is a community wide notice, via their Internet or “blast” communication system. It will also include individual notices, such as door hanger notices. If you are tasked to distribute these, figure that time and effort, or better yet include that as their responsibility in your assumption list. Regardless, you will spend time customizing the notices.
  • Logistics: This is the organization of a lot of test devices, log sheets, office blanks, randomly identifying field and office blanks and cleaning up of floorplans in advance of deployment. It is a lot more than grabbing your CRM and heading out the door.

Another time consideration is providing your insurance information, registering as a vendor, etc. with your client. These clients are often large concerns and have several hoops you must jump through before you do business with them.

  • Deployment: If you have spent the time organizing, this goes pretty quickly and to help make it go smoothly here are a few suggestions:
    • Use a two-person deployment team from your office. One person is logging device IDs, annotating locations on log sheets and floor plans. The other person deploys the device in the room. The two banter back and forth verifying locations and ID numbers. The deployment person also makes the determination if a room is really a testable location (such as this is clearly a storage room rather than an occupied room). The deployment person is also looking for occupied rooms that were not included in your estimate. It is amazing after conducting hundreds of large building surveys the pluses typically balance out the deletions and your original estimate is pretty close.
    • Require a building representative to accompany you. This should clearly be stated in your proposal. You don’t want to be unlocking doors or entering personal spaces on your own. Too much liability! Too many ferocious dogs! Discovery of illicit activities and accusations of stolen property. Let the building representative open door, say it is clear and then enter.

With a three-person team, with one being a building representative (who moves ahead of you unlocking doors) you can easily deploy devices in a location in a minute or less. So, a school for example with 75 locations can be done easily in 2 hours after including set up and reviewing plans and getting out. Also don’t forget to include travel time and mileage to the site and back.

  • Between Deployment and Retrieval
    • Organize all your logs and diagrams in a format that will be used for the final report. Formalizing the logs before you retrieve will help you catch possible mistakes
    • Use the formalized log sheets when you retrieve the devices to verify anomalies but take your handwritten logs for back-up.
  • Retrieval: Retrieval generally takes half the time of deployment, but you still have travel time and mileage to account for.
    • If possible, use the same two-person team and building representative as you did during deployment.
    • Check retrieved devices against the deployment logs to verify ID and locations, identify data entry errors, and to make sure all devices are retrieved.
  • Report: Most large building clients require a formal report.   The standards list a number of things to include in a report, but the time consuming ones beyond those listed include:
    • A table of results including individual measurements and averages of duplicates
    • A floor plan of building with results shown for each location
    • An assessment of QA/QC measures and survey confidence
    • A detailed description of the conditions that existed during the test
    • Recommendations for follow-up action
      • Need for investigation
      • How to address lost detectors or rooms that could not be accessed during survey.

A proper report can take several hours to prepare including re-drafts. So, allocate for that time and professionalism as well.

The previous should give you a basis for estimating your labor cost. As one can imagine, there is a lot more time involved in activities outside of deploying and retrieving the devices. In fact, most of the effort is involved in the front and back end, so one can see why pricing a survey on a cost per test basis can be problematic.

A few other things for you to consider or stipulate in your bid:

  • What happens if you deploy a device and it cannot be retrieved or is lost?
    • Will you attempt to re-test it later and at what cost?
      • Advice: Stipulate in your proposal that your cost is based upon a single deployment and retrieval and if some are lost you have grounds to negotiate a change order – if you choose to.
    • What happens if you cannot gain access to a testable location?
      • Advice: Stipulate that you are not responsible for lack of access to a testable location and there will be no reduction in contract amount.
    • Include normal overhead charges for insurance, certification fees, etc.
    • Include cost of devices (and QA/QC devices) and shipping as well as and cost for spiking (3%)
    • In some cases, especially when testing new apartments, the client may want you to test buildings as they are finished, rather than all the buildings at one time. Be certain to identify that schedule and plan for multiple trips and reports or stipulate in assumptions that all buildings to be tested concurrently.
    • When testing a building that is not occupied 24-7, such as a school or an office building, do not test over the weekend or holidays when the building is unoccupied. The HVAC system operates differently on the weekends and a survey done during those times is likely to be thrown out, which is very embarrassing to the tester.

So how do you price a survey?

Start with a floor plan of a building. Have your prospective client send you a fire escape plan. Go through it and mark what rooms you think should be tested. This is the crucial piece of an estimate as well as your final report. It would be a good idea to include a scan of the marked-up floor plan with your proposal to provide a defensible basis for how you arrived at your pricing. It can also provide your client with the opportunity to review what rooms are appropriate and make a revision. But again, avoid a per location test price as you have a lot of overhead to cover.

