Vented Attic Insulation? Here’s a trick We Stole From European Builders

What's the R value of that mustache?

Kyle from RR Builders has been showing of the Majrex in his latests buildings. He was inspired by The Build show to not just build sturdy buildings, but dramatically improve efficiency by "sweating the details." He has shown that you don't have to use spay insulation as the only way to get get great blower door scores. The Majrex is kind of like Gortex for a house. It's makeup (chemistry and weaving) makes it so moisture can more out at a much higher rate than moisture can move in. So it lets a building dry, while not allowing much if any outside moisture back in. The Swiss are doing some amazing things with Building Science. The materials aren't cheap, but the long term benefits to a property are fantastic. Low energy loss through air movement, moisture can migrate outward. Interesting that in this video as well, they show they are using a little bit of spray insulation in key spots, but can then switch over to cheaper blown in insulation, while still creating a super insulated house.

Just recently finished re doing my vented attic. Blew all the loose fiberglass to different corners and worked on air sealing penetrations and top plates then adding 2 layers of R15 rockwool, then clear a different section snd repeat. Then doubled the length of vent baffles to they'd actually be above the insulation layer unlike before where they were clogged with fiberglass. At the end i have an R30 rockwool layer and somewhere between R30-45 loose fiberglass on top. Also, anybody that has issues with insects like bees nesting in their attic, i suggest putting in a finer stainless steel mesh for the vents. I had tons of paper wasp nests in the vent baffles (palm sized range), so i put in a .22mm mesh, about what a window screen is, and sealed any non vent openings to the outside. No more bees should be getting inside, nor spiders, stinkbugs, or most things.

Matthew.... I mustache you a question, but I'll shave it for later.

Matt you have inspired a generation of future owner-builders to take pride and enthusiasm in their construction.

Just yesterday, I saw a commercial property (an old auto repair shop) fully resheathed with ZIP System. This would have been a pleasant surprise, except for... They didn't use any tape and/or liquid flashing. Yeah, they paid the extra money for ZIP system sheets, but skimped out on the tape and liquid flashing.

Steve's projects are often above the level that the energy codes require, and can be very expensive to build as you chase down heat and air loss. I doubt that the majority of builds in these areas are anything like this. I applaud Steve's creativity in finding new ways to seal and insulate homes.

I love the attention to detail and all of the energy you put into building science, but all of these videos need a quick explanation at the beginning of the location/climate zone. I’m a builder in MN and most of the insulation and air sealing methods on your channel would not be best practice here. People who are not experienced (my customer base) need to know why certain methods are best in certain climates. The scary thing is that there are likely a lot of DIY guys that are creating future mold disasters based off of YouTube advice for a different climate.

I’ve been building houses for quite some time now in Washington state. I’m assuming because of moisture conditions, our codes require more air flow throughout the building. I get that, and some climates, having things, sealed and airtight is necessary. But I’ll tell you one thing. I’d hate to be the person paying for all these extra details. All these companies trying to come up with new systems to sell more material for higher costs. I try and look out for my customers and only do things overkill if they’re 100% necessary. These look like some great systems but are they all necessary? How do you change out lighting if it’s sealed in the ceiling? And we use baffles in the attic all the time, but why run them so close to the peak? One baffle will keep your insulation from blowing away from the bird block. Again we have to deal with high humidity’s and lots of mold and mildew so it could just be the climate. But I’m curious?

😂 I literally decided to do this last week on our next build. Thought I will be the first. Awesome! Matt want some pictures of the build in a couple of months?

I was beginning to have Steve withdraw! Always a pleasure to see what he's up to!

Love these videos. Plan is to (eventually) self build a house similar to some of the techniques Matt brings us.

Just inspected a 6 year old house with big snow drifts of loose fill insulation near the porch overhangs, and big patches of uninsulated drywall, of course. Builders get annoyed with inspectors for "overthinking" but I'd say our building practices have a long way to go. Great info as usual - nice video!

I heard about that wrapping technique before. Cool to see it up close in practice. Great way to merge a couple of approaches.

In my new home we used 1/2" OSB as the air barrier on the ceiling, sealed with wet flashing to periphery and joints. Then ripped 2x6s in half and installed on edge for a service cavity for plumbing and electrical. Blower door tests out at .58 ACH.

Ah puberty and growing facial hair. Also the voice cracking high...which you clearly hear at the end of his videos when he says, "oooooon the build show". Matt's growing up so fast! sniff *sniff*. ;)

In 1992, we did something similar with 6mil poly vapour barrier: continuous from basement to attic, wrapping around and completely enclosing both the first and second floor platforms, in zone 5 (which required vapour barrier towards the interior and the bulk of the insulation outboard).

Why didn't you do a raised heel truss to get more insulation thickness above the ceiling under those baffles? You say r 80, but no way your getting r 80 under those baffles.

There are nails/connections going from the rafters to the top plate that break that air seal, right? Do you do anything to seal those?

You totally sold me on conditioned attics. There is no way I would ever want a vented attic in my house now. The way you did it in your own house is just the right way to do it.