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| Q: I live in the S.E. corner of British Columbia, Canada, and am currently working on a square log dove tail house with a timber frame roof system. I 've been looking into earth floors, and have come up short with enough info to try one on this project. I'm very impressed with Paul and Talmath's work and their write up about earth/abode floors. I would be interested in any other sources of info for proceeding with an abode floor on this project. I would like to do 1 1/2" layer over radiant tubes on top of an OSB subfloor. Anybody doing this? A: Adobe works just fine for radiant. That OSB floor needs to be very rigid so that there is little flexing under the adobe. It also needs to be very waterproof since the adobe floor takes some time to dry out. I would recommend a minimum of two inches adobe. That gets heavy. A: (Kelly) There is not a lot out there about how to actually make earthen/adobe floors. I did notice that there is a chapter in this book: Earthbag Building : The Tools, Tricks and Techniques by Kaki Hunter, Donald Kiffmeyer, 2004. Talmath has often done adobe floors over radiant tubing, and this works well, since the heat can used to help cure the adobe faster, and then the adobe becomes good thermal mass for the floor. Using OSB as a subfloor with adobe sounds risky to me, since this material will decompose when wet... R: I'll be putting 15lbs roofing felt as a bond breaker between the OSB and the abode, so moisture shouldn't be a problem, also considering using wire mesh over the radiant tubes, well see...... A: (Kelly) I have never seen wire mesh used this way with adobe floors, so it probably isn't necessary. I have seen it used under radiant tubes embedded in concrete to hold the tubes in place when it is poured... Will the OSB be able to breathe from below? If it can't, then any moisture that does manage to seep between the courses of felt and find its way to the OSB will never be able to exit. Solid plastic sheeting might be safer, and also be a better radon barrier, if this is an issue. Q: We are installing an adobe floor on a house in Huntington VT and are wondering about green products used for sealing adobe floors? A: Boiled linseed oil is my choice. Put on one or two coats without thinning to load up the pores. After 20 minutes wipe up any oil on the surface or it will become gummy. A day between coats is good. Thin the following coat or two 50% or less with turpentine or citric oil thinner to help make sure that the linseed oil hardens. It's an oxidation reaction. Again, mop up any residue on the surface after 20 minutes. Linseed is the hero of all the firefighters training movies because it combusts spontaneously better than anything else. So put any rags in a sealed container or in a bucket of water. Q: I will be laying fired adobe as patio pavers. I am wondering how they should be laid. Base materials? Depth? Sand? Depth? We are in metro Phoenix. 7" rain per year +- A: It is best to have 2- to 4-inches of sand under the pavers. The sand can be right on the existing soil if it is firm and has never been excavated. Otherwise, base course well tamped is in order. 4-inches of base course, then a geo cloth is useful to keep the sand from filtering down into the base course. Then the sand, then the bricks. I would say skip the use of grout and place the adobes as close together as possible. That way rain can drain down between the adobes and percolate down into the ground. Rain that stays on the surface has more time to penetrate the top surface of the adobes. Some people sweep sand into the spaces between the bricks. It will go faster if you can level large areas of the sand and then just drop the adobes into place without having to level each one. If the adobes have much difference in thickness, this shortcut is not that helpful. Q: I've been told to coat them with a turpentine / Linseed Oil mixture to also help keep moisture off. Does it sound right as well? A: I am not so sure that this is appropriate outdoors. If moisture gets into the adobes, then the turp/linseed surface keeps it from getting back out. In some cases the moisture may move up to the point where the turp/linseed begins and then break the connection between the raw and the treated adobe. I have definitely had this happen on a treated vertical wall surface. C: I've laid some 3x8x16 fired adobe on a patio. Because of thickness concerns I had to lay them in 1/2" sand. Those little suckers were so sway-backed that it was barely thick enough. A couple of brick have cracked as I tamped them. Oops. But boy do they look pretty. I think one inch is the minimum thickness I'd use again. Q: Are adobe bricks stabilized with cement an appropriate material for patio and/or walkway pavers? Q: I'm thinking of constructing a small outdoor patio, 400 sq. feet out of adobe bricks I make myself. I live in Portland, Or. Is this feasible and do any of the books on your website address this type of project? A: We would certainly like to see more adobe activity in Portland, Gary. The Oregon Historical Society has a photo of the concrete foundation of an adobe home in the Portland area. Pioneers coming in on the Oregon Trail used adobe along the trail until they got to the mountains. About 7 years ago adobe structures were put up in several neighborhoods mostly as places to sit near bus stops. Using adobe bricks flat on the ground will take extra efforts. They