Belinda, As always you have described the subject very well. Short introductions such as this are extremely useful, but I just wanted to elaborate on the rate of permeability. Diffusion of water vapour is, as you mentioned, dependent on the thickness of the material and the temperature at the time, but there is one other factor that should be considered and that is moisture content of a material. Wet masonry is less permeable, but conversely wet OSB board is more permeable, so the laboratory data given on the product is not necessarily true to in-situ performance. BTW the US perms are far better to understand than the Sd measurements (and others) we use in Europe.
Isn't Sd just another scale? Mu times thickness, so instead of higher number denoting more permeability it's reversed where a low value repreesents more permeability. Though granted i haven't done moisture calulations in a long time because problems usually occur in corners or places where normal calculations are not required or simply impossible (without 3d software).
Great video. As a new home owner all of this is extremely helpful. I appreciate the straightforwardness of your videos. No jump cuts or overly edited content.
I would love to see a “Part 2” to this video that runs through a few common wall systems and discusses why they are or are not addressing the four concerns appropriately.
IF I HAD HAD A TEACHER IN HIGH SCHOOL, OR A PROFESSOR LIKE YOU IN COLLEGE, I WOULD PROBABLY HAVE PERSUED MY INTEREST IN ARCHITECTURE. YOUR VIDEOS ARE BETTER THAN GOING TO SCHOOL. CLEAR, INFORMATION PACKED AND UNDERSTANDABLE.
This is ridiculously pertinent to my needs right now. I’m debating as to what ( if any) material I’ll be using on the ceiling of my soon to be built hempcrete home. Currently favouring wood wool board. Many thanks again Belinda, fantastic channel.
This is a great video on this subject. I am working on building with hempcrete and other natural materials and vapor permeability is super important in making sure that water does not get trapped at the wrong place in the wall.
Great video! I learned a lot. I was surprised to see Tyvek was as permeable as it is. I really appreciate the high quality information and presentation in your videos. Thank you!
Another great video. This is such an important but complicated topic. Please consider making a longer more in depth video with emphasis on where the vapor barrier should be placed. Thanks again.
Well described. That is why Insulation is so important and making sure there are no gaps in insulation or else those are the places condensation can happen in your walls and ceilings. I've seen yellow and black drywall in new homes because of lack of Insulation.
Really looking forward to your follow-up with actual wall assemblies! I'd love to understand more about the way these assemblies should change when moving between climate zones. For example, I'd expect differences between Texas (Zones 2/3) and Seattle where I am (Marine 4). We deal with way too much moisture up here to have the same humidity considerations!
Could you talk more on mold? Is there a point where all is lost and there would be no way to save a construction from mold that has permeated (for example Stiles Unit in Texas)? I wish I knew how it was constructed exactly.
Thank you for your thoughtful presentation. I have encountered a problem building an outdoor sauna in Seattle. Right now this small structure (67 sq. ft) has a slab on grade, walls framed with 2x6 studs, 1/2 inch CDX plywood sheathing covered with Tyvek, and a sloped roof covered with 11/2 in. CDX and asphalt shingles. The sauna would likely be used not more than five times a week year around, which would involve the 9 kw heater bringing the interior air temperature up to 180 degrees F over a 30 minuet time period, maintaining the temperature for 30 minutes, and then cooling. There would be no heating in the sauna at other times. I intend to use this primarily as a dry sauna, with relative humidity below 30% most of the time. A subsequent owner may decide to use it as a wet sauna where relative humidity could be near 100% for up to 30 minutes at a time. To assist in the cooling and dehumidifying the sauna after use, an exhaust fan will be operated for about 30 minutes, and, if necessary, a dehumidifier may potentially be added to the system. Sauna manufacturers routinely recommend filling the wall cavity and ceiling joist space with rock wool insulation and the use of a foil vapor barrier on the interior face of the studs and between the ceiling joists. The foil (with a perm rating of near zero) must be carefully installed with all seams taped with a special metallic tape. The foil is recommended to reflect radiant heat back into the sauna and to stop water vapor from passing into the wall cavity and attic where in cold weather it might be expected to condense on the interior face of the plywood sheathing and promote the growth of mold or cause wood rot. Given that it is difficult or impossible to install the foil well enough to prevent some moisture from entering the wall cavity, its use raises the risk of trapped moisture in the wall cavity (less so the attic which is well ventilated). The foil prevents drying to the interior, and drying to the exterior, while possible in warmer weather, would be minimal in the long cold wet winter here in Seattle. What are your thoughts about this wall design and what would you recommend for moisture management to avoid trapped moisture in the wall cavity?
