Air Sealing Buildings

I'm pulling these post from another thread of a dialog between myself and a new member Kevin that appears to have built a home using very tight air sealing methods that have been popular over in Germany called Passivhaus for over two decades, that has recently made it's way to US in 2013 called PHIUS (Passive House Institute US: http://www.phius.org/home-page) where we use different layered building techniques.

There is ALOT of controversy around this theory "Build Right Build Tight" with regards to Indoor Air Quality(IAQ) that is not properly addressed in both certifications IMO with the current ventilation rates using HRV's (Heat Recovery Ventilation) and ERV's (Energy Recovery Ventilation) needed since the building cannot "breathe" that are basically heat exchangers coupled to indoor/outdoor air cross over, the ERV having a desiccant to recover & maintain humility levels, per ASHRAE 62.1-2, Energy Star IAQ PLUS, or International Building Codes. The controversy is why I created a new thread and since natural materials(earth, lime, straw, hemp, etc) are not suggested by many to get certified.

Both entities use WUFI modeling for preliminary design certifications validated by a third party trained build "rater" "inspector" I am considering going through my first now on one of my designs I'll show soon but, they differ as well since Germany does not use alot of the building materials we use, they use more natural mass and not as many stacked layers(6-8+) as the US is what I have read anyway, that and different climates (the WIFI models uses accurate climate files in the software) so the two entities decided to "divorce" and go thier own separate ways. Prior to that American Designers were using a Power Point method of Germany's called PHPP to certify the most energy efficient building's in the world or get on board with the best but, it did work well in the US for many reasons. One IMO being the models struggle to quantify inert mass, as opposed to high r-value highly insulated building's, or, hygrothermal mass vs insulation.

WUFI accuracy has been under scrutinize since it has shown some existing building's to have mold issues when they do not due to inaccurate materials properties or ASHRAE 160 due for an update this year, mating of American materials, inaccurate user inputs, still under further development by Orlando National Labs (ORNL). None the less, for the most part it is accurate especially more so than people including "Building Scientist" predict without the knowledge and/or experience with these types of air and fluid flow design tools called CFD, or an area of physics called "Computational Fluid Dynamics", Germany is ahead of the world in "Building Science " technologies as seen WUFI modeling that does a decent job at modeling mold and mildew based on probabilities from decades of lab and field testing Germany has done, we in the US have not and are just now getting started in 2013.

Another tool that is coming is BIMs (Building Information Modeling) that captures the design, build, maintenance, that is held in a file by the designer/builder/jurisdictions to back calibrate models like WUFI. We hear often on Permies how "it lasted centuries" but no one has proof" as in records...there is a global effort to mandate BIMS: https://en.wikipedia.org/wiki/Building_information_modeling

Hi Kevin, first off welcome to permies. How about before we get into tech discussions about your first post below you tell us a little more about your training at PHIUS, I assume you took the consulting training? http://www.phius.org/get-professional-training What WUFI modeling software did you use on your house? Do you have a CAD model? Did you monitor any of the WUFI simulations to validate the design_build? Have you performed any IAQ testing? Is this a one-off or are you a professional that will design_build more? Can you post your WUFI output report? PICS of your build, walls, etc? Please post your certificate?

Kevin Derheimer wrote:I recently built a passive house and dealt with extreme air sealing. I used zip system on the ceilings, it's osb with a green air barrier on one side that would go on the room side. You then use their special tape to seal the seams. I ran 2x2 furring strips on top of zip system to attach either t&g aspen or drywall. Electrical goes in the 2x2 gap, ceiling electrical boxes fit in this gap. Any penetration was sealed with prosoco joint and seam filler. I did blower door test and got to 0.7 ACH on the first pass. This method has been used many times on passive houses and really works. Certainly not the cheapest, but mine with 21+" of insulation gave me around R96, and no air leaks.

Kevin Derheimer wrote: The house is the most comfortable I have ever been in! I did the passive house training a couple of years ago and have been studying methods and materials since. It's tough to find materials that do the job that are not either offgassing or environmentally detrimental. The passive house group does not like spray foam because of the nasty blowing agents. Air sealing tapes or wet flashing products are standard. Foam, by the way, is not considered an effective air seal. Plywood and osb are not air tight also, I talked to a guy who used unfaced osb and couldn't get good blower door results, he found air was traveling through the osb, I used foam backer rod and prosoco air dam to seal around Windows. I installed Viega radiant heat system myself as well as the Zhender erv. 14" walls, 8" geofoam under slab, 6" geofoam under footers, 4" external wall foam to move dew point out of wall cavity to eliminate chance of condensation in cellulose. I have hydro shark 10 heating house till I get solar thermal going, boiler core is the size of a beer can. This is the first winter and the house performed better than I ever expected.

Terry Ruth wrote:Sealing a Passivhaus (Germany) building's is entirely different than US (PHIUS) like apples and oranges different you can see in the WUFI models with regard to air flow & material mold. That is why PHIUS now exist, they disagreed and got a divorce in 2013. If one does not understand the difference it is dangerous, deadly, sealing in a sick home that an HRV/ERV won't cure. Just when you thought everything was comfortable and fine, well think again!!

Kevin Derheimer wrote:Hi terry, I did my training with phius in 2013 and am familiar with the "divorce". I understood it to be about treating different climate zones differently, not just using northern Germany as the base model. Your point is well taken, I modeled my design using climate data for my city and ran 10 year simulations on walls and ceiling. That is when I had my "aha" moment in regards to dew point. With no foam on the exterior I was showing a good deal of moisture accumulation in the dense pack cellulose, which means mold and rot! 4" of external foam moved the dew point out of the wall cavity into the foam and the simulation showed no moisture accumulation over the 10 years.

