Miscellaneous Questions about Natural Buildings

Dan Chiras has been involved in natural and alternative building since 1994 and lives in an off-grid passive solar/solar electric home in the foothills of the Rockies. His house is built from straw bales, rammed earth tires, and numerous green building materials and is powered entirely by wind and solar energy. Dan is author of The Natural House: A Complete Guide to Healthy, Energy-Efficient, Environmental Homes, published by Chelsea Green; The Natural Plaster Book: Earthen, Lime, and Gypsum Plasters for Natural Homes (with Cedar Rose Guelberth), published by New Society Publishers; and numerous articles on natural building and sustainable design, which have appeared in Mother Earth News, Natural Home, and The Last Straw. Dan embraces a comprehensive systems approach to building that offers a wide range of benefits to people, the planet, and our economy. He will field general questions on natural building and offers consultation on project design and construction, as well as lectures and workshops on various aspects of natural and sustainable design and construction.

Questions and Answers

Q: Have you seen any tabulation of the number of green buildings--residential, commercial or otherwise--by locality, state, region, or nationally?

A: Good question, but the answer is "No, I haven't seen any tabulations or listings of green buildings." The strawbale people have a registry at which individuals can register their homes. States and cities that have green building programs -- such as Austin, TX and Colorado -- might keep tab of the green built homes in their jurisdiction, however.

Q: Have you ever heard of the enviro-bricks? I am considering building with these...they appear to be totally recycled, etc. Do you know if there is any approval in California for these?

A: I have never heard of enviro-bricks, but did check out their web site. You should probably research this more fully and contact the company directly for information about approval for use in California. As for my opinion: I'm always slightly conflicted about the use of flyash. As you may know, flyash contains some heavy metals, such as mercury, which can be quite toxic. However, I strongly do believe we need to recycle the stuff, rather than dump it in landfills, and using it for a building material is probably quite safe to the home owner.

My major concern would be for workers at the production facilities and, to a much lesser degree, to workers on the job site (if bricks are cut, inhaled flyash could be inhaled and create potential health problem). That said, I think that worker exposure to heavy metals on the job site is probably a rarity. As I said, though, my lack of knowledge and experience with this product forces me to turn this one back to you to research. I'd love to hear about your experience with the product, if you should decide to go this route.

C: I read your response to a person interested in Enviro-Bricks which utilize fly ash in some areas. Certainly, fly ash is not new and is now used in most cement blends now that the attributes have been well defined regarding increased strength and durability over cement alone.
First, I want to stress that we only use fly ash in some area, and it is not mandatory, so those who may for some reason be against recycling this EPA certified inert material can choose not to have it used for their home. Class (c) fly ash has barely a trace of metals, as you had answered the question on fly ash, so I thought it was important to point out.

We use only a small percentage of class (c) fly ash for added strength in the manufacturing of our Enviro-Bricks. The majority of components are local soils, so our Earth-Bricks can be manufactured without fly ash as well. Class (c) fly ash is completely safe and is far less dangerous than cement is. With proper research into class (c) fly ash, I am sure you will find it a more than suitable solution for safe home construction purposes with no outgassing or negative environmental impact.

The small percentage of fly ash we use in our Enviro-Bricks is even less than what has been used in cements for years with no negative reports. Since fly ash is now banned from land fills as inert, this is a further reason to find productive uses for this easily recycled by-product of all coal burning power plants. Enviro-Bricks are comprised of almost 100% recycled material while offering far superior attributes over any other so called Green building materials. After all, recycling the soil from our earth is as Green as it gets when discussing environmental concerns.

Q: GERES, a French NGO, supports the introduction of passive solar architecture in Highlands of Afghanistan. In this cold climate, we face problems with ground insulation. Straw is available but not clay. Thus lightweight concrete (straw/cement) may be a solution. Would you be keen to advice us how to implement it practically (mix ratio) and how to avoid dampness and mouse problems ? Shall we focus on vertical or horizontal ground insulation.Our aims is to build something efficient and durable rather than something very efficient but a bit risky

A: Say, I'm not really sure what these guys are asking...But it sounds as if they are asking for a mix ratio to create cement/straw blocks. I've never used this type of material but have made blocks with cement, shredded newspaper, and sand. What worked for me was 5 percent cement, 30 percent sand, and 65 percent paper by volume. This makes a nice light-weight block that can be mortared together like an adobe block. It provides good insulation, too.