I’ve read comments before of people saying using closed-cell spray foam in your walls is bad if you do less than 2 inches, because it will trap moisture in the walls and cause rot/mold. Do you know anything about this?
Its a deep question you are asking. You need to go learn some building science basics. To answer your question the 2 inch minimum is because at 2in closed cell spary foam performs as a vapor barrier. If you have less than 2in then water vapor can pass tru which would condense on the colder interior or exterior surface on the foam. Since that foam is enclosed by either interior or exterior finishing material, you get mold. Also you just want one vapor barrier in a wall assembly because if you have two inevitably water will condense and be trapped between 2 barrier that wont allow drying and you get mold
Thank you for addressing and explaining this subject in such understandable way. In addition to my subscription to your channel, I have decided to create an extra folder (playlist) for this type of educational content. So that I can better share them and re-watch them myself too.
@@BelindaCarrQuite the task you've given yourself! I look forward to seeing the results of your efforts. I didn’t get into comparisons: I have the luxury of just installing the products specified by the design team. Although you quickly moved through the comment that older buildings leak air, may I suggest your audience might find it interesting to learn just how quickly an older building exchanges all air vs a new building that’s passed a blower-door test.
Yes, in that these products are assembled from steel or fiberglass they are vapor impermeable. None of these types of accommodations are particularly tight. They leak air. When they are tight condensation can appear on either the inside or outside of wall and roof surfaces (depending on climatic conditions) but the materials used resist water damage very well.
Wonderfully explained, Kevin. The one saving grace with all these tiny homes is that they contain a small volume of air that can be replaced quickly when a window or door is left open which will help the condensation issues.
i think you should be teaching architecture, or maybe construction management. you cut through the material (no pun intended) that would put most people to sleep and give concise yet comprehensive information that people who are designing and building structures need to know, and you make it easy to understand even for a laymen.
I enjoy your videos. I have a question. I live in central Florida. Doesn’t freeze. High heat/high humidity. My home is 100 years old with 11’ walls. I caulked all joints, edges & corners. Then painted 3 coats of quality paint. I painted the inside with quality paint. I have old double hung windows. I installed tight fitting wood/glass storm windows on the outside that can be opened from the inside. I installed press first wood/shrink wrap interior windows inside against the double hung windows. The house is up on piers. Air can freely blow under the house. I attached thick plastic film to the joists under the house and caulked. I have 18” of insulation in the attic with a small ventilation fan to move the air outside. I don’t get air flow through my walls. Many salespersons have told me that replacing my double hung windows and blowing in insulation through the side walls will save me a lot of money. That the energy saving will pay for the cost in just a year. Last year I used my furnace for 17 hours. I used the air conditioner for 93 hours total for the year. I am comfortable with just ceiling fans. A friend with a new super insulated house needs to run his air conditioner most of the summer. Mostly to eliminate the humidity. What is going on? Is my home design superior to new construction. Are triple glazed windows and insulated walls worth it for?
I wish you covered ICF construction in this analysis. I have been wondering for a bit about this. Matt Risinger has a video where he talks about the importance of a wall to be able to dry from the inside out- on second thought I may not have fully grasped the concept in that video. I think I see the importance of that ability though. There is going to be moisture on the inside of a house from showers, cooking, human respiration, etc, and that needs to be managed. Im guessing in an ICF house that is mostly vapor impermeable, and this moisture could cause problems if not dealt with. I hope mechanical ventilation such as a HRV, or an ERV, or a dehumidifier would be up to the task. What are your thoughts?
