Review of a construction method?

I just found this site:
http://www.planetaryrenewal.org/ipr/ultralc.html

He proposes an interesting building method. I'm posting it here, because it most resembles cob construction.

Essentially, he's creating a monolithic dome using light clay insulation, sandwiched between two layers of fibercrete, and reinforced with a fibercrete honeycomb structure.

He's doing this over a partially rigid, partially inflated form that can be disassembled and reused.

The biggest thing I see missing in his documentation is a water-proofing material on the outside. With ~12" of light clay and maybe 1" of fibercrete on both ends, it should be about R-20 on the walls and roof. The hexagonal or square dome design he proposes should be pretty strong and energy-efficient, as well. I like the arches that create flat walls that can be connected to additional units, as well.

Thoughts on this?

Hi Kevin,

This is another of the "fad" building methods to spring up in the "natural building" circles over the last 20 or so years. Like so many, I often find these "new ideas," a reinvention of (often better) "old ideas." As I ask clients, when they ask me to take an "outside look" at a natural build project...."what is the vernacular building modality for the area you are considering to build in, and/or what are the natural resources present.

This system (fibercrete, paper crete, etc) are all dependent on "bringing things" to a build (i.e. machines, materials, etc.) Often these "materials" are not the most economical choice for a given building location, nor germane. I think these "cretes" have merit...perhaps...in some applications and designs...yet have I found them (in the big picture) superior to historical/heritage methods.

Yes, his sight is void of many details in application, or comparative architectural analysis. Many of these "modern natural build gurus," get building concept into their heads, and drink a bit too much of their own "KoolAid." Very creative folks, glad we have them doing their "thinking and experimenting" and we learn much from these efforts. I am very grateful for that...Seldom do I find the methods overly applicable as they are often presented...and more a matter of "want to do it this way..." than an actual over all good concept in there entirety.

Regards,

j

If I understand you right, J...

Your critique of this method is that it has to import materials, like the Portland cement, conduit and plastic for rigging the form, and maybe even straw from a nearby agricultural source?

I can see a few advantages in these things. First, building codes seem to prefer the predictability of cement-stabilized materials. Second, this would go up very quickly. Third, it would have the structural, but insulating, properties similar to a SIP, but being monolithic, would be stronger.

Sure, we could achieve much of the same effect with hand-cobbing, but it would be much, much slower, and likely use more material than is actually needed as the structure is cobbed course by course. I also like the structural honeycomb concept.

When I compare it to less "faddish" methods, what do I see?

It is more insulative than earthbag construction, which is better for a mid-continental climate.

With an integrated roof, it reduces complexities involved with securing a roof in post & beam construction. Post & Beam also suffers from insulation issues at the posts (no matter how insulative the in-fill is, the posts are still wood, earth, or cement).

A lot of the less faddish, vernacular design methods use a "plastered light clay" in-fill in their post/beam construction. By making the "plaster" a vapor-transmissive fibercrete, it can become structural, rather than in an in-fill only option, or not?

If you are still considering Missouri, you can't do a dome unless you use a non-permeable outer shell. The freeze thaw cycles will spall any crete with moisture penetration. Paper crete will fail spectacularly in these conditions.

There are so many "natural" building methods that were tested in the southwest that are now being promoted for areas they are totally unsuited.

Papercrete would be great in-fill for timberframe if you have cheaper access than bales. Same moisture protection (hat and boots) needed.


What is your goal? Minimal imported material? Minimal embedded energy? Minimal cash outlay?

My favorite plan for MO type weather is still a large pole barn (cheap--even cheaper if you can source recycled power line poles for free) as the roof-first construction. Add permanent wall on prevailing wind side(s). Use tarps initially if you can't afford tin initially. Then build small cabin under this protection--bedroom(s) and kitchen living room--with super insulation but minimal weather protection necessary. Add screen rooms for summer living. Basically a park shelter house.

R,

I am well-aware that an integrated roof/dome would need to have some sort of weather-proof shell. That was my biggest complaint about that site's model. It would either require a different kind of cement on the exterior, or some sort of coating. The best weather-proofing coatings are industrial/chemical. I asked in another thread about some natural alternatives to this, but I'm doubtful.