Here's what I suggest they do...Try making these blocks with chopped straw -- two to four inch (5 to 10 cm) strands. Add sand and cement using a ratio similar to the one above. Make a block in a form...say using 2 x 4s or something like that. Let it dry and see how it looks. Don't put any lime in the cement, though, as this will eat away at the straw. Be sure the blocks are laid up on a good foundation to protect from moisture...Usually a foundation 6 to 10 inches high works well. The walls can be plastered after they're done to protect them from the elements. This will also protect them from mice...These blocks could also be made from subsoil if it contains around 20 to 30 percent clay. Subsoil usually contains a fair amount of clay.

Q: Cal Poly hosts a design competition every year where students design and build a structure in one day that they have to sleep in over night. The topic this year is "Sustain-A-Build," taking the stain out of sustainable. We have to build with natural products. It has to be light weight because we have to walk it up a mile long fire trial, and we should prefab the structure at school. Do you have any ideas on what materials we can use.

A: (Kelly) This what I would do to create cozy accommodations just about anywhere in the world: Take enough polypropylene sand bags (I know they are not natural, but what you put in them is, and they are very lightweight) to make a small dome, big enough to fit the number of people necessary. Also take some shovels to fill the bags with the soil wherever you do the building. Dig out the area inside the structure to fill the bags, so you are also creating more space and doing some natural berming. Also take along some clear plastic polyethylene (also not natural, but very lightweight and useful) to make windows and doors out of, and cover the thing on the outside for weather protection. Such a building could be quite habitable all year round. For more ideas about how to stack the bags, etc. you might want to obtain a copy of the book Building with Earth, available at our store.

Q: What type of plumbing (pipes) is best?

A: (Kelly) I have used both copper, and PVC for water pipes, but there are other types of plastic pipes also. The main problem with PVC is that it is toxic to workers during its manufacture, and some people who are really sensitive find it offensive. I think that copper is fairly safe, if the joints are not sweated with lead-based solder. I don't know about the other plastics.

Q: Can local builders can work with natural building techniques? Do you know anyone in the Virgin Islands doing natural construction?
A: (Kelly) Many of the skills involved with natural building technologies are easily learned and taught, and common methods of building involve many of the same skills. I don't know anyone there, but there likely are people doing this sort of work. I suggest that you become familiar with some of the natural building techniques through reading, viewing videos, or taking workshops.

Q: I live in South Florida and would like to start building my own earthen home. I had attended a Cob workshop, but feel that perhaps it's not my best choice in my area. The land is very sandy and I'm not sure what local materials I can use. Really there's sand and palms. I'd like to refrain from using wood as much as possible. What do you think?

A: (Kelly) Cob requires a certain amount of clay, as you know, to bind the material together. If your soil is too sandy, then you would need to import the needed clay to add to your sand. This would be true for both adobe and rammed earth as well. Another approach that could work with your local soil is earthbags, which can be filled with a wide range of soil types, including your local sand perhaps. Some sand works better than other in this application. If your sand is very fine and slippery, then it might not work as well as a courser, sharper sand, because this packs together better. I might suggest that you perform a simple soil analysis by putting about a pint of your soil in a clear quart jar, shaking it up thoroughly, and letting it stand for several hours. You will notice that the courser sand will settle to the bottom, while the finer silt and clay will form layers above this, and organic material will float or settle on top. With this information, you can see what % of the total sample the various types comprise. For adobe, etc., you need about 20-30% clay, but for earthbags, this could be much less. Then there is always the question of building codes, which can be a hurdle to jump when proposing unusual construction methods. You might need to check out what is possible in this regard.

