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Discussion of what defines earthen architecture, 2006

May 11, 2006 from Tony Crosby:

I need some input on the appropriate breakdown of earth architecture in the US to be described and illustrated for a US/ICOMOS earth architecture committee web site. What we have in mind is to have a map of the US broken down in regions that seem most appropriate for brief descriptions of the architectural types in those areas. This should lead eventually to more detail, such as inventory information in those same areas. I envision that one could click on the US map and a brief 1-2 page illustrated description of that area would come up. Obviously the first step is to identify the areas; a second step will be to develop the descriptions for the areas, and we will need for that as well. But, first things first. . .

I want to develop a brief survey, for the web site, of earth architecture in the US, and I want to begin the discussion of how best to break that down. After some thought, I think it needs to be geographically, although I think that there will be some possible variation in that. As an example, the web site would have a map of the US with different geographical areas identified, say the mid-west for example. If one highlights that area, a brief description of the type found would appear followed by a few examples. To begin this discussion I suggest the following possibilities:

  1. American Southwest (Texas; New Mexico; and Arizona - prehistoric; mission; territorial; "immigrant" and later)
  2. California (Mission Period; Republic [Monterey style]; statehood)
  3. Midwest (prehistoric [mounds]; "immigrant period")
  4. South (Including the Mississippi corridor with great examples of French architecture; earth chimneys, prehistoric mounds)
  5. Rocky Mountains (Some carry over from mid-west; pre-historic [Mandan mounds, etc.]
  6. Alaska - earth lodges, household storage, etc.
  7. Eastern US (pre-historic, if relevant; 19th century adobe and rammed earth)

In all of these cases, I think the contemporary use would also be listed.

Okay, lets get some discussion going. Remember, if you "reply" the message only comes back to me, so "reply to all" would be more appropriate for discussion. Of course, please feel free to reply to me only if you want.

May 11 from Ed Crocker:

Could you define "earthen"? I have always looked a Zuni as an earthen village even though a large part of the architecture is stone laid up in mud. Similarly, in Antactica there are shelters dating from the early exploratory period that utilized stone and mud. Perhaps a discussion of typologies with whatever limitations the group wants to impose would be useful.

May 11 from Kate Dowdy:

The Mandan and many others lived in the dome shaped earthlodges, but not mounds--and not just the Mandan. The earthlodge was a housing style of the Plains peoples in North America beginning as early as AD 700, and many were still using it during the early Historic period, not just the Mandan. But the mounds we know from the Plains to Northeast were not housing units, per se. Most were burial mounds, and some were truncated to serve as platforms for structures, more common in the Southeast.

May 11 from Tony Crosby:

Thanks for your comment Kate. Do you think the basic breakdown of regional types starts to make sense? I would certainly appreciate your comments on that as well. Also, it is my understanding that only a reconstructed earth lodge exists somewhere in the plains. Do you know where that might be?

May 11 from Kate Dowdy:

Yes, I think the regional delineation is a logical beginning, you have to start somewhere. I have my suspicions that it may begin to beg for an alternative approach -- for instance, techniques and materials -- but right now it's tough to know. Again, you have to start somewhere, you have to get into the actual surveying activity before we can be sure the best direction to take -- it will soon reveal itself, I think.

The first reconstructed earth lodge that comes to mind is north of Bismarck. I'll have to do some searching to know if that's true, but it won't take much to find out. (You recall perhaps that I spent a bit too much of my life in North Dakota back in the 80s? I'll make some calls.)

May 11 from Tony Crosby:

When we use the term "earth architecture" we probably have to be inclusive. If earth is used in any form to a significant degree, it should probably be included, such as the stone with mud mortar and structures of a monolithic nature utilizing earth and other materials. Would a Victorian house in central Colorado constructed of stone, lime based mortar (basically soil and lime) with a base coat of mud plaster be "earth architecture"? A "cat" chimney in Mississippi made of mud, moss and a wood frame utilizes mud as an important component, and in this case, structural to some degree. Is this a feature of earth architecture?

You can certainly make the argument that a wattle and daub structure is frame and the mud daubing has much less to do with the structural character than the example of stone with mud mortar, although most would consider it earthen architecture and the stone/mud mortar that of stone construction. I worked on a ca. 1800 timber frame/wattle and daub building in Kentucky because of my experience with earth structures. The problems were minimally those of earth and primarily those associated with the timber frame. In this case I would describe the structure as a timber frame structure with earth as the infill material. One thing to consider is related to the conservation problems that affect various types of structures. The conservation problems associated with a timber frame with mud brick or daubing infill are primarily those of wood and not earth. The problems of a mud brick structure with timbers embedded in the mass are primarily those of earth. A stone with mud mortar structure should certainly be considered "earth architecture", if a wattle and daub structure is.

