Papercrete vs Strawbale as earthbag insulation

So I've read a lot on this forum and abroad about the dangers of papercrete in regards to moisture retention, but I'm unclear on a couple of points and was hoping some of you might help shed some light.

A) I'm in upstate NY, and while we are accused of having pretty humid summers, I don't know if that counts as living in a "humid climate" where papercrete is not recommended.
B) I'm imagining an earth bag vertical wall (not dome) with a 5 inch layer of papercrete on the outside, and then cover the papercrete with a lime plaster. Overhang the whole thing with a good roof and eaves and plaster the interior walls with an earthen plaster. I haven't seen this sandwich idea suggested before, and was wondering if it would either solve the problem with the papercrete getting too wet or make it irrelevant as any mold would be buried from both sides.
C) Most people I've seen answering similar questions for my area recommend strawbale and cob for my neck of the woods, but I would think strawbale would suffer the same mold/rot problem if it was allowed to get wet, so I'm not sure what advantage that would have over papercrete. I find that I just don't *like* strawbale, and it doesn't resonate with me as well as the thermal mass and free-form structure of an earth bag wall, so I'd prefer to find a way to insulate earthbags. I've also read recommendations of scoria- or pumice-filled earthbags, but as there are no volcanic areas around me (nor rice-hull sources), those don't seem to be financially viable.

Am I just running into the unsolvable problem, or am I letting my personal preferences override my common sense and refusing to do what just works?

But the stage in strawbale where the bugs come out of the walls looks so fun!


So, no scoria, no rice hulls, no pumice. What else can you put in an bag to insulate?

Have you looked for perlite or vemiculite already, as well?

Beyond those, my first thought was wood. Perhaps lightclay, or in a pinch maybe sawdust mixed with lime? Looks like this is on Owen Geiger's mind too: http://www.naturalbuildingblog.com/woodchiplight-clay-earthbags/

Some more mentions of these options here: http://www.earthbagbuilding.com/faqs/miscfill.htm

I found the comment suggesting that crushed lime sets like concrete to be particularly interesting; I would have expected it to be tough and that sounds quite promising.

Obviously none of the wood options would be impervious to moisture, but may be alright, given the additives, and the good eaves you mention, and presumably a tall foundation/cladding to ward off splashes at base of the wall.

I'm assuming you'd do an earthbag wall for thermal mass/strength, then an insulationbag wall on the outside. But with suitable testing maybe you'd find a single-bag wall of one of these options to be workable...

I've looked into perlite and vermiculite, but I might not be looking in the right place. All I've seen is bags at gardening centers, etc. for about $.75/cubic foot. That would obviously get pretty expensive to fill a wall with. I do have plenty of wood, though. The entire lot is wooded, and we'll have to clear a bunch just to have a place to build, so maybe with a decent wood chipper, I could use that mixed with clay, which I also have plenty of. Or, there's a sawmill down the road where I might be able to get either wood chips or sawdust cheap or free. I'm all about using the materials local to the land, so if I can do it with what I have on the property itself, that's my preferred option.

I have concerns about a double bag wall with different materials. it seems to me like they might settle or compress at different rates, and then you'd have problems with uneven rows, especially at the top. I know you're supposed to run something like a figure 8 configuration with your barbed wire to adhere a double wall together, but that would also seem to lessen the tensile strength provided by the wire, and since I'm going for a more serpentine wall with a plumb vertical (no dome), tensile strength will be as important as compression. If I can find a solution that either fills a single bag wall, or which laminates over the outside of the bag wall, that "feels" a little more sturdy to my right-brained way of thinking. My general rule I'm trying to adhere to is to not build anything that won't last at least a hundred years with minimal maintenance.

Also, because I'm in NY, I feel like I can't get *too* experimental if I'm going to convince the code official to sign off. The code official in my area seems to be a pretty decent guy, but NY isn't known for its high levels of freedom. I'm going to have my work cut out for me, I think, just getting him to sign off on regular earth bag construction. At least with normal earthbags, I can point to existing structures and Nader Khalili's load tests.

