Jeremy Nodine wrote:Ok so I have been planning/researching/clearing my property for a year now and have around 5k saved to build my home with. I plan to start on it this spring and hope to be finished before our first freeze next year. There is just one problem, I still haven't decided on what material to use. After I attended my first workshop I came away inspired and dead set on using adobe mainly because I was a brick mason for awhile and laying adobe is essentially the same process and therefore felt the most comfortable to me, BUT as I tend to do I am second guessing myself.
My main concern is insulation. Its gets miserably hot here in summer and below freezing in the winter and I just don't see how a huge thermal mass home would be comfortable. I have considered wrapping the home in foam board but don't really want to, so finally my question --- Does anyone have any information regarding applying papercrete over adobe/cob as a insulation wrap? Or thoughts on how it might perform? Or should I just use straw bales instead?
Build it yourself, make it small, occupy it.
Build it yourself, make it small, occupy it.
Build it yourself, make it small, occupy it.
Foam is not like a moisture barrier...foam IS A MOISTURE BARRIER. This can be a bad thing in many applications, while in others not applicable.The foam is likely to act like a moisture barrier.
I agree with everything in that statement with the modification of "may cause damage if not planed and mitigated for."Water vapor will not be allowed to move through the walls, but be stopped by the barrier, turn into liquid water (especially when it's cold outside) and do damage.
This one is not fully accurate, as foam by it's nature creates a true "thermal break" because of the concentrated R factors over such a short distance. This would also be the time to bring up "dew point" and where it occurs inside the thermal matrix of a wall. If the "dew point" takes place within the foam layer, you do not get condensation, as the dew point is within the sealed structure of the foam where there is no moisture. So you can design a cobb wall with foam as part of the system and have it function...but as Kirk has pointed out, is it worth it, probably not compared to other systems.Placing foam inside of a cob wall will do the same as above AND insulate out half of your thermal mass. The outer mass will tend to stabilize at VERY COLD, drawing heat out of the building MUCH faster. Yes, even through the insulation
Here is the real question for not only the use of foam, but the use of cob itself in many applications. Compared to other mediums of construction, are you really saving any money or effort by trying to use cob? In cases yes, while in many others you are not.The kinds of measures that you will have to take to force them to work together will be greater than the benefits.
Foam is not like a moisture barrier...foam IS A MOISTURE BARRIER. This can be a bad thing in many applications, while in others not applicable.The foam is likely to act like a moisture barrier.
I agree with everything in that statement with the modification of "may cause damage if not planed and mitigated for."Water vapor will not be allowed to move through the walls, but be stopped by the barrier, turn into liquid water (especially when it's cold outside) and do damage.
This one is not fully accurate, as foam by it's nature creates a true "thermal break" because of the concentrated R factors over such a short distance. This would also be the time to bring up "dew point" and where it occurs inside the thermal matrix of a wall. If the "dew point" takes place within the foam layer, you do not get condensation, as the dew point is within the sealed structure of the foam where there is no moisture. So you can design a cobb wall with foam as part of the system and have it function...but as Kirk has pointed out, is it worth it, probably not compared to other systems.Placing foam inside of a cob wall will do the same as above AND insulate out half of your thermal mass. The outer mass will tend to stabilize at VERY COLD, drawing heat out of the building MUCH faster. Yes, even through the insulation
Here is the real question for not only the use of foam, but the use of cob itself in many applications. Compared to other mediums of construction, are you really saving any money or effort by trying to use cob? In cases yes, while in many others you are not.The kinds of measures that you will have to take to force them to work together will be greater than the benefits.
The trick to "thermal inertia," and higher R factors working in concert with one another in these "mass wall" systems is "air breaks." So, as an extreme example, say you went through the effort of using cob with a foam core thermal break. You would have to create and "air break" of at least 20 mm (~3/4) between the cob and the foam. These types of spaces can also be enhanced by the application of a "radiant barrier," but the air space in those applications must be "dead air space." With the foam to the outside of the cob mass wall, you will have to vent the air space back into the living space, which is fine to do, as the cob has little R factor to it in the first place, and the foam would then take the brunt of the thermal resistance work for the wall diaphragm. Then the exterior could be clad in wood board, shingle, stone, or a myriad of other systems.