In the training, we looked at several passive house failures, and I have since studied more of the building science. There are some critical things that most people miss or don't give enough attention to, like interior wall finishings. There was a single sentence in the training material that stated you could have only 3 coats of pain, ever! So 1 coat of primer and 2 finish coats is all you get, not very realistic in my opinion. That, surprisingly enough, didn't bother anyone but me! If the wall dries to the inside, and you seal the surface with too much paint, you get a vapor sandwich, which again means mold and rot. I decided to use American clay on most of the walls because it is very permiable and moisture regulating. Primers and paint were a different story, I spent months talking to all of the paint manufacturers about permeability of their paints and primers. I found nearly all had perm rating of 4 or less, compared to around 45 for drywall. (It was interesting that the paint mfgs were not asked about perm rating much). I found a primer (Roma) that could be tinted and used as final coat, and with sand added, was acceptable for primer for the clay. I think at this point, I think I have done a pretty decent job with addressing the building science part of the project. As they say, the devil is in the details, and time will tell.

If you are interested in this subject read this. I'll be back to try and explain/simplify what is going on here.....Please feel free to make comments or ask questions. Joe is one of few guy's that has my respect and he tells good jokes I think he is sponsored though and therefore ignores all the benefits of natural building since he can't make any $$$ at it.

Terry, Sorry it took so long to reply, been moving and trying to figure how permies works.

First off, I took my training with PHIUS in golden Colorado with Katrin. Both Phase 1 and 2 were in 2010 not 2013, boy how time flies.

I am still using PHPP to model, I had friends do phius training with wufi and did not like what I heard about having to repeatedly enter data
for multiple iterations. It my be different now, I have been thinking about retaking the training to get updated with current info.

I used WUFI to do moisture simulations, here are some runs I found, I have more but they are on a disk somewhere in a sea of moving boxes.







I have been trying to get the architect to use BIM, but he still uses autocad and sketchup. I took the time to learn revit and love it. After using it, I can't see why designers wont use BIM. I have PDF's of plans.

Not sure how to monitor the simulations to validate the design build. IAQ - will measure humidity in building when we are living there for extended periods. 40% is my target humidity. I spoke to a builder in Denver who has seen humidity mostly above 40%
year round. I will look into measuring particulate levels compared to outside levels.

This is the 3rd house I have done the passive house calculations on, first one out of the ground. I am currently working on the calculations for a 4K+ square foot house in Durango. I build my current Guest House/ Garage to see how subcontractors would deal with the rigorous methods needed, as well as giving me a place to live while building the main house. I am a certified contractor in florida and plan to build more in Colorado. I have BS in Forest Management/Wildlife management and a MS in EE/Computer Science, Did the 2015 online permaculture course with Geoff Lawton, as well as other technical training. I used the Durango property for the permaculture project, and will slowly implement it.

Not sure where my certificate is, I'm sure they gave me docs for phase 1 and 2, just don't know where they are right now.

Here is the mostly completed building





Double Stud Wall



Radiant Heating Tubes



ERV



PHPP Verification Page



I look forward to discussing details of the project

Kevin, are your pics showing on your browser. Attached is what I see in chrome....My PICS display fine on my browser and they are viewing fine on other threads.

Terry, I could see the pics in the preview window before I submitted, and I see the pics in the post on permies on my laptop in internet explore 11 on laptop. I had this problem with another post last night, I see the pics on IE, but not on my phone in safari. I'll try chrome and see what I get. any suggestions?

Terry, this is interesting, I don't see pics in chrome either! also in chrome, the "post reply" button does not work for me. can you look at post in IE and see if you see pics?

Not showing in IE or phone for me. I reported it here: https://permies.com/t/54537/tnk/Pictures-Displaying#450064

Can't recall where but I read someone else having issues.

Terry, Try it again in chrome. I had created a google photo account and linked to the photos there. I have created a shared album there now and placed all the photos in that album and i can nnow see them in the original post in chrome

Terry, striking out with permission problems, trying the attachment option

terry, more pics

Terry More yet

Although the issue may be complex the solution is embarrassingly simple......

No living mamal remains alive or healthy when sealed in a chamber, if the chamber is large the timeline lengthens but it does not change the reality that that air breathing animal is in a sealed in a chamber with no suplimentary air.

Chadwick, yes what you are saying is absolutely true, However I have a very efficient ventilator that runs 24/7, so I am constantly exchanging interior air with exterior air and filtering at the same time. Passive house is marketed as being "hygienic" in Europe because the interior air is measurably cleaner than outside air. The idea is to seal the house very tight so you have absolute control over the exchange air, capturing heat and moisture. With Leaky houses, or houses that "breathe" , it is impossible to treat the exchanged air.

Very true, so then it seems to be more about ones theology.....does one trust man made machine and the electric system or tried and true nature to handle the task of ventilation.

So I guess my preference lands on the side that doesn't require a machine that can break wear or not get the fuel it needs.

For me anytime nature will do the task, it requires less work or electric bill for me, I'm all for letting the earth handle that for me. Classic permaculture!

That may require living with the summer heat and heating in winter, but that has been done for all of our existence so.....

Chadwick, it may not appear so, but my goal is to rely more on nature and reduce my electric bill. The ventilation system does not have to be run, my windows are tilt and turn so natural ventilation can be used. The house was designed to take advantage of stack effect for natural cooling. Once I get the solar thermal going, the sun will provide 100% of heating and most of domestic hot water. I will also use rocket stove with coppiced willows to provide supplemental hot water if needed. A small solar powered circulator with solar thermal that can be grid independent may still be depending on mechanical devices, but with 70-90% reduction of energy usage plus a very comfortable living space, I think I'm doing well. Not off the grid yet, but that is the goal.

I was it in any way judging, in fact most times technology allows far more efficiency in this space, heating incoming air etc. you can create a lot of redundancy using machines and tech systems in houses.

It's just me that's all, I have a sneaky suspicion that our fore fathers had more correct than we give them credit for. They had airy houses and grew organic food by the sweat of their brow.......I worry that we might be overlooking the reason for that. My theory is that your health will be much improved by "the old ways" and that is my intention when I close on my 31 acres.

I will add that my family got very sick in the church house we lived in that was full of mold and fungus, my wife had fungal infections in her ears it was so bad, I left my position at the church it was so bad.