My initial response, is that for the purpose of this current "exercise" we need to be inclusive in describing all the way earth is used, but concentrate on conservation issues that affect mass mud as the primary structural system, such as rising damp, loss of cohesion, delamination, slump, response to ground motion, etc. Does this begin to make sense?

May 11 from Ed Crocker:

I think this is off to a really superb start and the list, as Kate notes, will self-define shortly.

I believe we should look at earthen architecture in the broadest terms and include such things as wattle and dauband infill walls in which cases the earth may not be structural but still demands treatment. I don't believe that you can write a spec for repairing a wooden armature and not spec the mud that encases it. Similarly, you can't spec the stone without a spec for the mud mortar and lime pointing. Thus, I advocate for the broadest possible survey and let the typologies settle out. Obviously, I am looking at this from a contractor's or conservator's point-of-view.

For everyone's information, we are currently working on what I believe to be the singular example of a Fachwerk construction in New Mexico. It is a house in Taos built on a limestone/lime mortar footing; full dimension 2 x 12-14" "studs" on sixteen-inch centers and infilled with mud; exterior was lime wash over mud with a later Portland plaster; interior mud with calcimine.

This exemplifies my above position: This building should be included in a survey even though the mud is infill. It is important both because it is unique in a region, and because by volume the earth is the predominant material.

May 11 from Gustavo Araoz:

May I suggest that this topic of taxonomy and nomenclature has given way to such hot discussion within such a short period of time, that it might be a major foundational issue that perhaps should be addressed at the global level by the International Committee, and that in fact, may be way overdue. Good taxonomy is what enables the natural conservation people to point the finger at critical issues and identify species that are endangered or disappearing. It is an approach that we in the cultural side should adopt and would ultimately benefit all at the global level. It would help identify uniqueness, patterns, representatives, etc - all important not only for establishing significance, but also priorities in treatments and protection.

I know that at the last evaluation meeting of World Heritage nominations, we encountered a very similar situation with rock art, which needs desperately to be classified and mapped at the global level, especially given the sudden avalanche of rock art sites being nominated as cultural landscapes. This trend will surely continue on the increase, and in order for us to be able to assess Outstanding Universal Value, we need to know the global context, the taxonomies and the geographic spreads. Similar efforts with earthen construction might actually accelerate the inscription of such sites in the WH List.

I might add that there are funds (not lots, but some) to undertake these global context studies. Good discussion, even if I don't know what you are really talking about!

May 11 from Nels Roselund:

Another class of California Adobes were residences built in CA in the 1920's and 30's up to the mid 1930's. The 1933 Long Beach Earthquake demonstrated their vulnerability to earthquake shaking and seems to have discouraged further construction of adobe residences in that period. Architect John Byer was a prominent who designed a number of houses, but designed no more after the 1933 Earthquake. There is a cluster of adobes in the northeast corner of South Pasadena of about the same period, built as an artist's colony. They seem to have made use of concrete foundations to provide above-grade support for the above walls, cementitious mortar, and, sometimes concrete bond beams.

I've heard that there are adobes in Carmel, an artist/writer back-to-nature colony of the same period. Robinson Jeffer's Tor House in Carmel, though built of stone, was built in the spirit of that time and place.

There may have been a small resurgence of adobe residence construction in the 1940 .s by owner builders using reinforcing steel. I looked at one in the San Fernando Valley damaged by the Northridge earthquake. There are probably few of these left . the problems of corrosion posed by steel rebar embedded directly in earthen materials was not understood at the time; the expansion of corroding steel tended to cause a lot of irreparable damage over the course of a few decades by splitting the adobe walls internally.

May 12 from John Feinstein:

Our categorization so far:

  1. Location.
  2. Construction type; by extension, sun dried adobe, pressed adobe, puddled earth, rammed earth, pise, sod, and possibly wattle/daub (jacal) [what if it doesn't hold up the structure but does constitute half of the wall material, this would address Ed's points. . .]
  3. Time period.
  4. People who were the constructors as a definable ethnic group.

AND, while not discussed as yet, USE. Fur trading forts such as Ft. Vasquez, Fort Lupton and Bent's Old Fort. WPA government buildings such as the "White House" in Center, Colorado (a city hall), the relatively new capitol of the Ute Mtn Utes in Towaoc, CO., and single block villages such as the Taos Pueblo. ETC.

