Green Home Building and Sustainable Architecture

Sustainable architecture is an exciting and important field, with many people reviving traditional methods of building and others creating innovations to established practices. Kelly Hart, webmaster of the popular website www.greenhomebuilding.com, posts text and photos featuring what he discovers from around the world.

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Location: Crestone, Colorado, United States

Kelly Hart has been involved with green building concepts for much of his life. He has also worked in various fields of communication media, including still photography, cinematography, animation, video production and now website development. Kelly has lived in an earthbag/papercrete home that he built and consults about sustainable building design.

December 24, 2004

Amazing Rice Hulls

I have recently become familiar with the use of rice hulls as a material to build with. These unasumming little bits of of debris that are often discarded have found new value as insulation in wood-framed houses and as filler for earthbag projects. They 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...a totally natural product that is often given away. The states where rice mills accumulate hulls include Lousiana, Texas, Arkansa, Missouri, Mississippi, Florida, and California. The hulls only weigh about 9 pounds per cubic foot, so weight is not much of issue in transporting them. They pack into a stable shape when mildly compressed; once they settle into a wall cavity or are packed into an earthbag, they are not shape-shifters.

Don Stephens has been experimenting with rice hulls in bags. He says, "I thought you might find this photo of interest...it's the bag-walled studio I'm mentoring/assisting the owners in building here in Spokane. The bags are just filled with packed, dry rice hulls and they are load-bearing, holding up the insulated bondbeam at the top and the poured-in-ricehull-insulated roof, which will end up planted, over its salvaged-carpet covered Mel-Rol waterproofing. There's been no settlement since construction and it feels SOLID, walking on the roof. The exterior will be stuccoed with slightly-stabilized cob and the interior will be earth plastered. The subfloor is of ricehull-liteclay, for insulation, and will be topped with cob-adobe.... : ) "

25 Comments:

Blogger Shannon said...

This was very helpful in my search for using rice as a material for sustainable housing. If you have more information such as how efficient rice hulls are in comparison to other forms of insulation, i'm very interested. Thanks so much :)

3:16 AM  
Anonymous Anonymous said...

There is more information about various tests that have been performed with rice hulls as insulation at www.esrla.com/shotgun/frame.htm , slides 24-39. Also the issue #47 (Fall 2004) of The Last Straw has a lengthy article.

12:39 PM  
Anonymous Anonymous said...

My company supplied the hulls for Don Stephens project. If any one is interested contact jpereira@rice-hulls.com. You can also check out the following web site about hulls as insulation: http://www.axwoodfarm.com/PAHS/RiceHulls.html

12:57 AM  
Anonymous Anonymous said...

What is the cost of Rice Hulls per ton or pounds----????????? Very interested in knowing these factors before proceeding to utilize.

10:34 AM  
Anonymous Anonymous said...

i'm 15 and i have to do a project on rice hulls and its very hard. this is sort of usefull but its not good enough. i need to know the advantages, disadvantages, radiation, thermal mass, and convection of a rice hull home. can you help me

6:58 PM  
Anonymous Anonymous said...

we are conducting a research bout mixing rice hulls a mixure for making a concrete wall ang study its effects... could someone help us out bout our study... tnx... =)

10:54 PM  
Blogger Terry Ann said...

Does it matter if they are ground or whole?

7:10 AM  
Blogger Kelly Hart said...

I would think that the hulls would provide better insulation if they are left intact rather than ground, because then they will create more effective air pockets. Also, ground or powdered hulls might tend to hold more moisture, which could lead to rotting and less effective insulation.

8:39 AM  
Blogger carmen said...

i'm carmen from the philippines. my project porposal is " minimize cost of hollow blocks by utilizing the rice hulls in toledo city as aggregates.my proposal is related to your study. i would be pleased if you will share topics related to my study. hope to read your reply soon.

10:50 PM  
Blogger Kelly Hart said...

Using rice hulls as an aggregate for lightweight concrete blocks might be quite effective. Such blocks should also be more insulating than conventional ones. I think this idea will require some experiments to see how well it works and to perfect the formulas. Let us know how it works out.

