You're Using Vapor Barriers Wrong | What You NEED To Know

[@dvatp]

A lot of people talk about building science these days, but your videos are the most helpful, concise, and technically accurate reference I've found on YT.

[@ASIRIDesigns]

Thank you so much, glad to hear the content has been helpful!

[@dianearnold5381]

So many videos are promoting a specific product and have a sales pitch. Yours are refreshingly free of that. Thank you. So refreshing. .

[@CharterRights]

As a fellow Building Scientist in my opinion, we can't discuss problems with moisture control without looking at the history of insulation and in particular the introduction of glass fibre insulation. Vapour barriers and air barriers were introduced to protect glass fibre insulation from moisture failure. in the beginning kraft paper backed insulation was only created to provide a simple means of installation, that being able to staple a membrane fitted to very loose spun fibre. The use as a vapour retarder was posited later as it became apparent that glass fibre was susceptible to moisture migrating from the interior of the structure. As time evolved thicker insulation and thicker more effective vapour barriers were believed to be the answer to an on-going issue. As the science has evolved it became apparent that missing small gaps in the vapour barrier resulted in higher concentrations of moisture entrapped in the framing structure arounds joints in the poly, around poorly sealed electrical and mechanical penetrations and where the walls met the floor, corners or the ceilings. Vapour-permeable air barriers were introduced to reduce the airflow through the structure but in my opinion offer very little benefit for the cost. While I still believe the jury is out on its effectiveness we need to go back to the beginning to explore the actual problem which I assure is use of glass fibre insulation. Mineral wool insulation does not experience the same issues as glass fibre. Theoretically speaking we can build without the need for vapour retarders or air barriers IF we look at the root causes and adjust at the design stage. From my continuous study (since about 1974 to present) industry has ignored the actual causes and instead taken a "don't fix it 'til it's broken" band-aid approach. We can build more efficiently and less expensive if we challenge the Building Code evolution beening mandated by insurers and manufacturers' lobbyists and developers' interests. Sorry for the length of this but you can see building science is a passion.

[@MattBell_USA]

Generally, are you a fan of mineral wool for applications in zone 4 of the USA? Frankly, as a layman, I'm trying to sort through this to determine the best option for a near-term future build. Spray foam will not be a product in our home.

[@rcook2608]

Mineral wool is good but more expensive than pink. Spray foam is the best if you can afford it, acts as a vapour barrier also

[@littlehills]

so building in a shipping container in 1c to 40c weather med dry where do i put it on the steel then build - or build insulate then barrier

[@adammacer]

@@rcook2608 Be careful recommending spray foam to anyone in light of recent news from the UK where a gov endorsed programme has left owners unable to remortgage their homes

[@elbowstrike]

So I need to beef up the insulation in my 1960 bungalow with 4x4 construction. No vapour barriers on or between any of the cement elements. If I go with my current plan ripping out the old drywall and paper-backed fibreglass then replacing with Rockwool comfortbatt R-14 for 4" studs, poly vapour barrier, and new drywall, is that going to cause moisture to accumulate? What do I do instead?

[@rkf053fitz]

As a budding building scientist, thank you for your work on these videos and your willingness to share your knowledge. Unfortunately, it's rare to find such quality and conciseness on a very important topic.

[@mikedalrymple9437]

This video is stunningly comprehensive. Thorough, accurate, and zero unnecessary babbling. This video should be required viewing for every university and trade school associated with construction. Design professionals absolutely need to understand this material and the skilled trades should have a better understanding of how their respective activities may impact the structure and why it matters. Well done, sir!

[@zsoltkarner2698]

I am in the renovation business in the past 35 years, but I have never seen such a nasty mold build up behind drywall or other type of interior wall coverings what you showed on the vid. We have plenty of old homes here in Canada, all of the without plastic ! Never seen any problems on them ! However, when you stop the natural air movement, that's when your problems starts ! Builders pot plastic in and around homes these days and install air make up units..... Smart/ stupid ??? You are right about the basement " plastic " too, concrete naturally obtain moisture, a lot !

[@shaquileoatmeal7365]

Seriously, I had a bad mold problem because the builders used paper faced insulation along with wallpaper in a very hot and humid climate. Every channel that I've come across says to have the paper facing the interior wall but this channel is the only channel that basically said NOT to do that in the climate zone that I'm in. He's right, I saw first hand what will happen... It was a nightmare scenario

[@ardentenquirer8573]

Great video I am glad you are mentioning with cold climates (Canada)

[@WhiskeyPapa42]

The drawings provided showing the layer stacks is exactly what I was looking for.

[@paulnandico2370]

I put plastic roll beneath the sheetrock on the first house I built for myself. During the winter, we put pots of water atop our wood stove. We were shocked to find water pouring down from the tops of the doorways. We were putting at least 10 gallons into the air daily. We reduced the amount of water atop the stove and ended up not having to tear out the sheetrock, but I would agree: let your walls and ceilings breath.

[@francoisbouvier7861]

Great information. I just attended a STEP program with an instructor from BCIT. Your information is very close to the theory they propose. They were really big on a continuous barrier.

[@eliinthewolverinestate6729]

Every video of yours I have watched has been spot on. We try to let moisture go outward out of masonry walls above ground and seal underground 0.17 (“dry”) to as much as 3.8 perms (“wet”) low perm vapor retarder. And at least 18" above grade for masonry to dry. And use mineral wool where it makes sense. We use spray foam around windows, doors, and bays next to them because condensation even with thermal breaks. Windows and doors have lower r values making cold spots and condensation in the walls around them too. I use my slab as thermal mass too so insulated to r 60.

[@MacroAggressor]

Wow. This was an _EXCELLENT_ video on vapor barrier techniques. I don't usually subscribe to smaller channels, but this is an instant sub! I hope you put out more videos like this.