Q: The material that you used to fill your bags - you mention that it is mined near where you live. I don't know a thing about this material, i.e., it's abundance, excavation process, or renewability, but is there any reason to be concerned that using materials that are mined (and not readily available on the site on which you are building) would somehow be environmentally degrading? Also, do you feel that it is more sustainable (green) to build using materials that are native to the particular region, or even site, that you're building on?

A: (Kelly) The material that I used to build my house with, scoria, is a very light-weight, pumice-like mineral of volcanic origin. This sort of material is common in the western U.S., but must be transported to other regions. Yes, it must be "mined", or collected somehow, and this can be disruptive of the site where this happens, but the deposits are generally on the surface and the area where this happens can be somewhat contained. I agree that the more locally one can find building materials, the better, in terms of the energy needed for transportation and the feeling of using indigenous materials.

Q: Is there a way to incorporate sustainable building materials into a prefab steel frame?

A: You could easily incorporate green building materials into a home built from a prefab steel frame. Your options are many. In fact, all materials you will be using to finish the structure have a green alternative--sometimes several alternatives.

Q: I am a retired ATT communications technician and a single mom. Everyone connected to me wants me to sell my 3k sq ft "Cape Cod" house in the suburbs of Atlanta, Ga. I would have to get it "sell" worthy but I do believe I may have a "sick" house. It is now 20 years old. It also takes a lot of electricity and gas to heat and cool it. Is it possible to use our red dirt to build with? I can no longer afford the utilities. And at my age (55) I don't want to get sick. What can I do?

A: If you have been living in your house for some time without ill effect (other than the cost of utilities), then maybe it is not so "sick". Most VOCs and other toxic materials used in building do eventually dissipate. It may be quite possible to retrofit your house in ways that would make it much more energy efficient and natural, such as increasing the insulation or changing some aspects of the design. Your red dirt may be just perfect for adobe or cob construction and you could add some of this to your house for more thermal mass.

Q: I'm looking to build a home from materials on my land. Summary of resources: 10 acres of rolling hills, 7 acres of hardwoods; elevation approximately 600ft, in the heart of the Carolina slate belt; lots of red clay. It's very humid, but mostly mild climate... average summer-highs are low 90's and winter-lows are mid 30's. My question is... What would be the best materials giving my resources for building (cutting down the least number of trees possible)? Insulated cast-earth seems perfect except for the humidity factor here... How would that work in NC humidity with the red clay? Are there better options?

A: (Kelly) The cast earth process is rather tricky to do, since it requires heavy equipment and a trained crew to do it right. I doubt that the humidity would be a problem for it. With all of that red clay, you could make adobes or cob by adding some sand and straw. This is not a very insulating material, but your climate is mild enough that some good thick walls might work quite well for you. Cordwood is another option, but hardwoods are not the best choice for this, and you would rather not cut your trees. Earthbags can be filled with any soil in your climate and can be a rather fast and easy way to build. All of these methods should work in a humid climate, especially if the walls are left breathable, you have a good solid foundation and a roof with substantial eaves.

Q: Do y'all sell or know of a resource for getting an indoor air quality test? A pretty thorough, yet affordable one for someone with MCS (Multiple Chemical Sensitivities)?

A: You should be able to check your local yellow pages for a local contractor who can run tests on the quality of your indoor air. They're usually listed under environmental services.

Q: Hi, I am wanting to build a home with either straw or cordwood. The problem that I am facing is that it has to be easily moved. I was wondering if you knew which of the ecological homes listed on your site would be best suited for a move?

A: (Kelly)Neither cordwood nor strawbale would be good choices for a house that needs to be portable; they both would have to be taken almost entirely apart, which is really impractical. I once designed and built a portable home from recycled barn wood, so something like that might be an option. I also recycled the materials from an earthbag/papercrete house once, but it was a lot of work and required completely dismantling it. Most natural building techniques do not lend themselves to this sort of use.

