Back in the 70's when I began as a carpenter, we would staple 4 mil poly on the framing, after the insulation was installed, for our vapor barrier. (install vapor barrier on the warm side) The boss wanted it over all the windows. It was not at that time cut out around the windows. Then when the sheetrock was installed, you could see how the outside air pushed against the poly as it tried to infiltrate the house at the windows. I was amazed at how much pressure was there. It would bulge out the plastic sheeting several inches in toward the room. When you pushed on it with your hand, it was like pushing on baloon. Lots of air infiltration happening, but the plastic sheeting on the warm side was not placed there for preventing air infiltration. It was there to prevent warm moist air from cooling off as it moved toward the outside, and reaching it's dew point and condensing inside the wall. We were not using any house wrap on the outside of the wall at the time. I wonder how much that would have helped, but I was amazed at how air was trying to infiltrate to the inside of the house and not the other way around. We had installed the windows directly onto the plywood sheathing, using the window flange and nailing through that. They were wood clad (with plastic) windows. Perhaps there was a lot of infiltration happening at that joint, between the window flange and the sheathing. I'm sure some of the air came through the weatherstrip of the windows also. They were casement windows. Sometimes we had trouble insulating in corners, such as on a hip roof, where it isn't so easy to get as much insulation in, and sometimes on a cold day there would be frost seen on the sheetrock in the corner, if the insulation installation wasn't properly done there.
This is a complex topic that is full of many different opinions. Add to that the variances in climate across the country and it gets really complex. I'm also of the opinion that many builders don't really think about these things.
Matt, I just recently discovered your channel and first of all I want to tell you thank you. Thank you for bringing all sides of home construction to the forefront for us to understand the correct science. A little background, after getting married we moved to a brand spanking new home in Southern Oregon around 2015 that my parents had bought, I realized how poorly it was built immediately. If you turned off the AC within 30 minutes it was the temperature of the outside and it took a bit before you could bring the temp back down. We decided to buy a home of our own after that, but were disappointed to find similar build quality throughout, so we bought a 115 year old home. Thanks to you I've done major improvements to our home were the AC does not have to be turned on until 3pm when it's in the 90's outside. Being a total engineering and learning nerd this is fascinating to me. Thank you again.
Fifteen years of attending ASHRAE meetings, first time I have ever watched a simple explanation of vapour barriers. Really appreciate your work, Matt, keep it up. You and Joseph Lstiburek are my building science heroes! Would appreciate you addressing the comments about drywall screws, related, liked the video about foaming electrical boxes properly that you did recently, need something like that for the other penetrations that we all make.
My previous understanding (potentially mistaken) is that yes it would be best to somehow be able to not have any penetrations onto the vapor barrier but you can't have everything be perfect so having a vapor barrier up still stops 98% of all the moisture that diffuses through the drywall than not having a moisture barrier, as the job of the moisture barrier is to stop diffusion through the actual drywall cells NOT holes in the drywall from nails or screws. The drywall screws/ nails I'm assuming is supposed to be sealed via joint compound/ paint and would just diffuse moisture as if that small section didn't have a moisture barrier, so yeah an 4X8 sheet will have maybe 20 screws or something but that only adds up to just 5 sq in. of non-moisture barrier drywall but the rest of the 32 sq ft has moisture barriered drywall.
I'm a licensed engineer/construction manager in FL and have recently chastised a contractor on a $20M project for showing me design details where they would install a vapor barrier on the inside of insulation in climate zone 1. I explained it to multiple designers on the contractor's side this is not how we build down here (they were from NC). I literally had 3 conversations and they still didn't understand, so I eventually had to direct them to remove the damn barrier altogether. I watch Matt's videos often so it came to me, I bet he has a good video on it and I'll send it to them! Love your stuff man, keep up the good work!
Thanks for mentioning the Canadians viewers. We loved your show. It is so helpful and unique. we really appreciate your work. Your faithful Canadian fans.
I was impressed by the teaching technique, the background, the ease of teaching, the pushing away of the paper displays, the entrance of the water bottles,... I was wondering how many takes it took to get this right, it would be neat to see a little blooper reel. Great teaching job
Cool to know about these type of new products that Siga has. The problem where I live in the states though, is not in the products, its in getting the installers to do a proper install. The only way this would work for me would be to do it myself.
Your videos are vitally important because of the huge amount of new people in construction and because, historically, no one cared much about these details. I worked as a building inspector and it was extremely difficult to get compliance because they were really not ready for prime time.
They're used to working one way and it's worked perfectly so far. The only thing is, requirements change over time and as windows and energy efficiency requirements evolve, techniques have to change as well. I have it from a tradesman that Velux windows are still being installed improperly because pieces designed to avoid air leakage around the corners aren't used because the professionals placing them don't know what they're for.
Well done! It's great that you are out there seeing the different ways people are building structures and expanding your ( and our) knowledge. All too often people get complacent and just stick to the same old same old mentality. Nice that you are a very forward thinker.. nice for us too. Thanks!
Just started using SIGA products on a home in Toronto, ON Canada. They had a rep come out to show us how to use the product as well which was very helpful. I'm sure we'll be seeing more of it in the future. Thumbs up!
I really don’t understand why people make vapor issues so hard when explaining it. If you use a 6” wall with fiberglass insulation as an example. You want to keep the water vapor out of that 6” of fiberglass. Warm air and holes in the warm side of the wall can carry moisture into that fiberglass. The goal of the 6 inchs of fiberglass insulation in the exterior wall in cold climates is that entire 6 inch area stays closer to the interior temp than the exterior temp. So if the air inside that 6” of fiberglass hits a vapor barrier against the exterior plywood in a cold climate you have warm wet air hitting a cold surface causing condensation. When that condensation overwhelms the wall framing you get mold inside the wall. If you put a vapor barrier on the inside next to the drywall then the air in that 6” area of fiberglass insulation will be warm and DRY. When that warm dry air hits the cold outside plywood there will be no condensation. So no mold. This is reversed in the hot climates when the cold is on the inside of your house and the hot is outside. You will get condensation on the drywall side unless you stop the vapor before it enters the 6” fiberglass insulation. In this video he was explaining how much holes in the wall can carry water vapor so that should also be delt with. But he did not describe how to do that. Maybe the material being installed behind him was supposed to help with that. Who know he never said.
Nice summary. I would hope there is some self sealing take that can be put over the vapor barrier over the studs. Then the nails holding up the drywall won’t cause leakage. Just my idea.
I put plastic over my 6 inch walls and noticed water vapor on the sun hit walls on the plastic before I drywalled...this scared me. I felt that is too much water to be trapped in that cavity...I took the plastic off the walls that were hit by direct sunlight...I feel that a wall needs to breath a little, especially when it is subject to drastic changes like sunlight heat. The building materials will store some moister and give it up as well. I felt trapping large amounts of water was a bad idea. So I have not had any problems and the house is now 23 years old.