[@magnusdanielsson2749]

An alternative to this method with mineral wool and plastics is to use natural insulation material instead, like sheep wool, flax wool, wood wool etc. These materials are hygroscopic so they can absorb and transport the moisture. Building with such insulation you should not have plastic barriers. Instead you need to make sure that the inner wall have 4-10 times higher moisture resistance than the outside. One way to acchieve this is to have a permeable wind barrier(gore-tex like) on the outside and one layer osb+ one layer gypsum board on the inside. Another solution on the outside is a bitumen infused fibre board that acts as the wind breaker (with the addition of insulating). Building like this makes the house ”breathe” and reduce risk of moisture getting trapped. However, excessive insulation thickness can make so the dew point end up inside the insulation. So consult a professional for this.

[@tealkerberus748]

If you use sheep wool, it's going to have to be drenched in fungicide and insecticides before it leaves the factory, the same as wool carpets. Otherwise it will breed moths, and they'll chew holes in everything they can and let water in and you'll have mould as well. If you've ever watched vids of people removing bees from a house wall and the sort of tiny gap they'll exploit, the moths that eat wool are a lot smaller than a bee. You might seal them out when you build the house, but don't assume they'll stay sealed out once the house is in use. The only way to protect the wool is by filling it with poisons. I'm not sure what the requirements are for plant fibre based insulations, but I wouldn't put any animal wool in my house that the manufacturer doesn't expect me to take out and wash routinely. I lived in a house once with moths in the wool carpet in one room and it was a complete disaster, but that doesn't mean I want to live with all those biocides either.

[@magnusdanielsson2749]

@@tealkerberus748 good point. I guess itll depend on where one lives. Here in Sweden many old houses are insulated with sawdust without any such issues. Some houses has stood like that for 100 years without any issues. (Although its common to get house flies in the roof area) But I guess the climate have a role in that. The natural insulation Im talking about are professional products. They do have additives like boron for insect management. One of the first such product were recycled paperpulp as blown insulation. Its been used for 40 years without any problem. Newer products like the wood fibre insulation Im using now are very dense sheets that withstand fire and insects. Even mice dont like it. Its made by Hunton in Norway. They have some interesting information on their site for those interested. One cool thing with the sawdust insulation is that its very resistant to mold and water damage (within limits). When the sawdust gets wet it clumps up and actually start a warming cycle after a while that dries the dust. So if the water is intermittent the damage is very small. The house I live in now had a leaking roof when I bought it. One wall were actually soking wet on the inside! But all I had to do was to remove a section of about 1,5 sqm of the indide wall and some of the sawdust that had ”burned”. Most of the sawdust was perfectly dry even though the inner wood was drenched. Its a very forgiving insulation if used correctly.

[@6061]

I bet if you consult 5 different "professionals", you'll get at least 3 different answers

[@rikardekvall3433]

Hmmm. I live in Scandinavia, northern Europe and we use the Vapor barrier on the inner studs of the outside walls. The heat and moisture stays in the house and by building regulations it’s vented out by a fan/recycle heat exchanger. On the outside it’s only a barrier that vents but blocks the water. Like the GoreTex principle. Then a cladding of own choice that withstand the rain and has an air gap to the barrier. The walls are insulated with mineral wool, preferably stone wool because it does not hold water or moister and no molde can grow in stone wool. We tried esp as insulation but molde started growing and our houses got sick and also the people. So the Scandinavian way, from inside, drywall, plywood/osb, 2x2 studs, stone wool and space for electric cables, plastic Vapor barrier, 2x6 studs, stonewool, outside wind barrier/outside drywall, 1x2 studs for air gap, outside cladding/panel/wood, bricks. We live in a climate of -35 to +30 degrees Celsius and are just fine. Houses are healthy and also we. Note that almost all newer houses have a hvac heating system that use a heat exchanger. Sucks in fresh air from outside in the heat exchanger and blows out the old air. This system works perfect in any temperature. Winter as summer. Warm house in winter and cooler house on summer. Big investment but big comfort. Better aftermarket prices on the healthy houses.

[@ducoh2093]

Im Dutch and I can see why your build up works really well in Scandinavia. Only thing that I am surprised you dont use is continuous rockwool insulation (a rigid one like comfortboard) on the exterior, both for eliminating thermal bridges as well as further reducing the chance of condensation on the studs. We mostly build with concrete and foam here unfortunately, but I know in germany they build the same way you guys do but only instead of mineral wool they prefer wood fiber, like Gutex or Steico. I Guess you Swedes/Norwegians/Finnish prefer something inorganic as stone wool to further reduce chance of rot in the insulation.

[@rikardekvall3433]

Thanks. More and more do they also use the comfort board as you mentioned. And many builders today blow woodfiber into the walls for sound dampening in interior walls. Blow insulation in outer walls also. Rockwool or SaintGroban.

[@HuFlungDung2]

I think a simple chimney solves a lot of moisture problems by creating negative pressure. My dad closed off his chimney when he went all electric heat, and his house was destroyed by mold growth. The chimney provides minimum cost ventilation, 24/7.

[@thelouiebrand]

I totally agree. What if we installed low level vents in the main living areas? You think that could work?

[@j10001]

Great insight!

[@Ariccio123]

It may not. If the chimney was wasting a ton of energy (losing indoor air up the chimney) he was probably then heating his house a lot more. A more aggressively heated house is dryer.

[@brettblack7049]

@@thelouiebrand Air to air heat exchanger.

[@lewisworkshop]

The algorithm fed me your video today. Great information. One suggestion - maybe slow down a bit. You are giving out great information, but your speech and slide transitions are so fast that it is a challenge to absorb it all. Take a breath, linger on the awesome slides a little more. We'll hang around. Thanks for sharing.

[@Ulices84]

Just hit replay 😂

[@Serious-Man]

Watch at .75 speed, or do what everyone did back in the day and take notes...

[@Guishan_Lingyou]

@@Serious-Man I watch most videos at 1.25 or even 1.5, but this one I watched on normal.

[@Auberge79]

come on! As a non-native speaker I have understood just everything here! You can also use slower playback speed if needed.

[@62Cristoforo]

Tons of good information here. I had to actually press STOP and let it sink in, every time you said something important, like every three seconds!