1:10 PM  
Blogger carmen said...

thank you for your comment. i'd be willing to share my studies with you after i will do all the experiments. let's make a greener environment and help save our rivers and mountains.

4:49 AM  
Anonymous Brother toner expert said...

In our province, we usually discard rice hulls because we don't know its use. I will suggest this one to my father so that rice hull would be of use to us.

11:14 PM  
Anonymous MAKI said...

I'm Jonas Makiramdam from Philippines. I'm a graduating architecture student and I'm doing some research to alternative building materials because I'm a proponent of Green and Sustainable Housing. I'll appreciate some information about rice hulls for a sustainable design, it would be a big help if you share the results of your research. Thank you. :)

6:15 AM  
Blogger Kelly Hart said...

I don't have any personal experience using rice hulls as fill for earthbag building, but there are a few other people who do, including the folks at http://recycledrice.org/rice-hulls.php where you can learn some more.

1:39 PM  
Anonymous Anonymous said...

I'm a civil engineering student and were doing a feasibility study and I'm thinking to use these rice hulls as a substitute material as wall, as ceiling etc.. if we process this rice hulls to be like in a plywood form what can be the materials that can affect to form chemical reactions that produces harmful effect and lessens its quality? opposed to this what can be be used to make this experiment a useful one? thank you...

6:33 PM  
Blogger Kelly Hart said...

Rice hulls are primarily useful as insulation because of the trapped air that they provide when loosely packed into a wall cavity or in bags. If you try to glue the hulls together somehow to form a rigid matrix, this will likely lessen the insulation value. Still, doing something like this may be worthwhile in provide some reasonably well-insulated material.

Rice hulls on their own do resist fire and mold, so this is a good basis for residential insulation. Beyond that, it will take some experimentation to find other useful ways to utilize them.

1:45 PM  
Anonymous Paddy Dehusker said...

Rice hulls are generally very durable and available for very cheap in India.. They could be put to amazing uses like producing elctricuty

1:39 AM  
Anonymous Rob said...

Hi
I'm looking at building a octagon shaped building for a tourist venture in the Philippines using rice hull bagged walls, adding steel connections making trusses out of bamboo. Bagged Rice hulls for the ceilings insulation with concrete roof.
I am searching if anyone has done any work on removing aggregate and replacing rice hulls for light weight concrete similar to what they do with polystyrene in tilt panel walls.??
rob_mccredie@yahoo.com love to talk to anyone else in The Philippines as well. Cheers Rob

11:51 PM  
Blogger Kelly Hart said...

Owen Geiger, my associate at www.naturalbuildingblog.com posted about using rice hulls and how effective they can be. See http://www.naturalbuildingblog.com/interview-maggie-chiang-dao-bb-rice-hull-houses/

9:00 AM  
Blogger melissa b. said...

hi kelly, have you ever tried, or heard of anyone trying, to use rice hulls instead of straw in cob? we are still trying to figure out how to make the easiest structure without using so many man made materials. i am def. using rice hulls but just not sure how yet. i talked to owen and he suggesting using rebar with rice hull bag infill which is great but the idea of rice hulls in cob is very fascinating and maybe something doable.

5:36 PM  
Blogger Kelly Hart said...

Melissa, I don't think that using rice hulls with cob would work very well because the main function of putting straw in cob is to give it cohesive strength through the long fibers; rice hulls would not do this.

8:05 PM  
Blogger melissa b. said...

as soon as i sent this comment i realized that was the case. but maybe we will use them in the earthen floor instead of slip straw.(:

6:36 AM  
Blogger Dianna said...

Dianna H.
We are getting ready to build in Northeast Texas this summer and have been looking at light clay straw wall construction. I am interested in using rice hulls for attic insulation and would like to know if anyone can help me find a source for the rice hulls.

3:50 PM  
Blogger Kelly Hart said...

Texas is one of the few states where rice is grown, so it shouldn't be too hard to find rice hulls for sale. One place I noticed online is http://www.morganbulkinc.com

5:01 PM  
Blogger Dianna said...

Dianna H.
Thanks, I have a few places to call. Most of the online listings want to sell it in 40 lb. bags and I need lots more and was hoping to find it cheaper too!

5:57 PM  

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