There's also a part of me that wonders if I'm too worried about insulating the walls. I'm talking about small spaces (maybe 100-300 sq ft) with heavy roof insulation and a RMH for heat. I know there are conventional stick houses around here that don't have any insulation in the walls, and while they leak heat like a sieve, they're not unlivable, just use up more heating fuel. I wonder if that concern is less worrisome with a RMH and plenty of wood on hand.

Check out the work of Rob Roy. He uses cord wood.

You are hundreds of miles north of where I would ever consider using earth bags. Wood chip clay might work.

Dale: Interesting, wouldn't have occurred to me that this would be too northerly for earthbag construction. Having followed the http://canadiandirtbags.com/ blog, they seemed satisfied with a singlewalled! earthbag setup in Alberta. Is this purely an insulation thing, or are you thinking about some other shortfall?


Jeremy:

Sites that might help you find a better source of perlite/vermiculite:
http://www.vermiculite.com/
https://perlite.org/

I agree that bags with different materials might compress differently; I would expect that this would need to be compensated for by adjusting the fill amount in the different bags. Hopefully settling would be pretty minimal due to the excellent tamping you obviously plan to do. I wouldn't think that both walls would need to be strong enough to count as structural, either.

My intuition says the opposite of yours, a layer of insulation in bags seems like it should be more stable than something that must adhere to the existing wall for stability... but this is not an educated/experienced opinion, and is thus worth what you paid for it!

Just because you're putting an insulationbag wall outside the earthbag wall doesn't mean you need to skip the straight lines of barbed wire, right? You could add figure-8, and/or short perpendicular lines, in addition to the original straight lines. Not pleasant work, and added cost... but in a structure so small it might be cheap peace of mind.

That sawmill sounds like a potentially valuable resource, maybe see what they can provide free/cheap before getting too set on a plan...

With all your on-site wood, have you thought about a timer-framed structure using something else(earthbag/insulationbag, or cordwood, or lightclay or...) as insulation/infill? Especially at the smaller end of that 100-300sf size, the timber frame would be pretty simple, relatively speaking.

On the subject of on-site resources, what is your soil like? Got clay?

I have considered timber framing. In fact, that's one option I'm thinking of for a self-supporting roof, with posts either inside or outside the earth bag wall. I think a lot of the strength of the earth bags would be lost by interrupting it with posts, so I want to keep that EB wall continuous and just work around the post and beam construction to support the roof.

I think the soil is pretty heavy in clay. I haven't tested it fully yet because I don't yet own it. I'm in the process of buying it now. Plus it's almost entirely under snow at the moment. But there are a lot of springs and small creeks on the property, so I don't think I'll have much problem finding clay. If anything, I might have to truck in sand to get the ratio right for cob/plaster, etc.

Hi Jeremy, et al,

I have been following along, and thought perhaps now would be a good time to through in my "2 cents," for what it's worth.

Am I just running into the unsolvable problem, or am I letting my personal preferences override my common sense and refusing to do what just works?

No...these are not "unsolvable problems." I do not even see any real challenges per se...

Yes...like many...our "mindset" (psychology) gets in the way of our "goal set," often clouding good judgement or inhibiting a "big picture" view of what we want to achieve.

So...lets look at big picture first and work backwards.

You are here so we can presume that "natural/traditional building" of some fashion is both a conscious and ethos choice of what you care to live in. Next comes the tangible aspect of region, local biome type, and specific location. From here I suggest to client/students to always look to the vernacular systems of a region and/or biome to figure out what the most "natural" and enduring architecture will be.