A good friend of mine, living in Minnesota insulated his cob building with wool/lime. So far, it appears to work well with no troubles
Hmmm you got me thinking....so let me see if I follow you here, are you saying I could for example build a pallet frame to hold the foam then cob around that leaving air space and then vent at top and bottom of the walls and it would work?
If so could I vent it to the outside?
So we don't go too far down the rabbit hole, this is a complex system we are discussing, with many potential pitfalls, which is what Kirk was warning about. It's not possible to "fully encapsulate the foam, as the foam is what is doing the encapsulation with this type of thermal envelope. the cob just becomes an internal structure to create a thermal heat sink by way of mass.Would I even need a vent if it is fully encapsulated?
I had already considered a pallet wall system with some form of insulation infill as it would likely save me time/labor overall.
Jay C. White Cloud wrote:
This one is not fully accurate, as foam by it's nature creates a true "thermal break" because of the concentrated R factors over such a short distance.Placing foam inside of a cob wall will do the same as above AND insulate out half of your thermal mass. The outer mass will tend to stabilize at VERY COLD, drawing heat out of the building MUCH faster. Yes, even through the insulation
Build it yourself, make it small, occupy it.
I do believe Kirk, you may need to go back and read your basic principles of "thermodynamics." You are correct "heat will move through no matter how good it is," but the time coefficient at which it does has a direct correlation to how effective the "thermal beak" will function. I am not sure where you got the idea that there isn't such a thing as a "thermal break," because if there wasn't the Shuttle would have had a real hard time at reentry into Earth's atmosphere, and there are several chemistry experiments that would not function well without there being sound principles behind the concept of a "thermal break."NO insulation is 100%, heat WILL move through no matter HOW good it is. There is no such thing as a "true thermal break".
Hmmm, I don't believe heat ever rolls or moves down hill without some convective or other physical motivation. Heat only moves up by principle. Cold can in theory, and principle roll down hill (or mountains) and does, which often creates "cold waves." I have a notion that you may be thinking about portion of the anomaly that is the "Mpemba effect," which is not a constant by the way. Your second premise would seem to suggest that if its cold outside, you will lose heat faster from a 90°F room than from a room that is 65°F, on that we would agree, just as when it gets hotter outside the harder "cooling devices" have to work. Nether of these counter the reality of a "thermal break," only that some material are more efficient than others as retarding these events.Heat ALWAYS "rolls down hill", always from hot to cold and the larger the difference in temperature, the faster heat will jump, in larger quantities.
Yes I agree, but that is exactly what I recommended in the first place; please reread the second to last paragraph of my entry on : 11/10/2013 5:11:03 PM I would further point out that this system is well understood and in good practice with several "mass wall" construction modalities. For example, several Rammed Earth wall companies have a percentage of the wall matrix's thermal mass on the outside as a "buffer" to "thermal inertia" further augmented by a "thermal break," of 100 mm foam insulation to increase wall efficiency to temperature coefficiency flux and then the majority of the thermal mass to the inside of the living space, which creates a "thermal heat sink," in winter and a cooling dampener in summer.People, in cold climates, ALWAYS put the thermal mass inside and insulate around it (to the outside). If you are going to vent between the thermal mass and the insulation (perhaps a good idea), vent it to the INSIDE of the building! Keep the heat in!
I would have to evaluate the schematics and design specs for an application like this, however on the face of it, I would never recommend "dipping" a "wool" or "fiber mass" that was intended for insulative value in a lime render, as this is only going to decrease its thermal efficiency, and facilitate other very possible denigration events.My friend dipped the wool in lime putty and just stuck it onto the cob.. A bit like a plaster, I suppose but NOT troweled down tight and put on rather thick (3 or 4 inches). He may have plastered over it, but I'm not sure of it.