Problem with this is I live in NC. Hot humid summers and cold winters. You just can’t win. I just made mine as air tight as possible, have insulation installed properly and control for internal moisture the best I can. Hind sight being 20/20 my next house I’m going with closed cell spray foam. Air seal, vapor seal and expansive to prevent gaps.
Just as important, you have to stop cold air from hitting the vapor barrier. I have seen countless times where 6 mil vapor barrier fails because of poor insulation allowing cold air into the wall cavities. In effect, this turns your beautiful vapor barrier into the condensing surface and creating a lake between the vapor barrier and the drywall. I've seen this happen to the point where the drywall started to fall apart mere months after installation on a brand new building.
I appreciate the mention of us Canadians. I as well as many other Canadian's appreciate your show, especially when it comes to insulation and vapour control. You go Matt!!
And correct spelling too! Being dyslexic spelling a burden to me so when people deliberately spell things wrong it really pisses me off. Colour and Vapour its not hard even for me. Mind you hearing Americans slaughter the word "Solder" and pronouncing it "Soder" is another pet hate :) its pronounced Sold..er for those needing to know.
Great breakdown....one comment... I'm sure people are annoyed at the pedantic nature of this comment but I think it's important that we stop saying "heat rises" when really "warm air rises". Heat doesn't care where it goes as long as it's from hot to cold. This and that we put more insulation into roofs (because there is space) makes people forget that there are other important elements of a house that insulation matters just as much in because they incorrectly believe that heat rises.
Thank you! It makes me crazy when people say that 'heat rises'. My framed wood floors are insulated to R36, with perimeter insulation to boot. The infloor heating system? We never use it. The floors are always warm and a wood stove heats the house. Visitors ask me "Why did you waste all that money on insulation? Heat rises!"
Thank you for this, just recently started watching your videos as a home owner, and you keep talking about these barriers and i didnt really understand it before.
Reflective on these older video's when it was before Covid in 2020! Gosh! Then building materials and chain supply and labour issues! Now in 2023 life is slowly getting to some normalizy....but with a recession allegedly....building material costs here in Atlantic Canada are considerably lower compared to in the pandemic! Crazy pricing during the pandemic! Thank you Matt and team for all your videos to help us along🙏 🇨🇦🍁
As an aside, conserving energy for the Swiss is a very big deal. Except for a handful of countries with north sea access [and I think Italy], nobody has oil. For that reason, market forces will have them leading the world in energy conservation - just discard the climate change nonsense injected by the politicians and follow the science. Getting Macron'd never solved a single problem.
Awesome and informative for Americans who haven’t realized that integrity contracting /building also exist outside of our country. Great new content Matt. I really enjoyed that as a long-time follower of you.
Different stages, not only in construction, but also of importance. Understanding the long term savings as to the initial cost differences, which includes the a comfort factor will go a long way in determining which direction to take. Just a Great Video! FR
I second what a prior viewer said. We can all see the product that was installed, presumably directly against the roof joists. What is the ideal goal any home builder should have when we address the space under the roof deck in terms of permeability of moisture? Is it realistic to presume that the number should be zero? Starting directly under the roof deck where we are going to insulate under the deck, should we put the vapor barrier up against the deck, then our insulation or should it be the reverse? I have also heard guys saying it is important to have passive air movement going from the eaves to a venting cap on the roof to help remove the heat buildup in the “attic”. I am not trying to add more complexities to the equation, I just really want to learn what are the best practices to have a sealed home environment where we are able to minimize the energy usage to keep the home very comfortable. I may be looking at building at least two different homes in different climate zones around our country. I am willing to make the initial investment so that they will still be standing generations beyond my life and still be well above code.
I've researched this and it's probably one of the most inconsistent area's of building in terms of whether it's required or not. Sadly, I still don't know what to do.
@@ecospider5 problem is a lot of people are in places that have 90 degree high humidity summers and 20 degree snowy winters all in the same spot. "hot climate" and "cold climate" are two extremes that dont represent the gray area inbetween
The other (5th?) major element a house needs to control is inbound solar radiation. Letting it in in cold regions/seasons, keeping it out in hot regions/seasons. This could be its own episode (specialised glazing on north vs south facing windows, overhangs, building orientation, thermal mass, etc.).
@@ZimorKilled thermal might actually be too general now that you mention it, air barriers manage convection, insulation manages conduction, and now we're taking about shading and coatings to manage radiation gain/loss. I like this train of thought
Hey Matt. Great stuff here. I saw your video about vapor barriers that you made in 2018 and it says that you basically don't need one. This one seems to say the opposite. I was leaning more towards not doing one. I live in the PNW which is mostly a heated climate (meaning I'm using heat more than cooling), but it isn't super cold here either. I am remodeling my upstairs bedroom. This is basically an attic turned into a bedroom with two sides still having attic space (where the rafters run down) The house is 1926 and the rafters (which are only 2x4s) meet at the peak with no horizontal supports. Basically like your new attic build in your home but without the horizontal supports on top about a foot down from the peak. I'm going to be using all the space so ceiling will be on the rafters. I'm using spray foam and then for the ceiling I wanted to use wood planks or some kind of wood faux backer board. If I'm using spray foam on the ceiling I know I need to seal the room as best I can. I was wondering if I used the wood planks do I need to seal every crack kind of like drywall would do? If I use the faux wood sheets can I just paint the back of them? I'm just not sure if I need to seal inside the spray foam.
My interpretation is that this material serves first and foremost as an air barrier and that the vapor permeability has a marginal impact. I wish Matt had actually explained the usefulness of this directional vapor flow.
@@hosmerhomeboy Can you not use vapor barrier with tape AND use the acouticseal as well? I am not at all familiar with acousticseal. I am a novice in terms of building but have done a little bit of everything over my many years. I am planning on either re-habbing an old victorian home with high ceilings out in the mid-west to retire to or have the framework of one built which I could then finish. I hope to act as my own contractor, studying up on all code requirements. Electrical I would leave to the pro's as well as the basic plumbing. I know building codes can constitute a book the thickness of a bible but am planning ahead and have time.
How about a video for existing homeowners and tips and tricks to airproof/vapro proof their house short of removing all interior drywall and exterior siding?
Hey Matt, if the roof sheathing has vapor barrier, and insulated with a 1.5 inch comfortboard 80. Eliminating the air gap and installing the metal roofing directly onto the Rockwool should not allow for vapor or moisture build up since the comfortboard should stop the radiant transmission into the roof interior or vice versa during the winter with the heat transferring out through the sheathing through the rockwool and onto the metal roofing.
Personally, I love the European theory regarding the lifespan of buildings (generations!) and the 'functionality', i.e. 3 pt. windows and 'Rolladen' window covers.
