Cold Climate Building Techniques and Concepts: Vapor retarder

[@myronp243]

This video saved me a lot of work and headaches.Great job,thank you

[@waitercheckplease]

Really excellent job on sealing that air barrier. Now hang your drywall, then cut a bunch of holes in it for electrical, plumbing, hvac, and hang a bunch of pictures with drywall anchors. :)

[@elendil354]

Yeah, he really does a great job installing the air and vapour control layer but since he is using plastic its just never gonna survive after people have lived in the house for a couple of years.

[@wallygoots]

I saw in another video that European cold climate builders put horizontal battens between the drywall and vapor barrier. They run their wiring (and sometimes plumbing) in that space rather than in the stud cavity. Wouldn't this reduce the problems mentioned? I like that idea and intend to try it on my build.

[@MegsCarpentry-lovedogs]

@@wallygoots Yes, it is called an Electrical service channel...super smart way to maintain air tightness.☺🇨🇦

[@IlyaBenesch]

We have another video that covers furring out (in) walls in the same playlist. Often here the builders will also add additional insulation either between the furring as shown in the video or behind the furring. Furring makes a big difference in preserving the integrity of the vapor retarder long term. Playlist: kzbin.info/www/bejne/iGm1foVjmpJ_oqc&pp=iAQB Wall Furring: kzbin.info/www/bejne/eHfTZKxmgK6Up80

[@waitercheckplease]

@@IlyaBenesch Excellent!

[@MegsCarpentry-lovedogs]

So much detail and so well done. 👍 A few questions: Is poly needed in cold climates if the exterior wall has R30 of layers of rigid foam? The building science behind no poly in the assembly is because the sheathing would only be able to dry from the Inside, so the poly would prevent moisture that got in the wall cavity from drying. The idea in climate zone 6 is to have more R outside compared to in the cavity, 60% R out, 40%R in cavity. The more outside insulation the more chance of keeping the sheathing warm, if you do not over insulate between the studs and use rock wool, permeable insulation. Some people are suggesting instead of poly to use Smart membrain by Certaintee. Smart membrain as vapour permeability on both sides...if a lot of exterior insulation, rigid foam is used because rigid foam is non permeable, especially at R30, 6 inch, thickness. Thoughts and thank you...from Prince Edward Island, Canada🇨🇦

[@skippingstones1343]

Excellent video!

[@theobserver6639]

This guy's amazing iwould get him to manage my home build

[@2point..0]

@ 6:47 May I make a suggestion to Pitching the Sill??? Using a wood beveled siding to set an angle, one piece for every window or door??? Then apply your sealing tape and roll it, Its inexpensive too!!! Let me know if you like that idea??? I am going to be building in Eastern USA in New Hampshire or Maine soon!!!

[@paulmaxwell8851]

It's a great idea, KJ. My wife and I did this very thing on our new home 15 years ago. Cheers from British Columbia, Canada!

[@MegsCarpentry-lovedogs]

yes and add a back stop and tape that down as well. Bevel is 5 degrees I believe...or like he said, a 1/4 inch slope. Cheers Prince Edward Island🇨🇦☺

[@IlyaBenesch]

Yes, beveled siding is great for pitching the sill. When we do it, we try to get our hands on beveled cedar. When we are building with exterior insulation where we have window bucks on the outside of the sheathing, we will also used beveled siding on top of the buck and integrate that slope into the weather barrier on the wall such that any water that makes it past the exterior insulation will be able to drain outwards and not remain trapped between the insulation and the sheathing. I think that in general it is a good practice to pitch the sill. That said, in some climates there isn't enough rain to warrant the extra level of detailing - especially if the windows are protected by big roof overhangs and there isn't much wind. It's hard to convince builders to go the extra mile when they feel the effort isn't warranted. It's a tough line to walk sometimes.

[@camilla74hansen]

Beautiful work!

[@matthewfunk6658]

Excellent lesson, master!

[@eliinthewolverinestate6729]

Seal the framing to the sheeting after window is cut out with sealant. We frame larger opening for thermal break to be installed around window. We then spray foam around thermal break. Also spray foam window and door bays and the ones next to them. And don't use vapor barrier on those bays. The idea being condensation from doors and windows being cold is allowed to dry. Ever wonder why it molds around doors and windows even with air tight seal? Or why window or door trim is cold. One of the changes we made after using thermal camera. We use the thermal break in the middle of headers too.

