Natural Insulation

Janine Bjornson is a natural builder, practitioner and educator. She began her career in natural building when she trained with The Cob Cottage in 1996. Since then, she has taught over 65 workshops in Canada and the United States, from east to west. Her passion for building with natural materials bloomed out of her love for the earth, in conjunction with her concern for diminishing ecological resources and toxic buildings. As a result of this, Janine has devoted the last 14 years to immersing herself in the world of natural materials and the knowledge of how we can shape dwellings that are healthy, healing, inspiring, and beautiful. She has developed a penchant for natural paints, and plasters and loves the concept of “naturalizing” any kind of home. She loves to share this knowledge with others and this is evident in her enthusiastic teaching style. Janine has assisted in organizing 2 Natural Building Colloquia. She has presented at the Natural Building Colloquium in Bath, New York, Kingston, New Mexico, and Kerrville, Texas. She taught the hands-on natural building component of New College of California’s EcoDwelling program, and Dominican University’s EcoDwelling program. She lives in Sebastopol, California. www.claybonesandstones.com.

Questions and Answers

Q: I'm doing an article for Canadian Home Workshop on eco-insulation. I would like to ask Janine Björnson about her experience using these green insulations. Are there any she prefers?

A: Yes there are a few natural insulations that I have had experience with and I do have a favorite. My favorite is Bonded Logic's UltraTouch insulation. It is made from recycled blue jeans, it is 85% post-industrial recycled. Naturally it is light blue in colour, soft and it does NOT itch. This is a huge factor during the installation process. It meets ASTM testing standards for fire and smoke ratings, fungi resistance and corrosiveness. This product is also LEED certified. The only drawback to this product, is that it can be tricky to cut. Especially if you are slicing strange shapes for odd shaped cavities (like oval roofs). I have seen good success using a Sawzall (metal blade). www.bondedlogic.com

I have also been happy when using blown in cellulose insulation. The brand I have used is called 'GreenFiber Cocoon'. This is made from 85% engineered paper fiber obtained from recycled newspapers and paper products. Made from locally available materials, GreenFiber Insulation is manufactured at 11 plants strategically located across the US. It has fire retardant qualities (see website for ASTM fire ratings). It was easy to use and did not itch like fiberglass. It was inexpensive and our large chain hardware stores supply the blower for free when purchasing the material there. It can be blown into ceilings, walls and floors.

The only drawback to this product in our area (California) is that to blow into a wall cavity during construction you need to blow it in 'wet'. As opposed to blowing it in 'dry' in an attic for instance. At the time, there was not any access to blowing it in wet in our area. The equipment was not available. This could have changed since then. In addition, colleagues I spoke with, had concerns of settling over time. www.cocooninsulation.com

Those are my top 2 'green' insulations that are available here in the western United States. I am still waiting for someone to begin to manufacture wool insulation bats like they do in the UK and New Zealand. Any takers???

Q: I need to use natural materials because I am chemically sensitive. What could I use to insulate my 1926 frame house? I would like to do it myself, inexpensively. Our summers are extremely hot, but winters are 10 below zero.

A: I realize that everyone that is chemically sensitive has a different degree of sensitivity so make suggestions and you will need to see if you are compatible with these options. I would suggest checking out the recycled denim insulation called ultra-touch. It is made by bonded logic 480 812 9114, or check out ''bonded logic.com" to read about it first. You may also be able to use the blown in cellulose insulation. There are brands available at most local hardware stores, it is inexpensive and they often let you use the blower for free when you purchase the insulation. However, it would not give you the r value that would be the best option given your temperature swing. There is one brand named "cocoon". Other than those two options on the market you may have to get more creative. In Britain and New Zealand they sell wool insulation batts. You could probably import them for a pretty price. Some people have made their own versions by acquiring wool and having it cleaned, then carding it, and insulating with that. That may be the most affordable option for wool that you would have.

Q: I am looking for a material to insulate a concrete floor slab used as a thermal mass. We are utilizing natural materials wherever possible and would like to continue doing so. We are building at very high elevation, 9500 ft. We have have hot summers and very cold winters(-25F).