Great video on a complex subject that many people in the industry doesn’t quite understand. Perhaps you could talk about how vapour permeance changes with relative humidity like smart vapour retarders in future videos.
Hello, thanks so much for all the information you provide. I am planning on converting a school bus. I had one question, do you know the perm rating for Mass Loaded Vinyl, I can’t seem to find any info on it. I know that it’s made from recycled rubber, but is it considered vapor impermeable? Thanks
I live in a colder climate, Canada, and have a question about insulation/vapour. We build walls with 2x material, have insulation in between them, vapour barrier on the inside, sheathing and housewrap on the outside. If we install sheet insulation on the outside of that, will moisture get trapped in the walls?
Sounds like you're building a split insulated wall which should work well in your area, provided it's a vapor retarder, not a vapor barrier. What exterior insulation are you planning on using?
1 perm = equalls 1 grain of water passing a plane in space the size of 1 gross of square inches in 3600 seconds. A grain of water?? a grain of sand, a grain of rice, wheat, ??? Just about enough to give me a migraine! I can barely fathom it even though that is about how tall I am. Man this U.S. unit system is a basket full. Belinda thank you for the attempt to shed light on this subject, some of the editors at Fine Homebuilding struggle with this. I do get some of it. Temperature/dewpoint spred can be used to estimate how high the clouds are above the ground (divide by 3F(U.S. sys) or 2C (metric sys) x 1000 (feet) or 300 (M)) So if clouds are forming in our walls we want that to happen at a point where they can eventually excape inward or outward I guess.
Something else I didn't know I wanted to know that helps me learn a little bit more, even if I'll forget it within a week. :) Would cement or concrete walls be considered Class IV permeable? I ask because I used to live on Guam and we lived through a typhoon back in the '70's where the wind was so strong is pushed water through the walls! Thank you for another informative video. I look forward to any follow-ups you do, especially if you manage to slip in a shipping container's wall example. :D
I’m confused.There’s many suggestions to use xps/eps ridged board insulation against concrete foundations with batts insulation in front to bring r-value up. But it’s not recommended to use poly tarp against foundation walls with batts. Aren’t both systems using a non permeable barrier? Why is one recommended but the other not?
In my zone (5) they require a 6 mil poly with unfaced batts . I would not do this on my own house knowing what I’ve seen in renovations (mold) .I prefer a more permeable product such as typar (not tyvek too high perm rate). Living on the coast we typically get higher temps with higher humidity during winters then most zone 5 areas.
Would whole home humidity control help out with this at all? It seems like the ideal whole home climate control system should have higher fresh air exchange rates, better dedicated filtration, and humidity control in addition to the temperature control we’ve come to expect.
I'm a philosophy phd student...how the hell did I end up watching and subscribing to this channel?! XD I mean, sure, I'm a generalist, but still...ehm...keep up the good work?
Thanks for the guidance, most useful and presented in an easy to understand way. As a side note have you changed your microphone or recording equipment? Your S pronunciation has become very harsh and whistle like, makes it a little more difficult to focus on your delightful voice.
I would like a house without plastic vapour. So many codes require them. Natural materials. What the condensation dew pint calculation in the codes does not take into account is the phase change from gas to liquid energy requirements for this. This goes to the position of the vapour barrier. American houses all appear to have HVAC ventilation. Not common at all in Australia.