Hopefully this article won’t discourage you from doing large surveys. They can be profitable if you look at the time and effort involved. In fact, the bulk of your effort involves fixed cost for planning, reports and the test devices represent a relatively minor variable cost for the project.


Doug Kladder

We often receive emails or phone calls from CERTI students who are challenged by clients when they are asked to maintain closed house conditions when a short-term radon test is performed. After all, to a homeowner it seems like an unnatural requirement and a condition that would increase radon levels to where mitigation is warranted at the time of sale of a property.

We also see websites of measurement companies state that closed building conditions are required by protocols period as if that should satisfy any doubts a homeowner may have. Although it is true that measurement protocols do state this, it would be good to be able to explain the rationale behind this requirement.

First there are two basic testing approaches: Short-term and long-term. Short-term measurements obtain a radon average over a minimum 2-day period up to 90 days, where closed building conditions would be required. Long-term measurements obtain an average radon measurement over a longer period with a minimum duration of 91 days, up to a full year, but without closed building requirements. So, what is the purpose of either of these approaches?

Short-term measurements are designed to determine the radon potential of the home independently of how an occupant operates the home. They are not designed to determine the actual exposure to radon. In the early days of radon (1980s), these were referred to as “screening measurements.” The purpose of a screening measurement was to quickly identify potential radon concerns which, if found to be elevated, would be followed up with additional, confirmatory measurements. The follow-up measurements recommended would often be long-term measurements to determine actual exposure.

Fast forward to the 1990s when testing at the time of real estate transactions was encouraged. Few homeowners or real estate agents wanted to defer resolution of a contract contingency with a 91 plus day test. Consequently, it became the norm to resolve radon contingencies in purchase agreements with a quick 2-3 day test, aka Short-Term test requiring closed building conditions.

In explaining the purpose of closed building conditions, it is good to relay what the results will mean. When performing a short-term test or screening measurement it is conducted in a manner to maximize the results of tests conducted in living spaces (not crawlspaces). Accordingly, we place the device in the lowest occupiable level where the radon is expected to be the highest because that is where it comes in before being diluted on upper levels with outside air. We also close windows and doors other than momentary entrance and exit. Under these conditions (and here is the key element) if the radon measurement is less than 4.0 pCi/L, one can say with reasonable confidence that radon levels on upper floors and under normal lived-in conditions will also be less than 4.0 pCi/L.

Bottom line: Short-term tests indicate radon potential of the home. Their results do not indicate actual exposure to an occupant as they live in multiple levels and with open windows and patio doors.

Caution: Be careful not to say that the result of a short-term test is a “worst case scenario” or that radon levels will never be higher than results from a short-term test. Although we attempt to drive up radon levels by testing the home and maintaining closed building conditions, we cannot control the weather and the operation of HVAC systems. Several studies have shown in homes with radon levels around 4 that on any two-day test period the result can be either above or below 4, even under carefully controlled conditions. Here is a phrase that might work for you:

The results of this test reflect the environmental conditions and how the building was operated during the period of the measurement.

The results indicate the radon potential for this home. If the results are less than 4.0 pCi/L, it is advised the home be retested in the future to verify continued levels less than 4.0 pCi/L.

How about just closing the windows in the room where the test device is located?

Often a homeowner may whine or cheat a little by opening a window in another part of the house than where you placed the measurement device. Closed building conditions refer to openings in the shell of the building. An open window anywhere on the shell will reduce the negative pressures throughout the building and reduce radon entry. So, closing the door to the room where your test device is located but opening windows in other rooms doesn’t cut it.

To illustrate this, CERTI conducted a test in a home that had a relatively high radon potential. A continuous radon monitor was deployed in one room and after a day a window in the same room was partially opened. Then the window was closed and after the measurements re-equilibrated a similar window located at the opposite end of the basement was opened to the same amount as the first one. The graph below shows the effect on the measurement device when each of the windows were individually opened.

Purposes of Closed Building Conditions Blog pic

As you can see, opening a window in the same room as the device or opening one 25 yards away on the opposite end of the basement had a significant impact. So, as you might be inclined to be a little forgiving, you can see the impact of not following protocols and the need to fully explain the need for compliance. Granted, you may not be able to detect such deviations, but that is why having a homeowner instruction sheet or agreement as well as the using the suggested language above makes sense.

Who said there was nothing new in Radon?


Doug Kladder

Technical Consultant to CERTI

Thursday, 05 May 2022 13:18

Where Can I Put My U-Tube?

Everyone in the radon biz has seen coutnless pictures and illustrations of U-tubes mounted on the side of the vent pipe on the suction side of the fan -- and why not? It is a convenient place to put it, provided the homeowner can see it easily.

Figure A

Common U-Tube Installation

Figure A manometer

A mitigator pops a hole in the basement slab and runs the exposed pipe up a basement wall and out the rim joist. The portion of the pipe in the basement is exposed and provides an easy place to mount the pipe as in Figure A.