@@irondiver292, though I believe I understand your reply and cannot completely disagree, I must ask; if Matt intended to encourage fans to research the system, (which is the definition and purpose of a 30 sec. commercial), why is Sig only appearing in the description and not in the title, giving the initial impression this was educational with scientific research on a particular subject rather than a particular product. What has a paid spokesperson that's usually considered sincere and unbiased in his seemingly normal atmosphere quickly abandoning the misleading, "attention grabber," hoping to appear as usual while fulfilling a contractual agreement to sell a product? (hint) Older brother to the 30 second commercial that leaves breadcrumbs to 16mins. of usually grossly exaggerated and questionable .....I have severally digressed. Though the answer is Infomercial, I understand making a few extra dollars, Matt, but the Texas accent plus the honest demeanor is your meal ticket.
it looks to me like the spot Matt was stuck in, and maybe could have navigated differently, was to discuss the need and benefit of having a vapor (and air) barrier, and show Siga's product as a good solution, without just parroting Siga's sales brochure about that product. Specifically, WHY does it matter if a vapor barrier is "one-way", what does "one-way" mean? Paraphrasing Siga's talking points on this would have been better than the too-brief mention those points got. The diagram of water/heat/air/thermal doesn't address this clearly enough for folks who are not already familiar with them. (okay, now that we're all done beating up on Matt, let's hope he does a follow-up video with a detailed on-site install of Majrex here in North America)
They flew him to Sweden and they have a product and sales model that's worth knowing about. The emphasis on correct installation and not just product specifications was refreshing. If you stuck around feeling an annoyed by the commercial relationship, that's more on you than the host.
I love how in this video Matt says you probably need a vapor barrier even though only 1/3 of a quart of water will diffuse into the wall cavity during the season, but literally in another of his videos he says you probably don't need a vapor barrier because only 1/3 of a quart will diffuse into the wall cavity during the season.
Being in the planning phase of renovating an old house my understanding is to stick to the materials which were originally used in the building i. e. real wood or clay (modern forms with straw or hemp f. i.). These materials last centuries. Larger amounts of spray foam are nothing I would use for any house, rock wool doesn´t isolate when it is moist, what you need is capilarity of your isolation materials, you don´t even need a vapor barrier then. Barriers won´t work over decades... Learn from old world wide prooven building technics! (I admit I´m no expert but that´s my food for thought, there are enough experts of different scools of thinking out there.)
Karl Ludwig Bonitz it’s your house Karl! Do as you please! 😀😀 that’s what I support 👍👍 we foamed because we car about efficiency.. we’re saving close to 700 a month in heating costs.. if you wanna keep it “original” more power to you!! I love the idea.. but, if spray foam was around in 1800s they would have used it 😆 cutting a million cords of firewood and having 4 fireplaces wasn’t for Ambience.. it was to stay warm in the winter.. but, it’s your renovation and your house.. you do what you want!! You need to be happy with it.. good luck!! 👍😀😀
Your Swiss / German tour videos were just in time, as I and a collegue went to the Dutch Build Show, there I met the Dutch Rep of SIGA and ordered some of their membranes and tapes for a small job in amsterdam, here's hoping it does what it says on the tin :D
bro, this is just so freakn cool! Just BS in general is freakn cool but im glad I have found out about your channel. I am trying to get into passive here in Oregon. If your ever up in the PNW come look at some projects!
Hi Matt, Great demos, thanks! QUESTION: I'm planning a whole house renovation (my house is about 27 yrs old and was built fairly well) I am planning on using as many of your recommendations (improvements) as I can. Can you point me to "the right way to finish a basement"? (waterproofing, vapour barriers, insulation, THE FLOOR, etc.) thanks!
As hellonko pointed out buildingscience.com is a great start. But also, what do you have and what do you want? Are you on a well-drained slope with no water problems, or is the basement catching water and you need to worry about infiltration and maybe adding a drain? Is it a "day-light" basement with some venting easily available, or fully buried under another story? Do you want an open recreation area, with good air flow, ect. Or, are you intending to have a kitchen and/or bathroom in the space which can add lots of moisture. Don't be afraid of engaging a professional to talk through your plans and ideas, you might get it for free, but a few hundred or a couple thousand dollars (depending on the project) of guidance and advice might get you something you're much happier with and save you money in the end.
Ive been a carpenter/renovator for about 5 years now, and I hear all the time from the old-schoolers how you want your house to breathe, and we vent bathrooms into the soffit here in swampy Eastern NC. However, I'm starting to learn that you may not (depending on conditions) want your house to breathe, but I haven't yet drawn a clear line between the two. What/when exactly do you want to your building materials or home to breathe? Could you compare and contrast the two, please & thank you?
If you have not already seen this video, it gives a good, quick review. A little too short, imo, but still good stuff. --> ua-cam.com/video/OJ9u3pDQeM4/v-deo.html
@@glencaple3888 Amazing video! Thank you for sharing. The short answer is a vapor retarder can be used in climates with both hot/cold, so in the hot the wall can dry out, in the cold it can resist letting water into the wall from the inside. Or use closed-cell insulation to avoid need for vapor barrier.
Thanks for the great and informative video. I have a question about wall construction. I live in Norway right now and most of the houses here are wooden constructions, just like in the US or Canada. The construction of the outer wall is a bit different. In the US on the outside of the studs usually they put OSB sheating, windbarrier membrane, furring strips and cladding. In Scandinavia they do not put OSB sheating outside, but inside of the studs right over the vapor barrier. According to the Norwegian building institution (SINTEF) it is mistake to install OSB sheating to the outer side of the studs, because it has a strong vapor barrier property and it hinders the airflow and venttilation of the inner constructions like studs, insulation. Why is this big difference, which one is better and why?
Thank you for the video! So…If I have a framed structure with a crawl space, closed cell, Tyvek on the exterior, Rockwell Insulation, and using T&G bead board for my interior walls, do I need a vapor barrier on the inside? I’m about to install the insulation and I’m not sure…Thanks in advance!!
Is the diffusion calculation based upon painted drywall or unprotected drywall. I do understand that a hole in the wall doesn’t matter, but calculations should be dramatically different between painted and unpainted drywall.
Thank you very much for your help! thank you for taking the time to make this video! I've been waiting for this. Siga has such a vast catalog, that I'm a bit confused as to what is available.
Matt, Remodeling a house in NY, climate zone 5a. If the house was built with a vapor barrier just underneath drywall is there issues with using zip on the exterior of the home?
How do you handle a installing vapor barrier in a renovation (down to the studs) without making it cost prohibitive by removing all cladding on a house that has 1950s fiberboard sheathing? Just install closed cell spray foam in the wall cavity?
Thanks again for producing these videos. So If you live in a climate where there are both cold winters and hot humid summers, you would put some sort of vapor barrier on both the internal and external sides of the walls?
Did you ever get an answer? A question I have been trying to get an answer to too but no one seems to ever want to answer the 50/50 climate question. My conclusion now since I'm insulting my attic is to put insulation with barrier facing down in rooms which will or would produce too much humidity e.g bathroom & kitchen and have face up on rooms that are directly getting the best of the sun heat but less humidity.
