The build show only ever does up to climate zone 3. I'm in climate zone 4. I went ahead and used a conditioned attic and vapor diffusion port anyway. Joe Lstiburek has stated that he thinks the assembly will work in colder climate zones. He also came up with the idea when confronted with failing roofs in Alaska. I just wish the build network would do more than hand wave at colder climates.
Spray Jones channel does a lot in colder climate zones as he is in Canada. Some of the published papers he goes over on conditioned attics in cold climates is very interesting.
I’m installing an unvented roof assembly on my 5 story DIY 48’ tall icf home that I am building. This information was super helpful because I will be using many of these details. The mechanically seamed metal roof will be a critical part of my house because I will be installing 20,000 kilowatts of solar on top using a clip system and I will have a roof top deck on the 1.5/12 pitched roof that has epic views of the mountains surrounding our valley.
Jake, I am thinking of building my first house, and since I live in climate zone 6 I would be very interested in a follow up video that covers cold climates. I have been watching a lot of videos from you, Matt, Steve, and a few others here on RU-vid. I don't know if my budget will support all of my ideas, but what I would like to do is build the house with no overhangs (what Matt calls Monopoly framing) using 2x4 staggered stud construction at 24 inches on center with 3/4 inch plywood for both the wall and roof sheathing, then apply a continuous fluid applied WRB. On the exterior walls I would have 2 or 3 inches of Rockwool comfortboard 80 (code here now requires R10 of continuous exterior insulation for 2x4 (R13) walls or R5 on 2x6 (R21) walls), then vertical 1x3 or 1x4 furring strips fastened through the Rockwool and sheathing to the studs with a bug screen and correvent at the bottom for a rain screen, with either fiber cement board or thermally modified wood siding. Then on the roof I would put a self sealing underlayment and/or ice and water shield on top of the fluid applied WRB, followed by butyl tape along where the rafters are (also at 24 inches on center). I would then put 4 inches of Rockwool comfortboard 110 (or their fiberglass and foil faced flat roof product if I can find and afford it) with pressure treated 2x4 furring strips put on top inline with the rafters, with the butyl tape sealing the screw penetrations through the roofing membrane and into the rafters. These 2x4s would extend out past the walls, with additional timber being ledgered onto the wall on top of the exterior insulation and extending out to meet the 2x4s from the roof to create the eaves and soffits. Correvent would be placed between the 2x4 furring strips at the edge of the roof insulation to allow air to flow from the bottom of the walls to the ridge vent at the top of the roof. A typical radiant barrier roof sheathing product would then be attached to the 2x4 furring strips, onto which a metal roofing would be fastened. On the inside of the house, the staggered stud exterior walls would have enough of a gap between the planes of studs that plumbing and electrical wires could be run between them. I would insulate the cavities between the exterior most 2x4 studs of the staggered stud walls, then put a smart vapor retarder (such as intello+) against those studs. These would keep me from having to try and air seal around all of the electrical boxes, and I would only have to worry about sealing penetrations that went to the outside. After all of the electrical and plumbing is completed in the exterior walls, I would put in batts of Rockwool between the interior studs of the staggered stud walls (assuming budget allows for it), then hang drywall or wood cladding. I think I will cover all of my bases with this setup to meet code and have a long lasting, comfortable house, but is there anything from your experience that jumps out as a potential problem? Also, thanks for all of the great information you are providing with this video series.
Same here. Interesting how Our brains do sort of an auto correct / fill in the gap thing to speed things up sometimes when we don’t stop to really examine it.
Yes cold climate! And man, what a confusing mix of what you can and can't use together... I think a lot of people mess this up, trying to add mixtures of new stuff to old buildings that weren't made to have these new barriers etc
We did get Certainteed Landmark Climateflex shingles in Minnesota after hail damage last year. They're class 4 hail rates and our homeowners insurance is actually providing a discount for what was a small upgrade price. Though, if I build a new home steel all the way.
In the various roofing assemblies, here's the part I don't get: how are the penetrations for the roofing material attachment sealed? In this case, it would be the metal mounting clips - they have to be screwed through every layer (membrane, dimple sheet, zip sheathing). Here, the dimple sheeting permits air movement but also provides drainage for water that might get under the metal roofing. Wouldn't that water potentially get into any of the screw penetrations? Or is this amount of water truly negligible, so who cares??