But what do you do when the pipe is not exposed, or the only exposed portion is within the crawlspace? This often happens with active systems for new home construction where the vent pipe is behind a finished wall, and the pipe that one would normally mount the U-tube on, is inaccessible.

We have seen some interesting approaches that maintains the incorrect assumption that U-Tubes must be mounted on the vent pipe.

Figure B shows a U-Tube mounted on the vent pipe in a crawlspace. For the homeowner to view the U-Tube, they would need to jump down into the crawl (after moving stored boxes over crawl hatch) and belly-crawl over to the manometer. That would not fall within the definition of easily viewed location.

Figure C shows a vent pipe that was behind a finished wall, within a living room. To find it the wall had to be cut. Later a hinged door was installed-sort of like the “peak-a-boo” door of a Chicago speak-easy.



Figure B

U-Tube on pipe in crawlspace

Figure C

Vent pipe and U-tube behind dry wall with hole busted into wall

U tube 2

U tube 3

Neither approach as shown in Figures B and C are appropriate nor are they needed. That is because:


U-Tubes, or any pressure measurement devices such as a pressure alarm does just that. They measure pressure. There is no air flowing through the tube to the manometer and hence there is no pressure drop in the tubing. Consequently, the length of tubing from the device (u-tube) to the point at which the measurement is being made (connection to vent pipe) makes no difference. In other words, the length of tubing could be miles long, provided there were no leaks in the tubing or its connections.

To illustrate this point, we set up a demo radon system and installed two U-Tubes that were connected to the suction pipe at the same distance from the fan. In one case, a U-Tube was connected to a hole drilled in the suction pipe and connected with the 3-inch tube typically provided with a U-Tube. In the other case, a 50-foot length of 1/4-inch tubing was connected to the suction pipe with a 3/8-inch NPT thread to 1/4-inch serrated fitting. As you can see in Figure D, both U-Tubes measured exactly the same vacuum-even though one had a 50-foot length of tubing between it and the radon vent pipe.



Figure D - Demonstration

Figure D pic 1 Figure D pic 2 Figure D pic 3

Demo Set-up:

  • Radon fan with piping on inlet and discharge
  • Two U-tubes mounted next to each other for ease of viewing.

Right U-Tube:

  • Typical installation with 3-inch tube from U-tube to hole in pipe.

Left U-Tube:

  • Connected to port in suction pipe with 50 feet of tubing between U-tube and port.

Demo Set-Up View

  • U-tubes are located next to each other for ease of viewing but the left one could have been 50 feet away due to length of tubing (50-ft coil) shown in left corner picture.

Results with Fan Turned ON:

  • Both read the same vacuum!


  • U-Tube can be remotely located and tubing routed to it.

This means that in the case of a crawlspace, tubing could be connected to the exposed vent pipe in the crawlspace and routed up into a utility room or closet directly above the crawlspace and mounted on a wall. It would be even nicer if it was mounted on a board with a label next to it that would advise the occupant as to what it was and how to interpret it.

The same would be true in a non-crawlspace house where the vent pipe is totally concealed. You will need to plan ahead and install the tubing and route it to a proper location before the walls are sheet-rocked.

One might argue the connection should be made to an exposed portion of the vent pipe in the attic or outdoors. Be careful of this because if the tubing is routed through a cold space, condensation can occur in the tubing and cause whacky readings and unneeded service calls.

Oh, and one last thing on U-tubes. Read your label and locate the label appropriately. Many labels have warning arrows that are to be located such that they point to “zero” on the U-Tube. The verbiage says if the liquid levels get to that point, then call for service. Zero means the fan is likely dead. Often, we see labels that are located above or below the U-Tube where the liquid level can never reach the point where the arrows are located. See Figure E

Figure E: Incorrect Label Location Relative to U-Tube

Figure E pic 1

Arrows should point to "Zero"


Figure E pic 2

Label is incorrectly located below U-Tube where the liquid level will never meet the "call for Service" arrows


Doug Kladder


Friday, 17 April 2020 09:43

Delivering Radon Programs

So you’re thinking about hitting the road and giving radon presentations?  Perhaps presenting to real estate offices, builders, county commissioners, or the general public.  That’s great and why not?  It is a good way to help spread the message while at the same time marketing your professional services -- provided you do it right!

Having just completed a new course on how to deliver radon talks, we thought it would be helpful to share a few insights from our experiences over the years, both good and bad. 

The first piece of advice is to have a mindset of being a “problem solver” rather than a “problem maker.”  There is a natural tendency of many radon pros to want to scare people into action.  They often start their program with less than happy facts like “there are 21,000 deaths each year due to radon” or “Radon Kills.”  Although this may be true, most audiences would prefer a more positive message and frankly are unable to relate to the significance of 21,000 deaths per year.  Furthermore, if you lead with this you are likely to be perceived as a “problem maker.”