[@ForestToFarm]

@ForestToFarm Great content. Thank you for your efforts. My son and I are currently starting the framing of our two homes on 20 acres that will be our small homestead/farm. Life long dream of mine. At age 61 it’s getting late but better late than never. We put Stego (yellow) under the slab of our 4.5’ tall crawl space. Eight inch block filled with concrete. No vents. There will be a dehumidifier down there. Typical wood framing. The exterior sheathing will be Huber Zip on the walls and roof. Gonna seal it up tight. I am planning on Rock wool insulation in the walls and roof/rafter voids. Is this a good idea or am I missing something? Our local air quality can be poor at times so I hope to be able to control the quality of air inside these homes. Thanks for any advice you may have. By the way we are physically building these houses ourselves. I am a State electrical contractor in South Carolina where we live in the northern part. We have hot humid summers and damp mostly moderate winters. We will start my home very soon then my sons. If you happen to follow along or check out our progress you are more than welcome to criticize our work and tell us what we are doing wrong so we don’t repeat those same mistakes on my sons home. 😊 I want these houses to be a good place for my grand babies to live someday if they choose to do so. Terry

[@JenTorresGroup]

Great videos! I am not in construction, but I have a small 1972 home in central Florida. A screened in patio was converted to a walk in closet with a flat roof. There was a temperature and humidity difference in the closet. After removing the walls we could see it wasn't constructed or insulated properly and the 2x4s weren't spaced properly. Given all the issues I have discovered in this home, I'm sure that even if we fix the gaps that a proper vapor/air barrier wasn't done on the exterior. It is constructed of thin concrete block with stucco on the outside. I don't believe they used plywood or tyvek. So I have been considering how to stop the humidity from coming in without causing a mold problem. I considered using drylock masonry water proofer on the interior of the block then using foil faced R5.9 board insulation (max I can do with space) before adding the dry wall. Or instead using a vapor barrier paint on the stucco outside the home. Would you recommend doing either of these? Would using a smart vapor retarder on the block before the foilback be a good alternative? Do you have any other suggestions? What do you think about the foilback board insulation? If you suggest the paint on the block or on the stucco, what type of paint would you recommend? Sorry I know that was a lot. Thank you!

[@helmanfrow]

What would be your air/vapor strategy for a backyard office (~10' x 12' ) in suburban Toronto? Already built: • 2 x 6 PT skid deck on patio stones on 3/4" aggregate • Durospan 250 insulation between floor joists • 2 x 4 walls on 24" OC layout • 3/4" Plywood deck • 7/16" OSB sheathing • single-slop roof (~12:3) • 2 x 6 rafters • 7/16" OSB roof deck • Asphalt shingles installed directly over OSB (no ice & water shield installed) Planned: • Fiberglass batt for the walls and roof (purchased) • Shiplap pine or cedar exterior cladding • Shiplap pine interior cladding (no drywall) • Mini-split for HVAC (purchased) • Tyvek housewrap • Poly interior barrier The contractor has no interest in: • Exteriror Insulation • Rain screen • Conventional building practices My sense is that the poly should be left off or replaced with a vapor-permeable retarder. Am I mistaken? The wall cavity occupied by the small (8/16) electrical panel will have no space for insulation with the panel installed flush. Should I have the contractor fit insulation behind the panel? EPS or batt? I'd have to trim out the edge of the box where it sticks out past the interior cladding but that's okay.

[@helmanfrow]

Upon reflection I can see that this might be a lot to take in. Basically, if we exclude the possibility of external insulation for this shed what's the best strategy for insulation and vapor/air barriers?

[@jeffpa8462]

Thank you for this. I'm in climate zone 5, and I'm currently doing a renovation and addition. Adding on the walls force field sheathing with 1.5 polyiso exterior and R15 inside. The problem is the vented attic with tons of penetrations what's best way to avoid all the humidity going through ceiling into attic I'm picturing icicles during the winter. Do not have the money to closed cell spray foam roof decking

[@whiskey4553]

Box in every penetration with 2" xps and foam gun. Make sure any fixtures are insulation contact rated.

[@brettblack7049]

proper roof venting is the solution.

[@tomcartwright7134]

I hope in the near future building sciences will better address the on going challenges of moisture management in exterior walls. I believe in the years to come mold and moisture will become a major health issue. We have learned a great deal about sealing up homes from the elements but as the technology has improved so too have the problems of moisture and water management and the consequent mold and mildew issues so prevalent in modern dwellings.

[@chipmhandle]

This was the most concise explanations of true building science!

[@ss4717]

Man you nailed the performance video of the year. Katwilliams giving thruth everywhere

[@towTruck42]

Really nice the way you assembled the series! I love some of the humorous moments that arise on the computer but not in the field "let's go ahead and remove the walls so we can install the floor"

[@Indefinite3Point14]

For basements, use Platon foundation wrap on interior foundation walls and floor before framing and subfloor. All moisture stays within the dimpled spaces with plenty of air movement and superior protection from building materials. If water or moisture accummlates it can dry out or flow toward floor drains because there's always an air gap. Platon also insulates keeping a basement warm, dry and/or cool and dry. - very comfortable and reduces dehumidification volume.

[@HamidA-to8vy]

There is analogy between heat and mass transfer, though I do not think the second law of thermodynamics related that much! the flow occurs when ever there is difference in pressure from high pressure zone to law pressure zone. Also especially gasses defuse from high density to the second density. In liquid, it is called osmotic pressure. Mechanical and chemical engineering students take course called ( heat and mass transfer)

[@Roofersprincess]

Insulation against the roof deck condensates. There must be an air gap to allow air flow. Applying spray foam directly to the deck will create a hot roof in colder climates and allow the formation of ice dams

[@Mikey__R]

With slab on grade, with a barrier sheet under the slab, what happens when that barrier sheet eventually perishes over time? (Entropy is inescapable and all plastic will fail, given long enough.) Can the building be saved? Could you retrofit a second barrier above the slab and below the subfloor? Would a dimpled barrier sheet work here? A lot of old Victorian houses in the UK had their suspended ground floors replaced with a poured concrete floor during the 60s and 70s. If they ever had a barrier underneath, it would have certainly failed in the 50 to 60 years since.