Jay C. White Cloud wrote:Hi Kirk,
I don't think we are at a point of having to "agree to disagree," yet as we may have to clarify a few points first, that one of us is not seeing certain principles of "thermal dynamics," clearly. I have asked John Elliott for advice on this, as his background in science would be very germane to this conversation. I also don't mean to be so "detail picky" but not understanding these principles is leading too many wall systems being built that are not functioning in application as the builder thought they would. This is part of the reason I write on Permies, so we can have the accurate information being applied to wall matrix, not the assumed, or misunderstood.
1. I don't believe I said any insulative material is 100%, but what I will state as a fact of science is that some materials have higher resistance levels (R value being the most common measure here in North America I do believe) than others.
2.I do believe Kirk, you may need to go back and read your basic principles of "thermodynamics." You are correct "heat will move through no matter how good it is," but the time coefficient at which it does has a direct correlation to how effective the "thermal beak" will function. I am not sure where you got the idea that there isn't such a thing as a "thermal break," because if there wasn't the Shuttle would have had a real hard time at reentry into Earth's atmosphere, and there are several chemistry experiments that would not function well without there being sound principles behind the concept of a "thermal break."NO insulation is 100%, heat WILL move through no matter HOW good it is. There is no such thing as a "true thermal break".
3.
Hmmm, I don't believe heat ever rolls or moves down hill without some convective or other physical motivation. Heat only moves up by principle. Cold can in theory, and principle roll down hill (or mountains) and does, which often creates "cold waves." I have a notion that you may be thinking about portion of the anomaly that is the "Mpemba effect," which is not a constant by the way. Your second premise would seem to suggest that if its cold outside, you will lose heat faster from a 90°F room than from a room that is 65°F, on that we would agree, just as when it gets hotter outside the harder "cooling devices" have to work. Nether of these counter the reality of a "thermal break," only that some material are more efficient than others as retarding these events.Heat ALWAYS "rolls down hill", always from hot to cold and the larger the difference in temperature, the faster heat will jump, in larger quantities.
4.
Yes I agree, but that is exactly what I recommended in the first place; please reread the second to last paragraph of my entry on : 11/10/2013 5:11:03 PM I would further point out that this system is well understood and in good practice with several "mass wall" construction modalities. For example, several Rammed Earth wall companies have a percentage of the wall matrix's thermal mass on the outside as a "buffer" to "thermal inertia" further augmented by a "thermal break," of 100 mm foam insulation to increase wall efficiency to temperature coefficiency flux and then the majority of the thermal mass to the inside of the living space, which creates a "thermal heat sink," in winter and a cooling dampener in summer.People.. (when)In cold climates, ALWAYS put the thermal mass inside and insulate around it (to the outside). If you are going to vent between the thermal mass and the insulation (perhaps a good idea), vent it to the INSIDE of the building! Keep the heat in!
5.
I would have to evaluate the schematics and design specs for an application like this, however on the face of it, I would never recommend "dipping" a "wool" or "fiber mass" that was intended for insulative value in a lime render, as this is only going to decrease its thermal efficiency, and facilitate other very possible denigration events.My friend dipped the wool in lime putty and just stuck it onto the cob.. A bit like a plaster, I suppose but NOT troweled down tight and put on rather thick (3 or 4 inches). He may have plastered over it, but I'm not sure of it.
Build it yourself, make it small, occupy it.
Jay C. White Cloud wrote:Hi Kirk,
I don't think we are at a point of having to "agree to disagree," yet as we may have to clarify a few points first, that one of us is not seeing certain principles of "thermal dynamics," clearly. I have asked John Elliott for advice on this, as his background in science would be very germane to this conversation.
I might need to go back and look again, though it is my understanding that temperature gradient MUST ALWAYS be a consideration in these types of calculations, regardless of the material.
In the case of the shuttle, appropriate materials were chosen to handle the gradient over time.. The same gradient over more time may not have worked quite so well, or a higher gradient over the same duration. Design tolerance and all that.
It was an experiment that appears to have worked (so far) in the case of my friend. Certainly, dipping the material reduced it's insulation values by quite a lot; he apparently had enough wool to make up for reduced efficiency of the material. As to the longevity of it, time will tell.