May 14 from Nels Roselund:

There is another set of California adobes, built by WPA during the late 1930's and into the 1940's. I've forgotten the story -- it's been a number of years since I saw two of them in the early 1990's -- some were already gone by then. They were built in small towns of the San Joaquin Valley as government office buildings. Shafter and McFarland each had one still in use in the 1990's. Delano's had been taken down. As I recall, the appearance of the adobe blocks was that of asphalt-stabilized adobe. Their thick adobe walls and their verandas helped keep the rooms cool -- they were a wonderful fit to the very hot summers of southern San Joaquin Valley. Perhaps someone knows more of this story than I remember.

These buildings are vulnerable to loss because of California .s URM seismic strengthening laws that require them to be strengthened or vacated. I had been asked to make recommendations for seismic strengthening for one of them -- it did not turn into a project for me, and I don't know the fate of the building since then; I hope its still in use.

May 15 from Mac Watson:

I'm not often comfortable with definitions, especially with anything as slippery and vast as the subject that we are discussing. But I would like to offer an attempt at a working description of what I think of as "earthen architecture."

"A term used to describe buildings where the principal structural material(s) used to construct the load-bearing walls is taken from the earth without subjecting it to a manufacturing process."

This description would include the use of materials such as soils and stones, but would exclude materials such as steel, Portland cement, and quicklime. Mortars and renders do not strike me as falling into the category of "structural materials" so the presence of mortar derived from quicklime might not disqualify a structure from being described as earthen architecture. Likewise, a wall of adobe or manipulated soil reinforced with plant materials such wood or reeds wouldqualify on the basis of its prevalent structural mass.

I'm sure that we can point out many exceptions to this description, but it might be helpful as a starting point for more discussion.

I think that for the purpose of the survey that Tony is proposing the regional distinctions that he makes would be useful. I am not sure how helpful it would be to attach typologies to the regions that he suggests.

Thanks for getting a good dialogue started Tony.

May 15 from Ed Crocker:

Without getting too anal I think we DO need to describe what earthen is. I think Mac's definition is good, but I would go one step further. Not subjecting a material to a manufacturing process by definition might leave out mass-produced adobes of perfectly good composition, or compressed earthen blocks that come out of a machine. I would say "un-amended" or something like that.

Can you call a house built with adobes that have 6% asphalt emulsion in them that are laid up in Portland, have a concrete bond beam, are sprayed with polyurethane and plastered with elastomerics an earthen structure? Anyone who says yes must resign from the listserve.

Mac, I disagree with you about mortars and renders not being structural. Though one is sacrificial (the render) and one is not, they are both crucial to the building as a system. Structural, in my mind, does not mean "bearing" but "integral." Any component that contributes to the systemic integrity of the structure is . . . well, structural. Paint doesn't qualify. Neither do floors in a one-story building. Windows aren't, etc.

May 15 from Mike Taylor:

Some of the material reported on in the CRM publication titled "Conserving Earthen Architecture" (volume 22, No. 6, 1999) that Jake and I edited may be of use to you for background information pertaining to regional earthen technologies in the U.S. Remember this publication? You, and a number of other committee members contributed.

May 16 from Gustavo Aroaz:

One small comment on Mac's definition -- it has to do with load-bearing. The great Franciscan and the earlier Jesuit Missions in Paraguay consisted of a large timber structure with columns and trusses, and then it was enclosed with an earthen walls that gave these churches their architectural definition. The adobe and the timber are free-standing from each other, thus avoiding the problem of the insects (topic of another one of your responses) secretly eating the structural wooden elements. I think of the missions as being primarily earthen architecture, but the earth is NOT load bearing, except for its own weight.

May 23 from Jullio Vargas Neumann:

The discussion about a geographic classification looks for me useful. Also if this geographic classification is divided into two parts: seismic areas and non seismic areas.

A material classification is urgent. Marcial Blondet, Nicola Tarque and me, presented a Paper "Reflections on the actual earthen code in Perú", at SismoAdobe2005.

We are proposing the following criteria to classify the earthen architecture in a seismic area:

Earthen Architecture: (Adobe masonry, rammed earth, and un-molded masonry) have a main resistant structure system of earthen walls, plain or with inner compatible reinforcement (cane, ropes or plastic meshes). Morters and stuccos are earth based material.