[@ASIRIDesigns]

Great question, you're thinking about it the right way, and a taped dimple mat would work perfectly in this scenario. You can also apply an epoxy coating if the moisture issues are minimal, but the dimple mat solution is my preferred strategy. I actually just uploaded a video about this a couple weeks ago: kzbin.info/www/bejne/fmndnaSKm7Jpbq8feature=shared

[@guytech7310]

Using a heavy duty slab vapor barrier will avoid it from failing for a very long time +100 years. Stego makes a really good slab vapor barrier.

[@ForestToFarm]

@@guytech7310. I just recently installed a Stego vapor barrier under my crawlspace slab. I was skeptical of how it would handle the traffic from the concrete slab pour. Boy o boy was I impressed at how well it performed. Top notch stuff for sure. I stayed right in there the entire time with patch materials at hand. Not a puncture hole during the entire install. Awesome stuff!!! Terry

[@shemicdee780]

What type of vapor barrier would you put on top of a cement floor in a garage I want to refinish it for a living space thinking of putting down the hardwood floor

[@guytech7310]

@@shemicdee780 In My opinion Tile would be better. For tile I recommend using Schluter Ditra. The issue I see using hardwood in a garage is there is no insulation in the slab, and it will get cold in the winter. You can still end up with condensation on floor even with a vapor barrier (from moisture in the garage, & significant temperature swings (would expands\contracts to temperature changes). If you're dead set on hardwood, I recommend contacting the hardwood mfg & ask them for a recommendation & installation instructions for slab installations. Alternative if possible apply some rigid foam insulation then install hardwood flooring. Maybe if you live in a warm climate you won't have any condensation, thermal expansion issues.

[@TroyStevensStelzerPaintingInc]

Absolutely packed with useful info. Thank you.

[@plinble]

Can be using foil panels with offset between the layers for your fabric based internal wall insulation (tapestry), installed by the householder after construction.

[@RileySalm]

5:00 building in a cold climate like Wisconsin. We would not need to insulate the stud cavity in a basement at all? The dual layer XPS foam will provide enough insulation? Or could we use a mineral wool solution in the stud cavity as well?

[@larsmils2994]

So what would you recommend for climates like vancouver island? High humidity, not extremely cold climates during winter, but cooler summers? Just drywall with latex paint? Or a smart vapor barrier?

[@ASIRIDesigns]

Vapor throttle on the exterior (i.e. a fluid applied or self-adhered WRB with a vapor permeance of between 10-20 perms) to slow inwardly driven vapor, and either a vapor permeable rigid insulation on the exterior or a taped smart vapor retarder on the interior.

[@larsmils2994]

​@@ASIRIDesignsthanks appreciate the reply.

[@Arch_Dude]

One thing that is very important to remember is the use and location of a vapor retarder depends on the geographic location of your building. I’m sure you know this, but I didn’t see any commentary about this. It seems your comments are related to cold climates where your practice is located, but the casual user may not understand that. It’s always best to get an architect involved as there are many nuances of getting all of the detailing right. In cold climates, such as climate zone 5, I don’t find condensation is an issue to be greatly concerned about during the summer months because the temperature delta from the interior to the exterior isn’t that great (especially for an extended period of time), and the assembly has the ability to dry if we don’t have two vapor retarder. Our designs might change with global warming, but it’s hard to design for an unknown future condition and the present condition. I would add, you want to avoid two vapor retarders in any assembly as this can trap moisture. I agree it’s best to avoid / limit vapor retarders in certain climate zone if you can as this promotes drying. The key to do this, is the use of continuous exterior insulation and a continuous air barrier. The problem with vapor retarders is they commonly have holes which are difficult to seal due to their typical construction and common installation techniques. As you state a small hole, just 1”x1” can transport a massive amount of moisture into the assembly, making the air barrier all more important. If you can get by with a class 3 vapor retarder, such as latex paint, in cold climates, that might be more successful as it allows some drying potential and a better continuous plane, but still not perfect. Wufi and therm are great simulation software for professionals, but they are not a perfect tool either as they assume a perfectly built assembly, which doesn’t always happen. Plus, they are very complicated softwares, with many assumptions and unknown variables, leading to possible simulation problems. Wifi and Therm are not a required tool, but useful in complicated or unproven assemblies. In this instance, I like using Wufi and therm, to compare multiple assemblies to see which one may be the better option, knowing the real world performance might be different.

[@ASIRIDesigns]

The best part is that you don't need wufi to determine this stuff, it's very basic physics. For example, if you install enough insulation outboard to warm the first condensing surface past the dew point temperature and control air leakage, and you're good to go (for most assemblies). If I design the assembly to dry to either direction, I don't risk trapping moisture. If the assembly is constantly being inundated with moisture as in the case of a slab, you need a vapor barrier. We tend to make these things more complicated than they need to be.

[@ardentenquirer8573]

Thanks for the input

[@58leebee]

This was a very timely video for me! I’m planning on finishing out an outdoor shed to make a small, insulated workshop. I’m putting in some outlets, fixtures and a small heater to keep the temps about 15C during the winter. My plan was to use the good old poly barrier on top of roxul in the walls then covered by .5X6 fence type boards I got from work for free. The floor will be covered by rough 1X3’s. I can’t access beneath the existing floor and the current plywood floor is not entirely up to snuff. Would covering the entire inside of the shed with the poly, taping all seams and penetrations and installing soffit and roof vents be my best option? I want to move my tools and equipment to the shed to get them out of the house and, to be able to use them during the winter. Insulating, moisture control and heating to keep them from rusting and being usable in the cold. I’m located in St. John’s, NFLD. Thank you for any suggestions.

[@guytech7310]

Best option is not to use a vapor barrier or retarder and install external insulation so the sheathing remains warm enough to avoid condensation.