So it may also be that I lived it, and know how poor you can feel living in toxic sludge.

Chadwick, no worries, no judgement felt. Mold and fungus is a hugely serious issue. I have a family member with health problems from mold exposure. I have spent a great deal of time studying building science to prevent conditions that will lead to mold problems. I agree that we are probably missing a great deal of useful gems that our forefathers took for granted. My ultimate goal is to be able to use natural materials to achieve what is now taking synthetic materials to get to the passive house standard, and be off grid.

I think the toughest will be vapor barrier, because there is no need for this in nature on a household scale, it may be hard to find a natural alternative that has a lifespan that compares with plastic.

Nature just does not seal off areas, therefore hard to find.....

Chadwick, we don't use plastic for vapor barrier. We need a vapor open material that stops air movement but allows moisture to escape. This may seem counter intuitive, since people are used to seeing clear plastic installed before drywall. Passive house wants walls to be able to dry. Tyvek is not adequate either. Right now, materials like rolled on cat5 from prosoco, or zip system osb, or special tapes, not very natural!

On the inside, natural clay finishes are great, if done properly, they allow moisture to escape, and moderate humidity. This is my preferred treatment.

Radon mitigation is also something I have studied and implemented. This is a generally overlooked issue in new construction, conventional as well as with natural methods.

Wow lots of confusion. Kevin, thanks for getting those pics and info up. We certainly don’t want to follow the large carbon foot print of our ancestors, IIRC 40% due to fossil fuel from building’s….I believe were on the right track air sealing but there is a lot of misunderstandings on how to get there.

Kevin, did you get a chance to read Joe’s article? Do you understand figure 1 and the four phases of water Joe touched on? Did you understand how WUFI has simplified air flow in layered assemblies such as yours and why air sealing to reduce convective air in wall cavities that dominate America is important? BSC also did a white paper showing how these flows trump r-value, have you seen that final report? Keep in mind in the wall /roof assembles we are talking about CFM in the wall cavity, not so much whole house leak down rates or ACH. In the past, air flows in popular fiberglass has shown very low r-value knock down factors. Do you understand when we discuss high r-value we are talking about one dimensional static (conduction or u-value, r is just the inverse of) not air flow, add moist convective air and heat results in changes based on materials (adsorbents) including the potential for microbials and poor IAQ (fungi’s & bacteria measured in parts per million ppm) depending on efficiency of the adsorbed surface layers or layer. What I am referring to has nothing to do with your ERV as “breathable” so far although I will get into that soon.

He really did not show applications in hydrothermal mass and phase change walls or materials that dominate the natural building methodologies such as COB, Earth Plaster, Hempcrete, Brick (common in Germany) or monolithic designs where an air or vapor barrier ruins enthalpy. In these designs that work under an entirely different mechanic “breathable walls” the wall/roof materials are the ERV or desiccant, just like an ERV they need airflow and heat to produce enthalpy, hidden heat of vaporization and condensation. That is the definition of “breathable” in this design. The envelope air exchange rate is ~.2 - .3 ACH which adds to the total. A .6 ACH at ~.9 value working under the principles of enthalpy would be more efficient and a totally different design than layered convective air loops. Now the envelope is acting as HVAC and ERV dropping both mechanical loads. Our ancestors had in right but not totally obviously. In addition, if we have less material interfaces due to monolithic natural mass there is less chance for galvanic chemical and physical reactions that cause microbial growths....that is just simple common sense. In layered highly insulated assemblies, there are a lot of mating materials involved typically without the proper analysis increasing the changes for poor IAQ.

Do you understand what I mean? Examples would be the difference between regular drywall and PCM (Phase Change Drywall)

In both methods we want to seal high levels of air flow but in different ways, and reduce penetrations especially large ones.

There is a lot more to it besides the envelop differences. Table 2 shows cladding ventilation I’d like to discuss next.

Are you beginning to see the large differences between Germany and America building sciences and the divorce had more to do with just climates?

My guess is the difference is jurisdiction........

Natural building is an area where people tend to forget to " observe nature" and emulate what you learn, nowhere in nature do you find a sealed ecosystem or organism......

Fore fathers living in the way I describe actually had very small carbon footprints, as I am speaking of pre industrial revolution living.....just a correction.

Kevin, sorry the topic has drifted off please stay focused on my questions, comments, your build, WUFI modeling, Joes and BSC publications.....

Am I reading your PHIUS data sheet right. Are your annual loads 2 tons for both heating and cooling so you are not at net zero? I thought to get PHIUS you had to be net zero you had to be at .5 ACH or did they allow you .6 the german standard due to size or is it because you are certifying to PHPP?

What WUFI product are you using?

Terry, haven't had a chance to reply to your last big post yet, have to finish taxes to get mailed tomorrow. On this post, heating and cooling are separate, but in btu's / square foot, not tons. Btu's make it easy to size radiant heating. I haven't looked recently, but 0.6 was value to shoot for blower door test

Terry, forgot to answer the net zero part. Net zero would be great, but not required. There is a tab in phpp where you enter electrical usage, it forces you to consider all proposed electrical appliances. The idea is to reduce primary energy, or energy generated at a power plant. You get immediate feedback on energy choices and can get info on the carbon footprint relating to your choices. In my experience, it really forces you to consider electrical Usage.

I chose surface mount ceiling lights, and 1.5" metal boxes in mechanical space. Ceiling is zip system with 2x2 furing strips, then drywall or natural t&g aspen. All lights are led or led capable.

I ran the simulations in an older version of wufi from oak ridge national labs.

Reading joes article now, I also hold him in high regard, have read other good article from him.

Hope I'm not coming across as "not nice"

Terry, Wow, I loved joe's article! I can't believe they actually printed the part about "coefficients" and "guesses", LOL! I've said that to people before but everyone just thought I was crazy! So, now I'm wondering if the wufi software I used took some of the different transport mechanisms into considerations. In the pics of my simulations there is moisture shown in the OSB layer behind the foam but it did not transfer into the interior insulation. I could not explain why this would show up, now it makes more sense.

