Andy Wojtowski

Podcast: Fixing Ice Dams the Right Way

Reuben, Tessa, and Bill discuss repair methods for ice dams on Minnesota homes. Before starting with Structure Tech, Tessa used to spec out insulation and air sealing work for houses with ice dam issues. The team discusses the cause of ice dams, how to fix them the right way, and things to look for when hiring an insulation contractor.
Also mentioned in this episode is Project Overcoat, which Tessa was involved in.


The following is a transcription from an audio recording. Although the transcription is largely accurate, in some cases it may be slightly incomplete or contain minor inaccuracies due to inaudible passages or transcription errors.

Tessa Murry: So to take a step back, let’s just talk about ice dams, what causes an ice dam in the first place? When you have heat that’s escaping from your house into the attic, that heat can warm up the roof deck and what happens when the roof deck gets warm? The snow melts, right? And then that water will re-freeze at the eave, the soffit where it’s cold, and you can get an actual dam of ice that builds up, and then the real issue is when snow continues to melt and that liquid water builds up behind that dam of ice, and that water can find its way up through into the attic space through the shingles.

Bill Oelrich: On last episode, we talked about storey-and-a-half houses, and the issue of ice dams came up. So we really wanna drill into that today, and let’s get to the bottom of ice dams.

Reuben Saltzman: And Bill, I know it seems weird talking about ice dams in the middle of summer, it seems like this can’t be on anybody’s mind, but it ties into what we were talking about last week. And not only that, but I just got an email from somebody asking about this, and I just wanna read this while we’re doing this right now. Joel says, “Certainly the biggest concern I always have is finding a quality contractor to address the problems and doing the problem solving that you talk about. So I wanna address ice dams in winter by sealing my attic air leaks and redoing the insulation, and I’m gonna hire someone to do it. But if I go up there and watch them, is that the only way to know that it’s done properly? And are they also gonna cap the ceiling lights? And what else should I be looking for?” And I thought I’ve got one of the most knowledgeable people period, when it comes to fixing this stuff, doing the podcast with us. I should just throw this over to Tessa and talk about what all happens when you’re specking work to have your attic re-insulated and have your ice dams fixed.

RS: Just to back up on that, this is how I found Tessa, this is how she joined our team. We were doing a ton of ice dam inspections back in 2009, ’10, ’11, and I was referring an insulation contractor, but I needed somebody else to work with. I wanted somebody really good. And I ended up interviewing different insulation companies, I found the company Tessa was working for. I mean, they knocked it out of the park, they were so knowledgeable.

BO: They were awesome.

RS: Yeah, Cocoon. And I said, “I’m gonna refer these guys from now on, ’cause they know what they’re doing, they understand the whole thing.” And that’s how I ended up meeting Tessa.

TM: So as you said, Joel, he asked you that question about what he should be looking for to make sure the work is done properly.

RS: Yeah.

TM: And I wish I could answer that in a short, short way, and I wish I could say there’s a black or white answer for that.

BO: You mean there’s not an attic insulation and air sealing playbook that…

TM: Oh, man…

BO: Everybody’s using?

TM: It is a lot more complicated than that. So to take a step back, let’s just talk about ice dams. What causes an ice dam in the first place? Well, if you have heat…

BO: Gutters?

TM: Yeah, [laughter] right.

RS: No.

TM: No, man, how many times have I heard that? Yeah, it’s not gutters. So when you have heat that’s escaping from your house into the attic, that heat can warm up the roof deck. And what happens when the roof deck gets warm? The snow melts, and then that water will re-freeze at the eave, the soffit, where it’s cold, and you can get an actual dam of ice. And that builds up and then the real issue is when snow continues to melt, and that liquid water builds up behind that dam of ice, and that water can find its way up through into the attic space through the shingles. So that’s the problem with ice dams.

RS: Yeah, but won’t the Ice and Water Shield stop it?

TM: Sometimes, sometimes it does, but I’ve seen so many houses that do have ice and water and they still have water intrusion from ice dams.

BO: Yeah, just so everybody knows, Ice and Water Shield is a product that is… It goes underneath the shingles and generally it’s applied on the maybe first three to six feet of your roof. And then they go to normal tar paper after that, but it’s extra thick, and when the nails go through it they’re supposed to adhere, and it’s a great product, but it doesn’t solve all the problem.

RS: Even the manufacturers don’t claim that it’s gonna do that, they call it a first line of defense, that’s it.