[@ardentenquirer8573]

@@guytech7310 Question is that true in zone 6 Canada if not what do you recommend? I heard 1/3 inside 2/3 outside any merit?

[@davidkatuin4527]

Interesting, I did use the poly sheeting for above ground walls. To overcome the condensation problem, the construction of a second cavity provides a suppressed condensation environment. Also increased thermal efficiency. Nice to see ideas being tried and shared. Thanks.

[@jpatt5054]

What wouls you recommend for climate zone 5. I cant afford to add exterior insulation at the moment however, I'm remodeling down to the studs. 2x6 framing, cdx shesthing. No air or WRB on house. My plan was a henry blueskin air barrier, liquid flash the sill and top olates. r23 mineral wool batts with siga vapor control barrier. 1/2 inch drywall and paint. Does this seem like a good plan?

[@ASIRIDesigns]

That should work just fine, as long as you're taping the SIGA Majrex, the reason being is that you need the smart vapor control layer to be airtight to prevent convective loops within the wall cavity.

[@jpatt5054]

@@ASIRIDesigns is it worth to to thru the trouble of using the mineral wool and VCB? You have to get the electrical boxes and everything just right otherwise you'll have problems! What about behind a shower? Same thing apply?

[@jpatt5054]

@@ASIRIDesigns btw, subscribed! Great content

[@ForestToFarm]

Great content. Thank you for your efforts. My son and I are currently starting the framing of our two homes on 20 acres that will be our small homestead/farm. Life long dream of mine. At age 61 it’s getting late but better late than never. We put Stego (yellow) under the slab of our 4.5’ tall crawl space. Eight inch block filled with concrete. No vents. There will be a dehumidifier down there. Typical wood framing. The exterior sheathing will be Huber Zip on the walls and roof. Gonna seal it up tight. I am planning on Rock wool insulation in the walls and roof/rafter voids. Is this a good idea or am I missing something? Our local air quality can be poor at times so I hope to be able to control the quality of air inside these homes. Thanks for any advice you may have. By the way we are physically building these houses ourselves. I am a State electrical contractor in South Carolina where we live in the northern part. We have hot humid summers and damp mostly moderate winters. We will start my home very soon then my sons. If you happen to follow along or check out our progress you are more than welcome to criticize our work and tell us what we are doing wrong so we don’t repeat those same mistakes on my sons home. 😊 I want these houses to be a good place for my grand babies to live someday if they choose to do so. Terry

[@CharterRights]

The single most important thing to consider when insulating stud walls is to provide a thermal break between the studs / plates and the interior or exterior environment. Consider that in stand housing construction approximately 17-22% of the wall surface is wood. Accordingly this can reduce the R-value of the wall assembly from R22 (as in batts between the studs) to R14.1-R15.6 depending on the stud spacing. A 2x6 spruce stud has an average r-value of only R6.7. In addition to that however, is that the gypsum board connected to those studs directly is conducting heat from the centre of a stud space through the stud to the outside. So adding a continuous insulation / thermal break increases the performance of the overall wall system.

[@machickman4041]

Awesome video! Need more of these informative videos.

[@jonasgranlund4427]

On a newly built house I have Ecotherm 375+ as outer wall part of wall, they have U=0,20 W/m²K and are 375mm thick and on the inside of that I have vertical 1x3 inch studs with C-C 600mm and mineral wool and inside of that I have vapor barrier, 3/4 plywood and finally gypsum board. I was always thinking that the condensation would happen within the Ecotherm blocks because I always thought of it as cold outside and warm inside. But do you think this setup can be a problem when it is warm outside and AC is on inside? Usually in Northern Sweden it never become warmer than 30 degrees, but it can still differ 10 degrees from outside to inside during summer. And during winter it can be a 50 degrees difference but towards the -30 degree celsius winter.

[@angkeats3685]

Thank you! Cold climate Canada with humid summers. I have a 4ft frost wall crawl space. Any suggestions on the best way to keep the moisture out? As in best thing to put on my concrete walls? 😊

[@paoemantega8793]

An excellent presentation, detailed and precise, albeit a little fast for my brain. The pause button is my friend. Thankyou for sharing.

[@Mark-id7fq]

Hi, been installing 6m polyethylene in Canada for years, would love to use a high performance vapour variable VP but the cost is 10X what 6m poly is. This would add $5000 to a standard size house and if it’s not required builder’s will not use.

[@ASIRIDesigns]

How much would a mold or rot remediation cost? Probably more than $5,000...

[@kerrryschultz2904]

What part of Canada are you building in.

[@Mark-id7fq]

@@kerrryschultz2904 BC Lower Mainland

[@scottanthonyd]

I live in southern Ontario, my home was built in 2021 with blanket insulation in the basement walls. Should I remove the insulation and vapour barrier then fix foam board to the foundation on the interior side before framing, insulating? Or can I just frame in front of the blanket insulation? What are your thoughts? Thanks! Videos are great btw

[@ASIRIDesigns]

Great question. Presumably you're referring to a fiberglass batt insulation, which is both air and vapor permeable. Removing the vapor barrier and replacing it with a taped smart vapor retarder would be the easiest and least expensive solution, since you wouldn't need to rip out the old insulation and purchase expensive rigid foam board. Thanks for watching!

[@CharterRights]

Fibreglass Basement wrap insulation was the worse invention ever made. I have yet to see one that didn't eventually fill up with water behind the vapour barrier. It is so full of gaps that even if the basement walls were bone dry (fully cured concrete and no ground water) they would still allow interior moisture behind the vapour retarder. Something to keep in mind is that keeping moisture out of the walls system is impossible. One can only take measures to reduce the infiltration by slowing it down with vapour and air barriers and by reducing quantities through the use of dehumidifiers and or energy recovery ventilators. Type 2 or 4 rigid insulation generally will not deteriorate when subjected to moisture but it will prevent diffusion of water vapour and cause (in some cases) moisture to bleed down the concrete walls. I prefer to use rigid mineral wool against the foundation (or at least a 1" airspace between the concrete wall and the studs), then a stud wall constructed of moisture resistent lumber (preserved wood or surface treated waterproofing).