Great info Belinda, Happy new year! We have solid wooden walls in my house and all the functions of vapour control, wind and rainproofing and insulation are well coped with for my subarctic climate, without any man made materials at all. The industry has not been kind to this building system here in Norway and it is cultural, instead of technical criteria that allows its continued use. A shame, since it is sustainable and makes for a fantastic indoor climate with good acoustics too. The calculation of R value is specifically designed to favour mineral wool insulation, but I find the true insulation properties of timber houses to be better than equivalent mineral-wool insulated houses here. The study of vapour movement is not new at all, the specific traditional dimensions of timber houses here have a lot to do with vapour movement and were perfected seven or 8 hundred years ago, the same is probably true for traditional buildings in Dubai..? Industrial companies make data that serves them, and their lobby power is formidable. We have a responsibility to give credit to our forbears where it is due, many ancient building systems are excellent and remain little changed due to them working. I have a film on my channel about untreated wooden walls and how they weather if you are interested. all the best , Lucas
Hi, Lucas. I completely agree with everything you said! I'm going to post a video on "R value myths" next week that will touch on what you said. Do you mind if I mention you in the video/description? When I said "new" I meant learning how vapor works with new methods of construction(150 years since we started using manufactured insulation), compared to solid wood construction, like you mentioned, that has been around for thousands of years. I'm going to check out your channel. Thanks!
@@BelindaCarr Belinda you are welcome to mention my site, if you would like to and I would happily make a film especially about this subject in co-operation if that would be interesting to you. My wooden walls film is about weathering rather than k-values. I have heard there have been studies done in the states about energy consumption in timber houses. Also Edinburgh university has some study of energy consumption and hydroscopics in thick brick walls and specifically how retro insulation resulted in higher energy consumption due to trapped moisture, if I remember correctly. At any rate I will continue you to watch your excellent films, all the best, Lucas.
has anyone thought of adding vapor barrier on back of Drywall ? and removing its paper surface, its time to rethink Drywall , the product needs an improvement .
Inoperable windows ? The moment I find out the house I'm considering has Inoperable windows is the moment I thank the person showing me the house, then tell them I'm not interested.
Belinda, As always you have described the subject very well. Short introductions such as this are extremely useful, but I just wanted to elaborate on the rate of permeability. Diffusion of water vapour is, as you mentioned, dependent on the thickness of the material and the temperature at the time, but there is one other factor that should be considered and that is moisture content of a material. Wet masonry is less permeable, but conversely wet OSB board is more permeable, so the laboratory data given on the product is not necessarily true to in-situ performance.
BTW the US perms are far better to understand than the Sd measurements (and others) we use in Europe.
Thanks a lot for this info! I'm pinning your comment.
@@BelindaCarr Thanks Belinda, I am a big fan of your videos because you bring so much clarity to deeply technical subjects.
Isn't Sd just another scale? Mu times thickness, so instead of higher number denoting more permeability it's reversed where a low value repreesents more permeability. Though granted i haven't done moisture calulations in a long time because problems usually occur in corners or places where normal calculations are not required or simply impossible (without 3d software).
@@MichielJorrickMeidem Yes, the lower the Sd (steam diffusion) the higher the perm rating
Great video. As a new home owner all of this is extremely helpful. I appreciate the straightforwardness of your videos. No jump cuts or overly edited content.
I would love to see a “Part 2” to this video that runs through a few common wall systems and discusses why they are or are not addressing the four concerns appropriately.
Trying to release that video tomorrow!
The video is up now! Hope you have time to check it out
Great video you have a real knack for explaining complex concepts in a way that can be understood.
Probably the best explained videos i've seen on this topic. Presentation, speed and info are all spot on. Well done!
Another fantastic presentation from Belinda Carr! I'm so happy I found your website. Keep up the brilliant work.
Thank you!
IF I HAD HAD A TEACHER IN HIGH SCHOOL, OR A PROFESSOR LIKE YOU IN COLLEGE, I WOULD PROBABLY HAVE PERSUED MY INTEREST IN ARCHITECTURE. YOUR VIDEOS ARE BETTER THAN GOING TO SCHOOL. CLEAR, INFORMATION PACKED AND UNDERSTANDABLE.
Thank you! It's disappointing that architecture and construction are seen as separate fields. We didn't learn ANY of this stuff in school.