Ok, The difference between layered materials and monolithic in terms of moisture transport (in any phase) makes a great deal of sense. It sounds like newer wufi software may handle this better, makes me want to re-simulate with newer software. I did not realize that the software was ignoring the more difficult transport mechanisms, troubling to me that it was not disclosed. I'm not sure it would matter to most people though, I know maybe 2 people who would enjoy that article as much as me.

I knew fiberglass has lower than stated r-value when installed poorly. This now makes more sense on several levels. I assumed it was just because of air intrusion (air flow in wall cavity). This article is awesome because it's making me rethink my reasons for different designs. I would like to see the BSC report, do you have the link?

I have been preoccupied with eliminating thermal bridging to eliminate condensation possibility (rot and mold possibility), the idea of galvanic chemical or physical reactions between layers that would promote microbial growth is both exciting and daunting. Do you have any examples of this?

I have looked at phase change drywall, looking forward to seeing field trials. Makes me think of the moisture regulating properties of natural clay finishes. I'm sitting here shaking my head thinking that we don't even know what we don't know.

My next question for you would be what would your optimum wall look like?

yes, I see the differences in how Germany and the US deal with building science.

I have seen the part dealing with rain, that was the main reason I implemented a rain-screen to break possible capillary transfer between cladding and underlying materials. In the simulation, I used polyiso, but after discussing its possible long term r-value degredation with an older cold room builder, I chose xps. Possible problems with polyiso may be due to moisture phase changes inside the insulation. I haven't seen an explanation for why polyiso may degrade. Under my cladding (cedar and stone over durarock), I used wrapshield SA over edges of z-joists to prevent moisture transport into the wood. I am taking for granted that the materials I picked to either prevent or direct moisture transport will perform as advertised.

Thanks for the article, best one I have read in a while!

Kevin, you still out there? I’ve been helping with a plaster job over in China and learning how to better communicate on forums. The later being more of a challenge.

I hope we can agree it should be obvious by the data as in electrical and HVAC loads new building’s are producing we are on the right track air sealing but, let’s not misunderstand what is meant by it. Unless we live in the tropics we certainly do not want big holes around fenestrations or in walls leaking cold weather in or conditioned air out. In open flow wall cavities we do not want moist convective air loops degrading r-values. In ventilation channels such as cladding we need high flow and little resistance due to air leaks at boundary layers. PCM’s(Phase Change Materials) we do not want air or vapor barriers. So we are talking several different modes of air transports aside from vapor modes of transport.

Terry, forgot to answer the net zero part. Net zero would be great, but not required. There is a tab in phpp where you enter electrical usage, it forces you to consider all proposed electrical appliances. The idea is to reduce primary energy, or energy generated at a power plant. You get immediate feedback on energy choices and can get info on the carbon footprint relating to your choices. In my experience, it really forces you to consider electrical Usage.

Good to know, I thought the building had to be net zero to qualify. Yes lots of software takes into account electrical/HVAC loads. I like SAM or Beopt since it also sizes solar systems based on building optimizations you can modify and it is free. I'm still bating around if I will completely ignore all these certifications or obtain them for third party bragging rights after I build, prove, and test the design. I'm more interested in the IAQ than anything since I am sure that is where most fail.

I chose surface mount ceiling lights, and 1.5" metal boxes in mechanical space. Ceiling is zip system with 2x2 furing strips, then drywall or natural t&g aspen. All lights are led or led capable.

To reduce penetrations I don’t use any can lights, I hang all my interior lights so I only have a romex wire penetration in my ceiling’s….all integrated LED fixtures, the light last as long as the fixtures and produce low e-loads. Continuous inner boundary layer wall/ceiling air sealing planes provides a nice place to deal with penetrations especially if self-sealing plastering. Not clear on your layering I'd need to see a drawing. I like the word furring strip as in cladding ventilation gap or rain screen much better than house wrap. I have no house wrap in my designs.

I ran the simulations in an older version of wufi from oak ridge national labs.

The ORNL free version they offer has very limited capabilities you can view here: https://wufi.de/en/software/product-overview/detailed-product-overview/
I played around with it too. I want WUFI- PLUS but I’m not sure it is worth the $5,000 USD. I would think not if one has a good background designing materials technologies. BTW: due to mix ratio’s and materials compatibilities there can be just as many issues mating raw natural materials without the proper tools and knowledge as manufactured materials.

Terry, Wow, I loved joe's article! I can't believe they actually printed the part about "coefficients" and "guesses", LOL! I've said that to people before but everyone just thought I was crazy! So, now I'm wondering if the wufi software I used took some of the different transport mechanisms into considerations.

No, probably not. I already mentioned some air transport modes as did Joe.... The vapor ones also apply and is where the term “breathable” is further defined. The mainstream industry issues are that most only use permeability rating or “perms” "perm rating" or vapor diffusion. The other two are hygroscopic adsorption/absorption.....capillary adsorption/absorption. The three modes better define the three dimensional material properties Joe touched on. I did a book review on George Swanson’ “Breathable Wall” here: https://permies.com/t/43637/natural-building/Breathable-Walls it has a lot of data review on it to include John Staube’s (two others of the few I respect). I also went to TX to see George's Magnesium and Durisol (magnesium, clay, cement ICF) homes, very nice!

In the pics of my simulations there is moisture shown in the OSB layer behind the foam but it did not transfer into the interior insulation. I could not explain why this would show up, now it makes more sense.

Ok, The difference between layered materials and monolithic in terms of moisture transport (in any phase) makes a great deal of sense. It sounds like newer wufi software may handle this better, makes me want to re-simulate with newer software. I did not realize that the software was ignoring the more difficult transport mechanisms, troubling to me that it was not disclosed. I'm not sure it would matter to most people though, I know maybe 2 people who would enjoy that article as much as me.
I’m not sure WUFI handles PCMs at all or the massive amounts of bacteria and fungi families always being found.

