vented attic insulation

Vented Attic Insulation Secrets Unlocked

Foreword by Ian Thompson, Editor

Get ready to pull back the curtain on a European builder’s vented attic insulation mastery with Matt Risinger and Steve Baczek. In this new video, we crack the code on vented attic assemblies – a specialized technique that can revolutionize your projects’ energy performance and structural integrity.

From the outset, you’ll witness the critical importance of an uncompromising air barrier across the entire roof plane. See how pros employ Siga blue tape to seal joints with a seamlessly folded edge, maximizing airtightness every step of the way.

But it’s not just about installation – it’s about verification too. You’ll learn the crucial step of buttoning up the home pre-window cutting to conduct blower door testing. This allows scientifically measuring the air barrier’s performance impact when penetrations are later added.

The ingenuity extends to advanced material selections like smart vapor retarder and Sega tape. As framing walls take shape, you’ll see them enveloped in a seamless blanket of folded membranes creating that pristine air-sealed shell.

Ventilation remains key though, which is why we dive deep into insulation baffles and their role in vented roof assemblies. Witness firsthand their impact on preserving critical airflow to expel moisture and prevent dreaded insulation degradation.

And this is just the beginning. We’ll cover techniques to enhance attic accessibility for maintenance, streamlined plumbing penetration methods, and pre-insulation blower door testing to validate your handiwork.

Join us now as we peel back the layers on one of the building industry’s most important systems. This in-depth exploration of vented attic assemblies will equip you with the knowledge to construct resilient, energy-efficient homes that are truly sustainable.

Over to Matt and Steve.

Vented Attic Insulation Secrets Unlocked

Video Transcript

What’s up guys? I’m Matt Risinger and I’m Steve Baczek now. Steve, we’re making a video about vented attics and doing insulation correctly. What the heck are we doing standing outside of this house?

So you know, on this one here we have the Huber as our external primary air barrier, but that only goes up the walls. Okay, so we have to be able to complete that form across the top and across the bottom.

The bottom’s easily solved with the concrete slab and some Stego wrap, and then we bring it up the walls, but the trick is how do we solve it at the top of the roof?

Okay, so what can we see on the outside that gives us a clue about that? So if you look up there, you can see a pretty little Blue strip taped to the primary air barrier. So that’s our air barrier going up and folding over, and then we make a series of connections inside to complete it.

I like it. We got a great video with some nerdy details. We’re basically talking about how you cannot utilize drywall, but instead use another material you’ve probably not seen before that’s very common in Europe that’s starting to take off here in America. Today’s build show is about vented attics and doing the insulation right. Let’s get going.

Steve, I noticed when we’re walking into this house, you’ve got headers in place but none of the windows and doors got cut out. What’s up with that? Yeah, so you know, on a lot of our projects when we can do it, I like to cut out the windows later because that allows us to test the integrity of our primary air barrier.

So if we say our ZIP R9 is our air barrier, and we don’t cut out the windows, we can get a blower door measurement of the ZIP R9. Then we can cut out the holes, install the windows, get another blower door, compare the numbers and understand what effect installing the windows has. Gotcha.

Okay, now back to our topic today, which is ceiling airtightness. Here’s where things start getting interesting. Steve, I walk up and I immediately notice there’s some type of fabric here on the ceiling, and then you’ve got some furring happening. Walk me through this detail, what is this material?

So the membrane that comprises the field of the ceiling here, it’s SEGA Myrex. It’s a smart vapor retarder, so moisture can pass through it very easily. It is a vented roof assembly. Okay, and it comes all the way to the end. You can see we have our RESCON tape here. Now what we did was when we framed the walls before we set the trusses, we folded over some SEGA Myves. It comes in an 18… see that I think down here? Let’s walk down here while we’re talking.

And so you took an 18-inch roll of this blue SEGA Myves material, and here it is right here. Yep, I’m going to take this light down so we can see a little better. So that’s fold that down and show us that it’s blue. So there it is. Okay, so that’s the blue we saw on the outside, right? So that’s over the double top plate and it comes down the wall, so that’s that blue tape line on the outside there. Got it.