I won't speak to the aspects of EB other than to suggest that it is a "reinvented wheel" of sorts that grew out of "disaster relief" and "war embattlement hardenings." This "bag architecture"was not originally intended for primary residency architecture. Not to say that it can't be such, but I personally feel too many EB are being built in regions where proven vernacular systems already exist, with proven track records. I commend those brave soles such as the ones reference in Canada that are conducting a "living experiment" with such systems and experiencing what does (and does not) work with them. So...as I often find myself saying...Yes we can always "make something work"...but why try when other more homeostatic systems already exist for a region.

The aspect of a timber frame, is what drew me into the conversation, as this is a wonderful, and well proven historical system with great flexibility. Cobb, and Kubbhus (cordwood or stack wood) systems have also been referenced. Rob (author R. Roy) lives in upstate New York, and is a friend...he can more than speak to the applicability of this system for the region.

I think this project has great potential, yet may require some "rethink" of which way to proceed, which must include skill sets, resources and fiscal means, as other factors to consider. I look forward to follow along further...

Regards,

j

Hi Jay,

Thanks for weighing in. I've read your responses to other similar posts on this forum and have seen this suggestion from you a few times. I might be misunderstanding, but as I recall from my high school history class, the "historical vernacular" of the native peoples of this region were green poles lashed together with layers of animal skins draped over them and open fire pits under a central skylight. As they were primarily nomadic people, this made sense for them, but doesn't really address the same goals as I have. I suppose you could look to early colonial architecture, which would probably lean towards log cabins, which still are commonly constructed today and even have references in the building code, but they do have their shortcomings, and I feel they can be improved upon. Speaking of which, I've heard you poo-poo earth bags before as being a new invention where none is needed, but I don't really see it as a reinvention of the wheel so much as an evolutionary improvement. While we don't have a lot of historical architecture in the area, parts of Europe are very similar in climate and have a deep, rich architectural history, which is, as I understand it, where we get cob from. To me, earth bags are an evolutionary step for cob building. It's largely the same material, but with improvements (namely the polypropylene bags and barbed wire) that were not available to those who first started working with cob. It seems to me that these add strength and, more importantly consistency to a cob wall, as well as adding a stabilizing mechanism, which is one of the primary areas code enforcement officials get hung up on cob structures (again, as I understand it. My experience is entirely book-based). I like to think that if poly bags and barbed wire were available to early cob or adobe builders, they would have used them, and I don't see technological advancement as something to be eschewed any more than it should be lauded for it's own accord.

I am somewhat interested in the cordwood approach, but probably only for one accent wall as I find the aesthetic too busy for a whole house. I suppose I could just plaster over the ends, but I'd be interested in Rob's explanations as a fellow New Yorker, because I would have thought that the mortar between the cordwood would act as a thermal bridge and would be about as insulating as an actual cord of stacked wood without the cob filler.

To flesh out the big picture a bit more, as you say, my goals are perhaps not as ideological as yours. I'm attracted to natural building more for the pragmatic reasons of easily available, dirt-cheap materials, able to be completed myself without hiring large expensive crews of specialists, and adding nothing to my home that is toxic to the inhabitants. I also very much like the energy-efficiency of passive solar and rocket mass heaters and the organic look of curved walls and earthen plasters. If I have an ideological dog in this race, it is that a man should be able to build his own home on his own land without having to work for the rest of his life to pay for it. I have an overarching attraction to building with quality made to endure, and creating self-correcting systems that require little to no maintenance. My immediate goals are to move out of our conventional house and onto the land within a month or so (hopefully in a temporary camping trailer, or tents if we have to), and to dedicate myself full-time toward putting together a simple, one-room structure that will be weather-ready by the time next winter hits. This first structure will be both a safety net where my family can know we can survive the winter storms and then take our time to build our main house the way we like, and also an educational experience to test my theories and learn the skills necessary to build a more complicated building. Once we build our permanent home, this first building will likely become a storage shed or possibly a guest house of some kind. My funds are pretty limited (around $400/month plus whatever materials I can scrounge up second-hand).