TM: Right. So that’s how ice dams form. So how do you prevent ice dams from happening? Well, you go to the root cause, you stop the heat loss from… You stop the heat from getting from the house into the attic. So how do you do that? Well, a lot of people think, “Oh, I’ll just blow in more insulation, I just need more insulation, that’s my problem.” So they hire an insulation contractor to come out, they blow in more insulation. You know what? Sometimes that can actually make the problem worse. You know why?

BO: Less space for air to move?

TM: That can be one reason. So if you take an attic that used to have good airflow, there was good attic ventilation so air was coming up through the eave and then circulating through the attic and leaving through the exhaust vents along the peak, that would help reduce the heat buildup in the attic. And if you blow in a ton of insulation, I’ve seen this happen a lot, now that insulation is so deep that it blocks the vent chutes and it blocks the airflow at the eave, and so you don’t have great ventilation anymore. That’s one potential problem. Another is too if you add a lot of insulation up into that attic, now, without doing any air sealing, you’re still gonna have some of that warm humid air leaking up into the attic space. And now that you’ve added a bunch of insulation, the temperature of that roof deck is gonna be much cooler. So what happens when you have a cooler surface temperature? Well, your potential for condensation increases and you can actually get more moisture buildup in your attic than you had before, and that can lead to frost in your attic and what we call a raining attic syndrome too.

RS: Yeah.

BO: So every year, two or three times a year during the middle of winter, Structure Tech’s phones will just blow up after the first 35 below zero 3-day stretch followed by a 32 or above stretch. Everybody’s got water raining out of their can lights in their attics, and, “What’s wrong? My roof is leaking.” No, it’s not leaking.

RS: And they call the roofer and blame them.

TM: Yes.

BO: Yeah, it’s got nothing to do with your roof. It has everything to do with all the condensation that developed in the form of frost that was just fine when it was cold, but then once it warmed up it started running and turned to liquid water.

TM: Yeah, exactly, so how does that moisture get into your attic in the first place? Well we talked about this on the previous episode, but attic bypasses. So attic bypasses are any little holes or leaks you have in that ceiling or a wall that separates the conditioned space to the unconditioned attic space. So electrical penetrations, recessed can lights. Those are huge sources of heat loss and air leakage into the attic. And all that warm air in the house in the wintertime is going to be finding its way into the attic through those attic bypasses because heat rises, it’s just physics, right?

So all that warm moist air is pushing up through these attic bypasses and getting into this attic space. And if you have a lot of air leakage and if you have higher humidity levels in your house, you can really create a bunch of problems, moisture-related problems in your attic.

RS: Tessa, that’s an awesome detailed explanation of this. We gotta take a break, but when we get back let’s talk about what homeowners can do to actually fix all this stuff. I gotta ask you this. I heard you say heat rises.

TM: Mm-hmm. Well, okay, so technically that is not correct. So, you’re right, heat always moves to cold, so it can move in any direction, but warm air rises.

RS: Okay, alright, thank you, thank you.

BO: Why does that bother people so much?

RS: It doesn’t bother me, I just know that it bothers Tessa, and if Tessa… Tessa is gonna hear herself say this later and she’s gonna kick herself.

TM: Thanks Reuben. Yeah, I have to make my professors proud. I do understand the physics, thank you . Yeah, no, but going back to how to fix these problems, right? Okay, so every house unless it’s been 100% air-sealed by an expert, is gonna have these places where that warm air can get into the attic and the moisture and create problems. So how do you know if your house is having that issue? Well, one, you’ll probably have ice damns, you could have frost in the attic, you might have had water stains or drip marks show up on the ceiling like Bill said, after a really long cold spell and then all of a sudden we get one warm day and you see these stains show up in your ceiling. You have no idea what’s happening. It’s not a roof leak, it’s all the frost in your attic that’s melting and dripping back down onto the ceiling, right?

Or, you can even pop your head up in the attic and take a look at the roof decking, and if you see dark staining, even white staining, that’s a sign that you’ve got moisture up there and you need to do something about it.

RS: So if you’re gonna hire somebody to come out and fix it, what are they gonna do specifically?

TM: Specifically they’re gonna have a human go into these attic spaces and dig them out and find all these little pathways where air is leaking from the house into the attic and physically seal them up. Usually, they use spray foam.

RS: Okay. And how do they access all this? Do they just know where to look or are you gonna have somebody come out there and just push all the insulation to half of the attic, and so it’s just completely exposed? How does that gonna work?