I think I understand the concept you're describing for Missouri. I had the thought that the traditional post-beam w/ in-fill is not so great, because the posts themselves would be heat conductors. If they are integral to the wall system, then they compromise the insulation.

I figure-- if you need to have good "hat and boots" to protect the in-fill material from the weather, and are best off with deep eaves, why not build the posts out at the perimeter of the eaves?

I think this is just what you're describing: You build a structure, almost like a park pavilion, with posts and beams, and a good foundation and roof, THEN build a much more light-weight insulating wall beneath it and within the post perimeter to surround the living space. Thus, the posts might be at the outside perimeter of a wrap-around porch. This could be screened/glazed or left open. The important thing is that the exterior walls of the living space are not structural, and thus could be built out of anything one desired for a particular thermal mass/ insulation profile, without regard to supporting additional weight or worrying about exposure to rain. This opens up far more options for the walls. In Missouri, and other places with a cold, dry Winter, and hot, humid Summer, insulation and humidity moderation are far more important than thermal mass. The nice thing about Missouri is that a lot of land can be bought with good trees that can be harvested for this kind of construction, as well as nearby farms that might bale straw.

One more advantage of Missouri is limestone. It can usually be found by digging into hillsides just a couple feet at most (where it's not already exposed). Limestone would make great rubble foundations, stem-walls, and piers for our posts (avoiding the need to bury wood). My biggest concern is how to insulate these limestone structures.

bingo.

Floor can be insulated or ground coupled-the dry area of the "porch" will act like a miniature PAHS/wofati umbrella and help keep it at earth temp.

I would build both winter and summer kitchens and bedrooms. A small cabin should be able to be heated just from the cooking and body heat in much of the winter. Much of the year sleeping in a screen room (or hammocks in the larger living space) to enjoy the naturally cool nights. Maybe use a small super-efficient AC unit to cool the insulated cabin in the worst of the hot/humid late summer. Most offgridders have a surplus of solar power in July and August here--enough to run an ice machine and an AC.

Last temporary cabin we built was two layers of square bales with staggered joints and used industrial racking to hold the roof. Once the "house" was done, the bales were sold (at a profit due to the drought) and the racking put to use as storage.

You could easily do Nebraska style bale with cob/earthen plaster to keep the bugs out. Minimal reinforcement needed.

Would there be no way of effectively creating a 4-season cabin?

For instance, using the sun-angle difference to use passive solar heat gain in Winter?

One thing I loved about the plans shown in the original post are their modularity-- the ability to connect up structures.

In Winter, particularly, I would love to be able to have a community of people never have to leave a sheltered space. My design parameters:

-- "Duplex" cabins. Essentially studios of ~300 sq.ft arranged so that there is a half-bath (with composting toilet) shared between two units. No kitchen or bathing facilities.
-- "Community Building". Commercial-size kitchen, communal dining/recreation area, bathing facility, laundry, library. Perhaps added wood-fired sauna/hot-tub. (Basically, most of the heating- power- and water- intensive applications are confined here).

We'd ideally like to have 6-8 of the "duplexes" per community building, serving 10-12 adults plus attendant children.

These could be arranged in little housing clusters, but we'd LOVE to be able to connect them all together in such a way that you could walk from building to building in slippers and bath-robe, even in Winter.

You could create a 4 season cabin, but it would be simpler to build 2 seasonal spaces if you have room. IMO.

This plan is extremely modular and could easily adapt duplexes or a courtyard common area arrangement. Completely enclosed would get expensive, but roofed and wind-protected breezeways can be built between large buildings for affordable prices. Good place to practice alternative building methods for weather resistance.

You can get HUGE pole barns for very little money as farms upgrade or go under. There are often large turkey barns for sale in MO for well under a dollar a sq. ft under roof. Good REuse of materials.

ETA: Here is a CL ad right now just as an example: http://loz.craigslist.org/grd/4481537318.html

Hi Kevin,

I am not a fan of anything with creosote in them (or other toxins) like telephone poles, but other than that (as a timber framer) R. Scotts advice is about spot on for speed, cost and ease of build in many areas..."pole structures" (which timber frames are a pseudo from of) "RULE THE ROOST" when it comes to fast and affordable (and flexible) DIYer project architecture.