I knew fiberglass has lower than stated r-value when installed poorly. This now makes more sense on several levels. I assumed it was just because of air intrusion (air flow in wall cavity). This article is awesome because it's making me rethink my reasons for different designs. I would like to see the BSC report, do you have the link?

The blown cellulose industry took this test and ran with advertising it stating the HD packed wall cavity has lower flow than fiberglass. Many do not want to look at the other elements that promote microbial growths such as the food in blowing agents and fire retardants. If it is not inert, look at what it reacts to. If one does not know do not use it. I like mineral wool but care must be taken with it too. http://buildingscience.com/document-search search " thermal metrics"

I have been preoccupied with eliminating thermal bridging to eliminate condensation possibility (rot and mold possibility), the idea of galvanic chemical or physical reactions between layers that would promote microbial growth is both exciting and daunting. Do you have any examples of this?

OSB & SPF or most chemically active building materials.

I have looked at phase change drywall, looking forward to seeing field trials. Makes me think of the moisture regulating properties of natural clay finishes. I'm sitting here shaking my head thinking that we don't even know what we don't know.

My next question for you would be what would your optimum wall look like?

Yes, there is a lot out there that is ignored and not sponsored discussions or even allowed on green sites, most following the mainstream building scientist will not learn about. Mass using PCMS like zeolite, magnesium chlorides, certain clay mixes, limes, diatomaceous Earth,: Fibers using hemp shiv, certain straws, fiberglass, basalt, cast around Timber Frames or light wood or with basalt of fiberglass rebars, Geopolymer Cements.

yes, I see the differences in how Germany and the US deal with building science.

I have seen the part dealing with rain, that was the main reason I implemented a rain-screen to break possible capillary transfer between cladding and underlying materials.

According to John and Joe the probability is very low, "1% of 1%, especially with a cladding ventilation gap as shown. The ORNL version you used does not simulate rain.

In the simulation, I used polyiso, but after discussing its possible long term r-value degredation with an older cold room builder, I chose xps. Possible problems with polyiso may be due to moisture phase changes inside the insulation.
Since any foam is a vapor barrier it will not handle phase change well. A PCM would much more efficient. I do not think there is a lot of quantified data for natural builders to use, although Staube and some others like ORNL, ASHRAE, are developing them. One thing good about WUFI Plus is one can define thier own materials properties and assign and benefit.
I haven't seen an explanation for why polyiso may degrade.

I read it outgases some claim for a short time after manufacture others say longer. I personally stay away from foams, too much controversy. About the only place toxic materials are acceptable to me is surrounded by an air stream.

Under my cladding (cedar and stone over durarock), I used wrapshield SA over edges of z-joists to prevent moisture transport into the wood. I am taking for granted that the materials I picked to either prevent or direct moisture transport will perform as advertised.

Time will tell

I have been trying to get the architect to use BIM, but he still uses autocad and sketchup. I took the time to learn revit and love it. After using it, I can't see why designers wont use BIM. I have PDF's of plans.

I believe BIMS is nothing more than a depository for building information as in models, PDF’s, maintenance records, test data, disposals, etc…..I’ll create my own.

I am currently working on the calculations for a 4K+ square foot house in Durango.

Do you have a 3D model of this? What simulation software for HVAC and electrical loads are you going to use for it? I thought everyone is getting away from PHPP and using PHPPUS or better now PHIUS_WUFI Passive?

I have a 3D I’ll post soon. Think I’ll run BEOPT first. I may buy WUFI Plus. In it one can define their own materials as in PCMs. I have 6 specs I want then I’ll be for hire running CAD and simulations when I’m not working, currently mechanical design. We use PLM (Product Life Cycle) Management software (same as BIMS) to store different CAD-CAM in. I’m using Chief Architect, just got an ASUS 4K gaming labtop along with two 4K 28” monitors. I’m looking at Lumina or Unreal for video rendering’s and walk throughs.

I’ll share soon little time right now for Homes.

Feel free to ask more questions or correct anything I write. I enjoy learning and am glad you joined, we can perhaps learn from each other. My strengths are in design_build not building trades.

Terry Ruth wrote:Kevin, you still out there? I’ve been helping with a plaster job over in China and learning how to better communicate on forums. The later being more of a challenge.

Yes, Still here, china is an pretty long commute!! sounds interesting though, I enjoy seeing how people in other countries deal with building issues.

I hope we can agree it should be obvious by the data as in electrical and HVAC loads new building’s are producing we are on the right track air sealing but, let’s not misunderstand what is meant by it. Unless we live in the tropics we certainly do not want big holes around fenestrations or in walls leaking cold weather in or conditioned air out. In open flow wall cavities we do not want moist convective air loops degrading r-values. In ventilation channels such as cladding we need high flow and little resistance due to air leaks at boundary layers. PCM’s(Phase Change Materials) we do not want air or vapor barriers. So we are talking several different modes of air transports aside from vapor modes of transport.

Yes, absolutely!

. I'm still bating around if I will completely ignore all these certifications or obtain them for third party bragging rights after I build, prove, and test the design. I'm more interested in the IAQ than anything since I am sure that is where most fail.

Yes, me as well, my problem is that customers look for the certifications even if you have no idea what you are doing. So I have been working on getting them to appease customers. My experience is that in 5 to 10 minutes, you can see who has a good understanding of underlying principles, and who is blowing smoke.

reduce penetrations I don’t use any can lights, I hang all my interior lights so I only have a romex wire penetration in my ceiling’s….all integrated LED fixtures, the light last as long as the fixtures and produce low e-loads. Continuous nner boundary layer wall/ceiling air sealing planes provides a nice place to deal with penetrations especially if self-sealing plastering. Not clear on your layering I'd need to see a drawing. I like the word furring strip as in cladding ventilation gap or rain screen much better than house wrap. I have no house wrap in my designs.