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I am a bit lost by this comment? I know I will have lots of water vapor if I keep a home at a healthy humidity level, and that I don't want the water vapor trapped in the interstitial wall system assembly or condensing on surfaces, but I am not sure about venting to the inside? Could you expand what you meant Al?I think we all agree that venting water vapor to the inside is a best use practice almost always
Jay C. White Cloud wrote:
Hi Kirk M.,
It is good that you have brought up "gradient," into the conversation. That gradient, though often a statistical measurement in some respects which can have a rather "squishing" interpretation, can also be very poignant to creating a mental picture. I would also state that the "steep slope," of the gradient is the "thermal break," I have been speaking of. It is that section of a wall system matrix that causes a long reduction of time for a temperature (hot or cold) to move through a material.
These types of home grown "experiments" can have great benefit to an individuals understanding especially if shared as you have. It is when lay folk will extrapolate information from these "little empirical tests," that are more based on assumption or subjective conjecture that I become wary. If I may use this case as an example, (please not it is not a criticism just observation base on experience) here was an attempt to increase "thermal efficiency" in a system, that in theory has merit, yet in practical application probably was not well thought out from the "far view."
Wool as an insulator is wonderful, but you have to ask first, what is its "real life-real time" durability to perform its thermal function? Will the lime rendering decrease the thermal resistance enough to not make the labor and cost worth the effort. Was the wool treated for infestation of pest that eat, and utilize wool as a nesting material? Is there a way to periodically check and/or service the inner function of the wall system matrix including the wool. Did the augmentation drastically or only marginally increase system performance? These are just some examples of questions I would have asked before even considering such an experiment, or having another conduct same.
When a concept is examined, take not just a few steps back but many, before considering "real time," application.
Regards,
j
Build it yourself, make it small, occupy it.
No it couldn't Kirk if it is the correct type of foam, (or even a properly vented void with something like "clay straw,") could be designed to work. I am not theorizing here, I have seen it done, and the inner wall probes are providing the data that when these systems are well designed and utilized in the correct environment, they work.My original point was that sandwiching foam insulation between two cob layers could GREATLY reduce the effectiveness of the insulation.
Well as I have already stated, you would be "imagining" incorrectly.If the cob mass on the inside is a comfortable room temperature and the cob mass on the outside were below (or at) freezing, I imagine that the effectiveness of the insulation between would be HORRIBLY reduced.
Yes, that is true, and why you need that gradient which is your "thermal break."Direct conduction, being the most efficient way to transfer heat, with no possibility of boundary layer effects to reduce heat escape, etc, etc, etc..
If you don't know what you are doing, and have not designed advance insulative wall systems before, I would tend to agree. This is not work for the novice builder, but that does not render the modality ineffective, if you understand all the systems and how they work in concert with one another.No matter how good your insulation is, the above scenario is just about the WORST condition to place it under..
If your insulation is saturated your system is not well designed and/or applicable for the biome you have built it in. House warps and "vapor barriers" (like many modern insulative materials) are great in concept, and in lab testing, but not "real world" application. I do not condone most of these methods, as they are not necessary, and should not be used. Those that think they should typically have not been designing and building for more than 15 years, and few have gone back for any in depth forensic examination of modern architecture that employ them. Make your house "draft proof" nor "air tight", use natural venting, and understand the insulative system you chose very well before using it, and the architecture should have little issue with effective thermal resistance.Furthermore, chances are quite good that the insulation would, over time, become saturated with water. Insulation materials tend to be good sponges, cold/hot transition areas tend to collect condensation; much evidence of this condition can be found ANYWHERE that a vapor barrier has been placed on the wrong side of an insulation layer. Far too many of the buildings built in the 80's that were wrapped in Tyvec are now having the lower 3 feet of joists replaced along with ALL of the insulation. The stuff is coming out of the walls dripping with condensate in some cases.
Build it yourself, make it small, occupy it.
Under what conditions would you sandwich insulation (rigid foam or otherwise) directly between two layers of cob?? I will remind you that the original post did NOT include venting, it talked about a direct sandwich, which is what we've been discussing. Changing the parameters changes the conversation.
I have even been pondering if imbedding foam board into cob as I built the walls up would work.
Build it yourself, make it small, occupy it.
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