Timber framing has a hold on my interest, to be sure, but that doesn't really address the insulating aspect, which is where most of my concerns still sit. And especially for this first build, wouldn't it be a more skill- and tool-intensive technique as compared to earth bags which lend themselves better to a shortened construction timeline? I have construction experience with conventional stick framing and sheetrock. etc., but I have never done timber framing, do not have the tool collection for it yet, and feel like a lot more skill and experience is necessary for it to be done well. It seems like something I may well incorporate into the main house, but for this first build, I'm concerned if I did anything much more than a simple roof, I would spend my whole summer learning it and not have anywhere to live come winter.

As Jeremy points out, the vernacular architecture of an area was shaped by the lifestyle, living standards, and available resources/skills. There is absolutely a lot to be learned, but in many cases some or all of these things have drastically changed, and improvements can be made. I think a west-coast cedar longhouse is an excellent structure, but if I was building one, I suspect I would be planning on substantially updated foundations along with insulation, and passive/active HVAC options. Given that I'm allergic to cedar, and that the value of that much of it would be fairly ridiculous, it definitely won't be happening, though.

There are many things things to be said for timber frames. Among these, it's an unarguably renewable resource, in many cases the needed timbers are already on site, and it can look truly gorgeous.

One catch is the availability of dryish timbers for a given building season; even if you are 'just' building a cabin, I recall Dick Proenke went in the previous summer to cut his wood and leave it to dry for his build starting the following year.

Another is potential insect damage and rot, things which don't really happen to earthbags unless you have organic matter inside.

A third is the lack of thermal mass relative to an earthbag system.


As far as cordwood goes, I quite like the aesthetic, myself. I think that you overcome the thermal bridging by using insulation in the middle and mortar on the outside edges, or possibly by using something with some insulation value, like cob, as mortar. And you build a nice thick wall.

However, it seems a bit... odd... to embed wood, 'vulnerable' end grain exposed, into a wall, if you have available the materials you need to build a very similar wall without the wood component. I worry about swelling/shrinking of the wood as moisture changes: I assume this is addressed in literature on the subject which I have not yet read...


Jeremy, I would have said that the foundation, drainage, load-bearing frame, rafters and roof are probably the most demanding aspect of a timber frame build. Adding walls and a floor might be quicker than doing all that previous stuff and then using earthbags or cob or...


Finally, since you've said this is an experiment... it would be pretty neat to do a timber frame roof above, say, one wall(curved) of earthbag, a wall of cordwood, a wall of cob, and a log wall. You could try out all four techniques, and pick your favorites for the main house. As a guesthouse/demo site I'd bet that would be a good draw! It could make for a fantastic workshop series during construction, too, which could be a real boost in speed of construction... Hire an expert or 3, pay them with the participants money, and you keep the results of the labour...

Dillon Nichols wrote:Jeremy, I would have said that the foundation, drainage, load-bearing frame, rafters and roof are probably the most demanding aspect of a timber frame build.

Yes. Of course you're right. I've been through several permutations of the build in my mind and must have blended a couple.

(note: there are links to blue underline text and Kanji)

Hi Jeremy, et al,

"Vernacular" can address both a specific region, historical time period, and/or biome type. It is neither fixed towards a single cultural type, yet more specific to what works "historical" in a region and/or biome. One could just follow a "native" tradition and adapt that to their needs or look to other cultures and forms from similar regions and/or time periods. New England has many European styles adapted to North America as it has similar climate to several similar regions in Europe and Eurasia. If I started describing just the Dutch, French and English forms of earth, stone and timber architecture it would cover many pages of single space text, not to mention the Native styles that go well beyond just "reen poles lashed together with layers of animal skins draped over them and open fire pits," as many First Nation cultures had structures as elaborate as those of the Nordic Cultures (i.e. Viking.)

Log architecture has much more to them than many understand. If we are speaking of a simple "rough notch" cabin in the woods...I agree these are not something I would suggest as a permanent residence though I know many have built comfortable versions of them. I would suggest that the 校倉 (Azekura) and French "Pièce sur pièce" (version of Post and Plank) log and slab architecture not only fit in the up state New York region there Japanese and Korean counterparts come from areas where these structures are found in identical climates. These are but a tip of the iceberg for choices in applicable vernacular styles...