@@BelindaCarr I KNOW. MSOTLY I JUST LEARNED TO DO THE DRAFTING OF BUILDINGS AND SITES, LITTLE ABOUT WHY OR HOW ELSE IT COULD BE DONE.
I always learn so much from your videos! Thank you!
This is ridiculously pertinent to my needs right now. I’m debating as to what ( if any) material I’ll be using on the ceiling of my soon to be built hempcrete home. Currently favouring wood wool board. Many thanks again Belinda, fantastic channel.
Woodwool is an excellent lime render and plaster carrier and is very diffusive. A good choice.
This is a great video on this subject. I am working on building with hempcrete and other natural materials and vapor permeability is super important in making sure that water does not get trapped at the wrong place in the wall.
Great video! I learned a lot. I was surprised to see Tyvek was as permeable as it is. I really appreciate the high quality information and presentation in your videos. Thank you!
Another great video. This is such an important but complicated topic. Please consider making a longer more in depth video with emphasis on where the vapor barrier should be placed. Thanks again.
You are awesome
I need a week off from work and watch all your videos
Well described. That is why Insulation is so important and making sure there are no gaps in insulation or else those are the places condensation can happen in your walls and ceilings. I've seen yellow and black drywall in new homes because of lack of Insulation.
Excellent! Thank you!
Good information thanks
You choose the best thumbnail.
Really looking forward to your follow-up with actual wall assemblies! I'd love to understand more about the way these assemblies should change when moving between climate zones. For example, I'd expect differences between Texas (Zones 2/3) and Seattle where I am (Marine 4). We deal with way too much moisture up here to have the same humidity considerations!
Planning on releasing that video tomorrow!
What are your thoughts on a “breathable” home in a cool, high humidity climate such as those found in the Pacific Northwest?
15 seconds in and what is not confusing is the fact that you look ravishing in this video. I'll go watch the rest now.
Finally got a much-needed haircut after 2 years :)
Could you talk more on mold? Is there a point where all is lost and there would be no way to save a construction from mold that has permeated (for example Stiles Unit in Texas)? I wish I knew how it was constructed exactly.
Thank you for your thoughtful presentation. I have encountered a problem building an outdoor sauna in Seattle. Right now this small structure (67 sq. ft) has a slab on grade, walls framed with 2x6 studs, 1/2 inch CDX plywood sheathing covered with Tyvek, and a sloped roof covered with 11/2 in. CDX and asphalt shingles. The sauna would likely be used not more than five times a week year around, which would involve the 9 kw heater bringing the interior air temperature up to 180 degrees F over a 30 minuet time period, maintaining the temperature for 30 minutes, and then cooling. There would be no heating in the sauna at other times. I intend to use this primarily as a dry sauna, with relative humidity below 30% most of the time. A subsequent owner may decide to use it as a wet sauna where relative humidity could be near 100% for up to 30 minutes at a time. To assist in the cooling and dehumidifying the sauna after use, an exhaust fan will be operated for about 30 minutes, and, if necessary, a dehumidifier may potentially be added to the system. Sauna manufacturers routinely recommend filling the wall cavity and ceiling joist space with rock wool insulation and the use of a foil vapor barrier on the interior face of the studs and between the ceiling joists. The foil (with a perm rating of near zero) must be carefully installed with all seams taped with a special metallic tape. The foil is recommended to reflect radiant heat back into the sauna and to stop water vapor from passing into the wall cavity and attic where in cold weather it might be expected to condense on the interior face of the plywood sheathing and promote the growth of mold or cause wood rot. Given that it is difficult or impossible to install the foil well enough to prevent some moisture from entering the wall cavity, its use raises the risk of trapped moisture in the wall cavity (less so the attic which is well ventilated). The foil prevents drying to the interior, and drying to the exterior, while possible in warmer weather, would be minimal in the long cold wet winter here in Seattle. What are your thoughts about this wall design and what would you recommend for moisture management to avoid trapped moisture in the wall cavity?