A: Your dilemma is a tricky one. One of the systems that several people have tried to do is the "sandwich method" in which straw bales are used in between concrete layers to insulate. There have been some problems with this method unfortunately. I would suggest you read the section in " The Serious Straw Bale" published by Chelsea Green, the authors are Paul Lacinski and another man I cannot remember right now. It discusses some of the research done on this method. To my knowledge there hasn't been too much done that's completely natural. The danger of course is water. You might think about mixing in something like a layer of perlite mixed with some fly ash or a small amount of concrete to up the insulation value. It isn't as pure as something like straw....but the choices are limited.

A: (Kelly) I live at over 8,000 ft. in Colorado, and I insulated my adobe/flagstone thermal mass floor with about 6-8 inches of scoria, a crushed volcanic rock that is locally available. Any light-weight volcanic material would probably work, and if this is not available, then you might consider using perlite or vermiculite for this purpose.

Q: I need to insulate a couple rooms in my house. I am interested in wool batting but the only company I found said that wool has to be treated to avoid moths. They soak their wool in something called Boron. Can you tell me more about this, what boron is and if it is a pesticide, what is a more natural way to insulate?

A: Boron is nonmetallic compound occurring naturally only in combination, as in borax, boric acid etc., Boric acid is a Boron compound. Borax which you may be familiar with in the form of a laundry additive known as "Twenty Mule Team Borax" is obtained from naturally occurring Borates. These are mined in the United States in the Mojave Desert. They are also found in Turkey. The Boron compound "pentahydrate" is used to make fiberglass insulation. ELEMENTAL Boron and the Borates are not considered to be toxic. They do not require special handling of any kind. I would suggest that you find out what kind of Boron is used with this wool insulation to be safe. It is only the more exotic borates that may be toxic. All this aside I would like to suggest something else. There is another option on the market for insulation. If you are interested in using pre-manufactured insulation batts you can now get them made from recycled cotton (mostly blue jeans). There are NO warning labels on this product. You can contact the company to see who distributes this product in your area. (see: bondedlogic.com)

You could also check out Cellulose Insulation, there are different brands available ( I can only recall one called "Cocoon" presently).This is recycled newsprint that uses Boric Acid as an additive for fire-proofing the material. It is most likely that Boric Acid is what they are using for the wool insulation as well. Cellulose insulation most commonly comes dry. You purchase bales of it from the hardware store, and insert it into a hopper which blows it dry into the wall or roof cavity. There is a wet version but it is less common.

Q: We are in the start-up phase of developing a natural timber frame cottage business in the interior of British Columbia. A big challenge for us is to offer an affordable, natural insulation. Our walls consist of stacked timber, so wool rope can be used to seal between them (small quantities). However, the ceilings and gable ends require something more affordable. I am very interested in light straw-clay and am wondering if anyone is producing light-weight straw clay insulating blocks or panels. Also, in your opinion, is the market for natural, sustainable homes growing?

A: Strawclay panel manufacturers appear and disappear regularly on the North American market. There are no consistent producers to produce gable end in-fill panels. You may have to produce them yourself. Habib Gonzalez of Sustainable Works in Nelson, B.C. regularly uses straw bales in the gable ends in both load bearing and beam systems. Kim Thompson, a straw bale builder from out east uses custom straw bales or bale flakes in gable ends. You can produce your own custom light clay straw insulation or use the bale options. However, there are some things to keep in mind. Clients and colleagues that are firefighter's of Habib's agree that bales can be dangerous in the ceiling. If the bales come down when there is a fire, it presents a hazard to rescuing people in a burning building. Also, in a recent addition, of The Last Straw the author's calculations state that bales are too heavy to be effective insulation for the amount of material it takes to support them. Aside from those straw options, you may want to consider recycled paper insulation. This is commercially available. It is made from recycled newsprint and uses borax as a fire retardant. You can use this in shallow pitched roofs, or in areas where it can be contained. This is a fairly inexpensive option.

I would also like to make a plug for the cotton blue jean insulation. There is a company making batts of this non toxic insulation out of Chandler, Arizona. Unfortunately, it is not cheaper than batts of fiberglass yet. However, it is nice to use and it is rated for fire. The product is called "UltraTouch", by Bonded Logic. Bonded Logic (480 812 9114 bondedlogic.com). I am personally looking forward to the day that there is wool batt insulation on the market like there is in Britain, and New Zealand. There is plenty of wool out there, we simply need to get it manufactured.