[@MegsCarpentry-lovedogs]

Pocket headers....insulation between window headers...a Steve Baczek detail....smart!👍🇨🇦

[@brandiminor1632]

Amazing. Thank you so much.

[@jorgearenillas4]

Awesome video, thanks for sharing. I have a question. If some water or vapor found its way inside the wall, how does it come out? Do you install some kind of wall ventilation?

[@MegsCarpentry-lovedogs]

in cold climates an ERV appears to be the unit to use. ☺🇨🇦

[@CMCraftsman]

You have to either be able to dry to the inside or the outside or both. Poly is actually never a good idea but it’s much worse if the exterior has a non permeable surface like poly iso foam. This creates a “vapor barrier sandwich” If you are wanting to use something between your drywall and cavity insulation you should be using a vapor retarder like Certainteed Membrane or Siga Majrex 200. If you have a lot of exterior insulation then you technically don’t need anything but it is important to air seal your drywall to the studs with something like big stretch caulking so that vapor can’t enter the wall cavity any way other than diffusion but a good primer and latex paint will slow that down as well.

[@MrAdam100576]

Question: If one does a continous insulation (both interior and exterior) with a big, code exceding r-value, does the interior vapor barrier become less important? As the dew point moves to the exterior of the roof's water barrier...or does this just make the air barrier more crucial on the exterior? Are these trade offs? Does material cost play into this decision? Is a proper seal, as you've brilliantly demonstrated, more likely in one scenario versus another?

[@MegsCarpentry-lovedogs]

Living in zone 6 here in Canada. Correct, paying attention to the dew point of sheathing is important. I think that if you have at least an R 18 on exterior the sheathing will stay warm all year around, so reduced condensation issues from moisture coming from the inside. I also learned, and will be applying to the extension build in the near future, that because there will be Outie windows, our Tyvek, or peel and stick vapour barrier will be applied to the most outer insulation, which is xps, 6 inches of it, with seams taped. The xps is an air barrier in itself, so we will NOT be putting an interior vapour barrier on the studs and the cavity will have rock wool because rock wool has a high vapour perm which will allow any moisture coming from the interior of the home to eventually dry to the interior when the colder climate comes, which drys the air, and therefore will allow any moisture on or in the rock wool to dry towards the interior. Building science eh! You got to love it....if you understand it. 👍 🇨🇦 As for sealing, ask yourself what Steve Baczek always says, It is now what you are sealing out, ask yourself what are you sealing IN. Are you sealing in moisture....which comes in a lot with air, and a little with vapour?

[@blackterminal]

What stops mold from building up on the plastic?

[@slavicn9420]

but when the warm air from a house meets cold air from the outside. Won't it create moisture?

[@andreycham4797]

Two questions : why did you put osb on outside of the wall and where is the crossing studs insulation on inside part of the wall ?

[@CMCraftsman]

What about in the summer now when you’re air conditioning and it’s hot and humid out? That condensation is going to occur on your drywall. Poly is not a vapor retarder, it’s a barrier. Shouldn’t you be using something like a smart vapor retarder to keep moisture out but also let any that did happen to find it’s way in back out?

[@randypowell4799]

nice details

[@rodmartel3143]

QUESTION: IN Northern Minnesota, we air condition the same building that is heated in sub-zero weather in the winter. Won't the hot moist air in the summer hit the air-conditioned walls and condense much the same way as you describe in the winter? I question using non-permutable poly for that reason. I'm new to this....

[@elendil354]

Dont think they get to do much AC in the summer in Alaska. Here in Sweden most new houses have switched from airtight plastics to vapour retarder membrane. Gives any moisture that gets in during summer a chance to dry out.

[@MegsCarpentry-lovedogs]

Eastern Canada here....instead of poly, if you air condition, use Smart membrain from Certaintee....the smart membrain can move vapour on both sides, so interior wall can dry to the outside. ☺🇨🇦. Air conditioning changes the building science of vapour transfer....lots on the topic if you google.

[@hisroyalblueness]

Is that 6mm poly actually 0.6mm? It doesn’t look 6mm and 0.6mm is iirc a generally used thickness for heavy duty polythene. Many thanks for all your good advice I’ve learned from watching this and I’ll be sure to follow👍

[@eliinthewolverinestate6729]

I always wondered about that when cutting roofs back for ridge vent. Wonder how many houses have rotten ridge beams from ridge vents?

