Flooring for 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: We are considering building a "green" type house. We are looking at bamboo flooring; but they all seem to be treated with aluminum oxide as a finish; we were just wondering if anyone has any information as to how safe that kind of finish would be?

A: I don't have information on this topic, but would suggest you contact David Adamson at EcoBuild. He can be reached at 303-545-6255. He sells bamboo flooring and may have some answers or may be able to refer you to someone who can. You can also write Debra Lynn Dadd c/o Natural Home magazine. She's an expert on healthy houses. Call the office to get her email or mailing address. The Natural Home magazine office is at 970-669-7672.

Response: Since I wrote you found out lots of new info...all of it pretty exciting to me. D.DarrellDATaolDOTcom, an architect, responded to us and explained that most cabinetry, almost all carpeting and the majority or better of wood floors as well as bamboo flooring contain uf...that is urea formaldehyde which outgasses constantly, so obviously it cannot be good for us. But since in referencing the Web I discovered at least one manufacturer who uses a tiny amount of uf in production of bamboo he tells us. His name is Doug and his site is bambooflooring.com. Darell explains that the finish of aluminum oxide is not the problem but the uf. I have since found a few good sources of "green" cabinetry who do use uf but in the most minimal amount they can manage.

Q: Our question is to do with earth floors.We are about to build on our acre of brush land in the south east of Tasmania.We are determined to employ as many eco-friendly alternatives in the building process as we can get information on & were hoping to use earth in the floor. Can you help with information on earthen-flooring, the mix ratio of cement &/or anywhere we can educate ourselves please.

A: Sounds as if you're about to undertake a wonderful project. I'm no expert on earthen floors, although I've worked on some and read a little about them, and there's not much out there (not much written material, that is) on them. I was just talking to a friend who builds strawbale homes with earthen plasters and earthen floors and he told me he uses the same mix for his plasters and earthen floors -- about 5 to 7 percent clay and the rest sand and silt. He doesn't add any flour paste or milk powder (both hardening agents) to his floor mix, however. Once the floor has been finished and dried, he treats them with linseed oil. To learn more on earthen floors, I'd recommend you getting a copy of The Art of Natural Building published by New Society Publishers. This book includes a chapter on earthen floors written by Bill and Athena Steen. Hopefully this will help you create a durable, beautiful floor.

C: A friend tells the story of how his bush relative some way back used white ant nests in the mix for their earthen floors.
When you think of how well these nests stand up to the elements it is believable that they would make good hard floors.
I guess it must have something to do with the white ant additive, saliva or something I guess.

Q: Is there such a thing as formaldehyde free osb stand board or plywood or a better alternative to these to use for the sub floor?

A: Yes, absolutely. There are low- and no-formaldehyde OSBs available on the market, but you will very likely have to have ask your local lumber supply outlet to special order them. If they tell you they have never heard of them, call someone else. Or contact me and I'll get you more information on the products.

Q: I am located in Venezuela at the moment, being involved, among other things, in building a small village of huts in natural materials. There of course are great traditions for using palm leaves and the like in this country. I wanted also to avoid cement for floor and foundation which is very common at this time. Traditional knowledge seems to have got lost in this area and our civil engineer does not know about it. From my home country, Denmark, I know clay is often used for floors with a finish of flax oil. One would then take the topsoil off, lay a layer of small stones, then shells, sand and clay. Here the climate is more extreme in terms of rain and I wondered if you had or anyone else on your panel had experience with natural floors in hot, rainy (and very dry) climates?

A: (Kelly) The floor that you describe is also used in the SW U.S., and is typically called an adobe floor...I have one in my house. We also added chopped straw into the sand and clay mix before pouring and finishing. I see no reason why this would not work in your climate in Venezuela, as long as you make sure that the floor is not prone to flooding of any sort. If there is any danger of water wicking up through the subsoil, you might place a layer of plastic to avoid this.

Q: Please describe an alternative flooring that can be installed over concrete.

A: You have lots of options. You can install natural linoleum over concrete, recycled tile, bamboo, and even natural carpeting (e.g., wool).

Q: I was hoping to find out how to do a "dirt" floor that is then finished with linseed oil???     