I’ve read comments before of people saying using closed-cell spray foam in your walls is bad if you do less than 2 inches, because it will trap moisture in the walls and cause rot/mold. Do you know anything about this?
Its a deep question you are asking. You need to go learn some building science basics. To answer your question the 2 inch minimum is because at 2in closed cell spary foam performs as a vapor barrier. If you have less than 2in then water vapor can pass tru which would condense on the colder interior or exterior surface on the foam. Since that foam is enclosed by either interior or exterior finishing material, you get mold.
Also you just want one vapor barrier in a wall assembly because if you have two inevitably water will condense and be trapped between 2 barrier that wont allow drying and you get mold
Love your videos. I appreciate your honesty.
Your videos are really really good. You know how to explain things so well. Thank you.
Thank you for this!
Extremely interesting and well explained, but it was just a tease! Looking forward to tomorrow's video :-)
I find your videos educational and so informative. I am a big DIY It's also nice to be eudcated on the many principles behind the scenes.
Thank you for addressing and explaining this subject in such understandable way. In addition to my subscription to your channel, I have decided to create an extra folder (playlist) for this type of educational content. So that I can better share them and re-watch them myself too.
Super informative!!
Very informative 👍
Excellent informative video! Thank you so much!
I knew about Tyvek, now I know more about it. Thx. I use a white salt indoors to help lower the relative humidity around the bathrooms.
Really appreciate your content. I'd like to see some analysis of sustainable building materials like straw bale, earthen plaster, etc. thanks.
You are awesome! Great info....
Very good overview of a very complex area of building science. I don’t think I’ve seen a video on ERVs and HRVs?
Thank, Kevin. I'm working on an HVAC, erv, hrv series with product comparisons!
@@BelindaCarrQuite the task you've given yourself! I look forward to seeing the results of your efforts. I didn’t get into comparisons: I have the luxury of just installing the products specified by the design team. Although you quickly moved through the comment that older buildings leak air, may I suggest your audience might find it interesting to learn just how quickly an older building exchanges all air vs a new building that’s passed a blower-door test.
Thanks for sharing.
I just love your channel
Thank you:)
In Nordic countries, we need more moisture in our homes thru the winter.
Can you do a review on intello plus vapor control barrier from 475 ?
Are there special considerations for caravans, mobile homes, campervans etc?
Yes, in that these products are assembled from steel or fiberglass they are vapor impermeable. None of these types of accommodations are particularly tight. They leak air. When they are tight condensation can appear on either the inside or outside of wall and roof surfaces (depending on climatic conditions) but the materials used resist water damage very well.
Wonderfully explained, Kevin. The one saving grace with all these tiny homes is that they contain a small volume of air that can be replaced quickly when a window or door is left open which will help the condensation issues.
Awsome vid extremely well presented .
I am a builder and am very interested in houses that are fit for purpose and dont cost the earth to run .
i think you should be teaching architecture, or maybe construction management. you cut through the material (no pun intended) that would put most people to sleep and give concise yet comprehensive information that people who are designing and building structures need to know, and you make it easy to understand even for a laymen.
Thank you!! We all have short attention spans so information has to be conveyed in as few words as possible.
Well explained in a brief video.
👍
Very informative, Thanks.
6:02 the chart shows that polyiso with foil face is better than xps all the way till XPS is 8” thick. How is that the best?
I enjoy your videos. I have a question. I live in central Florida. Doesn’t freeze. High heat/high humidity. My home is 100 years old with 11’ walls. I caulked all joints, edges & corners. Then painted 3 coats of quality paint. I painted the inside with quality paint. I have old double hung windows. I installed tight fitting wood/glass storm windows on the outside that can be opened from the inside. I installed press first wood/shrink wrap interior windows inside against the double hung windows. The house is up on piers. Air can freely blow under the house. I attached thick plastic film to the joists under the house and caulked. I have 18” of insulation in the attic with a small ventilation fan to move the air outside.
I don’t get air flow through my walls.