Your critique of this method is that it has to import materials, like the Portland cement, conduit and plastic for rigging the form, and maybe even straw from a nearby agricultural source?

Hmmm, not exactly, as other than locally sourced straw, I do not care at all for those other materials in a "natural build."

Sure, we could achieve much of the same effect with hand-cobbing, but it would be much, much slower, and likely use more material than is actually needed as the structure is cobbed course by course. I also like the structural honeycomb concept.

Actually this is probably more subjective that empirical, as both are going to take a first time builder a much longer time to facilitate...the cobb is going to be more enduring and of course, more natural a build and in line with Permaculture ethos.

When I compare it to less "faddish" methods, what do I see?

It is more insulative than earthbag construction, which is better for a mid-continental climate.

Sometimes, but not always...it would depend on the form of "bag architecture" you would employ...not all are filled with earth....

With an integrated roof, it reduces complexities involved with securing a roof in post & beam construction. Post & Beam also suffers from insulation issues at the posts (no matter how insulative the in-fill is, the posts are still wood, earth, or cement).

A lot of the less faddish, vernacular design methods use a "plastered light clay" in-fill in their post/beam construction. By making the "plaster" a vapor-transmissive fibercrete, it can become structural, rather than in an in-fill only option, or not?

Hate sounding this arrogant, but for lack of time (please forgive me) having been in the "natural and traditional" (a.k.a. permitecture) building field on and off since about 1968 I would have to disagree with the above statement...IF....you are an experience and seasoned Timberwright...If you are a DIYer then some of it could very well be true.

I am well-aware that an integrated roof/dome would need to have some sort of weather-proof shell. That was my biggest complaint about that site's model. It would either require a different kind of cement on the exterior, or some sort of coating. The best weather-proofing coatings are industrial/chemical. I asked in another thread about some natural alternatives to this, but I'm doubtful.

Simply put...there realy isn't any and this modalty (like many grown in the desert and in the imagination of "new age builders") has a long way to go to better more traditional or simpler systems...such as R. Scott has suggested in "pole architecture."

I think I understand the concept you're describing for Missouri. I had the thought that the traditional post-beam w/ in-fill is not so great, because the posts themselves would be heat conductors. If they are integral to the wall system, then they compromise the insulation.

If you go with a strictly infill method...that is true to a point on some of the traditional modalities, yet again, not always. It also depends on the skill sets of the designer and facilitator/builder. Remember, log cabins (I happen to live in one in Vermont) have low R factor but much higher U factor than conventional "stick builds" (what we call "icky stick building") yet can perform well...if built well. We had a horrendously cold winter, with an aver in three moths of less that 10 degrees F...yet only use one cord of would and $450 in propane, yet kept a snug 1400 square foot cabin warm, and that is with doors being left open and no curtains on "way too big" picture windows...(wife's choice there...)

I figure-- if you need to have good "hat and boots" to protect the in-fill material from the weather, and are best off with deep eaves, why not build the posts out at the perimeter of the eaves?

Hmmm,...don't see the logic in that, nor is it how it is (or was done.) The "hat" is important for many reasons other than just protecting the siding (no mater the form.)

This could be screened/glazed or left open. The important thing is that the exterior walls of the living space are not structural...

I may have missed something, but this caught my eye...I am not sure where you got the idea that the "exterior walls" are not structural (unless you meant the insulation portion) but the frame work most certainly is. The traditional post and lintel format of many timber frames (pole architecture) is to have an exterior living space surround the interior living space, both providing security, protection and a way to circumnavigate the structure while still being off the ground and out of the elements. This is called the "engawa" 縁側 (veranda) in Japanese architecture and is a very common and germane architectural practice.

Would there be no way of effectively creating a 4-season cabin?

Many, many ways...again look to the vernacular building systems with similar climate biomes.

I would love to be able to have a community of people never have to leave a sheltered space. My design parameters:

These could be arranged in little housing clusters, but we'd LOVE to be able to connect them all together in such a way that you could walk from building to building in slippers and bath-robe, even in Winter.

Japanese, Koreans and Chinese have been building this way for about 4000 years on and off...very good way for a agronomic culture to live...

Regards,

j

Kevin EarthSoul wrote:I just found this site:
http://www.planetaryrenewal.org/ipr/ultralc.html

He proposes an interesting building method. I'm posting it here, because it most resembles cob construction.