To answer your second question regarding the Natural Building market.... Yes, I believe the market is growing for natural, sustainable homes. I have really noticed an increase in education of natural building techniques over the last eight years and I have noticed a movement for many people to begin using these techniques in their own homes in the last three years. As our dwindling resources become more obvious to the mainstream public, as chemically sensitive people begin to multiply, and as more and more people begin to read magazines like "Natural Home", the literacy and the demand of these home increase. I can only imagine this trend increasing due to our current state of affairs regarding logging issues or health concerns. Beside those dry facts, natural buildings are gaining more popularity due to their incredible beauty, along with the complex but extremely obvious psycho-emotional response that human beings experience when entering one of these buildings. In addition, I would like to say to you that I would include stacked timer in this category. For me, a natural building is a building that is using appropriate and available materials that are pertinent to that particular climate and bio-region.

Q: I am considering spray foam for my home insulation. It appears to be the most energy efficient way to go. Could you advise me on this.

A: (Kelly) It is true the spay foam insulation has the highest R-values of any insulation around. The problem with it from an environmental viewpoint is that it has more embodied energy than other choices, and it can be quite toxic, especially if it ever catches fire.

Q: I have interest in trying to make my own wool insulation. I have a source of wool and would like to know how I might process it to make it usable. Do you know anyone who has had success with this process?

A: Over the years I have heard of many people that have dabbled in using wool for insulation. I cannot say that I have heard of one particular technique that is tried and true. I will give you the most clear method that I have heard of as follows:

1) Clean wool. This means that you need to remove any dirt, debris, and lanolin. There are various ways to clean the wool but you want to make sure that the method you choose does NOT felt the wool. Use COLD water to clean the wool, not warm or hot. You may try anything from putting the wool in burlap sacks and sinking them in the river with the cold water rushing over them to clean the wool. Or you may put the wool in front loading washing machine set on the 'gentle' cycle. Do NOT use the top loading machines or you wool may turn to felt. You may use an industrial detergent to clean the wool in the machine. You will know that the wool is clean and the lanolin is removed because the wool will feel soft like a wet wool sweater and your fingers should not stick together after touching the wool. If your fingers feel sticky, there is still more lanolin in the wool that needs to be removed.

2) Treat with Borax. You want to treat the wool with Borax (commonly sold as "20 Mule Team Borax Laundry Additive") to repel insects. Borax is also used as a fire retardant. If you are using the washing machine to clean the wool you could add the Borax instead of fabric softener. Otherwise dissolve Borax in hot water to make a solution and spray on the wool as you lay or hang it to dry. Do not rinse it out. Unfortunately, I haven't been able to find out how much Borax you should use.

3)Card the wool. You now need to card the wool (when dry) to fluff it up creating air spaces between the fibres which will give it loft and greater insulation value. Remember, things that are insulative are light and fluffy like a down quilt. You may be able to find someone with a carding machine, otherwise you will need to card it by hand.

4) Make batts.You can now get strips of kraft paper to attach the wool to. This will hold the wool in place when you put it in a wall cavity. If you are placing it between 2 x 4's as in standard construction practices, you will want to cut strips of kraft paper 16" wide and as tall as your walls (for example). Spray the kraft paper with adhesive and lay down your carded wool onto the kraft paper. It is important to use some kind of system like this so that the wool insulation will not slump and settle in your wall. If it does, you will lose the insulation value that you were trying to create. You will also have air spaces at the top of your walls that will transfer heat or cold through the walls.

Q: I'm in my attic trying to organize it. The insulation in there is from 1949!!!! When I'm in there working, I'm realizing that I'm coming out with fiberglass in my pores (even though I'm not touching the old insulation). I am looking to re- insulate this old attic. I've read some articles that say to insulate over the old insulation. Is this a good idea? I've also seen on HGTV that there is an insulation product out there that is "denim insulation". I'm thinking that this is a healthier way to go. Have you heard of this product? If so, do you know where I can purchase it?