The Siga tape is sticky as hell. If you are not carful one can also use it to remove hairs on your breast, legs or anywhere else. If it sticks it sits. Siga are also very big in Germany amongst builders everywhere.
Thinking of building small compartmentalized toilet closet and shower closet, (for lack of terminology), well ventilated of course. Seems like a great product for these locations. It’s all about air control! Deliberate directional movement.
Hey matt, I am building my home in Eastern Washington so advanced framing energy codes are very stringent, . I am planning on using R3 ZIP system and rock wool insulation with siga vapor barrier interior, will having an exterior insulated vapor barrier plus an interior vapor barrier be a problem because any potential Wall cavity moisture will have nowhere to go
Great video! EXCEPT... You never zoomed in and showed what the people behind were doing in detail. I was waiting the whole video to get more detail on what they did.
Great Video Matt.you have a British viewer as well.I actually live and work in the French speaking part of Switzerland in construction,I am a bricklayer by trade but do not get to do so much of that here in CH, It would be a good video explaining how a cavity wall super structure on a UK home performs,I’m not sure if you have masonry cavity walls in the US or they are solid.but the British can not seem to get away from them.while the rest of the world moves on. Anyway super informative series,thanks
In the video "Vapor barriers: need one or not"... 4:44, discussing diffusion - "There's very few places if any in the U.S. that you really need a vapor barrier" Also, 7:05 - "But its only really if you get in to the very coldest zone in America, which is climate zone 7 up there, where you might actually use a vapor barrier" This video, @ 6:10, discussing diffusion using the same example of 1/3 quart of water - "So do we need a vapor barrier? Yeah, we probably do" Well, now that's all cleared up....
That is my big problem. I had a company put in aftermarket windows and replaced the single pane to double pane but they did not seal out the water and every time it rains I get dripping around my window on the back side of my house. That is my next project.
I baught a house. It has 2*6walls. I tore out the dry wall. The insulation looks okay. But should I put up plastic or something before I put the dry wall back up. The insulation is bare fiberglass.
Thanks for sharing. I want to turn a 15 year old pole barn into a home. This is in MN (cold climate). I'm considering spray foaming the entire structure from the inside, but i'm worried about no air flow and condensation build up onto the foam. I would like to foam the ceiling right up to the tin if possible to leave beams exposed, then put tongue and grove pine over it. Is this a good idea? Do you think I will run into problems making it too air tight? There is no house wrap on the structure. And advice would be helpful. Thanks! Eric.
I live in South Florida, Where an interior vapor barrier should never be used. Yet home depot and lowes sell all this insulation with a vapor barrier attached.
I kept waiting for the discussion about whether using poly has any advantage at all, given that it gets penetrated as soon as the resident hangs their first picture, allowing all that moist air into the wall cavity anyways with less breathability for it to escape.
"And we use a lot of cooling in the summer time, if we don't control air" Easy saving tip: We don't usually have any cooling in central europe, so not controlling energy movement from outside into insulated space means simply suffering without recourse.
@@4philipp ^Well, personally I live in an old Building in the former Dutchy of Hannover. So british style sliding windows do something to decrease control of air movement and create constant breeze. But otherwise you may want to not have a direct outside breeze and let the thermal mass of the building equalise the outside temperature movements, vent cold air in through the night and keep the outside air out during the day. Maybe allow inside breezes by fan.
Related to this is the science of what to do to allow in makeup air for appliances that vent. If you want to suck air through your building envelope, turn on a clothes drier. I researched this a few years back and there didn't seem to be anything written on how do do this properly. Don't get me wrong, there was plenty written on the topic, but it all glossed over obvious questions about how to balance airflow so you know the air is moving through controlled channels and not through the building envelope. The fact that these questions were left unanswered lead me to believe that the powers that be don't really know how to solve this problem in a cost effective and energy efficient manner.
Back in the 70's when I began as a carpenter, we would staple 4 mil poly on the framing, after the insulation was installed, for our vapor barrier. (install vapor barrier on the warm side) The boss wanted it over all the windows. It was not at that time cut out around the windows. Then when the sheetrock was installed, you could see how the outside air pushed against the poly as it tried to infiltrate the house at the windows. I was amazed at how much pressure was there. It would bulge out the plastic sheeting several inches in toward the room. When you pushed on it with your hand, it was like pushing on baloon. Lots of air infiltration happening, but the plastic sheeting on the warm side was not placed there for preventing air infiltration. It was there to prevent warm moist air from cooling off as it moved toward the outside, and reaching it's dew point and condensing inside the wall.
We were not using any house wrap on the outside of the wall at the time. I wonder how much that would have helped, but I was amazed at how air was trying to infiltrate to the inside of the house and not the other way around. We had installed the windows directly onto the plywood sheathing, using the window flange and nailing through that. They were wood clad (with plastic) windows. Perhaps there was a lot of infiltration happening at that joint, between the window flange and the sheathing. I'm sure some of the air came through the weatherstrip of the windows also. They were casement windows.
Sometimes we had trouble insulating in corners, such as on a hip roof, where it isn't so easy to get as much insulation in, and sometimes on a cold day there would be frost seen on the sheetrock in the corner, if the insulation installation wasn't properly done there.
This is a complex topic that is full of many different opinions. Add to that the variances in climate across the country and it gets really complex. I'm also of the opinion that many builders don't really think about these things.
Matt, I just recently discovered your channel and first of all I want to tell you thank you. Thank you for bringing all sides of home construction to the forefront for us to understand the correct science. A little background, after getting married we moved to a brand spanking new home in Southern Oregon around 2015 that my parents had bought, I realized how poorly it was built immediately. If you turned off the AC within 30 minutes it was the temperature of the outside and it took a bit before you could bring the temp back down. We decided to buy a home of our own after that, but were disappointed to find similar build quality throughout, so we bought a 115 year old home. Thanks to you I've done major improvements to our home were the AC does not have to be turned on until 3pm when it's in the 90's outside. Being a total engineering and learning nerd this is fascinating to me. Thank you again.
Love hearing this! Thanks
Fifteen years of attending ASHRAE meetings, first time I have ever watched a simple explanation of vapour barriers. Really appreciate your work, Matt, keep it up. You and Joseph Lstiburek are my building science heroes!
Would appreciate you addressing the comments about drywall screws, related, liked the video about foaming electrical boxes properly that you did recently, need something like that for the other penetrations that we all make.
My previous understanding (potentially mistaken) is that yes it would be best to somehow be able to not have any penetrations onto the vapor barrier but you can't have everything be perfect so having a vapor barrier up still stops 98% of all the moisture that diffuses through the drywall than not having a moisture barrier, as the job of the moisture barrier is to stop diffusion through the actual drywall cells NOT holes in the drywall from nails or screws.