My ceiling starts with small strips of zip sheathing on top of the framed wall with trusses then sitting on top of that. the strips (green side down, sealed at butt joints) give you a small surface to tape to, making air sealing corners easier.
then the zip system is screwed to underside of trusses (green side to interior), and taped, screws are wetflashed. When completed, this is my air barrier on ceiling. Next, I put 2x2's @16"oc on top of the zip system. Electrical boxes for hanging fixtures and track lights were attached to zip system with backing where required. Wire was run from below as much as possible to minimize penetrations of the air barrier, where necessary, wires were run thru 2x members to make supporting the wires easier prior to wet flashing. The 2x2's did 2 things, first, they make a good electrical chase system, eliminating air barrier penetrations, second, they provide the attachment point for my t&g aspen planks, and drywall. This may seem un-necessary, but I found screw holes in the air barrier where someone had missed the truss, removed the screw, and forgot to fill the hole, and several electrical boxes were moved, again screw holes were missed. Now, most people said a few screw holes couldn't possibly matter, but during the blower door test, we were at 0.7, I calculated the total size of the gaps we needed to find and that amounted to the size of a quarter! so every hole matters! An old refrigerated storage room builder told me a hold the size of a pencil could cause hundreds of pounds of frost to form from the moisture coming in.

The blown cellulose industry took this test and ran with advertising it stating the HD packed wall cavity has lower flow than fiberglass. Many do not want to look at the other elements that promote microbial growths such as the food in blowing agents and fire retardants. If it is not inert, look at what it reacts to. If one does not know do not use it. I like mineral wool but care must be taken with it too. http://buildingscience.com/document-search search " thermal metrics"

Yes, exactly! Lower flow does not equal no flow! I did my best to air seal every drywall penetration, to try to eliminate air from penetrating into the insulation cavity. I also realized that I was sealing in whatever moisture was present in the insulation cavity, making it extremely important to study perm ratings of paint, primer, and clay finish. And the use of exterior foam to move dew point out of insulation cavity would prevent condensation of moisture already present. I like mineral wool and may use it in the future, but on this project, it was not easily available.

Do you have a 3D model of this? What simulation software for HVAC and electrical loads are you going to use for it? I thought everyone is getting away from PHPP and using PHPPUS or better now PHIUS_WUFI Passive?

Mechanical guy doing HVAC sim. Electrician doing standard load calcs. I have been thinking of getting wufi-passive, but a couple of friends used it and were not real impressed with how hard changes and multiple iterations were. That an price have kept me away until now.

Have you had to deal with Radon? My area has varying levels and I decided to be proactive and deal with it during construction. I read a tremendous amount of material on the health issue and mitigation methods and thought it was insane builders did not address it during construction. I have family member with crawlspace under their house, they found radon during inspection to rent the house (after years of living there) and the solution was to use a blower to bring in fresh air (even in winter) and flush the radon. I found that the majority of people find out they have a radon problem when they go to sell their home.

I found a company called Cetco, that specializes in foundation sealing and soil gas mitigation for brownfield building sites. They have a product called geo-vent, its 12"wide, 1" thick, comes in a roll, has geofabric cover, and airspace inside. You install in a continuous loop under the foundation. They have a transition fitting to go from the geo-vent to 2" pvc that I sleeved through footer and ran to perimeter drain which ran to daylight far from house. The idea is to provide a passive channel for the radon to escape before it builds enough pressure to enter the structure through the slab. It cost less that $200 to install, local contractors loved the idea so much that they are now using it as well. You could do the same thing with corrugated drain pipe, may be close or cheaper in price, but probably a lot more difficult to install.

I did use heavier moisture barrier under the slab, wet flashed and taped. I would think anyone building a tight house, natural building material or not, would be smart to deal with radon mitigation before construction.

Link to the geovent - http://www.cetco.com/DesktopModules/Bring2mind/DMX/Download.aspx?Command=Core_Download&PortalId=0&EntryId=104

I found a company called Cetco, that specializes in foundation sealing and soil gas mitigation for brownfield building sites. They have a product called geo-vent, its 12"wide, 1" thick, comes in a roll, has geofabric cover, and airspace inside. You install in a continuous loop under the foundation. They have a transition fitting to go from the geo-vent to 2" pvc that I sleeved through footer and ran to perimeter drain which ran to daylight far from house. The idea is to provide a passive channel for the radon to escape before it builds enough pressure to enter the structure through the slab. It cost less that $200 to install, local contractors loved the idea so much that they are now using it as well. You could do the same thing with corrugated drain pipe, may be close or cheaper in price, but probably a lot more difficult to install.

I did use heavier moisture barrier under the slab, wet flashed and taped. I would think anyone building a tight house, natural building material or not, would be smart to deal with radon mitigation before construction.

Link to the geovent - http://www.cetco.com/DesktopModules/Bring2mind/DMX/Download.aspx?Command=Core_Download&PortalId=0&EntryId=104

From what I can tell from little info I could find is this is a ventilation channel that comes in a roll that acts like a rubble trench with plumbing to attempt to move gases out of the building's IAQ. In theory there has to be a low pressure area around it from high air flow, or, enough ground pressures to produce flow to it, so that gases are sucked into the perforated rolled out channel then out vent pipes. I would think to get this to work would take more than just laying this product down, it would take an engineered understanding of the gases, pressures, and flows. I'm not sure I lay my life on the line for it. I could not find any proven designs over a long term field test could you?

This is interesting though since I think VOCS are becoming as much of a concern as radon in soils as we better understand what is causing poor IAQ and lung cancers. Back in the day the concern was what ground contaminates where leaching into drinking water, not into our buildings. What is as much or more of a concerns is natural building methods that surrounds themselves with walls and roofs not knowing. I know there is a big effort to try and solve brownfield issues and building IAQ by more natural eco remediation's and materials, not just vapor barriers and ventilation channels. There are some reports on the internet showing that it is not just a matter of shoving some top soils into an earth bag, or brick, or in form work, no more than it is layered manufactured products without an understanding of the mating reactions.

I think this product has a better chance when used in conjunction with air and vapor barriers. They do have issues as you noted since once a puncture occurs the flow to the low pressure area will be higher than over the entire barrier in many cases. In other words, a punctured air/vapor plastic barrier is worse than no barrier.