should be stabilized (waterproofed) with emulsified asphalt which can be obtained from asphalt paving suppliers. For your application, I would think about 20 ounces per wheelbarrow would be a starting point. You might want to make a few test bricks and see how they hold up. If you don't like the idea of asphalt in the adobes there might be some other chemicals but my memory sags at the moment. Emulsified asphalt is the most common stabilizer used in the Southwest. Additionally it would be good to lay the adobes on a bed of coarse sand or pea gravel to provide drainage below the bricks. In general people don't use adobe bricks as outside pavers but is has been done a few times. I can't think of any books that address outdoor patios. Most stick with interior floors where the weather is not a consideration. Some of the best information on floors comes from Bill and Athena Steen bundled into their strawbale construction books. Q: My husband and I are building a small (900ft2) hybrid type wood chip/light clay house in Quebec, Canada. I want to use as little concrete as possible but want a floor with good thermal mass. I would love a poured adobe floor but the labor, time, and timing involved are not practical for us. I am considering adobe brick/block and would like to make them myself. Is it a good idea to add a little cement for strength if they are being used as flooring? Do adobe bricks underfoot feel like concrete anyway? And how should they be finished/ sealed to get as smooth a floor as possible? A: (Kelly) From my own experience, I would suggest stabilizing the adobe bricks with some Portland cement or emulsified asphalt for a floor, although this is not necessary. Earthen floors do not feel like concrete; they have much more earthy give to them. You can use linseed oil to finish them. Q: I recently sealed our poured adobe floor with linseed oil and thinner (multiple coats begging with pure oil and progressing to higher percentages of thinner). The floor is now very well sealed, however, it is also a dust magnet. The slightest bit of dust from footprints of even slightly dusty feet or indoor shoes sticks to it and won't sweep off but needs to be mopped up. Is this effect common? Is there anything that can be done to help this, such as a final top coat of wax? A: (Kelly) I lived for several years with an adobe floor that I poured in my house in Colorado, and I had the same experience that you describe. It was especially noticeable after I had re-oiled the floor (which I did about once a year). I found that after about week, when the oil had thoroughly hardened, the effect was much less noticeable. I did make sure to wipe away any excess oil that didn't sink into the floor after about half an hour, so that there was no build-up of oil "scum" on the surface. I did not wax my floor, partly because I didn't like the way the wax left uneven whitish marks on the surface. I don't know whether wax would have improved the situation with dust. Every once in awhile I would take a damp mop to the floor to brighten the luster, but there was usually a dull, dusty appearance that I just got used to. Q: How are your earthen floors holding up to doggy toenails? A: (Kelly) I love our adobe floors. They do take some maintenance, especially around the inset flagstone, but the good news is that they can be repaired, unlike most flooring material. As you know we have two rambunctious dogs, one of whom is prone to scratch the floor with his nails. At first I thought this might be a problem, leaving permanent scratches. As it has turned out, a light mopping or wipe with an oiled rag will remove the marks. Q: My wife and I are remodeling a 50's rancher with 2" t&g subfloor raised above grade. We would like an earthen floor, and wondered if there is any problem with applying it to the wooden subfloor? We have already run our hydronic heating attached below the subfloor, so that is done. We were considering wood, but it's expensive, and there is something about the earthen floor that really appeals to us. Someone described it as feeling like leather. Wow! that just sounds great. A: (Kelly) Putting an earthen floor over an existing wooden subfloor could perhaps be done, but there would be some concerns. First of all, an earthen floor requires an absolutely solid, non-flexing base, or else it will likely crack in many places; this is hard to accomplish with a wooden floor, even if it is 2" thick. Second, an earthen floor is typically at least 3" to 4" thick, which means both a lot of weight (which must be born by the subfloor and foundation) and it will raise the level of the floor in the house by that much, likely interfering with doors and such. My third concern is that with hydronic heating you rely on the heat radiating upward. You have already compromised the efficiency of this type of heating system by placing the tubes beneath the wooden deck, since wood is an insulating material and will not readily pass the heat through. Earth is a much better thermal mass material than wood, but several inches of it may not pass enough of your heat into the room. Earthen floors with the tubes placed within work well, but I am not sure how well your situation would work. If it were me I would consider placing tiles over the subfloor, since these are a good conductor of heat, but are not too thick to have the other problems mentioned above. Q: I was concerned that putting the radiant pipes under the floor