Earthen Mixed Technologies: (Wood/earth-quincha or bahareque, Bamboo/earth, reinforced concrete/earth, un-reinforced or reinforced cement based stuccos and mortars for adobe walls) have the main resistant structure system of a material different from earth. Earth material play a secondary structural role, as a cover, or as an insulation, or an infill. Morter can be of earth or other material.

It is important to define if seismic areas or non seismic areas are a subject to make differences in this approach. Maybe not.

It looks like the "structure" word comes from engineering, but has really a more wide meaning.

I hope you find this idea useful in your discussions.

May 23 from Leslie Rainer:

Following up on other descriptions of earthen architecture, I think that Ed Crocker, Mac Watson and Julio Vargas Neuman have made some really good suggestions. Regarding the categories, I think the idea of a category called "earthen mixed technologies" is a good one. This could also include the use of stone with earth mortar and plasters (such as Mesa Verde) or grotto sites with earth plasters. This would eliminate any confusion if just "stone" were used as a term (implying stone and lime masonry or cobble construction).

I always go back to the descriptions and categories set out by CRATerre-EAG in the Traite de la Construction en Terre or Earth Construction: A Comprehensive Guide. They do a very good breakdown of earthen construction systems. Their categories are (from Earth Construction: A Comprehensive Guide):
excavated earth or subterranean structures
•  dug out
•  earth sheltered space
•  in filled
cut earth
•  sod
•  cut blocks
compacted earth
•  rammed earth
•  tamped blocks
•  pressed blocks
shaped earth
•  direct shaping
•  stacked earth
molded earth
•  hand shaped adobe
•  hand molded adobe
•  machine molded adobe
extruded earth
poured earth
earth on form/structural framework
•  straw-clay
•  cob on post
applied earth
•  wattle and daub
This could probably simplified and combined. It actually does not include stone and mud mortar, which would be a masonry category, but otherwise it seems to include pretty much all of the methods of using earth in construction.
Another system (slightly simplified) might be:
•  excavated or dugout structures
•  massive earth
•  masonry
•  earthen mixed technologies

John Warren also gives a breakdown of earth construction systems in his book on Conservation of Earthen Structures. I do not have that at hand right now. It would be worth looking at also.

Thanks to all who are giving so much thought to this and to developing a description of earthen architecture and regional examples for the US.

May 24 from Jerry Erbach:

In north Yemen and southwestern Saudi Arabia they use earth laid up in bands and compacted with a wooden paddle to build houses up to six stories tall. Very impressive stuff. Not sure where it would fit into the suggested categories.

May 24 from Julio Vargas Neumann:

Dear Jerry, those experiences in north Yemen and southwestern Saudi Arabia, looks like are a rammed earth because the compaction, but is a mud masonry.

Dr. Archie G. Walls, explain the layered technique noted in Oman (1977) in his paper "Arabian mud brick technology: Some thoughts after the Bam earthquake" (2003), originally hand molded or adobe blocks were laid in mud mortars and rendered with mud plaster taken over every three blocks courses. This is a layered mud masonry.

Both different mud technologies are clear examples of Earthen Architecture.

Unless other opinion.

May 24 from Tony Crosby:

Jerry Erbach described a form of earth architecture in southwest Saudi Arabia and North Yemen where builders layup bands, or lifts of earthand compact the masswith a wooden paddle. This is a good description of a technique that is found in many parts of the world. In the CRATerre - EAG publication that Leslie Rainer referred to by Hugo Houben and Hubert Guillaud this technique is "direct shaping" and is described as, " . . . It makes use of a plastic earth and makes it possible to model forms directly without using any kind of mould or formwork." In the American southwest this technique is referred as "puddled adobe", although thatlatter term is not descriptive of the actual technique. In central and south America the general technique is known as tapia. I think there is a difference of opinion of the term "tapia" to describe, but we should hear from some of our Spanish speaking colleagues for clarification. . . .

A similar method is referred to as "stacked earth" inHugo and Hubert'schart of 12 basic types of earth construction. In the UK this is known as cob and defined as " . . . consists of stacking earth balls on top of one another and lightly tamping them. . . to form monolithic walls. . . ." Stacked earth, direct shaping and rammed earth are the three primary types of monolithic earth construction.