[@IlyaBenesch]

Good point. The venting should function appropriately relative to the local climate. In Fairbanks, as a general rule, a dam on the roofing below the ridge vent slots in the sheathing (ie J metal termination at the top if its metal roofing) and a generous properly bent and sized ridge cap are adequate in keeping out weather. In arctic maritime Western AK we've designed ridge vented homes that are right on the coast built to withstand a design wind load of 160mph. So even on an 'average' day there's typically enough wind that it rains sideways. Climate is too windy to support trees. In those cases we've been using ProfileVent as that product was advertised as meeting the Dade County 110mph wind driven rain test. We talked with the manufacturer at some length about install specs and at the time (5 years ago) it was the most robust tested product we could find for such extreme conditions. It's on our short list of places to return to and inspect by physically pulling up the ridge cap on several homes to see how things look.

[@__t__s__]

Hi, is there any benefit to attaching membranes when wall is vertical, rather than when the wall is laying flat?

[@IlyaBenesch]

Yes, there are certainly times when it makes sense to do so. Typically we do this with exterior weather barriers with multistory buildings where adding the layers off ladders and scaffolds complicates the construction. Sometimes we will finish an entire second floor wall with windows and siding before raising it. On the interior, with a poly vapor retarder, we'll sometimes install it with double walls when the inner wall is laying down and the vapor retarder is on the back side of the inner wall. With conventional framing, generally installing the poly with the walls standing up is also pretty convenient as gravity can help in hanging the membrane and keeping things flat and quick to install. It really just depends on the situation. With a standard 8' tall wall, it's pretty fast to install the vapor retarder with the wall standing up.

[@redsresearch]

why not use vapor barrior

[@elendil354]

Why not use intello instead or plastic? And if you must use plastic, a good idea is to frame a second layer of 45mm studs with insulation on top of the plastic before drywall is hanged. Gives you an installation layer for electical and so that people can hang a picture on the wall without destroying the air tightness of the whole house.

[@MegsCarpentry-lovedogs]

Its called an Electrical Service channel.....clever and smart👍☺🇨🇦

[@TH-wr1dv]

why you do not use that special tape what is ment for vapor retarder? Example prof DIN 4108-7

[@IlyaBenesch]

I'm familiar with that tape, but haven't used it. It's hard to source some of this stuff - especially for us in Alaska. Not to mention the cost. The general issue with most tapes- in my experience- is that they have difficulty sealing the vapor retarder when a fold or a wrinkle occurs in the plastic. And folds and wrinkles are inevitable when installing 6 mil poly. The bigger the area, the greater the potential for wrinkles. The Tremco, being a mastic but quite soft, can be used as a bedding surface for the poly such that it can also seal localized wrinkles and imperfections along the overlap. We recently did an inspection on a commercial ceiling that was taped but Tremco accoustical sealant was not used. There were some big folds in the plastic (due to a sloppy install) and even though the poly was flat behind the drywall, the building pressures (due to ventilation imbalances) were enough to force warm air past the folds in the plastic. Often we'll put tape over the plastic if there's any concern the plastic edge could get lifted due to other work going on before the drywall goes on. The other potential problem with tapes is that contractors will generally use whatever is available in the store that is rated to do the job. Not all tapes are created equal -and the unfortunate truth is that though a particular tape may be advertised as having good adhesion to poly, long term performance is sometimes severely lacking. Tremco Acoustical sealant has been in use in Alaska as a vapor retarder sealant long enough now that we have opened up walls built 30 years ago and it is still is going strong.

[@thinde88]

Looks like Dexter built it.

[@simedogz]

Why not just put all of the insulation on the outside? what am I missing?

[@MegsCarpentry-lovedogs]

Yup...that is what should be done. R 30 would be nice in climate zone 6 and that way no poly on interior using rock wool R18 between the cavity. The rock wool will allow any vapour to dry to the inside and the sheathing will always be warm if you do not Over insulate between the cavity. 60 % R outside to 40% R in cavity for zone 6 and above. ☺🇨🇦

[@CMCraftsman]

If you tried to put all of the insulation on the exterior, it would be a real tough situation for your windows, doors and siding. All your windows and doors would be sitting outside of the structure and you would need really long nails or another layer of sheathing to attach your siding. They do roofs that way and add that layer of sheathing because you typically don’t have many penetrations and no doors or windows on a roof (typically)

[@uncle_creepy2743]

I tape my tape that tapes over the tape on my staples😢