I dunno, after I see a radon and soil test I would then decide it I were going to even build on the site and/or hire the required professionals.

Yes, me as well, my problem is that customers look for the certifications even if you have no idea what you are doing. So I have been working on getting them to appease customers. My experience is that in 5 to 10 minutes, you can see who has a good understanding of underlying principles, and who is blowing smoke.

I think the only rating that matters right now is the HERs, did you get that? Did you try and qualify your building for EEM's? Energy Efficient Mortgages, or Fed and State Tax breaks? Passive house is not being used as far as I know. It is too new to the USA. Energy Star has an IAQ not sure any bank or anyone is seeing the value in it yet. It's going to take educating clients on some of the sales hype builders have achieved in the past like LEED certified sick building's. IMO the future in is IAQ. Perhaps a tuff sell to smokers but for the most part.

Terry

From what I can tell from little info I could find is this is a ventilation channel that comes in a roll that acts like a rubble trench with plumbing to attempt to move gases out of the building's IAQ. In theory there has to be a low pressure area around it from high air flow, or, enough ground pressures to produce flow to it, so that gases are sucked into the perforated rolled out channel then out vent pipes. I would think to get this to work would take more than just laying this product down, it would take an engineered understanding of the gases, pressures, and flows. I'm not sure I lay my life on the line for it. I could not find any proven designs over a long term field test could you?

Been trying to find study talking about radon building up pressure in soil and causing intrusion into foundations. No luck yet. That article is what prompted me to explore the cetco product. The cetco product I used is supposed to allow a channel for the radon to escape to the outside before there is pressure enough to allow intrusion into structure. Heavy, sealed vapor barrier helps as well. My understanding is that you don't need lower pressure to suck radon into the channel, the pressure in the soil Is relieved by the channel, so, theoretically, radon would never be able to reach a pressure level that would allow it to infiltrate the structure. I know "theoretically".

I looked into the active and passive stack method to remove radon by causing lower pressure and sucking the radon out. I went the channel route because I figured I could air seal the foundation (so lower pressure in house could not draw in soil gas), and the channel would relieve soil gas pressure. It is possible that a break in foundation air barrier would allow stack effect to pull soil gas into the structure, but with the channel, and knowing radon is 9 times heaver than air, I am thinking that it would be air, drawn in from the end of the tube, rather than radon. that is what I am thinking, may be totally out to lunch, only way to tell will be when I borrow the radon test machine and let it run for a week.

This is interesting though since I think VOCS are becoming as much of a concern as radon in soils as we better understand what is causing poor IAQ and lung cancers. Back in the day the concern was what ground contaminates where leaching into drinking water, not into our buildings. What is as much or more of a concerns is natural building methods that surrounds themselves with walls and roofs not knowing. I know there is a big effort to try and solve brownfield issues and building IAQ by more natural eco remediation's and materials, not just vapor barriers and ventilation channels. There are some reports on the internet showing that it is not just a matter of shoving some top soils into an earth bag, or brick, or in form work, no more than it is layered manufactured products without an understanding of the mating reactions.

Yes, my thoughts exactly. I was thinking of the wofati as I have been thinking this over, people building with more natural materials would benefit from taking steps to ensure that soil gases do not end up in their structure, negating all the work and thought that went into a more natural structure.

I think this product has a better chance when used in conjunction with air and vapor barriers. They do have issues as you noted since once a puncture occurs the flow to the low pressure area will be higher than over the entire barrier in many cases. In other words, a punctured air/vapor plastic barrier is worse than no barrier.

If you use a heavy, sealed vapor barrier, coupled with a system to allow soil gas pressure to escape, do you think a puncture would be worse? I'm thinking you would have air in the channels, as well as radon, since radon is heaver than air, wouldn't air be pulled into the structure rather than the heaver radon? If vapor movement was into the structure, air would be drawn back into the drain tube, and ultimately Into the structure. Voc's would be a different story, I would think their movement would be into the puncture first.

I dunno, after I see a radon and soil test I would then decide it I were going to even build on the site and/or hire the required professionals.

I talked to some guys that did radon testing and researched radon soil testing, and did not get a good feel that a radon soil test would accurately forecast potential long-term radon levels in a future structure.

I think the only rating that matters right now is the HERs, did you get that? Did you try and qualify your building for EEM's? Energy Efficient Mortgages, or Fed and State Tax breaks? Passive house is not being used as far as I know. It is too new to the USA. Energy Star has an IAQ not sure any bank or anyone is seeing the value in it yet. It's going to take educating clients on some of the sales hype builders have achieved in the past like LEED certified sick building's. IMO the future in is IAQ. Perhaps a tuff sell to smokers but for the most part.

working on getting HERs and leed platinum. Did not know about the EEM, will explore that. The only break I found available was rebate from electric company based on blower door test, was not much. Real Estate listing databases don't list passive house yet, you can put note in description section.

You had mentioned rain screen in a previous post, I would like to hear your thoughts on that subject. My wife wanted natural stone on the façade, which complicated my rainscreen since I have 4" of foam on the exterior. I used a technique that I saw "hammer and hand", a pacific northwest passive house builder use, called z-joists. Consists of a 2x2 glued and nailed to one side of piece of plywood cut to width of rainscreen, and another glued and nailed to other opposite side. The first 2x piece provides screwing attachment member, the second provides nailbase for exterior finish. picture at end of post. I researched the weight of thin veneer natural stone and came up with about 35lbs/ft2. Then looked into ways to fasten the foam, and was not happy with having a fastener going thru 4" of foam and not having the whole exterior façade sag under the weight of the stone. I had structural engineer look at the z-joist and he blessed the approach. This then prompted me to talk to the screw manufacturers to get shear strength of the fasteners I wanted to use, to ensure they would hold up under the massive weight of the stone veneer. The GRK fasteners rate 1100lbs+ per, screw, and at 12" spacing, worked out with many times carrying capacity. I put the foam in tightly between the z-joists, and used wrap-shield SA over the ends of the z-joists. I have 3/4" rainscreen cavity under wood siding, and 4" behind durarock base for stone (more space because I have 6" geofoam against the stemwall, and needed to have the stone proud of the foam). I used cor-a-vent to keep bugs and other critters out of the rainscreen. Stone mason put 1/2" plywood strips on top of the concrete apron in the front of house to preserve rainscreen opening and pulled the strips when complete. I'm using that 1/2" space to gauge any sag of the stone veneer.