A: (Kelly) You can certainly put an adobe floor over concrete. If you live in a cold area and your concrete is not insulated, you might want to put some insulation board between the concrete and adobe.

Q: I have tons of sand. Can I make great floors this way? Can I seal them and make them washable and water resistant? I'm about to make a 20,000 sq ft floor area building for my business and I'd like it to be beautiful and healthful!

A: (Kelly) You can make adobe by mixing about 2 parts sand to 1 part clay mixed with water, with some chopped straw added to help bind it, and use this to make beautiful adobe floors. The same mix (minus the straw) can be used for rammed earth floors. The process of doing this is not really so simple that you could expect to do it well without some prior experience or training...so I suggest that you seek this out. Both adobe and rammed earth floors are fairly durable, and can be made water and stain resistant by oiling and waxing. These floors are not as maintenance-free as concrete or tile would be.

Q: What's the ongoing maintenance that they'll need?

A: (Kelly) We had an adobe floor throughout much of the house I built awhile ago, and the regular maintenance mainly involved giving it a light re-oiling with linseed oil once a year. Beyond that I had to periodically repair particular spots where the adobe chipped up for some reason. I did this by mixing the original powdered adobe soil with straight linseed oil to make a paste and troweling it into place.This would dry over several days into a very hard patch that was hardly visible.

Q: I am looking to replace my laundry room flooring with tile--it is now ancient vinyl--yuck -I would like to do this with non or low off gassing as the room has one small window--what can I use for the sub floor and install that would work --the stores I go to suggest Hardiebacker board???

A: While I know a lot about healthy houses, I don't know all of the products that are currently available. For example, I don't know whether Hardiebacker board is free of VOCs.  You could ask the suppliers or even the manufacturer directly. Do you know that you can special order OSB made with low or no formaldehyde resin?  Contact your local building supply outlet and see if they can help. They should be able to assist you. Be persistent, though, and call several if one can't help you.

Q: I am planning on laying a Kahrs non toxic engineered hardwood floor and they recommend 15lb felt or roofing paper to level an osb subfloor. I don't know much about felt paper besides it's made from asphalt, which is made from crude oil. Is this a toxic substance my family would be breathing in and are there alternatives for my situation?

A: I would be wary of installing roofing felt under a floor for the reasons you are concerned about. I do believe there is a nontoxic roofing felt, but am on the road right now and don't have access to references that list alternative materials. You could check with the folks at the Healthy House Institute or try searching for the products on the Internet. Why not ask the manufacturer or supplier of the flooring? They should be aware of this problem and should be looking for healthier alternatives.

C: Bamboo is a great renewable resource, but beware. The manufacturing of bamboo flooring, which is made up of heavily glued strips of bamboo, can contain quite a lot of urea formaldehyde glue. Look for bamboo flooring that is UF-free. It is out there.

Also don't discount using all wood products. Look for wood products like plywood and flooring that are FSC-certified, which means it meets the standards of the Forest Stewardship Council and comes from responsibly managed forests.

Q: What is the best (least complicated, affordable) way to do earth floors?

A: Most people are pouring their floors now over a base, rather than applying the earthen materials in several layers, compacting each one before the next one is applied, but frankly I'm no expert on this subject. You might want to consult with Tal Mesenbrink for details. He's the expert. He's a professional adobe floor installer and might be willing to give you advice...www.mudcrafters.com

Q: I Live in Pennsylvania. A friend has red clay in his crawl space. He would like to dig out the clay and rock to turn the crawl space into better living/storage space. Can the clay be mixed with Portland and sand to make a floor which will compare to a pour concrete floor ? I read Portland doesn't like clay. I'm trying to reuse materials and not throw them away.

A: This might work but based on my experience with soil cement you will need to create a mixture of clay and sand that is primarily sand - maybe 90% sand and 10% clay. My advice is to prepare some test samples. Be sure to compact the sand/soil/cement mix. You only need to dampen the mixture for it to set up properly.


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I specifically disclaim any warranty, either expressed or implied, concerning the information on these pages. Neither I nor any of the advisor/consultants associated with this site will have liability for loss, damage, or injury, resulting from the use of any information found on this, or any other page at this site. Kelly Hart, Hartworks LLC.