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And then this simply just gets folded up. We have our double-sided SEGA tape here, so this gets folded up to there, and now we have a flange that we can bring our SEGA Myrex over to go under that, tape it off, and we’ve now main maintained continuity in our air barrier across the ceiling. That’s pretty cool.

So in other words, this membrane now is put up in place for airtightness instead of drywall. Now we’re still going to put drywall up for aesthetic reasons, but we’re no longer worried about caulking, sealing, doing all that stuff because this membrane is going to be our airtightness layer.

And even more interestingly Steve, it looks like you put a 2×4 on the flat down on top of your top plates. We have a number of 2x4s there, and that provides a 1 and 1/2-inch raceway now for all of our recess lighting, our smoke detectors, any electrical boxes. Got it.

So this is left off for that very reason. The plumbers, the electricians, they all need access to the attic to get rid of the vent pipes, potentially run some electrical across the attic, got it? Etc. and we’re not having any HVAC up there, but mostly for the plumber. And the beauty of having the Myrex there is we could do our plumbing penetration, we can seal it up, and then we can test it immediately before any of the insulation gets in.

And now Steve, you said it really quick but I want to make sure that everybody caught that who’s watching this, there’s no HVAC equipment in the attic whatsoever. We’ve eliminated that. We’re either going to go up from the floors up, you know, from a lower system in the basement coming up. We might go out the walls for ERVs or for exhaust fans, things like that. And then what’s happening with this spray foam that I’m seeing over here, Steve?

So the spray foam, you can see the black baffles, those are our insulation baffles. It’s a totally vented roof system that goes down to a vented soffit. The air baffles go down, and then we basically seal them in. The blown-in insulation here is the ability to get really good R-value.

We’re probably at like R84. Wow, in our value, but we get it at a really inexpensive price because it’s simply blown in. It’s the cheapest install we can get, but the problem is, is it’s air permeable. And so you don’t want to degrade the performance of the insulation by having cold air blow in through the side of it. You want all of the vented air to go up and around it, so we create that air barrier there.

So we take the air permeability and we put it into that system. And if we didn’t have these baffles in place, the wind when it blew up through our side vents could blow that insulation away from the edges, and we could end up having great insulation in the center but hardly any insulation at the edges. I’ve made that mistake before, and we’ve seen that in New England. You go up in the attic and there’ll be a big scallop here, yeah, where all the insulation is stored in the middle of the roof.

So it’s not that you can’t use drywall as your air barrier, it’s just a lot more details. And there’s a ton of great videos from Steve Baczek and from others like Jake Bruton on our website showing how you can use drywall as your air barrier, but this is a fascinating product that Steve and I have seen all over Europe and traveling, and it’s starting to really take hold in the US as well.

And this works very well here, but understand if you’re in climates like climate zones six or seven where you’re required to have a vapor retarder at the ceiling level, we have a smart vapor retarder. Got it?

So this is a detail that you can move up into different climate zones, and it still becomes the solution in the colder climate zones. It’s a great detail, and I really like this, especially in the north where we are here. We’re outside of Boston, makes a lot of sense.

We’ve got a basement, we’ve got our furnaces usually below. I wouldn’t use this if you’re thinking about HVAC equipment in your attic. This is not a detail that we want ductwork running through that attic space, but if you want to do a ventilated attic, which is a great assembly, it’s very forgiving. This is a great way to go. Steve, impressive stuff guys.

We’ll put a link to these products that we talked about from Sega in the description below and check out Steve’s videos. He’s done a bunch of videos on this house and these details in particular over on the build Lastly this particular house we’re in C’s making a whole series of videos called it’s the multi gen on a budget.

So this is a multi fam house on a budget. It’s going to be a really fun project. We’ll look for that coming soon on the build That being said go follow Steve on Instagram go check ou this videos. Hit that subscribe button below. We’ve got new content here every Tuesday and every Friday. Follow us on Facebook or Instagram otherwise we’ll see you next time on the build[Music]show 

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