Essentially, he's creating a monolithic dome using light clay insulation, sandwiched between two layers of fibercrete, and reinforced with a fibercrete honeycomb structure.

He's doing this over a partially rigid, partially inflated form that can be disassembled and reused.

The biggest thing I see missing in his documentation is a water-proofing material on the outside. With ~12" of light clay and maybe 1" of fibercrete on both ends, it should be about R-20 on the walls and roof. The hexagonal or square dome design he proposes should be pretty strong and energy-efficient, as well. I like the arches that create flat walls that can be connected to additional units, as well.

Thoughts on this?

Great site! Great ideas! Nothing new, it has been done in auto and aircraft for centuries. I skimmed through it....lets start at the beginning. "Natural Insulation" section using clay soaked bales, nothing new as noted. Putting skins on over it of any kind is the natural builders answer to SIPS, which is also referred to as "Sandwich Construction" old as dirt.

Next "Structural Materials" he provides ALL kinds of materials to locally source, from clothing to high tech fiber like helix, to gain any property you need, any perm rating you need, the sky is the limit. Well perhaps codes.

Tomorrow I'll look at some more sections in more detail with ya, done for the eve

"Fibrous composites (papercrete, fibercrete, etc.), can also be very insulating, depending upon their design density, but can have structural capabilities as well."

"Or it can be used as an insulated fill material for the honeycomb construction method as described in the Design section"

The best weight-to-strength from fibers is obtained from continuous ones. Woven cloth offers it in uni-directional (two), others such as "tape" have the continuous fibers in one direction. You can make hybrids depending on what direction strength you want. You can lay 45 degree, 90, 120, etc.....great for skins over honeycomb core, used in aircraft a long time now, hand lay-ups are labor intensive. Automation has taken over but the tooling is expensive.

The least strength comes from broken fibers in a binder or resin persay. The strongest I seen is Helix due to the torque it imposes.

Concrete or an earth mix can be brittle so if it sees any tension from bending it cracks. It does better in compression. All materials crack in tension so it's no different. Rebar, the nodes on it like bamboo, resist tension or pulling apart by it's bond with portland cement to aggregate. Helix fiber strands are twisted like a drill, so it resist tension better no rebar require in most cases.... it is a fiber I think graphite, light costly tho. All the others ones need to be tested and quantified for tension resistance in whatever binder and aggregate it is placed in.

I think it is important to match materials. If you are using flex bales use a flex clay plaster scratch coat to handle moisture and flex to bale prevent cracking from load shifting, finish with an endurance stiffer coat of fiber composites if you need to transfer shear strength from the roof to the foundation, beyond bales ability, or siding.

"Composite materials can be sprayed (using compressed-air driven sprayers), or poured, or packed directly onto a reusable formwork (using hand methods)."

I like the idea of "sprayed" as in gunnite, or poured....take labor cost down compared to troweling by hand. Has anyone tried spraying or poring a structural fiber reinforced earth mix on bales?

SCIP mentioned is spraying shotcrete on foam with steel mesh, not that I like toxic foam, but some homes have successfully been built air tight, net zero or close. I hear though from a builder in Denver I talked with that shotcreting depending on the contractor can be expensive if you do not know how to mix and loose alot to ground...If you using an earth mix that may not matter as much since the material cost loss is much lower than shotcrete.


I got more on honeycomb designs later He makes some misleading comments in his "Engineering Principle" section too I'll try and clarify more..

Jay C.--point taken on the creosote (or worse) of utility poles. It is one of my compromises being in termite country. I will accept free toxins in utility poles over paying to bring in treated lumber, especially old poles that have already leached most of what they will ever leach.

R-Scott: Where would you find the poles free? If they had creosote could it milled off, I don't know if it is just a surface finish I am assuming what 1/8-1/2 thick?

I don't get where you guys are coming from. I'd set structural poles in tied to roof protect them with an outer non-structural(or perhaps structurally redundant) bale wrap continuous insulation and air tight seal. Not sure I'd want creosote for Indoor Air Quality though ..outer bale wrap also work for tornado ballistic proofing in the central planes.

Yes, I think there is a way out of portland cement if the skins are taking loads or protecting clay plaster.