Q: I'm a graduate student at Stanford University in California and I'm trying to find information on "consumer attitudes" towards green building. This includes whether consumers place a high value on energy-saving features in new and/or remodeled homes, how much people are willing to pay for these features, etc. A lot of information I've found so far is private and/or expensive - mostly studies from market research firms which I don't have access to. Do you happen to know of some resources I could use to find out information on consumer attitudes?

A: I don't have any access to the information you are requesting. You may want to log on to the web site of What's Working and contact David Johnston through that organization to see if he can help you out on this one. If anyone would have the information or know where to get it, David would.

Q: I have begun a sculptural surround for a free standing wood stove and am interested in a natural earth or plaster covering. Both sides consist of a free form bench and one side has an alcove (to hang coats in) that stands 60 inches. I have constructed an armature of wood with chicken wire as lath but need advise on the proper materials to proceed with. Originally, I had thought to create something similar to the simple lines of Santa Fe beehive fireplace but during it's creation, it has become an intuitive one-piece-at-a-time sculpture...I am not an experienced builder but this project has inspired me to investigate educating myself. I especially like natural materials in sculptural applications. I could use guidance in my seeking as well.

A: I have no experience with projects of the nature that you are contemplating. You might want to contact Kiko Denzer or take a look at his book on cob ovens. Ianto Evans or Linda Evans (Cob Cottage) might also be of some assistance. You can probably reach them through the North American School of Natural Building.

Q: I want to know whether it is advisable to use dry walls in Africa, Ghana, West Africa. Cement blocks are been currently used and I want to know whether there are other alternatives.

A: Are you asking if the product called dry wall or sheet rock is appropriate for building in your climate?  If so, I would think so...Dry wall works well in many different climate zones.  Drywall, however, is only used on interior walls. In the United States, it is typically used in wood-frame houses. The outside walls are sheathed in oriented strand board (OSB). Siding is applied to the sheathing material to prevent moisture from reaching the OSB. You may also want to consider building with adobe or cob, two natural materials made from dirt containing about 30% clay and 70% sand. Some straw is added. The mud mixture can be made into blocks (adobe) or applied directly to the foundation in clumps (cob). Earthen walls such as this are very good, but need to be kept dry. That is, they require a good overhang, a water resistant layer of plaster, and a good foundation.

Q: Are there any health risks/harm from sheetrock dust or sheetrock mud /paint ???

A: I'm not an expert on health risks of building materials. But I suspect that sheetrock dust is not good to breathe in. You should wear a mask at all times...a good quality mask to keep from inhaling the stuff.  Now, as for sheetrock mud...This stuff contains some chemical additives so that it sets up quickly. I don't know how dangerous they are. Sorry. You might want to check with the folks at the Healthy House Institute. I believe they are in Indiana. You can find them on the Internet and probably e-mail them with your question or pick up one of their many books on healthy building.

Q: I am building a house in the lower regions of Himachal Pradesh (India). Summers are hot and winters are very cold. I want something natural, airy and yet can be warm in the winters and yet maintenance free.

A: You might want to consider building a passive solar home from strawbales or straw-clay or perhaps even an adobe home that's passively heated and cooled. You may want to obtain copies of my books, The Solar House and The Natural House to learn more about these ideas.

Q: Can an Earthwall home be built in SW Florida?

A (Kelly): Earthen homes can be build almost anywhere in the world, as long a certain design precautions are observed: they need to have substantial foundations that hold the earthen walls well above grade and potential flooding, and they should be protected by substantial eaves that protect the walls from driven rains. In Florida, you would want the walls to be quite thick (maybe 18" at least) to keep the home from getting too hot.

Q: I don't want to use wood for building. I heard of plastic 2X4's that are stronger, cheaper, bug proof and more fire retardant. Do you know of this?