I suppose one could always take the position of "improving" any system of design. I seem to find many trying to "rethink" or "re invent" better ways of doing things...which is part of human nature it would seem. There seems to be sometime a form of hubris with many trying to build something. Often it falls under the spell of, "I can build it better." It has been my experience that I can add little to the 10000 years of masterful expression of those that came before me and what they have created. I can barely keep those lessons in my head...let alone improve much upon them...I had more than one teacher here and overseas make reference to,

"...master a craft first...then, and only then, can one even imagine on improving it..."

Cobb is anything but "European." Its roots are much older and deeper, and seem to take form in Africa and the Middle East. Today the list starts and don't seem to end in the myriad of "earth architectural styles." From modern interpretation of vernacular Slip Clay Straw/Chip-Cob (Cobb-Clom)-Tabya-Adobe-Bousillage-Colombage-taipa-bajareque-土壁 (Doheki=daub), 土塀 (Dobei=earth wall)...the list just keeps on running through languages and cultures too numerous for me to write about all of them I have either learned or witnessed and each year I find more...Many would be more than applicable in the New England region.

I don't believe even in this conversation I actually dismissed "earthbag architecture," yet I did reference that I think it has been "overplayed" in my experience and taken to far out of context from its origins in "disaster relief" and "war embattlement hardenings." If anyone cares to explore and experiment with this style of architecture, I say go for it, and good luck. There always has to be a "first time" and a process of "adaptation" for any style or modality of architecture. It is a "reinvention" as the foundational elements have been around ever since the first "picket box" or "bamboo gabion" was created to "harden" a river bank or embattlement, yet this I agree is part of an evolutionary process. In such cases as suggesting to a client or person building a home for themselves...I don't see experimentation and evolutionary method as the optimal path to suggest to folks. If someone cares to, by all means...have at it. I think we could place "earthbags" in a large category with "earth based architecture" but it has little (if anything??) to do with cobb or similar styles. I do believe we could, very much, place "earthbag" in the contemporary "gabion architecture" family. This now moves us into an academic discussion on architectural styles and applicable modalities. Considering that the "polypropylene bags and barbed wire" are part of the "challenge" with this style of architecture, I am not sure I could ever consider these an improvement by any means to what Cobb architecture already is. I would (and have) listened to others discuss this topic, yet until one has worked for some time in both modalities under different application, it is difficult to validate individual recommendation for or against. I have done both, and generally do not recommend EB; outside its historical context, and/or more arid and sparse environs. I do like your concept of using them as an infill method, but I am not certain this would be logistically, ergonomically or fiscally superior to other methods for the suggest build location.

I like to think that if poly bags and barbed wire were available to early cob or adobe builders, they would have used them, and I don't see technological advancement as something to be eschewed any more than it should be lauded for it's own accord.

This is the "if you build it, they will come" concept. I hear/read it among woodworkers all the time about "hand tools vs power tools." Very often folks will ask why I do something a certain way, and then suggest the notion that if someone had a "table saw" in the 1300's they would have loved it...This is a speculative subjection at best, seemingly always coming from those that wish to "invent or change" a method to their own understanding. Having worked and being around many Master Artisan, from tile makers to boat builders, I can say with some authority it is absolutely not true. Many find (such as my original Amish teachers) that they find the "process" and "meditative exercises" of building a certain way imparts a character, charm and soul to a craft, artform and/or architecture that can not be achieve any other way...