TM: That’s a great question. And I’d say it’s different for every contractor. So there are some seasoned contractors who have done air sealing for a really long time, and they kind of know where to look in an attic to find these major attic bypasses. A lot of times it’s obvious places, right? Like it’s around a B Vent or a chimney, so they know to go to these places and plumbing vents and dig them out and seal them. But that’s no guarantee that you’re gonna get all of them. A lot of times there’s no way that you can just kind of hunt and dig in random places and find them all. You have to remove all the insulation to find them and then seal them.

BO: And it wasn’t common back in the day for people to seal up and caulk around these openings, right? So you’d have a chimney that… You have a round chimney that might go through a square hole and… That’s just a… It’s like a highway of air moving through there.

TM: Exactly, yep, yeah. A lot of air leakage. So you can hire an insulation contractor to come out and they have different ways of finding these air leaks. But what we used to do when I worked at Cocoon is we would use a blower door and an infrared camera. And how that works, the blower door is basically a tool you can use to de-pressurize a house, and so it’s like a big fan that you set up in a temporary door and you turn that fan on and it sucks all the air out of the house, and you de-pressurize the house, and by doing that you’re pulling in all of the outside air through all the little cracks and leaks in the building envelope. And if you’ve got a temperature difference between inside and outside, you can use that infrared camera to scan the ceiling and the walls and find where those cracks and leaks are. That then gives you a road map of to where these air leaks are happening and where you need to do the air sealing.

BO: Is it fair to say that’s the easy part of that project?

TM: I would say that it’s very true, Bill, yes. So back to Joel’s question, “How does he make sure they’re doing everything right?” Well, part of the problem is in these… A lot of times these storey-and-a-half houses, you’ve got air leakage happening in places you just can’t really get to, you physically can’t get to them. So these houses a lot of times, you can send someone into these side attics or an upper peak attic and they can seal what they can get to, but you’ve got air leakage happening in a lot of other places that you physically can’t get to unless you were to remove the roof or remove the interior finishes. You’re still gonna have some air leakage in those spots.

BO: Are you ever better off to just let it leak? Are you chasing your tail to a degree, or…

TM: You know, there are some situations I’ve seen where we’ve gone into a house and we’ve air-sealed portions of it. And remember what I said about unintended consequences? You air seal one portion of the attic and now the air leakage is occurring worse in another area that you haven’t air sealed, and now you create a moisture problem in that area. So I have seen it create problems. So really I would say it’s about getting a contractor who understands the house as a system and can evaluate the whole house and develop a strategy for air sealing and insulation and to kind of do a… The best that you can do on that house without creating problems, if that makes sense.

RS: Yeah, yeah and there’s so many varying levels of quality for work that’s done. I have a friend, she lives in a town home and she just sent me some quote. She’s like, “Who’s doing it right?” And it was all these different quotes from insulation contractors and one said they were gonna seal all the accessible bypasses and bring it up to R49 for the insulation and they’re gonna seal the attic access hatch and do all this. I’m like, “Yeah, that sounds pretty good.” But then the next person was like, “Oh and we’re also gonna build boxes for all the recess light, and we’re also gonna beef up the insulation at the eaves with closed cell foam ’cause there’s not enough room for traditional insulation there.” And I’m like, “Oh yeah, that’s even better. That’s great.” And both of them are legal. All the state requires is that if insulation is being added, and a side note, this is an important thing to know if you’re having insulation added, the state requires the insulation contractor to perform air sealing. That is law.

BO: All right, Tessa, what’s the right way to interview a contractor and make sure you’re getting the right person to complete your project?

TM: That’s a great question. I would say if you are looking to make some improvements in your house, make sure that you interview your insulation contractor and that they at least mention and talk to you about air sealing, because if they’re just going to blow in insulation they’re not going to be fixing the problem. They need to do air sealing as well.

RS: Now Tessa, taking the other side of it, I can’t imagine there’s a single insulation contractor out there today who’s not gonna bring up air sealing. This is the law. They have to at least bring it up. Is there anything else that they should be talking about that’s gonna tip you off to let you know that, look, they just have a cursory understanding of this and they’re just saying this because they have to? What’s some good stuff that they might bring up?

TM: As a homeowner you may not like to hear this. So from a sales perspective, you know that you’re getting an honest contractor when they bring these things up. So one would be unintended consequences like you said. By doing all this air sealing work in your house, you can create problems with moisture, mold, indoor air quality. And so you might need to add some additional ventilation for your house. It could be an HRV, ERV system, a bath fan, what have you. You can also create problems with back drafting water heater. So if you’ve got a natural draft water heater and you air seal your house and make it a lot more air tight, sometimes that can cause your water heater to back-draft. And that’s a health and safety issue ’cause there’s carbon monoxide in the exhaust gas. So if you’re talking to an insulation contractor and they start talking to you about needing to add another fan or replace your water heater, that’s actually very impressive.