As a “problem solver,” especially when talking to real estate professionals, a more positive approach would be to say: “Hundreds of thousands of people across the nation have taken the US Surgeon General’s recommendation to test their homes, or homes they are purchasing, and, where elevated radon levels are confirmed, have taken positive steps to reduce their exposures by employing cost-effective and proven techniques.  The purpose of my talk today is to share those approaches and to discuss how this can be done in a manner that does not jeopardize a sale.

The message of the second approach is that lots of folks are doing it and it can be done right.  This is a more constructive message and portrays you as a “problem solver.”  In today’s environment, where most people are familiar with radon, you don’t have to get into health risks and mechanisms.  Rather, focus on proper testing and proper mitigation with a catch phrase like: “All homes can be fixed - and I am going to share how that can be done in a timely manner.”  Boom -- Put on your Captain America suit and get ‘er done.

Another piece of advice is to speak to the capability of the radon industry, rather than just what you or your company does.  And never, ever slam your competition.  If you show your audience how testing is properly conducted, and/or photos of proper mitigation systems, while pointing out elements of the standards, they are smart enough to recognize or recall non-compliance.  Put yourself out there as a knowledgeable person and not a whiner.  If you gain the respect of the audience by the objectivity you display as well as your command of the technology, they will find you or refer business to you when the need arises.  In other words, let your professionalism be your business card.

A third recommendation has to do with your mindset.  You want to “engage” the audience and to do so you need to empathize with the audience.  In other words, step back and Be the Audience.  You need to do this when you prepare the program as well as when you deliver the program.  So, when rearranging or creating your slides, ask yourself what you, as an audience member, would want to learn?  Remember, this is about them - not you.  Also, ask yourself what gripes or objections they might have and be prepared to speak to them.  That shows you are empathetic to their needs rather than forcing a canned presentation down their throats.

As far as nervousness goes, there is no reason to be nervous if you have prepared yourself well enough and have anticipated questions that may arise.  The key is to realize that you know a lot about the topic and are honest enough to admit it when you don’t know something.  Honesty is better than making something up, which an audience can spot in a heartbeat and cause you to lose all credibility. 

As far as questions, train yourself to repeat the question.  This not only allows the audience to understand the context in which you are providing an answer, but more importantly, gives you a moment to think before you put your mouth in gear and say something wrong.  Repeating the question can also allow you to rephrase the question to where you can provide a much more appropriate answer.  Simply listen to any news conference (and we have had a lot lately) and you can experience how important it is to repeat the question and how some speakers do this well and others do not.

These are just some of the highlights but if you are considering getting up in front of the crowd but are little uneasy, we encourage you to get additional training to do so.  It can be enjoyable; it helps the outreach effort, and it is a good way to market yourself, as a radon professional, helping to solve a serious problem.

C-16-111 - Delivering Radon Programs (CERTI-327) - 16 CE credits


Douglas L. Kladder

Wednesday, 15 January 2020 14:45

Thinking Outside the Pit

As an instructor at CERTI, I am often called upon for advice when our students are tasked with reducing radon in large buildings. Often they have installed several ASD systems with little to no reduction even after replacing fans with bigger and bigger models or even stacking them. “Stop” I say and suggest they return to the underlying question of why there is a radon problem there in the first place.

Tuesday, 16 July 2019 11:49

New Technical Reference and CE Course

As a radon professional, have you ever wanted to have a reference document that covered pretty much everything? In other words, a single document that covered radon measurement, mitigation, and how it is applied differently in homes, duplexes, schools, office buildings, etc. Well, thanks to a collaborative effort sponsored by the Colorado Department of Public Health and Environment’s Cancer, Cardiovascular and Pulmonary Disease Grants program, one now exists -- and we have constructed a CE course around its content!

money 200 x 112Since taking an entry level radon course is the initial step for people wanting to offer radon mitigation services, we often receive calls from prospective students on what magnitude of investment may be required to start their business. So, we thought we would provide a little input within this blog ...

Prepare exam 3 200 x 134Over the years of teaching radon certification courses, students have asked me “What do I need to know to pass the certification exams?”  My answer has always been that it is more important to prepare for “life after exam” than to become fixated on the independent certification exam.  However, after 20 some odd years helping students succeed in the radon industry I also realize they cannot begin their radon careers until they clear the initial hurdle of passing the exam, so I thought I would share a few tips for those who want to become certified in the radon industry

MeasDevices 1 aIndividuals planning on entering the radon field often call with questions about which device they should use. After all, there are a lot to choose from and it can be a little daunting. So, in this post we thought we would share some tips for our perspective students.