Many salespersons have told me that replacing my double hung windows and blowing in insulation through the side walls will save me a lot of money. That the energy saving will pay for the cost in just a year.
Last year I used my furnace for 17 hours. I used the air conditioner for 93 hours total for the year. I am comfortable with just ceiling fans.
A friend with a new super insulated house needs to run his air conditioner most of the summer. Mostly to eliminate the humidity.
What is going on? Is my home design superior to new construction. Are triple glazed windows and insulated walls worth it for?
I wish you covered ICF construction in this analysis. I have been wondering for a bit about this. Matt Risinger has a video where he talks about the importance of a wall to be able to dry from the inside out- on second thought I may not have fully grasped the concept in that video. I think I see the importance of that ability though. There is going to be moisture on the inside of a house from showers, cooking, human respiration, etc, and that needs to be managed. Im guessing in an ICF house that is mostly vapor impermeable, and this moisture could cause problems if not dealt with. I hope mechanical ventilation such as a HRV, or an ERV, or a dehumidifier would be up to the task. What are your thoughts?
Great video on a complex subject that many people in the industry doesn’t quite understand. Perhaps you could talk about how vapour permeance changes with relative humidity like smart vapour retarders in future videos.
Will do in the future! I need a break from this topic for now :P
Hello, thanks so much for all the information you provide. I am planning on converting a school bus. I had one question, do you know the perm rating for Mass Loaded Vinyl, I can’t seem to find any info on it. I know that it’s made from recycled rubber, but is it considered vapor impermeable? Thanks
a credit to us all - and such a joy. Life should be more Belinda Carr and less - all the rest
I live in a colder climate, Canada, and have a question about insulation/vapour. We build walls with 2x material, have insulation in between them, vapour barrier on the inside, sheathing and housewrap on the outside. If we install sheet insulation on the outside of that, will moisture get trapped in the walls?
Sounds like you're building a split insulated wall which should work well in your area, provided it's a vapor retarder, not a vapor barrier. What exterior insulation are you planning on using?
Do not worry about it , when vapour barrier fails moistuer will be trapped by osb sheathing on the outside
Any chance you could address the best way to retrofit a 1930s cut stone exterior with modern insulation techniques while avoiding rot/mold/etc ?
1 perm = equalls 1 grain of water passing a plane in space the size of 1 gross of square inches in 3600 seconds. A grain of water?? a grain of sand, a grain of rice, wheat, ??? Just about enough to give me a migraine! I can barely fathom it even though that is about how tall I am. Man this U.S. unit system is a basket full.
Belinda thank you for the attempt to shed light on this subject, some of the editors at Fine Homebuilding struggle with this. I do get some of it. Temperature/dewpoint spred can be used to estimate how high the clouds are above the ground (divide by 3F(U.S. sys) or 2C (metric sys) x 1000 (feet) or 300 (M)) So if clouds are forming in our walls we want that to happen at a point where they can eventually excape inward or outward I guess.
🙏🙏🙏
Something else I didn't know I wanted to know that helps me learn a little bit more, even if I'll forget it within a week. :)
Would cement or concrete walls be considered Class IV permeable? I ask because I used to live on Guam and we lived through a typhoon back in the '70's where the wind was so strong is pushed water through the walls! Thank you for another informative video. I look forward to any follow-ups you do, especially if you manage to slip in a shipping container's wall example. :D
I’m confused.There’s many suggestions to use xps/eps ridged board insulation against concrete foundations with batts insulation in front to bring r-value up. But it’s not recommended to use poly tarp against foundation walls with batts. Aren’t both systems using a non permeable barrier? Why is one recommended but the other not?
In my zone (5) they require a 6 mil poly with unfaced batts . I would not do this on my own house knowing what I’ve seen in renovations (mold) .I prefer a more permeable product such as typar (not tyvek too high perm rate). Living on the coast we typically get higher temps with higher humidity during winters then most zone 5 areas.
