Have you ever wondered what goes into engineering a radon mitigation system? What makes a house easy or challenging to mitigate? We had the opportunity to discuss some of our most frequently asked questions with Chad Robinson. Chad is the lead mitigation trainer for Kansas State University and owns a radon mitigation company, Building Performance, in Salina, Kansas. The written transcript has been edited for length and clarity.
Jesse: Why don’t you tell us a little bit about your background, Chad?
Chad: So I’m a mechanical engineer by schooling, for what that’s worth now, because I haven’t used that degree specifically for a long time. But it has really helped me understand a lot about building science, how energy moves through buildings, and how, temperature differentials can cause air and moisture to move through structures. It was a good background for me, but then I got into doing energy efficiency work 12 years ago now. I did that for a while. And then the radon part of my business, which started up about the same time, just really took over. And I started working with Bruce [Snead] a few years after that doing training. So that’s really the short version of my background.
J: Okay, so we’ve got nobody better to answer all these questions than Chad. I’ve learned so much of what I know from him. So thank you for that, Chad. So our first question is:
J: What goes into engineering a radon system? Mitigation systems don’t seem that complicated.
C: So let’s tackle the second part of that question first. This could be a one-hour answer, and, well, I’ll try to distill it down as much as possible. But radon systems don’t seem that complicated because, in theory, they’re not that complicated, right? We’re just sucking on the ground harder than the building is sucking on the ground, and that seems really simple.
The problem is there are all the complicating factors that go into it, like how come we can’t get suction from over here to over there and trying to figure out a way to make that happen while using the most energy-efficient products we can. Not necessarily going overboard in that sense, but giving the best value to our clients, right? And then also making those products as quiet as possible because we’re in a home where people are sleeping, and we want our systems to be as quiet as possible. Then the third thing, and most important thing, is we need to get our systems to create as much radon reduction as possible. We want to have super low radon levels, just like outside, when we’re done. So you add all those things together, and you add in a finished basement, or um…
J: Center footings.
C: Center footings.
C: Yeah, all of the things. It just can make it really complicated. Taking all of those things into consideration and building the best, most efficient system possible that’s what makes an engineered system.
J: What makes a house easy or hard to mitigate?
C: Okay, so yeah, we could go all day on this, but I guess in our previous question, we just partially answered this, right? A fully finished basement where it’s not easy to run pipes to get the suction that we need under the slab or under the crawl space membrane, and, really, things that are hard. Crawl spaces are never fun, right? I don’t know anybody that’s really just wanting to jump into a crawl space and clean it out, put the membrane in there, crawling around on their stomach on dirt, that kind of stuff. That’s more difficult, and it’s not that it’s difficult because it is really hard to get radon levels down in crawl spaces. It’s more that it’s difficult because it’s just a lot of work.
J: Yeah, the labor side of it.
C: The labor side is pretty intensive. And there’s just not a lot of people that want to do that kind of work.
So, but then, oh man, we could really just go on for a long time about the things that make radon mitigation more difficult, but ultimately it all comes back to, can we get negative pressure under the slab? And if you have a bigger footprint, it might be more difficult. If you have really compacted soils, it obviously can make getting suction more difficult; or if you have very permeable soils like you all see up your way sometimes, getting enough airflow in those situations can be difficult.
J: When activating a passive system, why would you do more than just install a fan?
C: So in the intro class we’re teaching here this week, we have four slides’ worth of reasons you might need to do something other than just install the fan. And they’re things like the pipe was run up through a 2×4 wall, and the outside diameter of 3-inch pipe is 3.5 inches, so exactly the same size as the wall itself, so there’s sheetrock touching on both sides. It’s not a problem when it’s a passive system, but you put a fan on it, and then all of a sudden, the vibration from the fan, even though it doesn’t have to be significant, it’s touching the sheetrock on both sides; you just made a big bass drum. Not very many people want a bass drum in their house, right?
Probably more common than that even is the pipe was installed by someone that is not a certified contractor, and it’s not their fault, but they just don’t know better, and they installed the pipe shoved down into the dirt. So when the concrete is poured back, the pipe doesn’t move around, but you can’t get any airflow when the pipe is shoved 3 feet into the ground, right, instead of in the gravel layer or into the drain tile.
J: Sealing is a big one. Like we just did a passive system last week, and it was sealed with polyurethane. But that concrete continues to shrink, and there’s still a gap there, so we had to reseal it, and we went from a mid-range fan down to a small fan just by doing the sealing. We like tripled our pressure field extension just by spending an hour or two sealing just the mechanical room. The rest of the basement’s finished. So operating costs obviously plummeted when we did that.
C: Right. Yeah, so many different things that- especially when it’s not us, a certified contractor, that’s installing the passive system components.
[To see an example of a passive system installed incorrectly, watch this video.]
J: Indoor versus outdoor [system]?
C: Okay, so I live in Kansas. Freeze-up is not as big of a problem where I’m at as it is where you’re at. And so you’ve probably done some videos on freeze-up as well, right?
[You can watch our video on freeze-up here.]
C: Okay, so a big, big reason to run interior systems in the North, in Minnesota, is the potential for radon pipes freezing up in the winter time because we’ve got condensation that’s forming inside the pipe. That condensation can freeze up. The soil gases we’re pulling out of the ground are probably almost 100% relative humidity, no matter where you’re at in the country.
So we’re going to be pulling some humidity out of the ground, causing condensation. It’s going to freeze up where you’re at. Though the house just looks nicer.
J: Yeah, I’m a big fan of that.
C: Right. And I mean, there are times when you can get by with outside systems for performance. You know, if somebody has a rental house, they don’t really care that it has a radon system on the outside, okay? It’s all right. I understand that. But if you’re concerned about how the system looks, we can almost always find a way to get the system through the house. Two-story houses are obviously more difficult, but that’s probably a couple of the biggest reasons we would want to do an interior run versus exterior.
J: Yeah. For me, it’s looks, and then it’s the freeze-up issue. So we did the heat cable stuff, and that seems to have fixed it, but still, it’s so ugly I would never put it on my own house, so I don’t recommend it to my customers unless it’s kind of their only option.
J: So we only do a few a year.
J: How do you mitigate a townhome?
C: Well, it depends. If it’s a townhome that’s owned by a central owner, one owner owns the whole place and rents out everything, and they want to fix the entire townhome, that’s a different story than a townhome that is each townhome is owned by the individual owner.
You would love to be able to fix the building, right? But unfortunately, when there’s only one owner- or there’s an owner for each individual unit, it’s a little bit more difficult to make that happen. So you do the diagnostics on the unit you’re in, and usually, that’s going to at least fix the unit you’re in. You might fix the neighbor’s house, too. Call that collateral mitigation. But that’s how we approach it, anyway. If we can get everybody to work together, we love to do that. Fix everyone. We might be able to fix all of the townhomes with a single system because there’s going to be some connection to some degree. And I’ve actually seen times where the drain tile from one unit goes into the next unit, and when that’s a situation, you have to actually talk to the neighbor next door.
J: Yeah, seal their sump or something like that.
C: Yeah, like, “Hey, we’re not charging you for this, but we’re going to fix your radon problem. And we have to do that in order to be able to fix your neighbor’s problem, and they’re paying us to do that.”
J: Okay. Well, I think Chad has to get back to teaching, so we’ll wrap that up here.
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