Of the twelve main methods of using earth as a building material described in the referenced publication nine refer to earth as the primary structural component. In addition, the chart contains a combination of both the production of building units as well as the construction technique. The publication providesmore detailed descriptions of the various techniques that help in our understanding. Of these twelve main methods, seven are described as the most commonly used. These are (1) adobe. (2) rammed earth, (3) straw-clay, (4) wattle and daub, (5) direct shaping, (6) compressed earth blocks, and (7) cob. I have taken the liberty to include the graphic used in the publication. As has been suggested by others such as Ed Crocker, Leslie Rainer, Mac Watson, and Julio Vargas there are different levels that would be useful in clearly describing and classifying earthen architecture.Some that have been pointed out are whether earth is the primary component, whether the earthen component is load-bearing, and if it is monolithic or consists of building units. All these are useful. There are certainly "gray" areas when classifying the earthen architecture, but these simply lead to a better understanding of the materials and the construction techniques. There are also many variations on the same basic theme. . . .

Before I forget it, the reference for the English of the Houben-Guillaud publication is:

     Houben, Hugo and Guillaud, Hubert. Earth Construction, a Comprehensive Guide. Intermediate Technology Publications, London, UK; CRATerre-EAG, Villefontaine, France, 1994. ISBN 1 85339 193 X. The original version in French was published in 1989.

There are other important resources such as the John Warren one that Leslie pointed and all contribute to our understanding.

May 25 from Pamela Jerome:

The method in Northern Yemen is the same used in England known as cob (or clob or clom, if I remember correctly). It is simply a type oframmed earth without formwork. I think this method is also known aspuddled earth. Although the English also erected the material in lifts, the Yemenis make decorative use of the banding and the bandslift up at the corners, which may help key in the corners for addedseismic stability.

May 25 from Jonathan Bell:

Many Tibetan structures also use this type of rammed earth with a simple formwork, sometimes just thin branches interwoven together.

Even when structural walls are made of stone, a flat, rammed earthen roof is common and results in the types of problems you can imagine when not maintained regularly. When available, the roof and walls often incorporate a lime-rich soil known as arga throughout the Tibetan diaspora.

May 25 from Ed Crocker:

We might be running a little far afield since Tony's original intent (I think) was to categorize earthen typologies in the US. This is an amazingly informative discussion which I, like most of you I'm sure, have been reading with interest and filing. I might be good, though, to get back to the job the Chairman asked us to do which was to describe the various US forms for posting on the EA website. Then, I think, we could globalize.

May 25 from Gustavo Araoz:

To the ICOMOS Earth People:

As an amateur, but very interested observer of your exchange, it seems to me that you are at the point where a task force should be appointed to define the challenge, and develop a rigorous methodology to begin to draw up the taxonomy that you propose. Sure it is a lot of work, but this is important work for which funding might be obtainable. So let him/her who has ears, hear.

As the ICOMOS Vice President in charge of the International Scientific Committees, it has been a great pleasure to eavesdrop on this informal and informed discussion. However, for your work to have value for ICOMOS, it needs to acquire a certain rigor, and have an end product that then all ICOMOS and points beyond can benefit from and use. For instance, one of the big challenges in fulfilling our responsibilities in evaluating nominations to the World Heritage List lies often in our inability to say with unwavering certainty that a nominated site is the only one of its kind, the best of its kind or perhaps even the most representative of its kind. This recurring problem lies with the "its kind." Whether it is earthen architecture, rock art, vinyards, bridges or historic cities, some of our taxonomies / typologies are not far enough evolved to give us that certainty - we simply do not have complete and well thought-out lists related to some categories of heritage. I encourage you to continue with this constructive process, and to begin to think of the next steps. Perhaps you could eventually link to the Vernacular Architecture Committee and invite them to test whether the various techniques or typologies of earthen construction can be linked to certain typologies of vernacular buildings or vernacular settlements; and to the Archaeological Heritage Committee to apply your typologies to past cultures, etc.

And in my other role (or my real life / day job) as Executive Director of US/ICOMOS, I would simply remind you that our Specialized Committees in the US are urged (or required??) to submit to the Board an annual work plan with a related budget. The Program Committee evaluates the work plans of all committees, and then decides / prioritizes how to best support each. You guys have an "inside connection" in that Pamela Jerome, the Chair of the US/ICOMOS Program Committee is a "mud people" who understands the full importance and need of what is being proposed. Because of this, she can be your champion when it comes to establishing priorities.

Whether you decide to this at the level of the US, at the US-Mexico or at the global level (the latter is preferred), I again, urge you to march on. If in emulation of Sherwin Williams paints, you decide to cover the globe, I would suggest that you engage the entire membership (or potential membership) of your International Committee in this discussion, as well as in any more formal projects that spring from it. In this sense, I remind you that all ISCs will be required to submit their triennial work plan for Advisory Committee review and Executive Committee approval at our 15th General Assembly in Xi'an next October.

