That New Attic Insulation? It's Probably Installed Wrong

You can drop thousands on blown-in attic insulation and still live with drafts, a scorching second floor, and energy bills that refuse to budge. The uncomfortable truth is that insulation is not an air barrier. If air can move through your attic floor, fiberglass will not stop it, it will only hide it. We walk through the one rule that changes everything for home energy efficiency: seal first, insulate second.

We break down how the stack effect turns your house into a chimney, pushing warm air out through attic leaks in winter and pulling hot attic air down into living space in summer. Then we get specific about where those leaks actually are: top plates along every wall, recessed can lights, plumbing and wiring penetrations, attic hatches that fit like loose drywall, and even gaps around HVAC boots. We also talk about indoor air quality, because the same airflow that wastes conditioned air can drag dust and insulation particles into your home.

To prove the point, we share a blower door test case study where air leakage stayed exactly the same before and after adding insulation. That is why skipping attic air sealing can become the most expensive shortcut: fixing it later may require vacuuming out new insulation just to reach the leaks you needed to seal in the first place. We close with a simple checklist mindset: air seal, confirm attic ventilation from soffit to ridge, then insulate to the right level for your climate zone (often around R49).

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Transcript

The Expensive Insulation Mistake

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So you just paid a contractor to blow insulation into your attic, and maybe it cost you a few thousand dollars, maybe more. But your house is still cold in the winter, still hot in the summer, and energy bills haven't moved. It's not actually the insulation's fault. The contractor skipped the one step that makes insulation work. And the worst part, he buried the evidence when he blew that insulation in. Now it's going to cost you more to fix than it would have cost you to do it right in the first place. Today I'm going to walk you through exactly why that

Insulation Vs Air Sealing

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happened. So here's the short version, and then I'm gonna go a little deeper in a minute. Insulation slows heat transfer. That's its job. What it does not do is stop air movement. Air can move right through fiberglass insulation. That's why insulation and air sealing are two completely different jobs. Air sealing is what actually stops air from moving, and air sealing has to happen first before a single bag of insulation goes in. Seal first, insulate second every time, no exceptions. Most contractors skip air sealing not because they're trying to cut corners, but because it's genuinely hard work. Most homes already have insulation in the attic. That means before you can seal anything, you have to move it or remove it. A lot of insulation contractors don't have the equipment for that. And even if they do, it adds hours to a job they could otherwise finish in about two. So they blow in the insulation, collect their check, and move on. Not always bad intentions, but let's face it, most people take the path of least resistance. That's why this falls on you as the homeowner to know what to ask for before anyone touches your attic. Real quick, I put together a free guide called the Attic Air Seal and Insulate Guide. It gives you a complete checklist of every air sealing and insulation task in the correct order, plus seasonal tips so you know what to check for and when. Link is in the description. Totally free. Now let's

Where Attic Air Leaks Hide

SPEAKER_00 2:03

keep going. You see, here's the thing: your ceiling is not solid. It's full of gaps. Many recessed lights leak air, especially older ones. Anything from plumbing pipes or wire comes through your ceiling is a potential gap. And that board that sits on top of every interior and exterior wall in the house called the top plate almost always has a gap where it meets the drywall. And that gap runs the entire length of the wall. This wall behind me, right now, if I hadn't air sealed the top of it, it would be leaking right up into my attic. And your attic hatch? That thing's basically a hole with a piece of drywall sitting loosely over it. I've been in countless attics where I could literally pull the insulation back, see the top plate, and drop a coin down between the drywall and the top plate. And because your house works like a chimney, warm air rises, finds every one of those gaps, and escapes right up into your attic. In winter, that's your heated air leaving. In the summer, that hot attic air is being pulled down into your living space, which is usually why your second floor is so hot. And for every cubic foot of air that escapes out the top, your home pulls in a cubic foot of air through the bottom. Typically, that's through your crawl space or your basement. Then you have to heat that cold air that's coming in through your basement or your crawl space, it escapes again, you have to heat it again, and it escapes again. You see, insulation doesn't solve that problem, it just buries it. And it's not just about energy, that same air is being pulled down into your home every time you heat and cool. And this creates dust from the attic, insulation particles, whatever's up there comes right down into your living space. Most people never consider that their attic could be affecting their indoor air