The drywall screws/ nails I'm assuming is supposed to be sealed via joint compound/ paint and would just diffuse moisture as if that small section didn't have a moisture barrier, so yeah an 4X8 sheet will have maybe 20 screws or something but that only adds up to just 5 sq in. of non-moisture barrier drywall but the rest of the 32 sq ft has moisture barriered drywall.
The screw presses the drywall to the stud. I don't see it being a problem.
I'm a licensed engineer/construction manager in FL and have recently chastised a contractor on a $20M project for showing me design details where they would install a vapor barrier on the inside of insulation in climate zone 1. I explained it to multiple designers on the contractor's side this is not how we build down here (they were from NC). I literally had 3 conversations and they still didn't understand, so I eventually had to direct them to remove the damn barrier altogether. I watch Matt's videos often so it came to me, I bet he has a good video on it and I'll send it to them! Love your stuff man, keep up the good work!
They shouldn't be building like that in NC either...
An eye opening video. Thanks.
Thanks for mentioning the Canadians viewers. We loved your show. It is so helpful and unique. we really appreciate your work. Your faithful Canadian fans.
Tasmanian viewer here :-)
I was impressed by the teaching technique, the background, the ease of teaching, the pushing away of the paper displays, the entrance of the water bottles,... I was wondering how many takes it took to get this right, it would be neat to see a little blooper reel. Great teaching job
Cool to know about these type of new products that Siga has. The problem where I live in the states though, is not in the products, its in getting the installers to do a proper install. The only way this would work for me would be to do it myself.
Your videos are vitally important because of the huge amount of new people in construction and because, historically, no one cared much about these details. I worked as a building inspector and it was extremely difficult to get compliance because they were really not ready for prime time.
They're used to working one way and it's worked perfectly so far. The only thing is, requirements change over time and as windows and energy efficiency requirements evolve, techniques have to change as well. I have it from a tradesman that Velux windows are still being installed improperly because pieces designed to avoid air leakage around the corners aren't used because the professionals placing them don't know what they're for.
Well done! It's great that you are out there seeing the different ways people are building structures and expanding your ( and our) knowledge. All too often people get complacent and just stick to the same old same old mentality. Nice that you are a very forward thinker.. nice for us too. Thanks!
Since finding your channel I have really viewed how to build a home properly extremely differently than I did before. Thanks.
Just started using SIGA products on a home in Toronto, ON Canada. They had a rep come out to show us how to use the product as well which was very helpful. I'm sure we'll be seeing more of it in the future. Thumbs up!
I really don’t understand why people make vapor issues so hard when explaining it. If you use a 6” wall with fiberglass insulation as an example. You want to keep the water vapor out of that 6” of fiberglass. Warm air and holes in the warm side of the wall can carry moisture into that fiberglass.
The goal of the 6 inchs of fiberglass insulation in the exterior wall in cold climates is that entire 6 inch area stays closer to the interior temp than the exterior temp. So if the air inside that 6” of fiberglass hits a vapor barrier against the exterior plywood in a cold climate you have warm wet air hitting a cold surface causing condensation. When that condensation overwhelms the wall framing you get mold inside the wall.
If you put a vapor barrier on the inside next to the drywall then the air in that 6” area of fiberglass insulation will be warm and DRY. When that warm dry air hits the cold outside plywood there will be no condensation. So no mold.
This is reversed in the hot climates when the cold is on the inside of your house and the hot is outside. You will get condensation on the drywall side unless you stop the vapor before it enters the 6” fiberglass insulation.
In this video he was explaining how much holes in the wall can carry water vapor so that should also be delt with. But he did not describe how to do that. Maybe the material being installed behind him was supposed to help with that. Who know he never said.
Great summary, thanks
So what do we do when we live in a climate that features 30.C summers and -10.C winters?
Nice summary. I would hope there is some self sealing take that can be put over the vapor barrier over the studs. Then the nails holding up the drywall won’t cause leakage. Just my idea.
I put plastic over my 6 inch walls and noticed water vapor on the sun hit walls on the plastic before I drywalled...this scared me. I felt that is too much water to be trapped in that cavity...I took the plastic off the walls that were hit by direct sunlight...I feel that a wall needs to breath a little, especially when it is subject to drastic changes like sunlight heat. The building materials will store some moister and give it up as well. I felt trapping large amounts of water was a bad idea. So I have not had any problems and the house is now 23 years old.
Problem with this is I live in NC. Hot humid summers and cold winters. You just can’t win. I just made mine as air tight as possible, have insulation installed properly and control for internal moisture the best I can.
Hind sight being 20/20 my next house I’m going with closed cell spray foam. Air seal, vapor seal and expansive to prevent gaps.
Just as important, you have to stop cold air from hitting the vapor barrier. I have seen countless times where 6 mil vapor barrier fails because of poor insulation allowing cold air into the wall cavities. In effect, this turns your beautiful vapor barrier into the condensing surface and creating a lake between the vapor barrier and the drywall. I've seen this happen to the point where the drywall started to fall apart mere months after installation on a brand new building.
Amazing! You're going to hit that 1M by April 30 I bet. Building season BEGINS.
I appreciate the mention of us Canadians. I as well as many other Canadian's appreciate your show, especially when it comes to insulation and vapour control. You go Matt!!
And correct spelling too! Being dyslexic spelling a burden to me so when people deliberately spell things wrong it really pisses me off. Colour and Vapour its not hard even for me.
Mind you hearing Americans slaughter the word "Solder" and pronouncing it "Soder" is another pet hate :) its pronounced Sold..er for those needing to know.
@@williamarmstrong7199 and caulking, not cocking..lol
Thanks for the great points about vapour barriers! It's definitely something homeowners should pay more attention to!
Great breakdown....one comment... I'm sure people are annoyed at the pedantic nature of this comment but I think it's important that we stop saying "heat rises" when really "warm air rises". Heat doesn't care where it goes as long as it's from hot to cold. This and that we put more insulation into roofs (because there is space) makes people forget that there are other important elements of a house that insulation matters just as much in because they incorrectly believe that heat rises.
Not annoyed at all, its spot on. It
is hard to get people to grasp this. Some never do.
I've heard it said that hot air floats. I like that phrase.
Thank you! It makes me crazy when people say that 'heat rises'. My framed wood floors are insulated to R36, with perimeter insulation to boot. The infloor heating system? We never use it. The floors are always warm and a wood stove heats the house. Visitors ask me "Why did you waste all that money on insulation? Heat rises!"
Thank you for this, just recently started watching your videos as a home owner, and you keep talking about these barriers and i didnt really understand it before.
Reflective on these older video's when it was before Covid in 2020! Gosh! Then building materials and chain supply and labour issues! Now in 2023 life is slowly getting to some normalizy....but with a recession allegedly....building material costs here in Atlantic Canada are considerably lower compared to in the pandemic! Crazy pricing during the pandemic! Thank you Matt and team for all your videos to help us along🙏 🇨🇦🍁
Wow, I am a C10 contractor, Matt Risinger is from the future, a lot of learning from his instructional videos.