RS: Yes, yes.

TM: Yeah, very, very impressive.

RS: It means they know what they’re doing. They understand houses as a whole. They’re not just a insulation contractor, “One and done and I’m outta here on to the next”.

TM: And the other thing I would say too is that depending on your house they may or may not be able to guarantee that you won’t have ice dams. So there were a lot of storey-and-a-half houses that we worked on and unless you’re going to do all that crazy work we talked about before, you can make some of these areas better by air sealing insulated spots that you can actually physically get to, but you can’t fix the slants. You can’t fix other areas. And so we would never guarantee to these homeowners that the problems would be completely resolved even with the work that we did.

RS: And now, Tess, real quick, just to answer one of the questions we had at the beginning here, what about recess lights? What would you have done with those?

TM: That’s a great question. If you’ve got a recess can light you should have basically a box of rigid foam insulation built so that it can go over top of that can light in the attic. And then you need to air seal that insulation box to the attic floor. That’s the second part of it. So you can’t just put the box over the can light. You have to spray foam around it to air seal it as well.

RS: Now, I know when you were spec-ing the work that was about all there was. Within the last five years or so there’s been a bunch of products that have cropped up to take the place of these insulated boxes that are basically made on site. What do you think about some of those products you can buy at the store today?

TM: I’d have to look at them. That’s a good question Reuben, ’cause I haven’t seen what they look like with an infrared camera and a blower door test.

RS: Okay, all right.

BO: Technical details.

RS: Maybe, maybe.

TM: They’re probably better than nothing. They’re probably better than nothing.

BO: All of this work seems very labor intensive.

TM: It is. It’s hard work.

17:32 BO: It’s messy, you’re on your stomach crawling across an attic, trying not to fall through the ceiling.

TM: Yeah, squeezing in tight spaces, working in all that insulation, it’s very hard. It’s very difficult to do that.

RS: I’ll have people say, “Oh yeah, well I’ve been thinking about fixing it, but we don’t wanna do it in the winter. We wanna wait until it’s warmer,” and I’m like, “No, you definitely wanna do it in the winter. It’s gonna be unbearable up there once it gets to about 70 degrees outside.”

BO: It feels like the ratio of man hours to supplies in these kinds of repairs is about 90 to 10. [chuckle] Mostly people hours up there and the rest is just a minimal amount of supplies.

RS: Yeah, that sounds about right.

TM: Hey Reuben, how much do you think it’s gonna cost to do this air sealing insulation? Average price?

RS: I’ve talked to a lot of contractors out there and it doesn’t vary that much. It’s typically between about $2 and $4 a square foot. So if you’ve got a one-story, thousand square foot house, thousand square feet. And then you multiply that times somewhere between two and four, that’s about what you can expect to pay to have somebody do all the air sealing and insulate it to today’s standards.

BO: On a standard house with a flat ceiling. This is not a story and a storey-and-a-half house…

RS: Yeah, where you can access it. Storey-and-a-half houses, you can’t fix those. I’m sorry, Bill.


TM: You can’t.


BO: Reuben, I know you’ve blogged a ton about this information. Can you tell us where to get this?

RS: Yeah, you can go to our website, if you type in Structure Tech Blog or Reuben’s Home Inspection Blog, I have a ton of information about everything we’ve talked about today. And if you’re a homeowner and you wanna know the unbiased truth about what’s causing these problems, you want someone to come in and tell you, “Here’s the issue and here’s what to do to fix it” we do that. We do single item inspections. I’ve probably done hundreds of these for homeowners who have ice dams and attic problems. Tessa, I know you’re basically taking over. I don’t really do these anymore. Now you’re the one doing all of them.

TM: It was a busy winter, this past winter.

RS: Yeah, yeah, you did a lot of those.

TM: Yeah, tons of inspections about ice dams, moisture in the attic, all that.

RS: Yeah, so we are for hire.

BO: Clearly it’s important that anybody in a real estate transaction consider a home inspection and it doesn’t matter where the house is in its life cycle. It’s super important that you find a qualified home inspection expert to come out and do a thorough evaluation of the real estate you’re considering. Thanks for joining us. We’ll catch you next time.