Proof From A Blower Door Test

SPEAKER_00 3:50

quality. I was researching online and actually found a documented case study that shows this perfectly about how insulation does not air seal. A homeowner went through a state energy program. The contractor came out, said you need more insulation, came back, blew in fiberglass, took about an hour, and then left. And guess what? The house was still cold and drafty. The house was cold and drafty before the job, and the house was cold and drafty after the job. The homeowner had no idea why. I know why, because the contractor didn't do any air sealing. Not a single gap sealed. He blew insulation right on top of every air leak in that attic floor, and now those air leaks are buried under an additional foot of insulation. Because this was under an energy program, they measured the air leak before the insulation was blown in with a blower door test and found that 1,865 cubic feet of air per minute was leaking out of the house. Guess what? After the insulation was blown in, they did another blower door test, and exactly 1,865 cubic feet per air was being moved out of the house. The insulation did nothing to stop the air leak. As I said, insulation does not stop air. It never did and it never will. So to fix it the right way, they had to vacuum out all the insulation using large gas-powered insulation vacuums that created bags and bags of insulation that they had to haul away that included dumpster fees and extra hours of labor. All just to get back to the attic floor so that they could seal the air leaks that should have been sealed before the first bag of insulation was ever blown in. I see contractors do this every day. I got called out on a job up in the Tri-Cities a few years back, and the homeowner I met with said that every insulation contractor she had come out did not air seal. We were the only company in the area that offered air sealing of an attic before blowing in more insulation. And that's why Crawl Space Ninja always recommends air sealing

How To Seal Common Leak Points

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first. So now I'm gonna walk you through exactly where I find most of the air leaks in an attic. As I mentioned before, usually the biggest air leaks I find is along the tops of the interior and exterior walls. Now they may only be an eighth of an inch or a quarter of an inch wide, but it runs the entire length of the wall and moves a lot of air. The fix is pretty straightforward. You just pull the insulation back and run a bead of spray foam right across that gap over all the top plates. And then just put the insulation back over it. By the way, quick tip if your insulation seems like it's not very fluffy, get yourself a rake and go up there and fluff it. It'll restore a lot of the R value that it could have lost over the years. Now, another area homeowners overlook is recessed can lights. I've been in attics with six, eight, ten of them in a single room. Some homes have 40 to 60 to 80 can lights. It's unbelievable. And most all of them are leaking air. I've done several videos about using rock wool covers for can lights. They are fantastic. I've got a link in the description if you want to check them out. And of course, the attic hatch. That is the one most homeowners don't even think about leaking air and they look at it the most often. Most attic hatches are just a piece of drywall sitting in a hole. They're not air sealed, they don't have any insulation on the back, and that air just goes right from your living space around that drywall, straight up into your attic. They make some great attic hatch covers, whether you have a pull-down ladder or an attic scuttle. I'll put a link to some of those in the description. And of course, anywhere a pipe or a wire comes through your ceiling is worth checking as well. I've been in attics where the electrician, when they were building the house, would drill like three or four holes and then decide to move the outlet over there. Do you think they covered up those three or four holes they drilled? You need to pull that insulation back and take a look. And lastly, your supply ducts connect to the ceiling vents. There are often gaps around the metal box where the duct meets the ceiling. Make sure you foam or caulk those as well. So this is the kind of thing we break down every week. So if you haven't subscribed yet, now's a good time. And also I want to mention for all you DIY enthusiasts, or perhaps you want to get better educated before you hire a contractor, I wrote a book on this called Seal First, Insulate Second: the Complete Homeowner's Guide to Attic Air Sealing and Insulation. I'll put a link to it in the description. It's a breakdown of where every leak location could be located, the materials you should use to seal those up, and how to properly insulate your attic in the best order. Believe it or not, finding the leaks in your attic is easier than most people might think. All you have to do is go up into your attic and pull back a little bit of insulation over a top plate. If you start to see a lot of dirty insulation around can lights or the HVAC boot or things like that, usually that insulation is filtering the air that's coming up from your living space, and it's a lot dirtier around those air leaks than the rest of the

The Right Order And One Key Question

SPEAKER_00 8:42

insulation. So make sure you air seal every place where a pipe, a wire, a duct comes up through the attic, the tops of your interior and exterior walls, the attic hatch, all of it. Next, make sure your attic ventilation is working properly. From your soffit vents all the way up to the ridge vent, there should be a clear path. Then you want to add enough insulation for your climate zone. I recommend at least R49 in most of the United States. If you'll do it in that order, every dollar you spend works. Skip the first step and you'll just be covering up the problem and then you'll have to fix it later. Now, before you let anyone start working on your attic, I want you to ask this question. Will you be air sealing the attic before you add insulation? If the answer is no or they seem confused, I would keep looking. That one question could save you thousands of dollars in energy lost and having to redo the job over. Plus, it's just gonna make your house more comfortable. Now that you understand why air sealing has to come before insulation, the next question is why is that bonus room over the garage still hot even when it's insulated? That's exactly what we're gonna cover in the next video. So if you've got one of those rooms in your house that always seems hotter in the summer and colder in the winter, make sure you subscribe so you don't miss it. I'm Michael Church with Crawl Space Ninja, and I hope you make it a happy and blessed day, and we'll see you later.