Green Building Discussion

 

Wood Chip and Clay Building Blocks

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All postings are the opinion of the writer, and BuildingGreen can take no responsibility for their accuracy or appropriateness.

John Abrams wants to know about using wood chips

From: John R. Abrams
Sent: Saturday, November 02, 1996 3:07 PM

First I want to thank everyone for the many astute questions and comments I've eavesdropped on this past month or so.

And next, a question. We've been working to develop several approaches to use the (meager) natural resources of our island region to better advantage as building materials. Clay from excavation of our hilly upland building sites and woodchips from the continual clearing of brush and scrawny trees are two materials that people often dispose of. We've been considering making building blocks from a mixture of these materials.

Recently Frank Andresen, a German clay builder, came to visit. In Germany traditional wattle and daub building methods have evolved to straw/light clay and woodchips/light clay. Some of the brick manufacturers make blocks out of these materials. You can call, place an order, and have them delivered.

My question is this: is anyone in this country making such blocks, on any scale, from seat-of-the-pants/backyard to cottage industry to industrial process? And has any analysis of the thermal and structural characteristics been done? I'd appreciate thoughts and comments about this.

John Abrams 508 / 645-2618 (W) jabrams@smc.vineyard.net John R. Abrams 508 / 645-3182 (F) P O Box 359 Chilmark, MA 02535

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Bill Christensen suggests Faswall

From: greenbuilding Conference @ txinfinet.com
Sent: Saturday, November 02, 1996 3:45 PM

The closest thing I can think of is Faswall, in which "mineralized" wood chips are coated in a cement slurry and formed into light, insulating blocks used as concrete forms.

They have a plant in Atlanta and one in Ottumwa, Iowa, that I know of. There was talk of one starting up in Houston, but I haven't been keeping close tabs on them.

There's also a similar product coming from a company in Canada-- Toronto area, I think. Anyone have contact info on them?

There are three Faswall homes and one addition in my (admittedly alternative-leaning) immediate neighborhood, built by two different builders. They all came out real nice, though not inexpensive.

Bill Christensen billc@txinfinet.com Green Building Conference Nov. 7-10 http://www.greenbuilder.com/conference/

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Norbert Senf with some resources

From: Norbert Senf
Sent: Saturday, November 02, 1996 7:45 PM

We have a paper on our site that you might be interested in titled "Proof-of-Concept, Development and Testing of The Biocrete House Construction System", located at:

http://mha-net.org/msb/html/papers-n/biocrete/biocrete.htm

Norbert Senf email: mheat@mha-net.org Masonry Stove Builders website: http://mha-net.org/msb RR 5, Shawville fax: 819.647.6082 Quebec J0X 2Y0

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Marc Rosenbaum tried some

From: Marc J. Rosenbaum
Sent: Sunday, November 03, 1996 5:17 PM

John -

I'd like to know how they do it in Germany. I've been interested in combining the same two materials, so when I took Robert Laporte's straw/clay workshop I brought a couple of 5 gallon pails of wood chips with me to mix with the clay slip. I thought that that way I would at least be confident that the slip was of adequate quality. In any case, the material seemed to not want to stick together (whereas the straw/clay mixture had high integrity.)

Marc

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Alan Wickstrom with some more resources

From: BuildingOnline: Alan Wickstrom
Sent: Sunday, November 03, 1996 7:10 PM

Our friends at EBN have a good article online about Faswall at: http://www.buildinggreen.com/products/faswall.html

Their is also a loonnggg discussion thread about Faswall from The Center for Renewable Energy and Sustainable Technology starting at: http://www.crest.org/efficiency/strawbale-list-archive/9606/msg00332.html

George Swanson, Swanson Associates, Austin, TX will discuss the use of Faswall in building at the Green Building conference on Saturday, November 9, at 4:00pm... read about it at: http://www.greenbuilder.com/conference/schedule.html

An article appeared in Energy Source Builder #35, August 1994, also breifly mentions the use of Faswall in a Habitat home as reprinted on Oikos web site at: http://oikos.com/esb/34/HFHhouse.html

All these links found via the Building industry's search engine at: http://www.BuildingOnline.com/blsearch.shtml

Cordially, Alan Wickstrom ~ webhead@BuildingOnline.com

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Tom Hahn on cement-straw blocks