I think it would be worthwhile to consider a Kubbhus style for your structure. I can assure that this style will have much less "thermal bridging" than bag architecture unless the bags are filled with sawdust, or some other very light material, yet then rises the issue of "interstitial moisture" which is very much a challenge with "earthbags" done with poly and not burlap or other organic textile. I like pragmatic, and this was the only reason I shared on this post thread. Most of my views are actually rooted in such pragmatism and of course health of planet and human alike. The idea of someone building their own home I too support and very much love. That is why, I suppose, I built my first "solo" timber frame when I was 19 years old back in the 80's. Timber frames don't address insulative aspects as that will always require an infill or other method. EB doesn't address insulation either...unless filled with insulation, as it is a "mass form" of architecture and as such, not always applicable per se in northern climes, but can be "made to work." My timber frame at 19 only cost me my time and the tools I had to either make or barter for. I am not sure I would look at EB as either faster or more cost effective, but I own that is just my view, others can more than disagree. Considering the amount of 'free info' there is on timber framing...I am not sure if it actually is more difficult to do than EB is to facilitate for a first time builder. In my experience, I would suggest EB is at best, as difficult to build, and definitely not as well proven...if designed and built as a permanent structure and not transient. There is no "catch" in "dryish timbers" at all. Timber frames are not built with "dry timbers," never have been and in most application should not be...The concept of "seasoning" wood is a very modern take on the matter and often out of context to what ancient text mention or implied. Some wood, in some applications is "seasoned" but this moves the conversation out of "base vernacular" and into the realm of the Luthier or Buddhist Temple structures yet even then 'green wood' is often employed. Rot should never happen to a timber frame if built correctly and roofed. I routinely work on frames over 300 years old and many very much abused yet still strong and solid...so rot too is a non-issue. Thermal mass comparatives aren't relative until a final design matrix for either is examined and well understood by the designer of the structure.

If, as these concepts progress, any specific questions arise that I may address, please do ask, otherwise I will be silent and just listen from this point on...

Good luck and Regards,

j

Hi Jeremy,

   Just caught on to this thread from some years ago. I'm over in the Berkshire of Western MA. in the design stage of a first building and reaching out to you to learn of any progress toward your goals. Have you built?

Jeremy Franklin wrote:So I've read a lot on this forum and abroad about the dangers of papercrete in regards to moisture retention, but I'm unclear on a couple of points and was hoping some of you might help shed some light.

A) I'm in upstate NY, and while we are accused of having pretty humid summers, I don't know if that counts as living in a "humid climate" where papercrete is not recommended.
B) I'm imagining an earth bag vertical wall (not dome) with a 5 inch layer of papercrete on the outside, and then cover the papercrete with a lime plaster.  Overhang the whole thing with a good roof and eaves and plaster the interior walls with an earthen plaster.  I haven't seen this sandwich idea suggested before, and was wondering if it would either solve the problem with the papercrete getting too wet or make it irrelevant as any mold would be buried from both sides.
C) Most people I've seen answering similar questions for my area recommend strawbale and cob for my neck of the woods, but I would think strawbale would suffer the same mold/rot problem if it was allowed to get wet, so I'm not sure what advantage that would have over papercrete.  I find that I just don't *like* strawbale, and it doesn't resonate with me as well as the thermal mass and free-form structure of an earth bag wall, so I'd prefer to find a way to insulate earthbags.  I've also read recommendations of scoria- or pumice-filled earthbags, but as there are no volcanic areas around me (nor rice-hull sources), those don't seem to be financially viable.

Am I just running into the unsolvable problem, or am I letting my personal preferences override my common sense and refusing to do what just works?

I am curious as to the final outcome as well.
Kevin, what style are you considering?

John C Daley wrote:I am curious as to the final outcome as well.
Kevin, what style are you considering?

Hello John,

   I'm considering Adobe or Earth Bags.

I have been involved with about 500 Adobe houses, I may be able to help.
Where are you located?
I see its this  place- What is special about the Berkshires?
Image result for Berkshire of Western MA
The Berkshires region of western Massachusetts is known for its outdoor adventures like hiking and water sports, as well as cultural experiences.

John C Daley wrote:I have been involved with about 500 Adobe houses, I may be able to help.
Where are you located?

Right on.. Western Massachusetts