Thanks Matt.
As an aside, conserving energy for the Swiss is a very big deal. Except for a handful of countries with north sea access [and I think Italy], nobody has oil. For that reason, market forces will have them leading the world in energy conservation - just discard the climate change nonsense injected by the politicians and follow the science. Getting Macron'd never solved a single problem.
I love the drumbeats that follow right after he says "on the buildshow" :) very smooth transition
Every show I watch I end up adding another idea to my next house-build. Thank you, Matt, for all the inspiration.
Awesome and informative for Americans who haven’t realized that integrity contracting /building also exist outside of our country. Great new content Matt. I really enjoyed that as a long-time follower of you.
Thanks Scott. Much appreciated!
This is where you shine Matt! This was a great video!
Loved the style of this video, and all your latest videos out of Switzerland. Inspiring and well shot, cheers to many more Matt!
SIGA:: enjoyed learning about them and getting educated in the process.
I am so glad I watched your clip today. The informatipm is so helpful. Thank you very much！
Different stages, not only in construction, but also of importance. Understanding the long term savings as to the initial cost differences, which includes the a comfort factor will go a long way in determining which direction to take. Just a Great Video! FR
I second what a prior viewer said. We can all see the product that was installed, presumably directly against the roof joists. What is the ideal goal any home builder should have when we address the space under the roof deck in terms of permeability of moisture? Is it realistic to presume that the number should be zero? Starting directly under the roof deck where we are going to insulate under the deck, should we put the vapor barrier up against the deck, then our insulation or should it be the reverse? I have also heard guys saying it is important to have passive air movement going from the eaves to a venting cap on the roof to help remove the heat buildup in the “attic”. I am not trying to add more complexities to the equation, I just really want to learn what are the best practices to have a sealed home environment where we are able to minimize the energy usage to keep the home very comfortable. I may be looking at building at least two different homes in different climate zones around our country. I am willing to make the initial investment so that they will still be standing generations beyond my life and still be well above code.
Just bought a tiny little home with issues that need to be fixed, this was outstanding!!
Thank you so much!
I've researched this and it's probably one of the most inconsistent area's of building in terms of whether it's required or not. Sadly, I still don't know what to do.
Actually it's very straight forward. If you insulation can not breath to the outside air, you need one.
What about if you have 2" of exterior foam board below grade? Where will the water condense?
a vapor barrier needs to be in a different location for hot vs cold climates. So there is no single answer.
@@ecospider5 problem is a lot of people are in places that have 90 degree high humidity summers and 20 degree snowy winters all in the same spot. "hot climate" and "cold climate" are two extremes that dont represent the gray area inbetween
@@shoyrushoyru Exactly, so what is the answer for a climate with hot humid summers and cold wet winters?
The other (5th?) major element a house needs to control is inbound solar radiation. Letting it in in cold regions/seasons, keeping it out in hot regions/seasons. This could be its own episode (specialised glazing on north vs south facing windows, overhangs, building orientation, thermal mass, etc.).
I like it - Solar. Could put this in Thermal? I would also add Insect Control. Matt has a good video on controlling insects with BoraCare.
@@ZimorKilled thermal might actually be too general now that you mention it, air barriers manage convection, insulation manages conduction, and now we're taking about shading and coatings to manage radiation gain/loss. I like this train of thought
Hey Matt. Great stuff here. I saw your video about vapor barriers that you made in 2018 and it says that you basically don't need one. This one seems to say the opposite. I was leaning more towards not doing one. I live in the PNW which is mostly a heated climate (meaning I'm using heat more than cooling), but it isn't super cold here either. I am remodeling my upstairs bedroom. This is basically an attic turned into a bedroom with two sides still having attic space (where the rafters run down) The house is 1926 and the rafters (which are only 2x4s) meet at the peak with no horizontal supports. Basically like your new attic build in your home but without the horizontal supports on top about a foot down from the peak. I'm going to be using all the space so ceiling will be on the rafters. I'm using spray foam and then for the ceiling I wanted to use wood planks or some kind of wood faux backer board. If I'm using spray foam on the ceiling I know I need to seal the room as best I can. I was wondering if I used the wood planks do I need to seal every crack kind of like drywall would do? If I use the faux wood sheets can I just paint the back of them? I'm just not sure if I need to seal inside the spray foam.
My interpretation is that this material serves first and foremost as an air barrier and that the vapor permeability has a marginal impact. I wish Matt had actually explained the usefulness of this directional vapor flow.
I have never seen anyone explain what happens to that beautiful vapor barrier when you put several hundred drywall screws through it.
not to mention the hundreds of thousands of staples used to fasten it which will 99 times out of 100 not be taped over.
is it 100% tight? nope. Is it 99% better than no barrier? yup
Those screws and staples are of no consern
@@hosmerhomeboy Can you not use vapor barrier with tape AND use the acouticseal as well? I am not at all familiar with acousticseal. I am a novice in terms of building but have done a little bit of everything over my many years. I am planning on either re-habbing an old victorian home with high ceilings out in the mid-west to retire to or have the framework of one built which I could then finish. I hope to act as my own contractor, studying up on all code requirements. Electrical I would leave to the pro's as well as the basic plumbing. I know building codes can constitute a book the thickness of a bible but am planning ahead and have time.
The screws seal the hole. Barrier integrity is maintained.
How about a video for existing homeowners and tips and tricks to airproof/vapro proof their house short of removing all interior drywall and exterior siding?
Hey Matt, if the roof sheathing has vapor barrier, and insulated with a 1.5 inch comfortboard 80. Eliminating the air gap and installing the metal roofing directly onto the Rockwool should not allow for vapor or moisture build up since the comfortboard should stop the radiant transmission into the roof interior or vice versa during the winter with the heat transferring out through the sheathing through the rockwool and onto the metal roofing.
Personally, I love the European theory regarding the lifespan of buildings (generations!) and the 'functionality', i.e. 3 pt. windows and 'Rolladen' window covers.
Very well presented. Also amazing company and representative.
Thank you Matt! Another excellent video! :)
Disappointed in this infomercial, Matt! First time I didn't have one word written on my notepad from your show.
John Bazemore I think it’s more of a
Bread crumb to encourage you to research the system
@@irondiver292, though I believe I understand your reply and cannot completely disagree, I must ask; if Matt intended to encourage fans to research the system, (which is the definition and purpose of a 30 sec. commercial), why is Sig only appearing in the description and not in the title, giving the initial impression this was educational with scientific research on a particular subject rather than a particular product. What has a paid spokesperson that's usually considered sincere and unbiased in his seemingly normal atmosphere quickly abandoning the misleading, "attention grabber," hoping to appear as usual while fulfilling a contractual agreement to sell a product? (hint) Older brother to the 30 second commercial that leaves breadcrumbs to 16mins. of usually grossly exaggerated and questionable .....I have severally digressed. Though the answer is Infomercial, I understand making a few extra dollars, Matt, but the Texas accent plus the honest demeanor is your meal ticket.
it looks to me like the spot Matt was stuck in, and maybe could have navigated differently, was to discuss the need and benefit of having a vapor (and air) barrier, and show Siga's product as a good solution, without just parroting Siga's sales brochure about that product.