"Ping pong" - nice Joe Lstiburek reference. I've read the articles, watched the videos, and the air-permeable insulation conditioned attic moisture situation has been solved ad nauseam. Joe and Matt briefly say that with closed cell "you dont have to worry about it." And i get that. But please do a video talking about it. It's very common for people to have closed cell conditioned attics. The moisture will still be there. So what do we do then? Just control it reactively with dehumidification and/or hvac? Whereas in your situation, you're letting it out with a vapor diffusion port. Please do that video for all of us wondering and for your channel 😁
That's exactly the roof layout I was planning, thanks for the verification. I probably won't use zip so I'm planning SA on ply, then dimple. Never thought of adhering SA to dimple
You didn’t mention a hybrid roof for climate 3.. at least R5 polyiso sheets on top of the decking and fluffy in the rafter bays. Supposedly this stops condensation from forming on the decking because the polyiso keeps the dew point temp correct. So no need for diffusion port and no need to vent from eve to ridge. Please correct me if I’m wrong.. However you can’t simply add more and more fluffy without adding more polyiso to the top side of the decking..
Looking at re-roofing and looking at unvented attic to support transition to Heat Pump and Solar panels. I currently block the AC vents before winter, but with a heat pump air handler in the attic, I would want to keep those vents open (of course) and having the air handler inside the envelop of the house would help in the winter.
Hi Jake. Perhaps in addition to doing another video on unvented attics in climate zones 4, 5 and 6 you could also talk about vented attics in these zones? Also, what are your and Peter’s takes on having a plastic dimple matt product under a metal roof during a wildfire event? I’ve heard that heat from a wildfire can radiate through a metal roof and set the roof sheathing on fire and therefore you should use a high-heat underlayment. Does Sharkskin recommend using a plastic dimple matt (which may melt in a wildfire event due to high radiant heat) along with a high heat underlayment between the matt and the metal roofing material or should you skip the matt entirely?
I'm in climate zone 5 where it gets down to single digit temps in winter and up to upper 90s and humid in the summer I'm planning a full remodel of my 1962 built ranch with full basement. I'm going with a high performance unvented enclosed vaulted roof, but I will also be adding exterior insulation on the entire envelope. Figuring out the proper order of all the different layers for my climate is what I need help with. My idea of the perfect unvented roof assembly (no attic) would be - 24ga metal roofing, peel and stick WRB, 5/8 plywood, 1x3 strapping as vent gap, 2 layers of 2in foam board insulation with staggered seams, peel and stick WRB, 5/8 plywood, 12in vaulted roof trusses (dense pack cellulose in truss cavity), 1x3 strapping for service cavity, 5/8 dry wall, interior living space. It's basically a homemade SIP. Not sure I need the upper WRB layer, might skip that. This would be an expensive roof assembly, but it would be extremely efficient (roughly R-75) and have bullet proof durability. The exterior wall assembly will be pretty much the same, excluding the outer layer of plywood. My goal is a maint free house that achieves ultimate comfort. Thoughts?
I would look for a local sheet metal company that offers sharkskin, and they should be able to help you. I'm in the middle of a high 5 and low 6 and am about to do a new roof, so not only do I want the layers known, but I also would like to put at least 2" of insulation on the roof as well because it's either burning up in my house with a vaulted roof or it's cold in the winter.
I thought moisture moves from heat to cold?? So wouldn't interior moisture stay away from the the vapor port at the peak since that is where most of the heat would collect, and rather get stuck in the lower parts of the rafter insulation?
Care to show me the data sheets that support any wind load rating for that dimple mat beneath the underlayment in hurricane and tornado areas? Because I don’t think sharkskin has any…..
@16:23: What I know is the water molecule slightly larger than O2 - and more or less the same size as N2 . I assume that the water in this product is brought to the outside in liquid form via capillary forces
No, a watermolecule is smaller than O2, N2 and CO2. A drawback of vapor open foils is that they cannot transport water in liquid form to the outside as they lack the needed capillary properties (if the vapor condenses against such a foil, you get droplets at the inside). Boards made from wood fiber (LDF, MDF,...) or fibre cement boards do have capillary properties and will transport water in liquid form to the outside in the case of any condensation.
@@koenraadprincen7212 Ok, you're right about the size. I've looked it up now. I remembered it wrong. I haven't dealt with the video topic yet. But I work professionally in the chemical industry and can't believe that such a precise size filter of 2.7 Ångström (kinetic diameter of H2O) to 3.2-3.6 Ångström (N2) is installed here on a large scale. Can you perhaps write me any references here (not advertising, but academic references if possible)? I'm interested in the topic and would like to find out more about it. Edit: I think I understand it now. Please feel free to correct me if I have overlooked something. Although I would really appreciate getting an academic reference from someone. With a certain diffusion resistance, the membrane allows water vapor and air molecules to pass through at a fairly equal reduced rate. The filter cutoff range is much higher, because for liquid water the surface tension is the dominant force, which acts on a much larger size scale.