[@DiscoFang]

@@CharterRights The other fundamental problem with fiberglass batts is their insulative properties drop to almost zero with the slightest amount of moisture let alone being saturated.

[@emblemcc]

I read a awesome book now "Builder's Guide to Hot-Dry and Mixed-Dry Climates" this video is like its visual representation. Btw the book is really awesome, unlike the 15 books I have read earlier ;) as it addresses solutions per climate and points to many common problems people repeat over and over again.

[@DiscoFang]

Thanks for the tip on the book. I'll check out getting a copy. Here in NZ we have a predominantly temperate climate and the timber construction in the last century was very similar to west coast USA. In fact in the early 1900s a large percentage was almost identical to the Pasadena style.

[@ph3818]

Hi ASIRI, I have an old house in zone 6 (new brunswick) canada with lath and plaster on the interior and a blown in green insulation (no signs of paper) that may have been retrofitted. The exterior sheathing is 6inch boards with cedar shakes that are painted ( likely in a oil paint, it is peeling pretty bad). I am in the middle of gutting the bathroom and from what I gather it would be wise to use a smart vapour retarder. The bath is on the second floor with the ceiling being the attic and the bath is unfortunately on the exterior wall. Should I install the vapour retarder behind the cement backer board and also waterproof the backer or just stop the vapour retarder on the one wall section where the backer board will be and then waterproof the backerboard? And is drywall appropriate over the vapour retarder?

[@davidzhu1772]

for a vented crawl space, how would you recommend to seal off the vents after a vapor barrier has been laid over the soil? In my case there's not enough clearance in the crawlspace to install rigid foam under the floor joists

[@elbowstrike]

Okay so in northern Canada like gardening zone 2-3 how do I improve the insulation of exterior walls of a 1960 bungalow with 2x4 construction? There are no vapour barriers on or between any of the foundation/cement components so they're in direct contact with the wood framing which appears to be treated fir. We're planning on ripping out the old interior drywall and fibreglass insulation and replace with Rockwool comfortbatt R-14 for 4" studs then poly vapour barrier and new drywall but it looks like you're saying that's going to cause accumulation of condensation? What do I do then?

[@machinemaker2248]

What scheme do you think would work best for a relocatable home, like tiny homes, mobile homes, and rv/camper/travel trailers? I was thinking both sides sheathed with plywood and covered with tyvek.

[@LvPatriot1]

Thanks for the video, but how about and older build. We live in a cold climate and the building does not have vapour barrier. For example, there are two problems, attic is cold and vented. Is it a good idea to install a vapour barrier on the upper side between the attic beams, then put back insulation, maybe eco wool? And another problem, we want to insulate the building, but it is a timber stud frame with air gap on and brick facade, how to avoid problems, maybe it is better to remove brick, insulate and make an vented facade? Thanks in advance

[@tellsitasitis]

I'm wanting to build a storage pod in my back yard for a SeaDoo, which would be heated. What would be the best barrier? It would just be left open in the summer months because the Sea Doo will be at the lake. Hints? I could add a dehumidifier as well.

[@digrdusty1]

Thx for great content. I'm building a new pole barn soon, which will have a couple separated conditioned spaces. The builder tells me he will place bubble wrap under the metal roofing. I'm not sure that is necessary. Do you cover this in your info? Thx Dusty

[@truthhearit1471]

You are talking about metal which has different properties. That refltex is a necessity, but dont let them place any insulation with it. You can also do blown wool.

[@plinble]

There was a writer for the Daily Telegraph (GB), Jeff Howell, who said there will always be a leak in something like a vapour barrier, so let everything breathe. Now there are reasonable cost relative humidity meters (USD 10) and dehumidifiers there is no need.

[@fooflateka]

How do i know what to do if i am gut renovating a 1960s construction in a mixed climate like NY with brick veneer siding. Changing roof and opening up the ceiling so no/minimal attic. Above grade basement.

[@andrewcarr2431]

the building code states that you should put your vapor barrier on the exterior in hot climate and interior on cold climate. that is great for the North Pole and Florida but what about the rest of us in a 4 season climate? Technically you should turn your house inside out for May, June, July, August then back again for Dec, Jan Feb? This video is very good promotional video for the modern building science vs old fashioned construction. I see many new builds (ours included) which the external insulation boards being installed, as usual it is costs that get in the way of a good design.

[@laius6047]

As long as you have cold season, vapour barrier should be inside, because in warm season the humidity would evaporate due to ventilation. I'm froms Europe and we don't really have this issue with condensation, unless it was built by someone with zero knowledge. Basically interior side gets vapour barrier, exterior side gets breathable membrane. 200mm of insulation as a minimum between the barriers. With A++ ratinf it goes up to 350mm in total if I'm not mistaken.

[@tealkerberus748]

As far as I can tell, what we're working toward here in Australia is no vapour-proof layer anywhere in the wall, just multiple layers that keep liquid water out and conditioned air in, and a whole lot of insulation between the two. Roofs are detailed for the expectation that there will be condensation under the metal most nights of the year, and the condensation has to either drain out or be held safely to evaporate the next day. It would be nice if all the 'science' weren't so unsure of itself, or even worse, sure of itself and then catastrophically wrong. It all seems very experimental still.

[@DiscoFang]

@@tealkerberus748 Australian climate and construction practices and materials are quite different to the North American ones. Absolutely NO vapour barrier in the walls or ceilings is the same here in NZ. We also have very strict controls on adding insulation to exterior walls of existing buildings (require permits to do so) because of the moisture control problems it can introduce into a building construction not designed for it. Spray-foam does not get used here either for such reasons.

[@GoldyMcGoldface]

I've been trying to find a solution to this exact problem. I'm renovating a 1200 sqft slab on grade workshop into living space. I'm in Zone 5 in Ontario and the slab is 40 years old. There's no vapour barrier or insulation underneath. Do you think a frame floor assembly of concrete>tape polyethylene VB>2x6/mineral wool>finished floor would be viable? This seems to be a rare situation and I'm having a hard time finding guidance.