was not efficient. This is the problem with working with people who want to move faster than I can fully research things. So, if I put, say, flagstone over the subfloor, that would still be a better conductor of heat, and storage of heat, than using a wood floor over the subfloor, even with the hydronics below the subfloor? This would keep the level of the floor closer to where it should be, too. A: Yes, I would say that stone or tile over your subfloor would perform better than more wood. It will gather and hold the heat that rises through the wood and provide a more even temperature throughout the floor. Q: I am wanting to build a tamped earth foundation for a guesthouse/art studio of 12' x 18'. I am unable to find a precise formula indicating an appropriate ratio of sand, clay, dirt, and water. I am planning on doing 6" of gravel, 6" of pumice, 3" of silty sand and soil mix, and then for floor layers--two layers of one inch each, clay soil, sand, chopped straw, water. It is just not clear for both the silty sand soil mix layer and the clay soil, sand, chopped straw, water layer, how much of each item to put in the mix? A: 30/70 percent of clay/sand is best. Lots of soils work as they are or with a bit of clay or sand added. We have to experiment at each location. I would skip the pumice. It is very hygroscopic and will get damp and stay damp if it is in contact with surrounding soil. Any insulating value it has will be lost in a below grade situation. We used it as an under floor insulation at the Ghost Ranch Sundwellings in 1976. The buildings were heavily instrumented by Q-Dot at Los Alamos and they found the loss of insulative value in the pumice. (Editor's Note: If the pumice is kept dry with layers of plastic sheeting, it does fine as an insulating layer.) As for the various layers, silt never contributes any value to a brick, mortar, plaster or floor. If it is there, use it, but if soil is available without it that will be the better choice. Back to 30/70 clay/sand. The straw is then not necessary but some like the texture and color it gives a floor. It does help control cracking if the clay content is over 30 percent. As for water, just keep adding it till you get the consistency you like. Some folks like very stiff mud to spread and trowel out, some like it almost pourable. With 30/70 it all works. Since all soils are different, whether you are in Bali, Ethiopia or Berlin you just start out and experiment until it works. Two million Central Germans figured it out. Q: I am designing a passive solar house in upstate NY. I need to top my concrete monolithic slab floor with another product that will effectively conduct heat and be softer on my husbands hips - he has had 2 hip surgeries. Can you suggest a product that will not compromise the efficiency of the concrete and be softer on some old hips? A (Kelly): The first thing that comes to my mind is good old adobe. It is natural, holds and passes heat very nicely, and definitely is easier on the body. I lived with an adobe floor for several years, so I can personally attest to this. You can read an article that talks about this. Finding someone in your area who might be able to help install this might be the most difficult, but there are some directories of green professional listed partway down my home page. Most products that are thermal mass that might be used for floor are not very resilient. Cork is nice, but it is also insulating. Q: I live in India and would like to know which product in India is available to make an adobe surface waterproof. The floor is created with mud, straw, adobe clay, tile, cow dung, cake emulsion and cement grouting. Could suggest to guide? A: I am not very familiar with the availability of materials in India. If you can find a fish oil emulsion, that might work. They use it in Chile with good results. It can be painted on but works better mixed into the adobe surfacing material before it is applied. Linseed oil and several other seed oils make adobe stronger and waterproof. They are painted on after the adobe material has thoroughly dried. Polyvinyl Acrylic the clear liquid used in many water based paints also works. Usually there is an elder person in most every village who has a recipe for something that works. |
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Quentin
Wilson and
Associates, specializes in solar adobe design and construction. He grew
up in the South Valley of Albuquerque, New Mexico where he watched adobe
bricks being made. In the fifth grade, he made miniature adobes on cookie
sheets in his mother’s oven in order to construct house models for
a class assignment. By age thirteen he made full-sized adobes in the back
yard and ruined the grass. Later, he traveled a bit, went through the
Army, and graduated eventually from the University of New Mexico with
a major in physics, minors in math, chemistry, and education in 1970.
After teaching high school two years and community college math for three
more, Quentin moved into professional solar adobe construction in 1976
as the Project Manager and Instructor for the Sundwellings Demonstration
Project at Ghost Ranch, Abiquiu, NM. He became a licensed general contractor
in the State of New Mexico in 1982. He has been building homes and teaching
seminars and workshops ever since. In the fall of 1995 he established
and taught the full-time Adobe Construction Program at Northern New Mexico
Community College. His website, 
