Episode #76: Building from the Inside Out: A smarter approach to continuous insulation. Mickel Maalouf, building science manager at Huntsman Building Solutions

Yeah, so what we're talking about is basically, uh, you know, as I said, it's, it, it's an assembly that is insulated from the inside, but that still gives you the benefits of outside insulation.

So, uh, continuous insulation that cuts the thermal bridges and that gives you a perfect insulation and air barrier.

So, um, you know, traditionally, before the new energy efficiency code, uh, you know, w- we would say, "Okay, I need an R-20, I need an R-24." So, you know, you put a R-20 batt in the wall a- and that's it, you meet code.

But now, since the thermal bridges need to be dealt with, they need to be taken into account, it's not this total R-value that we need to meet anymore, it's the effective R-value that takes into consideration all this heat transfer through the structural members.

So the way we tackle it from the inside, uh, with the D-MAX wall is, is, is very simple.

Uh, traditionally we would have, for example, our studs.

Let's take a, you know, a high-rise re- residential or, or a commercial building.

We have metal studs, let's say six inches, uh, we have our sheathing on the studs, and then we have continuous insulation on the outside, um, and we may have, you know, Z-girts, uh, for metal cladding attachment, or we may have brick ties, right? With the D-MAX wall, we've basically simply inverted, um, the positioning of the Z-girts and the sheathing.

So now the Z-girts are installed directly on the studs, and they're, uh, th- they are of, um, variable thickness.

And on the Z-girts we install the sheathing, and it's the space that is created by the Z-girts that we are gonna spray with foam to cut the thermal bridges.

And then depending on the effective R-value that we're trying to reach, uh, uh, either to meet code or to, to go above code, uh, we're gonna continue the thickness, our desired thickness of insulation in the studs.

So the thermal bridges are gonna be cut horizontally and vertically through the Z-girt thickness and through the studs.

And, um, so, so this is how it happens.

Uh, you know, for, for, for people who are, you know, paying attention, you're gonna notice that there is still thermal bridges that are punctual, and this assembly is the metal-to-metal contact where the z- where the Z-girts are screwed into the studs, right? So, uh, uh, the code doesn't tackle this metal-to-metal contact, uh, um, in all, um, provinces.

But in Quebec, for example, where the D-MAX started, uh, this is not code compliant, right? I- i- in- in the prescriptive path.

It is potentially code compliant in the performance path, right? So we can demonstrate that, yes, although there is a thermal bridge, we can take into consideration the mechanical, the windows, and other components of the building envelope, and have our wall less performing but compensate elsewhere, right? But prescriptively, to make it code compliant, you have to have a thermal break, uh, at the stud to, um, uh, at the stud a- and Z-girt junction.

And this thermal break that we've tested...

By the way, everything is tested, uh, externally at UL, uh, for U-values, for all code compliant tests are t- are, are tested externally.

And to make it code compliant, it's not, you know, we didn't test with a iso clip, with a Cascadia clip that are, you know, five, six, $7 per unit.

We really tested with the least expensive, the most generic materials such as, um, you know, half, uh, half an inch, uh, Usin.

So half an inch polypropylene thermal break that you buy like a box, so, you know, many, many units in the box for, uh, you know, very few dollars.

Um, and you just basically screw it at the same time as you s- as, as you screw the studs, uh, the, the Z-girts into the studs, and it's gonna basically separate this metal-to-metal contact and make your, um, your, your wall way more energy efficient, uh, with, with minimal, minimal, um, uh, costs added.

So, um, you know, traditionally, n- now with the new energy code, if you wanna go traditional, like a traditional assembly, typically you would need six-inch studs filled with fiberglass, and you would need, um, you know, if you, you know, whatever continuous insulation you wanna use on the outside, whether it's mineral wool, whether it's board stock, whether it's insulation, you're gonna need two, three, maybe four inches on the outside.

Uh, so your wall is getting thick, uh, you need more insulation because now it's the effective R-value that we're trying to meet, right? You need to cut the thermal bridges, so you need more insulation.

The walls are becoming thicker.