[@Daniel08353]

This is interesting… I’m trying to figure out if I need a vapor barrier on my walls and my vaulted ceiling of a manufacture home with 2x4 exterior framing, for southern Kansas.. I’m using mineral wool for them. Any ideas on this situation? I removed al Sheetrock after finding mold. I believe it was from an old roof repaired after being compromised for too long.

[@ASIRIDesigns]

A taped smart vapor retarder membrane is what you are looking for. Allows for inward drying while preventing diffusion into the cavity that could result in condensation. This will allow you to use mineral wool in isolation.

[@foundationsupportworks2922]

What about basement systems and, all their amazing products. They employ all your same philosophies. Thank you Larry Janesky!

[@magda4762]

5:30 picture shows dimple mat mounted incorectly. Dimples should be on the concrete site.

[@eugenec-k9v]

Is there a purpose to the 2x4 service cavity between the interior smart vapor membrane like Siga Majrex and drywall for renovation scenarios where the MEP's will remain in the framing and be air sealed individually? What is the solution as well to sealing the nail holes that will undoubtably happen over the years that pierce the smart vapor membrane (majrex) with or without a service cavity?

[@fretman6]

Lots of great info here. Too much to absorb effectively. Would love to see this in print, especially those section drawings. Is that available on your website?

[@MrAndzzeys]

Great video. Cheers from Latvia... the weather here is more like in Canada!

[@andrewcarr2431]

never understood how installing a barrier on a wall, sealing it, then sticking hundreds of holes in it mounting drywall is actually effective? You cannot glue it as there is no substrate to bond the drywall to. I like the concept of building "Two" walls. An exterior perimeter that is insulated and air sealed. Then a second wall in front of it to install your mechanical and hang finish material onto. You can then glue the drywall up, which reduces screw fills and finishing work. If you need to access inside it is easy to work with and move stuff, you don't have to worry about sealing around penetrations for electrical, plumbing, etc as it is "an internal wall". And any exterior penetrations (windows, vent pipes, etc) are already effectively sealed inside this exterior wall without cutting/reducing your insulation R value by having to modify it around ductwork, plumbing pipes, electrical boxes. yes you have added costs and some dimension changes as you end up with a 2x8 thick "finished" (2x6 + 2x4) wall rather than a 2x6 one filled with penetrations. Obviously this can be achieved by spray foam insulation, however that is still very expensive compared to regular batt (pink fluffy stuff brand) products on the market.

[@zh4k]

What is the cheapest vapor retarder you recommend. Do you believe the Siga Majrex hype with their variable based on the seasons wrap, or is any of these new type of materials good enough and thus I can go with the cheapest option? Just doing dense pack cellulose in a wall assembly that will be 10 inches thick. At that thickness is the Majrex even needed? Also, if any is good, what is the best in the cheap area?

[@littlehills]

so building in a shipping container in 1c to 40c weather med dry where do i put it on the steel then build - or build insulate then barrier

[@RobONeill-j1b]

Interesting, so vapour barrier warm side in cold climates like Canada, what about wet climates loke Ireland / UK, wouldnt have the same deep freeze as Canada?

[@hillandskyranch]

For vented roofs - what about humid climates in the southeast? Would you still recommend a smart vapor retarder on the interior side of your insulation? From my understanding, in humid climates in the warmer months, vapor can get trapped in the insulation from condensation. Or is the venting typically going to help push moisture up and out of the attic?

[@AC.Prince]

Home Builder here from the southeast, in 2021 I was building a vacation cabin in the Appalachian mountains, got the cabin framed and sheeted with OSB, used gaf wrap to cover the OSB in April, and left the cabin for about 6-7 weeks and the osb was covered in mold once i returned in late May, Could push finger thur the osb decking. There were scape pieces outside uncovered that were fine. The roof was a total loss, in my 50+ years I've never seen anything like this. Any ideas of what caused this? The OSB on the walls where fine just the decking that was covered with the gaf roof wrap

[@jteau2239]

Another terrific video!

[@alastairgillis5717]

Definitely opposing therory to all studies I've seen. Do you have any lab data to support deposition of moisture within the wall? I agree that incompletely sealing both sides of the wall can lead to moisture condensing in the wall but this is usually controlled so that any air movement through the wall doesn't reach the dewpoint until it is outside the envelope and can be drained away.

[@tylerdarling4646]

great channel, you deserve more subs. Ty for this.

[@SheenaRea]

Good information. I'm trying to "fix" the problems in my brick home, zone 4/5 (Cincinnati). Has terrible mildew issues and no vapor barrier was installed (but there is a 1-1/2" air cavity). Currently adding a vapor retardant on the north side interior walls where there's too much dampness. Also the attic has "balsam wool" batts with double-sided kraft paper above the ceiling which I believe were not the best. Can a person lay new insulation on top of the balsam wool in the attic? I believe I have to remove the B.wool... 😞 I've read the double-sided batts are useless. Can they stay and new insulation be placed on top? They are about 2" high. Thanks for all the details in this video. It's helping me understand what the heck I've got going on in this 1948 era house. 🙂

[@truthhearit1471]

That kraft paper is part of the problem

[@xokissmekatexo]

5:31 @asiridesigns question regarding exterior basement insulation. In zone 5 (provo utah) should I use exterior insulation on the basement if I use Comfortboard 80 + comfortbatt on the interior? In your previous videos for slab on grade you are using exterior insulation (I didnt see a full basement video w/ exterior insulation?) I would like a warm basement for medical reasons. And to clarify, I do not need to put a “diaper” over the Rockwool in the basement if I follow the picture @5:31? Thanks!

[@octane_rl4659]

Im here because a client of mine, has a hot water recirculating pump and the copper pipes in the slab are not sleeved, and only 4 inches below in the slab, the heat produced from the pipes were over sweating causing the wood floors to cup and separate, we jackhammered 500 sq feet and the ground was soaked under the slab. What a mess!