@@1912INDY No, when building a house, you need actually two air tight layers (foil, membrane, board, sheathing,...), one on the inside to keep your conditioned air in and one on the outside to keep the unconditioned air out. And in between those layers you put thermal insulation to reduce heat loss (winter) or heat gain (summer). Now enter water vapor... as living creatures, we produce a lot of water vapor (breathing, cooking, showering,...). And as you know, water vapor will condense depending on the temperature and RH (%). And what we want to avoid at all cost, is that water vapor will condensate inside our wood framed walls or inside our insulation layer. Now, water vapor (damp) can travel from one place to another by two means: 1. Due to the displacement of the air that holds the water vapor. ==> This is way you need air tight layers in the first place. 2. By diffusion (driven by "partial vapor pressure difference"). ==> This is way you use vapor retarders or even materials that are vapor tight. The amount of water you can displace via air transport is more than 100 times more than the amount you will dispace by diffusion, hence the importance of air tightness. If you live in a climate zone that's warm and humid you can make the outer air tight layer more vapor tight - or more vapor retarding - than the inside layer. In a cold climate, it's the other way around. It's always advised to keep one air tight layer - the coldest one - more or less vapor open in order to prevent locking in of any moisture in case of water leaking inside your walls.. In a mixed climate zone (hot summers, cold winters) it's best to make sure that both air tight layers are also vapor open. And as said in my first reaction, you should also check for the capillary properties of the airtight layers that you are using... and this is where most commercial foils and membranes fail and solid products like fibre boards (LDF, MDF, cement...) shine.
@@koenraadprincen7212 Thanks for the detailed answer. I understand all of that and it all sounds logical to me. My main point was that the section in this video where the difference in size between air molecules and water molecules is highlighted as an active principle/separation principle for vapor retarding membranes is almost certainly wrong.
@@1912INDY I don't think it's wrong... it's possible to produce a plastic foil where water molecules still can pass while air movment is more restricted. You might be right if you go to the extreme...a foil that's 100% air tight but still fully vapor open might be impossible to produce. That's maybe why most foils that pretend to be vapor open are advertised as only "wind tight". Some foils can be controlled by temperature to make them more vapor open, i.e. Pro Clima Intello. Others pretend to be unidirectional, vapor can only travel through the foil in one direction, i.e. Siga Majvest (external use) and Majrex (internal use). Pro Clima even speaks about "active diffusion" for their Solitex Mento foils... Lots of black magic ;-)
They definitely glossed right over the part people don't understand. You can either hole saw large holes or cut a channel through all of the sheeting at the port line and then seal it with a highly vapor permeable and air impermeable product. I used Dorken Delta Trela on my roof. Matt Risinger used Delta Foxx on his roof. Pick a product in that class, but the key is that there is no sheeting at the port. It's a port- an opening.
I can't imagine putting asphalt on a roof. I don't even know if that's legal here. I know asphalt roads can melt when they get hot, and I know the rainwater running off them needs a lot of cleaning before you can use it for anything .. why would you put that stuff on your roof? We banned timber shingles long ago because a roof just isn't a good place to store your kindling, and then you're putting asphalt up there instead!?
So it sounded like you said that you could use closed cell Spray foam in that cathedral set up between the rafters And I think I heard you say that you were thinking moisture will travel through that I’m just wondering why you would say that
Roof SIP panels DO rot, and they do get moisture intrusion in them. The. You get rotting of the outer osb panels near the peak. BSC has found that providing a vent strip at the peaks allows the vapor to find a way out. The only totally vapor sealed construction involves 100% air impermeable membranes that generally dont exist in construction.
You basically want airflow on both sides of your sheathing so it can dry if need be. You're correct, it's 'probably' not needed. Jake even says this; but since in this profile, insulation is put directly under the sheathing (and not on top of the ceiling drywall) there's no way to inspect the sheathing for rot from leaks. So giving the top of the roof sheathing the ability to breathe massively mitigates the ability of the moisture from an unknown leak the ability to get trapped and rot the sheathing. I would not use this stuff on a ventilated roof assemble where you can get into the attic and see the underside of the sheathing. However, when the underside is covered, the dimplemat is a, I hate to say it, belt & suspenders approach.
Respectfully brother, this is too slow of an intro.... when you're 4:32 into your video and finally say "I want to start by saying...", you're 4:31 seconds too slow. Can't watch your videos anymore. If you have something important to convey, tell your audience what it will be in the first 5-10 seconds.