From: Tom Hahn
Sent: Thursday, November 14, 1996 11:31 AM

I have heard a rumor about a cement/straw block similar to Faswall but using straw instead of woodchips. It is apparently made (going to be made?) in Canada. My source said it was called 'PailloBlock'. They flew a 'trial balloon' on the 'Net over the summer in the US, and got swamped and have since pulled back, I believe. Does anyone know anything about such a product? We are planning the next issue of The Last Straw to focus on Alternative Fiber Use for building, including straw, bamboo, hemp, wood chips, etc. and I would like to track down a unit masonry made with straw. Any leads on this or other materials would be greatly appreciated.

Also, has anyone else had experience with Integra Block, made here locally by Superlite, but marketed around the country by Oldham Industries? It is a specially designed block with only one web (only half-height, too) connnecting the faces. It is a post-tensioned wall system, so there are no grouted cells. High-performance polyurethane is injected after laying-up to get a latest version series-parallel rating of R-27 in a regular 7-5/8" masonry unit width. It has not been hot-box tested, as far as I know. Their standard foam (and the one in the rating) is an R-7/inch polyurethane, but we have used the non-CFC/HCFC Super Green, and I suppose Icynene or Air-Krete could also be used. It is wet-laid with mortar just like standard masonry, so requires no bond coat (or other exterior finish, except a sealer, for that matter) and has a complete ICBO report for the system.

We were able to get Superlite to use 27% flyash in the mix, as well as getting the masons to use it in their mortar, to offset the cement EE. I looked at a lot of test data from as many different masonry and insulated-form (e.g. ICEBlock, Insteel, Rastra, etc) manufacturers as I could get and didn't find one with reliable specs better than that, that also didn't need an exterior finish (to save material/labor/resources). The closest were ones called IMSI or OMNI Block and Thermalock (which may be the one referred to that has no webs connecting the faces, it uses an interlocking foam insert to connect them). I've heard one of the mixed material insulated-form companies claiming R-34 in 8". Seems pretty high for a block with a lot of bridging and concrete poured in.

Any way, I would be interested in everyone's thoughts on such a system in broader use.

Regards, Tom Hahn The Last Straw - The Journal of Straw Bale Construction P.O. Box 42000, Tucson, AZ 85733-2000, USA (520) 882-3848 thelaststraw@igc.apc.org (e-mail) (Web)

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Buzz Burrell on different kinds of block

From: Buzz Burrell
Sent: Tuesday, November 05, 1996 10:51 PM

There are many different blocks being made. The chief difference is that some are "natural", like adobe, and some are manufactured, like Faswall, Hebel, Rastra, etc. I have a list of every manufacturer of this type of material, in case anyone wants to see it.

The manufactured blocks (which are basically a progressive C.M.U.) almost always have been tested for "thermal and structural characteristics". The natural ones have been tested generically, but not usually specifically, since the batches are often site-made and therefor will vary.

My general comments are this:

Manufactured - The "green" CMU's, like Faswall, have basically the same amount of cement as any other CMU, and only somewhat more insulation. This means the embodied energy of Faswall is probably higher than that of a "cinder block", and you still have to add insulation; neither of these observations are prominant in the promotional literature. The new masonry blocks also cost at least 3 times as much as the concrete block your local self service car wash was constructed of.

My personal belief is that the green CMU's are the future of the building industry in America, just like they have been in Europe for many years, and in Japan today, where they ran out of wood centuries ago. However, there is a steep price/value curve that us pioneers are currently having to pay in order to get these technologies up and running in the US.

At the present time, a viable and economical wall system is to simply dry stack regular concrete blocks, plaster the sides with a structural stucco like Q-Bond, fill the cavities every 4' with concrete and rebar, and pour cellulose down the rest. You could also put an EIFS on the exterior for real insulation. This system would be stronger, cheaper, more insulative, and easier to get a permit for than most.

There also are concrete blocks that are specially designed for precisly the above application; they have no thermal bridging.

To me, the real advantage of Faswall, and also the "Rastra" or "Ener-Grid" systems, is that the surface is so porous the stucco can be done in 2 coats with no mesh; this is a major cost savings. If you are not a DIY'er, the REAL cost of these wall systems is not the wall itself but rendering it.