Hi all,

No, unfortunately, milling the "poisons" off or out of these poles is impossible. We have several saw mills in our group of artisan (I own two of them) and we are turning folks away all the time that believe they can do this. The poles are "pressure cooked" with the toxins in a "bath," and when complete...the toxins are "through to the pith" when done well, and at a minimum, reach a 20% saturation through almost the entire interstitial matrix.

R.Scott, I understand the worry over termites, yet as a former state superviser in pest control...I can share with you...it may not be as bad as you fear. There are natural and/or more benign remedies to look to other than the poisons that are in these poles, or the support of the industries that are behind them...Remember, timber frames are "pole barns," and come in many different forms and types. Some complex...some "simple easy" to do...

Terry, I am with you on this one...except for "air tight"...draft proof yes...airtight...not good. I want may structures to be permeable and "breath." (and "yes they do," to you readers that claim buildings don't breath)..Be it a house, a barn or an office complex...with occupants...those buildings most assuredly do have respiratory systems, not only their own but those of the occupants) and "air tight" is a sure fire way to find yourself with "sick building" syndrome and/or the need for more technology to make the structure functional, which is kinda silly as you can build well without all the "tech."

Regards,

j

Jay, if your straw bale wall is not air tight how do you propose to keep moisture away? Wood does not do good around moisture and convective loops and can rob r-value as much as 40% test have shown depending on the density of the insulation...higher than thermal bridging. Here is a hot box test by BSC all using worse case loose filled fiberglass batts:http://www.buildingscience.com/documents/special/content/thermal-metric/BSCThermalMetricSummaryReport_20131021.pdf

They used a hot box test to infiltrate and ex filtrate and induced air loops in a closed wall cavities at the lower sill through 1/32 " gaps to set up the cavity loops. Then they cycled the walls -40 - 120 F using CO2 and moist air pressure to simulate indoor humidity and wind driven rain. They had thermocouples and air gages at center wall and through r-value to compare steady state and dynamic flux loads, develop a knock down value to r-value for future manufacture and design use. The 8 walls were of different geometry, the closest to a bale wrap was #7-8 a REMOTE foam wrap, dry to the interior, dew point they say but can not prove in the outer foam not in the wall. Using bales of more density I would be less concerned about loops and more concerned about damage from moisture that would drop the r-value, since broken dry air is the best insulator and all the insulation does try and stop convective loops. There is some testing shown that dense packed cellulose is unlike a loose fill that codes were developed to, and therefore some codes are allowing a sealed wall or vaulted roof. I think the other main concern most fail to understand I think you will agree with is, that fungi loves a lack of movement, IF, you have sealed in a fungi such as a fire retardant bromine. If you used a dense cellulose or mineral-rock wool natural insulation that is fungi resistant by nature, or in the case of cellulose a borate additive fungi resistant, they problem is minimized. If you seal wood in this wall (which I am opposed to in any form) then dry rot can occur some studies have shown, now fungi can grow......I'm not sure what method I agree too, it depends on the materials and design. I favor mineral or rock wool from the factory it also has a minimum embodied energy...check out Roxul. I can get bales for $3-5 ea here. I am looking at cost now. If the bales can take the loads if beats stick builds to hold batts. I have opened a dialog with my AHJ recently and we have two bales houses here for prescriptive code compliance, since I am not sure where to get compression and shear allowables? That is just the beginning, I as a builder have to get past insurance, appraisals, comps, loans, marketing, clients, etc......If I use my own construction money I won't have banks inspectors breathing down my neck about something like bale construction they do not understand, too. So you see, when you are looking at a natural builder spec production homeruns, using "local materials" sounds and looks good on paper, just not easy to put into practice. Further, try and energy wrap a home to make it more energy efficent when you do not have 14-16" outside the perimeter...4-8" of foam is easier.

I do think it is a sin to take beautiful wood craftsmanship and jointly and hide inside a wall or to the exterior.I'm so tired of reading all the problems with lite 2 x 4 construction infilled with insulation, all the opinions and people making money on it as "gurus" or building scientist, when all they have to do is revert back to nature. They won't since the wood and concrete, insulation, etc, industry that lobby for codes to increase their production rates do not want to hear it or even discuss it. That is why I am a Permie now