A: (Kelly) There is a company making batts of jeans insulation out of Chandler, Arizona. The product is called "UltraTouch", by Bonded Logic. Bonded Logic (480 812 9114 bondedlogic.com). I also would recommend leaving the old insulation there and adding new to it, for several reasons: it is good to recycle material, especially if you don't have to work to do so; taking out the old fiberglass will really get it into your pores; and the more insulation up there the better. You might read about insulation at: naturalbuildingQandA.htm#insulation.

Q: I was wondering if you had any advice on how to renovate a mobile to make it more natural, and also to fix the problem of them losing a lot of heat.?

A: (Kelly) Mobiles tend to be so small inside that adding thickness to the walls in that direction is usually not such a good idea...better to try adding insulation on the outside, possibly with strawbales, or earthbags. This approach requires a lot of thought and care to make sure that a new roof covers them and they are on a good foundation (if using straw).

Q: I am investigating the possibility of using pumice or using something natural which can be used as insulation. We have had too many bad results with man-made materials, i.e. inhalation and lung maladies, that if we could use pumice or scoria or heat the correct rock-type into a form which can be used for insulation in construction, then possible we'd have a heat-resistant, light-weight, sustainable product which could save a lot of trees and aid in sustainable development. If you know of links which explain the possible process of making this type of insulation or the feasibility of it, I would be delighted.

A: (Kelly) One natural product that you might consider is perlite or vermiculite. See www.schundler.com for more information. Another possibility is discarded rice hulls. See earthbag.htm#ricehulls for more info.

Q: I am a musician in New York and I am building a soundproof room in my basement-the soundproofing engineers I have consulted all recommended vinyl, vinyl foam, mass-loaded vinyl, etc. to line the walls and ceiling and acoustical caulk to seal the holes, but I have heard such bad things about vinyl that I am searching for a more ecologically safe solution.

A: I forwarded your question to a friend of mine (Tim Wiedenkeller) that is a professional musician and studio technician as well as natural builder. Here is his reply:

Soundproofing can be challenging. I'm not sure about vinyl - maybe you actually mean foam which is a common solution - but it's foam. I've seen lo-tech solutions such as hanging rugs around the perimeter of the room, obtaining old mattresses and fastening them to the walls...old carpet/padding can be out-gassed-out to a high degree which can be attached to walls, baffle-shapes, etc. Hmmmmm. Not an easy one. Professional studios build an extra layer of walls, floors and ceilings - often floating these installations. I haven't seen any natural solutions apart from the obvious - using straw-bales.

Comment: The only two things that stop sound waves are mass and absorption. In the case of a music studio, the bass notes have very low frequencies , which means longer wave lengths. ( I spent 14 years soundproofing houses around an airport). The most effective thing to do is to put 1/2" cementboard ( trade name Durock) on the inside surface of the outward facing walls, and then put absorptive materials in front of that , on the occupied side of the room. The cement board has to be about 1/2" away from the surface - this aids the sound reduction. Use furring strips or metal hat channels to furr out to get this space. Caulk between the cement board joints with acoustic caulk - this does not harden. The materials are not expensive ( the caulk is more expensive) but the method is labor intensive. But this WILL cut down on the sound that escapes from the room. The same method can be used with Sheetrock, but depending on the thickness you will not get as much mass.

Q: I am interested in using rice hulls on top of the existing insulation in my 1930's California bungalow. We have a very small crawl space and need to blow the material in. I am having a hard time finding information on flammability, rodent resistance, etc. to satisfy the local insulation provider's questions. Any ideas? And, can I convince the county to give me a rebate, like it would if I used other (less green) materials?

A: (Kelly) Rice hulls are a durable and renewable material that will not easily burn or decay. They are reported to be about R-3 per inch as insulation, and will not harbor mold or fungus because they don't retain enough moisture to do so. All of this is without any added chemicals. The issue #47 (Fall 2004) of The Last Straw has a lengthy article. You also might refer to http://www.appropedia.org/Rice_Hulls_in_Construction

Q: I am an alpaca farmer looking for alternative uses for fiber that is not suitable for garments. I'd like to insulate my new fiber arts studio with alpaca and have read Janine Bjornson's advice on treating wool fiber for insulation. Since alpaca contains no lanolin or oil of any sort do I really need to wash the fiber before insulating? Would using the Borax dry (i.e. just sprinkling it on the fiber as we insulate) be as effective as applying it wet?