Natural Blocks - The original post mentioned clay soils and seemed to ask for a low-tech solution. Obviously, adobe, or its modern counterpart, compressed earth block, should be considered.

Since the original question did not give a location or explain the situation, its impossible to comment intelligently. I will say that I definitly would NEVER put wood chips in any kind of earth block. A rise in humidity, and you will have a nice little pile of dirt instead of a block, as the wood will swell. There is no reason to do it anyway, as earth is cheap - usually free.

The Southwest Solar Adobe School is certainly the leading resource for this sort of thing. For C.E.B. and all forms of earth construction, the French are by far the most experienced, having built all manner of remarkable structures all over the world.

Good luck on this one - its a vast and complicated subject.

Buzz Burrell * buzz@diac.com * Boulder, CO

Project Manager: Geneva Cohousing Community - 176 acres N of Lyons, CO Owner: Bolder Building - solar adobe house (finished) in Paonia, CO Co-founder: Colorado Friends of Tibet - hosting the Dalai Lama in 1997

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Norbert Senf on dry-stacking

From: Norbert Senf
Sent: Wednesday, November 06, 1996 7:29 AM

I agree with most of Buzz's comments. It is worth noting that dry stacking regular cmu's and surface bonding them as described above, even without the grouted rerod, results in a much stronger wall (in shear) than a conventional cmu wall. The two tension skins turn it into a stressed skin wall. When dry stacking conventional concrete blocks, it is advantageous to have a supply of metal shims (brick ties cut up into 1" lengths, for example) handy. Blocks that are expressly manufactured for this purpose, such as Sparfill, are usually machined flat.

Conventional 2 coat cement/lime stucco is routinely applied to regular cmu walls without mesh, and has been for ages. It is not as foolproof as onto a very rough subtrate such as Buzz describes, however, so would not be as amenable to unskilled labour. Ditto for rendering onto a surface bonded wall, although the tension skin could be left intentionally rough as a "scratch" coat.

Norbert Senf email: mheat@mha-net.org Masonry Stove Builders website: http://mha-net.org/msb RR 5, Shawville fax: 819.647.6082 Quebec J0X 2Y0

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Darrel DeBoer on making it a party

From: DDarrelD@aol.com Sent: Monday, November 04, 1996 12:45 AM

I think I've seen the ideal format for a conference. This past week, about half the boardmembers of ADPSR joined with 100 other wonderful people for the Natural Builders Colloquium for 7 days of 3-5 concurrent sessions of both slides and (mostly) hands-on building. Spending 14 hours a day immersed in the philosophy of doing things the way we all intuitively feel sustainability is really all about caused a great reversal of the standard peer pressure of compromise. All told we built

A stone stem wall directed by the son of Ken Kern

The framing of a greenhouse with crotches of manzanita for posts and an arc of madrone for a ridgebeam - if only rosewood could look as great as what we already waste in our own forests.

A fiber-reinforced monolithic adobe wall structure with a compressed earth/gravel floor

Earth-pigmented adobe-plaster walls incorporating beautiful sculpture, with a team of women directing the bearded hordes.

An earthen oven that began life as a frog, but ultimately had a species change to a snail. While sculpting the face, the mix was moist and pliable enough that it was felt literally to come to life.

A double curvature bamboo-reinforced strawbale vault (almost a circle in plan with a straight, horizontal ridge) designed by the world's experts - Kelly Lerner, Bob Theis and Dan Smith. And who says architects won't get their hands dirty? They seem never to tire of it. The venturi effect through the vault should be very interesting next summer.

A hexagonal timber-framed gazebo, by Robert LaPorte. Milled entirely on-site with very complex mortise and tenon joints. I still can't believe that was built in a week.

Wanna hear about the rapid-fire 2-3 hour slide shows each evening? The live bamboo plumbing system? The 3 vegetarian meals each day, with some of the best food I've ever tasted? The halloween party that didn't seem to end? The amazing musical talent concentrated in this small group?

I feel a great debt to those who organized this and kept it affordable. I"d like to give the advice that you should begin freeing up a week to attend the next one. Better yet, consider helping to organize it. Unforgettable.

Darrel DeBoer