Specifically, WHY does it matter if a vapor barrier is "one-way", what does "one-way" mean? Paraphrasing Siga's talking points on this would have been better than the too-brief mention those points got. The diagram of water/heat/air/thermal doesn't address this clearly enough for folks who are not already familiar with them.
(okay, now that we're all done beating up on Matt, let's hope he does a follow-up video with a detailed on-site install of Majrex here in North America)
They flew him to Sweden and they have a product and sales model that's worth knowing about. The emphasis on correct installation and not just product specifications was refreshing. If you stuck around feeling an annoyed by the commercial relationship, that's more on you than the host.
The main reason I watch this show is for new products. 2nd is technique. So whatever dude, this is valuable
Hi Matt, just turned into your channel. Thanks for all the good information, and your presentations are world class! Glad to find you.
This is a great video Matt, thanks!
I love how in this video Matt says you probably need a vapor barrier even though only 1/3 of a quart of water will diffuse into the wall cavity during the season, but literally in another of his videos he says you probably don't need a vapor barrier because only 1/3 of a quart will diffuse into the wall cavity during the season.
It can be useful for the air leakage if your other layers don't do this adequately.
ON The BUILD SHOOWWWWWW!!!!! Awesome video!! Heck yeah, love the vapor barrier, that product looks cool.
the lighting in that room is wild
Such a fantastic video Matt. Just moved into 1850 stone farmhouse, and the penetrations are overwhelming. I'll be referencing this video many times
Rand Thor were in an 1806.. we’re completely renovating.. spray foam was our choice mixing with rock wool..!matt actually helped us decide this too. 😀
Rand Thor our results have been amazing!! Find me on Instagram if you wanna chat about it. 👍
Air-caulk might be worth it.
Being in the planning phase of renovating an old house my understanding is to stick to the materials which were originally used in the building i. e. real wood or clay (modern forms with straw or hemp f. i.). These materials last centuries. Larger amounts of spray foam are nothing I would use for any house, rock wool doesn´t isolate when it is moist, what you need is capilarity of your isolation materials, you don´t even need a vapor barrier then. Barriers won´t work over decades... Learn from old world wide prooven building technics! (I admit I´m no expert but that´s my food for thought, there are enough experts of different scools of thinking out there.)
Karl Ludwig Bonitz it’s your house Karl! Do as you please! 😀😀 that’s what I support 👍👍 we foamed because we car about efficiency.. we’re saving close to 700 a month in heating costs.. if you wanna keep it “original” more power to you!! I love the idea.. but, if spray foam was around in 1800s they would have used it 😆 cutting a million cords of firewood and having 4 fireplaces wasn’t for Ambience.. it was to stay warm in the winter.. but, it’s your renovation and your house.. you do what you want!! You need to be happy with it.. good luck!! 👍😀😀
Looks like the German could pinch your head off. :) Great video. Thanks Matt for all you do.
Haha his subconscious knew he was going to misspell vapour anyway. 😄
Your Swiss / German tour videos were just in time, as I and a collegue went to the Dutch Build Show, there I met the Dutch Rep of SIGA and ordered some of their membranes and tapes for a small job in amsterdam, here's hoping it does what it says on the tin :D
16 mins and no answers LOL! Just a high level explanation of the importance of having a barrier. It was mostly an advertisement for SIGA
😆
bro, this is just so freakn cool! Just BS in general is freakn cool but im glad I have found out about your channel. I am trying to get into passive here in Oregon. If your ever up in the PNW come look at some projects!
Hi Matt, Great demos, thanks! QUESTION: I'm planning a whole house renovation (my house is about 27 yrs old and was built fairly well) I am planning on using as many of your recommendations (improvements) as I can. Can you point me to "the right way to finish a basement"? (waterproofing, vapour barriers, insulation, THE FLOOR, etc.) thanks!
Start at buildingscience.com :)
As hellonko pointed out buildingscience.com is a great start.
But also, what do you have and what do you want?
Are you on a well-drained slope with no water problems, or is the basement catching water and you need to worry about infiltration and maybe adding a drain?
Is it a "day-light" basement with some venting easily available, or fully buried under another story?
Do you want an open recreation area, with good air flow, ect. Or, are you intending to have a kitchen and/or bathroom in the space which can add lots of moisture.
Don't be afraid of engaging a professional to talk through your plans and ideas, you might get it for free, but a few hundred or a couple thousand dollars (depending on the project) of guidance and advice might get you something you're much happier with and save you money in the end.
Love the whiteboard stuff!
Ive been a carpenter/renovator for about 5 years now, and I hear all the time from the old-schoolers how you want your house to breathe, and we vent bathrooms into the soffit here in swampy Eastern NC. However, I'm starting to learn that you may not (depending on conditions) want your house to breathe, but I haven't yet drawn a clear line between the two. What/when exactly do you want to your building materials or home to breathe? Could you compare and contrast the two, please & thank you?
If you have not already seen this video, it gives a good, quick review. A little too short, imo, but still good stuff. --> ua-cam.com/video/OJ9u3pDQeM4/v-deo.html
@@glencaple3888 Amazing video! Thank you for sharing. The short answer is a vapor retarder can be used in climates with both hot/cold, so in the hot the wall can dry out, in the cold it can resist letting water into the wall from the inside.
Or use closed-cell insulation to avoid need for vapor barrier.
Incredible information, you do the industry proud. Thanks
Excellent video.
Awesome instructional video, keep them coming!
Thanks for the great and informative video. I have a question about wall construction. I live in Norway right now and most of the houses here are wooden constructions, just like in the US or Canada. The construction of the outer wall is a bit different. In the US on the outside of the studs usually they put OSB sheating, windbarrier membrane, furring strips and cladding. In Scandinavia they do not put OSB sheating outside, but inside of the studs right over the vapor barrier. According to the Norwegian building institution (SINTEF) it is mistake to install OSB sheating to the outer side of the studs, because it has a strong vapor barrier property and it hinders the airflow and venttilation of the inner constructions like studs, insulation. Why is this big difference, which one is better and why?
Szia Attila, Tudunk kommunikáli emailben vagy telefonon? Köszönöm Matyi
@@matyasfarkas1080 messengeren írtam.
@@matyasfarkas1080 vagy hetvn otvnhárom otvnnegy háromotvnhárm
@@locsei105 Mat Wolf néven vagyok fent. De holnap hívlak. Köszönöm
@@locsei105 Ez milyen körzetszámmal? Vagy +hetven-nel ?