Even during your darkest hours, the Earthen Architecture Committee has always been exemplary in terms of you relevance and activities in your field - for that I am looking forward to more eavesdropping.

Good luck! If I can help somehow, in either of my two personae, let me know.

May 25 from John Hurd:

I have just read the thought provoking exchange on definition, and reading it as a digest demonstrates the detail and direction that can be achieved in a short time. The exchange so far has triggered many thoughts. Typologies are a wonderful study and I am already struck by the similarity with structures known in Europe although I suppose it's not surprising. I am sure that Ian Bowman in New Zealand could draw comparisons, and indeed Scotland, Scandinavia and Ireland et al.

Once you have advanced further in the US typology, we might, as Gustavo suggests, look to other regions and compare the typologies, perhaps to migrations and adaptation.

In ICOMOS UK, earth group we did a similar thing in 2000, we published our findings as 'Terra Britannica', with the help of English Heritage. I do hope that I sense a 'Terra Americana' in the offing.

Insects have different impacts in different climatic regions. In the Steppes we have hundreds of insect inhabitations including termites. Spiders, scorpions on a sort of insects from hell register. The damage, like that of the masonry wasps and bees in Europe tends to be surface only or as you say, at interfaces within the construction, especially connections to wood, or in damp areas, and at worst, when fungal mycelium are present, as they so often are, ants then can become a particular problem as do termites, capable of converting a straw filled adobe wall to a fantastic termite 'city' within a few weeks. So yes, a very important thought and another thing worth quantifying and describing.

Ed Crocker's points are of course always close to my understanding, thing is. That I still haven't reached the edges of the definition of earth 'building' or 'structure'. There seem to be three main divisions in Europe. Historic, ethnic, aboriginal, in Britain that starts in pre-history and continues through into the mediaeval where the types then start to form up into those described very adequately by the CRATterre 'mandala'. Traditional might describe the next category, and Modern the third, in Europe meaning perhaps mid 19th C. onwards.

Then of course there is another importantly different group. My oldest contractor pal in UK, once reminded me that you do not 'dig' a trench, you 'form' one, an entirely different thing. 'negative' construction should fall within any typology, (the WW1 trenches at the Somme in Flanders are something which have been considered as 'earth' structures as well as prehistoric terracing and bank and ditch defences, including city walls, however primitive.

So yes Ed, we should, at least broadly define where the boundaries lie; 'archaeological' certainly does not represent any barrier or 'ancient'. Is an earth-banked levee an earth structure or an irrigation canal in Ur?

Thing is Ed, and this may earn me an immediate Ed Red card, when a group of boys build a clubhouse in India, made of reclaimed cinderblock with earth poured in as a thick soup, which fills the voids and holds the blocks together, then coated with tar to keep the weather out, I have to call it perhaps 'composite' earth, and it is relevant. More than that, entirely recyclable and leaving virtually no imprint, I have to admire it. So earth, 'construction', 'stabilised earth' every kind of 'infill'. Sometimes it makes me shudder too.

I would avoid percentages of earth as an index of validation as little than a flexible parameter. It is, of course, a perfectly reasonable approach, but a lot of buildings, while having only a small percentage of earth, depend on that earth for structural cohesion. This does not make the structures earthen, but asks the questions, are mortars and plasters, ceilings and perhaps most importantly floors, included amongst 'earth' structures? I think that they are. Stone with earth upper stories surely must apply.

So yes. Definition and its value.

I shall follow the US progress with great interest, thank you for putting me in the loop.

May 29 from Richard Pieper:

I have not added my two cents to the flood of emails about what constitutes earthen architecture, but, for the record, here in the NY/NJ area we have Dutch influence wattle and daub (say 1650 to 1800) English influence cob (not much, but say 1750 to 1825), perhaps English influence wattle and daub (uncertain), German-Russian mud brick or mass clay/straw nogged timber frames (Buffalo, NY area concentration reflecting settlement patterns, early 19th century) and the mid- nineteenth century (1840-1850) load-bearing masonry adobes I have reported on, which are English tradition, via Canada, and popularized in the US by Ellsworth and others. I am frequently told of "cob" octagons but these are invariably "gravel wall" in the Orson Fowler tradition that use a very high clay content in the cementing matrix, but have no straw or other fiber in the mix. These pose an interesting question: Are these to be considered clay adulterated early mass concrete? or natural cement stabilized clay/stone mixes? The influence is Fowler, so it's a bit academic

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