A: Congratulations...we need green builders like yourself. There is a lot of plastic lumber being used these days by smart builders, but mostly for decks and fences. It's expensive but outlasts wood and dramatically reduces maintenance. I have never heard of anyone using 2 x 4 plastic lumber for framing, if that's what you are saying. That may be the case, I just haven't heard of this practice. To avoid termite damage, a lot of builders in affected areas use steel framing, which has its pluses and minuses.  Some builders are also starting to build with Bluwood ( www.bluwood.net ), a specially treated wood that is treated with a supposedly safe chemical that's helps combat termites, moisture problems, mildew, and mold. It's not inexpensive, however. It will add $3,700 to the price of a 2,500 square-foot home.

Q: Do you think that Energy-10 would be a good program to evaluate a small earth sheltered home? I have tried Equest but the wizards are too limited to model anything involving earth sheltered elements. I want to know what I can achieve before I build.

A: Energy 10 would be a good choice for an energy analysis, but the learning curve is rather steep and long. I prefer Builder Guide for Windows, now called BGW 2004. It is less expensive and the learning curve is much less steep. This program is produced by Fred Roberts, an architect in Colorado. His company is Solaequis. Once you locate the web site, you might want to contact Fred and tell him what you want to do and see if he thinks his program will work for you. (I'm not sure what  R-value you would enter for an earth-sheltered home, but suspect that Fred would be able to provide some sound guidance on the issue.

Q: Do natural buildings make installing utilities such as plumbing and electricity easier, harder, or do most natural buildings incorporate permaculture utilities like hydronic heating, composting waste, and solar panels?

A: (Kelly) Installing plumbing and electricity in natural buildings is neither easier or harder, but it does sometimes require different ways to accomplish. For instance electrical wiring can be buried in earthen plaster if it is rated for "direct burial" and is imbedded at least an inch and a half under the plaster. Concepts such as hydronic heating, composting waste, and using solar panels can all be employed in natural buildings...but they don't have to be. These can be employed in conventional buildings as well.

Q: What is your opinion on whether wood or straw is more economical and environmentally friendly?

A: (Kelly) Straw is definitely more environmentally (and probably more ecomnomically) friendly. While wood is ostensibly a renewable resource, we have gone way beyond sustainable harvesting and have ruined enormous ecosystems. So use wood as decoration or cull dead trees for structural supports, but find other ways to make building components.

Q: I live in Oklahoma, where temperatures range from about zero in the winter to 105 in the summer and it is very humid most of the time. What kind of natural materials would you suggest building a home with in this region. I have some land and want to build about a 2200 to 2800 sq ft. home.

A: I'd strongly suggest straw bale in a regions such as yours. If you build it right -- relying on energy efficiency and passive solar heating and cooling -- you can stay cool in the hot summers and warm in the winter.

Q: I would like to build a home with natural materials but there are a couple of things I'm unsure about. First of all, we live in the northeast and I'm not sure the climate would make it possible to use some of the materials that I've been reading about. Are there alternative building materials that would be suited to the long snowy winter and muddy spring weather we experience here? Second, is that my son has allergies and asthma. Is it generally a problem with building with natural materials that they might start to decompose and cause health issues (straw bales for instance; would it be likely they could get wet and grow mold?)

A: I understand your concerns, very much, but want to assure you that there are many natural homes in the Northeast and they do fine. So do the people who live in them. Thing is, you have to build them right...just like any other home. Your natural home will need a "good hat and a good set of boots" -- that is, a roof that protect the walls and a good foundation the prevents moisture from seeping up into the walls. You'll also need a water resistant exterior like a lime-sand plaster. All of this is true of any home. ' Please bear in mind that you can have mold problems, and often do, in any home if it is not built right. That is, If you build any type of home incorrectly -- that is, in ways that allow moisture to enter the walls -- you'll have problems. Be sure to hire a builder who understands how to protect against these problems... I recommend that clients seal their homes tight and avoid building products like OSB and conventional paints, stains, finishes, and carpets that can cause allergies or other health problems.  Also be sure the home is properly ventilated. You'll very likely need to install an energy recovery ventilator to provide fresh air. You might want to read more on this in one of my books, for example, The Solar House or The Homeowner's Guide to Renewable Energy.

Q: I live in Seattle and would eventually like to build my own home with some of the materials presented on greenhomebuilding.com. What are the best materials to use in Seattle?