[@-Sean-]

What about in a sauna with rock wool insulation is foil ok?

[@PSNDonutDude]

This is super helpful. Im planning to finish our 150 yea rold basement, and the wall cavity will surely be moist with damp air as the foundation is stone with mortar. My plan was to use dimple membrane along the floor and partially up the wall to keep any water instrusion away frkm organic materials (we don't get any water inside even during downpours, but id rather be safe than sorry, and it keeps anything organic off the moist concrete floor). Then a 2x4 stud wall with insulation and a smart vapour retarder to act as a moisture barrier in the winter, but allow that drying of the air cavity in summer with a permanent dehumidifier going in the basement. Then gypsum. Anyone have any suggestions on a way to make this better or anything that could go wrong?

[@ASIRIDesigns]

I'd recommend checking out this other video I posted a few weeks ago on waterproofing and insulating old basement assemblies safely: kzbin.info/www/bejne/gp6comuOZ7Fnbasfeature=shared

[@KevinLe]

This is a great video. I'm going to be putting up mass loaded vinyl to soundproof my shed/office in Boise, Idaho, but i don't know if i need to add a vapor barrier too. Thoughts?

[@johnathanstephenson8107]

I need to know what I can do to control moisture in an existing basement that has no vapor barriers installed

[@bdubs8620]

Long time ago when I started my career, plastic over insulation before drywall was an enforced code. These folk forcing codes that produced unhealthy environments for homeowners have zero accountability.

[@RLLUMB]

Can you please come and advise me in the UK.

[@lexluther2347]

Great content. Thank you.

[@pseudopetrus]

We have to follow code here in Ontario.

[@elbuggo]

Thanks, for another excellent video!

[@robbobcat7286]

rockwool why no vapor barrier on it when you buy it?

[@guytech7310]

Because of the issues with vapor barriers discussed. With no vapor barrier, moisture can escape. You can always add a vapor barrier separately .

[@XYZ-Drafting_and_Designs]

Great Info..thanks

[@abacab87]

I don't see anything about the use of vapor barrier primers or paints. That's what I have done all along because I always felt like plastic was a bad idea on the backside of the drywall.

[@DiscoFang]

He did mention applied barriers in the part listing the grades of permeability.

[@wolflahti412]

Every informed sauna design dictates an impermeable barrier under the interior paneling, the reasoning being the high interior heat and humidity. The wall of an outdoor sauna, from the outside in, comprises cladding, optional furring strips, WRB, sheathing, batt insulation, kraft-paper-backed reflective foil vapor barrier, vertical furring strips, and horizontal paneling. This video says this is a poor design. What would be best practice in this special-case scenario?

[@samyoungblood3740]

Would building in a A frame style help?

[@oldschooljohnny]

Handy info

[@bruce-le-smith]

this is great, thank you so much

[@foxxyboxxy9348]

I'll never go vapour barrier again. just stick to cellulose or wood fibre and make sure it can get rid of all the moisture by ventilation etc. Done this when renovating our house. Checked couple of years later, everything fine, no mold no rot.

[@gogomogo3632]

Great videos! Thank you :)

[@patrickday4206]

I keep seeing these builders building hyper sealed houses and i really wonder how it's going to look in 50 years when walls are ripped open

[@CMCraftsman]

They’ll look fine as long as there was mechanical ventilation installed. If not…. Pretty bad.

[@madwithpower62]

BE science is like 3D chess when one considers where cold and moisture are coming from; could be from outside, inside, below or above and changes depending on the time of year. FUN!!

[@markc5593]

I have found mold under the vapor barrier in crawl spaces.

[@ncironhorse8367]

What if we have a shed we want to insulate? How do we manage the moisture? And how do we find what climate zone we are in?

[@js-lp6om]

imo its the fact the outside of homes are done properly lack of thinking how would trapping moisture between two plastic layers with cellouse food for mold to grow and have moisture find its way in and not back out... like I dont know how many times I have to fight with people on how to install windows properly let alone explain how cladding should be done... sad lots of knowledge has to be google for anyone to realize its not everyday knowledge for alot who just need a job that end up doing these tasks....

[@Z-Ack]

I remember i went over to some super rich dudes house when i was young with my parents and the house was just built and didnt even have furniture. I remember the guy talking about how air sealed the whole place was and that he could turn off the ac and venting and youd end up suffocating eventually. He closed the doors and windows then turned on the ac system and made your ears pop.. if you just opened one door all the dust and stuff would get sucked out the door.. was wild. I bet hes got the lowest heating and cooling bills ever..

[@hu5116]

This was a great video with one exception. On some of the vignettes (but not all) you talked about a barrier here or there but then did not highlight it in red like in other vignettes. Your description was not detailed enough (or maybe went a little too fast) to make up for not explicitly highlighting the barrier in the construction, which then left me wanting. However, you mentioned there is more at your site so I’ll go visit there to fill in blanks.

[@floydffrogfloydffrog7453]

Fascinating.

[@EarendilTheBlessed]

Most contractors can't even write or read. A insurance approved contractor came to my house. He proposed to put vapeur barrier all over the place because he had no clue what to do with them but it looked he did and definitely tried to charge for it. He'll he even put a vapor barrier, wood and another vaper barrier.

[@kiefmanning7394]

*vapor. Huh. I can read

[@joem7062]

I installed new siding on my house. Above grade walls Chicago area. Every wall in the house had plastic vapor barrier. One wall had the vapor barrier removed during a renovation many years ago. The walls with vapor barrier had no rot. The one wall with no plastic vapor barrier was rotten due to condensation. Half the studs were rotten. The bottom plate was rotted. The studs rotted from the outside in due to condensation forming in the underside of the sheathing in winter. There was no other source of moisture intrusion and old siding was intact. Insulation was craft faced fiberglass. My point ? 6 mil poly vapor barriers under drywall in certain climates most definitely prevent rot.

[@Tealeafsong]

thank you!

[@peterxyz3541]

Thanks useful