Do you need Vapor barrie if you use paper backed insulation. I had a house built in 1970 and it had no plastic Vapor barrie
Would whole home humidity control help out with this at all? It seems like the ideal whole home climate control system should have higher fresh air exchange rates, better dedicated filtration, and humidity control in addition to the temperature control we’ve come to expect.
cool video! :)
very cute
'"Inch of fiberglass R35"
You forgot a decimal point. R 3.5
I'm a philosophy phd student...how the hell did I end up watching and subscribing to this channel?! XD
I mean, sure, I'm a generalist, but still...ehm...keep up the good work?
Funny!
I think, there for I am, I think
Thanks for the guidance, most useful and presented in an easy to understand way.
As a side note have you changed your microphone or recording equipment? Your S pronunciation has become very harsh and whistle like, makes it a little more difficult to focus on your delightful voice.
Thanks for letting me know! I probably need to remove the mic cover and move it further away. I'll make the change in future videos.
WOW! Belinda, I want to buy a house built BY YOU with the guarantee; Belinda Carr
I would like a house without plastic vapour. So many codes require them. Natural materials. What the condensation dew pint calculation in the codes does not take into account is the phase change from gas to liquid energy requirements for this. This goes to the position of the vapour barrier.
American houses all appear to have HVAC ventilation. Not common at all in Australia.
Great info Belinda, Happy new year! We have solid wooden walls in my house and all the functions of vapour control, wind and rainproofing and insulation are well coped with for my subarctic climate, without any man made materials at all. The industry has not been kind to this building system here in Norway and it is cultural, instead of technical criteria that allows its continued use. A shame, since it is sustainable and makes for a fantastic indoor climate with good acoustics too. The calculation of R value is specifically designed to favour mineral wool insulation, but I find the true insulation properties of timber houses to be better than equivalent mineral-wool insulated houses here. The study of vapour movement is not new at all, the specific traditional dimensions of timber houses here have a lot to do with vapour movement and were perfected seven or 8 hundred years ago, the same is probably true for traditional buildings in Dubai..? Industrial companies make data that serves them, and their lobby power is formidable. We have a responsibility to give credit to our forbears where it is due, many ancient building systems are excellent and remain little changed due to them working. I have a film on my channel about untreated wooden walls and how they weather if you are interested. all the best , Lucas
Hi, Lucas. I completely agree with everything you said! I'm going to post a video on "R value myths" next week that will touch on what you said. Do you mind if I mention you in the video/description? When I said "new" I meant learning how vapor works with new methods of construction(150 years since we started using manufactured insulation), compared to solid wood construction, like you mentioned, that has been around for thousands of years. I'm going to check out your channel. Thanks!
@@BelindaCarr Belinda you are welcome to mention my site, if you would like to and I would happily make a film especially about this subject in co-operation if that would be interesting to you. My wooden walls film is about weathering rather than k-values. I have heard there have been studies done in the states about energy consumption in timber houses. Also Edinburgh university has some study of energy consumption and hydroscopics in thick brick walls and specifically how retro insulation resulted in higher energy consumption due to trapped moisture, if I remember correctly. At any rate I will continue you to watch your excellent films, all the best, Lucas.
And I now use to think that too much vodka confused my thinking. Thank you for introducing to me a new level of confusion... (argh).
Belinda, thanks for your video.
I really don't like the 100% sealed no leak design. There is moisture everywhere ; a house is not a spaceship.
has anyone thought of adding vapor barrier on back of Drywall ? and removing its paper surface, its time to rethink Drywall ,
the product needs an improvement .
Confuse . I have to watch the video again to get a anderstanding
Inoperable windows ? The moment I find out the house I'm considering has Inoperable windows is the moment I thank the person showing me the house, then tell them I'm not interested.
My head hurts!
Vapor --> As they used to say in the '60s, it's a gas...😉
Love me some of this building science porn!
She is happily married fyi. Now go wash your mouth with soap!
God those perm units are silly... why are the Americans the last ones using British units?