A: (Kelly) Since Seattle has a fairly humid climate, materials that withstand moisture would be good to use. Actually with proper design, most of the materials shown on greenhomebuilding.com can be used safely; this often means having a good foundation well above grade and a roof with good eaves to keep most of the moisture off the walls. I also know that it can get fairly cold in that region, so a well insulated house will be more comfortable and energy-efficient. Bearing all this in mind, I feel that cordwood might be a good choice for you, with strawbale as a second choice.

Q: What can be used instead of Tyvek in the walls? I understand that it is composed of recycled newspaper, polyester, boric acid but also formaldehyde. Any idea's?

A: What can be used in place of Tyvek? First, I don't think there is any formaldehyde or recycled paper in Tyvek. Tyvek is plastic...I use it all the time. I did hear through the grapevine that the folks at Environmental Building News just featured in one of their monthly publications a more environmentally friendly product. You might want to try to Google that and see what you come up with.

Q: How healthy is living in a modular house Is the glue toxic? They use it all around and in between the beams to make sure that during transport to the building site the parts of the house will not open.

A: It's hard to answer your question. Why? Because modular homes vary with respect to materials. If you want to buy a healthy modular home, look for a company that builds green modular homes...but be sure to ask about the paints, stains, finishes, adhesives, and materials. If you can find a builder who produces modular homes with low- or no-VOC products, especially OSB, living in a modular home could be healthy. You'll need to research this very carefully.

Q: I built an ICF home my self during 2008-2009. Are there any federal tax credits for owner/builders of energy efficient homes? I can only find credits for contractors.

A: You are correct, the only tax incentives for building energy efficient homes are for contractors. You can claim credits for energy-efficient windows, so long as they meet federal standards, and other efficiency measures (I believe). You might contact a knowledgeable accountant for advice on various measures that you can claim.

Q: Is hempcrete fireproof?

A: (Kelly) Yes, hempcrete, with all of that solid lime, is fireproof.

Where can you get the stuff?

Hempcrete is made from hemp hurd (in inner core of the hemp plant stalk) and lime. Hemp is commercially available in Europe and Canada but is difficult to source in the US due to legal restrictions on growing hemp.

Is there a spray on version?

I don't think there are any sprayers that can handle it.

Currently (2018), it is completely legal to cultivate hemp seeds in fourteen different states; each state has their own statues that regulate the sale and what happens to that hemp after it’s planted. Furthermore, there are over thirteen states that are introducing industrial hemp growing programs and seven states have already established industrial hemp programs. States which have completely legalized the cultivation of hemp are as follows:

Q: I recently found out I have a health problem and have now started to detox our house. One area is to ensure we minimize the VOC's in the house and this has led to us using more natural materials.  We soon get a wooden kitchen top installed and I am keen to use a natural oil to seal the wood. One I have come across is from Auro 108 oil.  I was wondering if you have any experience of using this and hopefully it is OK.  If not can you recommend something else? Also, I will need to use a natural sealant to prevent water escaping down the back and at joins etc. What do you recommend in this case.

A: (Kelly) I have not had any experience with Auro 108 oil, so I can't vouch for its safety or effectiveness. My go-to natural oil for finishing wood is boiled linseed oil, which does have a bit of VOC off-gassing for the first few hours after applying it, but then it becomes a hardening oil as it cures. The trick is to always wipe away any excess oil after about an hour so it won't congeal on the surface of the wood. This oil can be reapplied over time to keep the wood protected. The other wood oil I have used for furniture is Tung oil, which is also a natural wood finish, similar to linseed oil. If I were to finish a cutting board or wooden surface where raw food is processed, I would probably choose a food grade oil, such as olive oil or safflower oil, because then I would know it to be completely safe for ingestion.

I would use silicon caulk for this myself. It only off-gasses for a few minutes while it cures, then seems to be quite stable. There might be a tree resin product that is more natural, but I have never tried this, and would actually expect it to smell for a much longer period.

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