I have house I florida with 4' of stone on the front. It is a concrete product, applied over the normal paper and lath our stucco guys use. It does touch the mulch covering the ground in some places. I have had to pull off 12" of drywall inside of house, that showed signs of moisture and do mold remediation. That experience convinced me of the need for a rainscreen. I know the stone is a concrete product, and as such, will wick moisture, although, I thought the colored coating would prevent some wicking. That experience proved to me that the "traditional" method of applying stone veneer over tar paper and lath with no rainscreen is going to lead to moisture problems. Took 8 years to be bad enough to need to fix, but I wonder about the IAQ all those years where there was no obvious signs, but hidden problem!

My understanding is that you don't need lower pressure to suck radon into the channel, the pressure in the soil Is relieved by the channel, so, theoretically, radon would never be able to reach a pressure level that would allow it to infiltrate the structure. I know "theoretically".

I called Cetco to see if my understanding is correct. He struggled explaining it to me so I put into perspective for him…..He said something about a low pressure is needed by the vent strip and I said one way that would happen is with high velocity/low pressure flow and he agreed, also that engineering is required. I asked if they had any proven field data, he said yes, we agreed that it would not mean much at other fields due to variations. End of discussion. Add exhaust ports, temps, differential pressure drops all over the building, and I think this product along with much of the industry tries to make sense out of something no one really understands. Take a completely open air loop with no porous materials like soils/ rocks, various gasses, and we struggle understanding it in different conditions enough to establish proven standards.

To make things less clear read this: https://www.lewrockwell.com/2003/11/bill-sardi/the-radon-fraud/
The same story with formaldehyde's, all these regulations with no proof at what minimum level does it causes cancer? Where are the dead bodies and links? Where is all the usual world class news media or epidemics?

If you use a heavy, sealed vapor barrier, coupled with a system to allow soil gas pressure to escape, do you think a puncture would be worse? I'm thinking you would have air in the channels, as well as radon, since radon is heaver than air, wouldn't air be pulled into the structure rather than the heaver radon? If vapor movement was into the structure, air would be drawn back into the drain tube, and ultimately Into the structure. Voc's would be a different story, I would think their movement would be into the puncture first.

IIRC it’s not all about molecular weight, more ionic charge or Atomic Number, also some that convert a gas to a solid that sticks to other solids then can become air borne and enter the lungs, bodily fluids, as a solid particle. It gets VERY complex, who knows!

I talked to some guys that did radon testing and researched radon soil testing, and did not get a good feel that a radon soil test would accurately forecast potential long-term radon levels in a future structure.

Probably hard to detect prior to construction, I guess look at the map if in an area of concern follow with more testing.

I suppose all we can do is be safe rather than sorry until the REAL scientist get it right (all I need is another coefficient and I'm good to go , reduce the levels within reason and not buy into too much of the sales hype. Radon mitigation IMO is best addressed passively first with perforated plumbing that depressurizes slabs on grade or basement on gravel/20+ mil plastic, with a vent stack to an attic where an electrical provision is installed in new construction if the levels get higher than recommended (4 pCi/l). That should not break the bank, and the fan is located inside a vented attic or mechanical room or outside the IAQ if it leaks. PV tied if it needs to run 24/7. Probably the best it gets until we get real data.

I agree with your rain screen findings. I don’t think most understand what is leaching from inside their walls, and a lot of which is not detected by visual inspection methods or smelled such as the gases we been discussing. What’s more insane is these building scientist, some, actually think exchanging air through a heat exchanger ERV/HRV that can accumulate particles like any other sold surface and suspend them is a cure all for air tight building’s. That is why we find no correlation to air borne or attached toxic particles in ASHRAE 62.2 (the ventilation standard for passive houses), nor any test data showing that by some miracle more ventilation will go get the microbial in walls cavities and expel them outdoors. I’d say this extends to natural site building methods and materials as much as manufactured.

With that said, I’m not sure where they got this table from or how it was developed nor how to inspect to it. It is not just a matter of adhering to the specified gap, more the CFM (Cubic Feet Minute/FT2) and/or ACH (Air Changes Per Hour). So we can say we understand the need for a ventilation gap and people will say that all day long, and design it in, without knowing if it is actually working, how to obtain and inspect it. If one were to consider the complex dynamics that surrounds a building(as mentioned earlier with radon/formaldehyde gases) in both temp, pressure, and moisture, etc, these recommended gaps could be way off and ineffective. Time will tell, or it could be a bunch of sales hype to sell lumber, more layers, etc…It does not take long for microbes to adhere to a surface and once they do, again, there is no stopping microbe growth or poor IAQ by increasing air flow or exchange in most cases. In most cases, having a ventilation gap is not a license to create material interfaces that do not make sense and will produce microbes regardless of airflow. The international Society of IAQ, PHDs, don’t understand spores, bacteria’s, now and always emerging in buildings and the correlations to cancer, so how does a ventilation gap or air seal, or plastic barrier, or vent stack? They have a IAQ Seminar in Europe I wish I could attend coming up soon.

Mass ACH is not noted in the tables. In my mind it is critical to have a small ACH of .2-.3 or lets say I subscribe to the theory of drying by passing air through walls without large condition air losses, not sealing them in certain cases. In some climates, having a ventilation gap outside or inside mass like earth construction is needed. Now we are back to what is the flow and ACH that prevents microbe growth? Also, can these gaps if designed right speed construction drying times? Or is it safe with the designed gaps to not dry in to less than 20% core moisture contents? Some of which can take drying times as long as months, or prohibit it in certain marine climates. I think I know the answer to some of these questions