Thank you for the video! So…If I have a framed structure with a crawl space, closed cell, Tyvek on the exterior, Rockwell Insulation, and using T&G bead board for my interior walls, do I need a vapor barrier on the inside? I’m about to install the insulation and I’m not sure…Thanks in advance!!
Is the diffusion calculation based upon painted drywall or unprotected drywall. I do understand that a hole in the wall doesn’t matter, but calculations should be dramatically different between painted and unpainted drywall.
I assume painted; who leaves drywall unfinished?
I truly appreciate this video...
I now know I want a "passive house"
Beautiful explanations!
Thank you very much for your help! thank you for taking the time to make this video! I've been waiting for this. Siga has such a vast catalog, that I'm a bit confused as to what is available.
Thanks for the Canadian plug.
Thank you Matt. This is a great video explanation of not only products but also the role of water, vapor, and air
Very nice explanation! Thanks a lot!
Great really informative, I am going to watch more sessions as I am interested in building a cabin in Flagstaff Arizona with my son!
Great tour Matt and Siga from Philly.
Those robots beginning at 9:20 are incredible!
Matt,
Remodeling a house in NY, climate zone 5a. If the house was built with a vapor barrier just underneath drywall is there issues with using zip on the exterior of the home?
How do you handle a installing vapor barrier in a renovation (down to the studs) without making it cost prohibitive by removing all cladding on a house that has 1950s fiberboard sheathing? Just install closed cell spray foam in the wall cavity?
Thanks again for producing these videos. So If you live in a climate where there are both cold winters and hot humid summers, you would put some sort of vapor barrier on both the internal and external sides of the walls?
Did you ever get an answer? A question I have been trying to get an answer to too but no one seems to ever want to answer the 50/50 climate question. My conclusion now since I'm insulting my attic is to put insulation with barrier facing down in rooms which will or would produce too much humidity e.g bathroom & kitchen and have face up on rooms that are directly getting the best of the sun heat but less humidity.
So should I put 1x4's blocks at top of cavities between floors of 150 yr balloon framing?? Or keep it open to breath better?
The Siga tape is sticky as hell. If you are not carful one can also use it to remove hairs on your breast, legs or anywhere else. If it sticks it sits. Siga are also very big in Germany amongst builders everywhere.
Thinking of building small compartmentalized toilet closet and shower closet, (for lack of terminology), well ventilated of course. Seems like a great product for these locations. It’s all about air control! Deliberate directional movement.
On the build showww!!!
Hey matt, I am building my home in Eastern Washington so advanced framing energy codes are very stringent, . I am planning on using R3 ZIP system and rock wool insulation with siga vapor barrier interior, will having an exterior insulated vapor barrier plus an interior vapor barrier be a problem because any potential Wall cavity moisture will have nowhere to go
Great video! EXCEPT... You never zoomed in and showed what the people behind were doing in detail. I was waiting the whole video to get more detail on what they did.
That's the trick of it,
Great Video Matt.you have a British viewer as well.I actually live and work in the French speaking part of Switzerland in construction,I am a bricklayer by trade but do not get to do so much of that here in CH,
It would be a good video explaining how a cavity wall super structure on a UK home performs,I’m not sure if you have masonry cavity walls in the US or they are solid.but the British can not seem to get away from them.while the rest of the world moves on. Anyway super informative series,thanks
In the video "Vapor barriers: need one or not"...
4:44, discussing diffusion - "There's very few places if any in the U.S. that you really need a vapor barrier"
Also, 7:05 - "But its only really if you get in to the very coldest zone in America, which is climate zone 7 up there, where you might actually use a vapor barrier"
This video, @ 6:10, discussing diffusion using the same example of 1/3 quart of water - "So do we need a vapor barrier? Yeah, we probably do"
Well, now that's all cleared up....
These are mainly air barriers not vapor barriers like a poly sheet.
That is my big problem. I had a company put in aftermarket windows and replaced the single pane to double pane but they did not seal out the water and every time it rains I get dripping around my window on the back side of my house. That is my next project.
Where do you put the vapor barrier on the wood framed sloped roof and ceiling in Nova Scotia Canada ?
I baught a house. It has 2*6walls. I tore out the dry wall. The insulation looks okay. But should I put up plastic or something before I put the dry wall back up. The insulation is bare fiberglass.
Awesome episode, Matt!
Thanks for the great vids ya big dork.
Thanks for sharing. I want to turn a 15 year old pole barn into a home. This is in MN (cold climate). I'm considering spray foaming the entire structure from the inside, but i'm worried about no air flow and condensation build up onto the foam. I would like to foam the ceiling right up to the tin if possible to leave beams exposed, then put tongue and grove pine over it. Is this a good idea? Do you think I will run into problems making it too air tight? There is no house wrap on the structure. And advice would be helpful. Thanks! Eric.
Is there any water membrane on the structure? You need something to keep the water out, but iirc spray foam can act as a vapour barrier & air barrier.
Matt, you didn't answer my question. I live in north Florida and do I install vapor barrier after or before insulation ?
I live in South Florida, Where an interior vapor barrier should never be used. Yet home depot and lowes sell all this insulation with a vapor barrier attached.
I kept waiting for the discussion about whether using poly has any advantage at all, given that it gets penetrated as soon as the resident hangs their first picture, allowing all that moist air into the wall cavity anyways with less breathability for it to escape.
"And we use a lot of cooling in the summer time, if we don't control air"
Easy saving tip: We don't usually have any cooling in central europe, so not controlling energy movement from outside into insulated space means simply suffering without recourse.
G+1121494 open a window. A nice breeze is all you need.
@@4philipp ^Well, personally I live in an old Building in the former Dutchy of Hannover. So british style sliding windows do something to decrease control of air movement and create constant breeze.
But otherwise you may want to not have a direct outside breeze and let the thermal mass of the building equalise the outside temperature movements, vent cold air in through the night and keep the outside air out during the day. Maybe allow inside breezes by fan.
Us being control freaks is part of the problem. I like fresh air.
Related to this is the science of what to do to allow in makeup air for appliances that vent. If you want to suck air through your building envelope, turn on a clothes drier. I researched this a few years back and there didn't seem to be anything written on how do do this properly. Don't get me wrong, there was plenty written on the topic, but it all glossed over obvious questions about how to balance airflow so you know the air is moving through controlled channels and not through the building envelope. The fact that these questions were left unanswered lead me to believe that the powers that be don't really know how to solve this problem in a cost effective and energy efficient manner.
In Japan ventilation holes in the walls are common for intake air. Personally I'd minimize combustion appliances.
Well done Matt.
OK so is the vapor problem and solution the same for hot climates with air conditioning and block walls??
Matt, great video, but what’s the solution for existing construction? I like to improve my house structure.
Thanks Matt I appreciate your expertise and videos hopefully one day I will meet you in person.
Is a vapor barrier necessary in an attic underneath blown cellulose insulation? Thanks
Thank you Matt. This is great content!
I've been using the Siga Wigluv product for a while and absolutely love it.