A: I do not think it would be necessary to wash your alapaca wool unless there is some kind of dirt or debris in the wool that would render it desirable to insects or the like. In regard to adding the borax dry, I think that it would not be as effective. Dissolving it in water and spraying it on would ensure better coverage. All the recipes I have looked at (like this one below) recommend dissolving the Borax first.

Making children's clothing flame retardant: Mix together 9 ounces 20 Mule Team Borax and 4 ounces boric acid in one gallon water. If the article is washable, soak in the solution after final rinsing, then dry. If the garment is not washable, spray with the solution. This solution, recommended by fire departments, may wash out of clothing and should be used after each washing or dry cleaning.

Q: I have a two car garage that I am excited about turning into an earthen apartment. It has standard construction 2x4 stud framing, truss roof and T1-11 siding. My plans at this point is to do Leichtlehm within the stud walls voids for insulation, then do a lathe and plaster using earthen plaster. I live in Portland Oregon area and had a little concern about moisture passage due to the T1-11 walls. Have you ever heard of anyone doing something like this or maybe you have some experience? I just don't want the walls to build up moisture in them and well we know what happens after that - I get very sad. Oh, I am also adding some Borax to the Leichtlehm as an added measure for pests, not that this is going to effect the moisture passage but thought I would throw it out there...

A: I haven't heard of anyone doing what you are planning to do. However, I have asked about this years ago. I built a Light Straw Clay house in Coastal Northern California. At some point in the building process I had a talk with Bill Steen of The Canelo Project. He suggested that if we had wanted to do board and batten on the exterior that he would recommend leaving an air space between the straw/clay wall and the wood. That way, moisture that may condense wouldn't be sitting on the straw when it did. We didn't choose board and batten siding (we did earth plaster, with an exterior coat of lime plaster).

By the way, I don't use lathe over straw when I plaster. It isn't necessary with earth plaster. Simply bridge all dissimilar materials (wooden studs and the like) with some kind of material. I use burlap and clay slip (clay slip both sides, staple into studs, and secure into straw before plastering). If I am bridging a 2x4 I cut my burlap 5.5" wide for example. The earth plaster will stick to all of this easily if your mix a good and your apply it well (good adhesion methods!).

Q: I'm trying to learn all I can about using white pumice as insulation under heated and passive solar slab floors. Oregon code requires only R-10. I'm wondering if the pumice (available near Bend) should be crushed, just enough to produce angular bits that will firm up under a (lightweight?) vibratory plate compactor, and fill the R-value-reducing large voids that round rock would leave with pumice bits, with smaller voids and better insulative value?

A: (Kelly) You certainly don't need the R-value between a floor on grade and the soil that you would for walls or roofs. In fact many solar designers claim you shouldn't have any, and just let the soil become part of the thermal mass. I do prefer to add insulation there, as I did in building an earthbag home here in the Colorado mountains. I used crushed volcanic stone for this (it is available locally, called scoria). I think it has rather similar in attributes to pumice. The aggregate was crushed to 3/4" and minus, and I screened it to eliminate the fines that would have filled up the voids and reduce the insulation. I used between 6 and 8 inches under my flagstone and adobe floor, and this worked great. I believe that scoria has an R-value of close to 2/inch, so this would produce about R-12 or so under the floor. This house performed remarkably well as a passive solar design. I did not compact the scoria much, just enough to keep it from settling.

Do I need drain rock (under road cloth?) under it, or will it will create its own capillary break?

I did not use drain rock below the scoria, but then I was building on well-draining sand. I did place a plastic sheet there, mainly to avoid any possible radon intrusion. Unless you are in an area with a high water table, the floor should remain pretty dry.

Q: I'm interested for a DIY lightweight insulation material. We have an abundance of material here in my place (Angeles Pampanga, Philippines) lahar or pumice, rice hulls, rice hull ashes, cement. What material should I use and what mixture ratio to form a 2 ft x 4 ft x 3 inches thick insulation material. What could be the approximate "R" Value.  Looking forward for your advice, our weather is very hot and wet(rain).

A: (Kelly) Both pumice and rice hulls can be used for insulation. They can be placed directly in bags  and then stacked or placed in cavities without needing to cement them into blocks. Rice hulls provide about R-3 per inch  and pumice is about R-2 per inch.

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