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Last February, I took the opportunity to attend a “Building With Straw Bale” seminar. I’ve always been fascinated with straw bale homes ever since I became involved in sustainability, but knew little about the true pros and cons of building with straw. The technique has been around in America since the middle of the 19th century. One helpful reader chimed in with the following history: “Strawbale home techniques were developed in the the Kinkaid Sandhills region of Nebraska. With the invention of the baling machine around 1850. Pioneers of the region started using these strawpackages towards the end of the 19th century to mount walls of homes and agricultural buildings due to a lack of other building supplies and a need for shelter and housing. With the coming of the train around 1940, this technique was replaced with more “conventional” and “traditional” and “modern” building methods, as building with straw was perceived as demonstrating a lack of social prestige and displaying poverty.” Only recently, with concerns over the health effects of building materials and home insulation, has SB experienced a revival in home building. After a couple hours of education, allow me to explain to you and dispel the myths, of this perfect, simple, and relatively easy home insulation solution.

Okay, so let’s get the obvious out of the way: Straw Bale house building is essentially building your home with walls of straw. But it’s not the only thing that goes into it. Almost all Straw Bale homes have a timber frame skeleton. This timber frame support can either be on the inside of the straw bale or directly integrated with the bales. We’ll get to the details of design in a moment; but first, why build with straw in the first place?

Straw Bale is probably one of the most insulating materials you can use to build your home. It has certified R value of roughly 27.5. To give you some perspective, fiberglass insulation has an R value of about 13. Walls are created by stacking bales on top of each other, fastening them together with either wooden stakes (vampire-method), and then plastering each side to seal and weatherproof. People who live in SB homes find them incredibly comfortable because the walls–rather than let heat seep out–actually radiate the energy back into the room. This creates less temperature differentials throughout the home and allows for a lower thermostat setting than what you may be used to. But, let’s get to the real questions that may be bugging you:

1.) Will my house catch on fire?
This is a very common concern and one worth bringing up immediately. The great misconception with straw bale design is that your home is more susceptible to fire than your neighbor’s. The real truth is, SB homes are difficult to burn down. Because the bales are so tightly packed together and covered in plaster, there is little oxygen available for fire. The plaster coating on both sides itself is an excellent retardant to flame. In a test conducted on straw bale walls, almost 1,000 degrees F was reached before the bale wall caught fire. As an example of the radiant features of the wall, the other side not exposed to the flame experienced only a 10 degree rise in temperature! Most bale fires, like any other home, occur in the roof where there is plenty of oxygen.

2.) What about rodents? Will they enjoy my house as a snack?
Don’t expect to hear scurrying in your walls. Pests might like straw, but they would have a difficult time chewing through the plaster to even reach it. Second, they also like plenty of space to move around in–something that is difficult, as mentioned above–with straw bale walls. Rest easy that your densely packed and well covered bales will not be inviting to outside visitors. Once again, there are no guarantees on your attic!

3.) What about Rot?
With proper moisture control, your straw bale walls will last as long as any conventional home. There are some pointers, however to keep note of. First, overhangs on the outside of the home are imperative to keep rain and snow off of your walls. Each overhang should be about 18′’ (24′’ for two-story homes). Second, the bales should actually be raised about 24′’ off of the foundation of your home to reduce capillary action of ground moisture. This actually gives builders some great design leeway, with beautiful stone foundations or other creative borders. Third, if overhang design is not your thing, siding can also be placed directly over the plaster to reduce moisture exposure. This is not say that the plaster you place over your bales is useless against weather. Plaster is actually very strong and waterproof–however, it sometime depends on what type of plaster you’re using. Over the past few decades, a cement plaster mixture was often used over bale walls. The problem with cement is that it is not very permeable. Therefore, many walls have trouble ‘breathing’ and releasing any moisture that did creep in. Today’s solution is to mix cement with lime to increase the permeable properties and allow your home to release any moisture present. This, ironically, is how many straw bale home built centuries ago, as still standing today. Why mess with what works?

One other new development in Straw Bale Design to consider is the use of rebar. Rebar is a metal often used to spike straw bale ‘blocks’ together when fitting them as a wall. The problem is, metal is susceptible to condensation and homes built with these spikes often experience small levels of rot around the poles. Some building codes, such as California’s are, are still not updated to reflect this–so make sure your home does not not fall victim to this old practice.

4.) What are the best types of bales? They should be made of wheat, oat, or barely (anything with few seeds works best). You really want the entire bale to be made of nothing but straw. The strings surrounding the bales should be extremely tight and should not lift off the block. Straw lengths should be between 12′’-18′’ and the bale should be very, very dry. If you have any doubts regarding moisture content, simply break open the bale and have a look. It should also be noted that straw building is a seasonal event. Bales are generally not available until June or July–so make sure to plan accordingly.

5.) So, is this cost effective? By most building estimates, straw insulated homes cost roughly the same as conventional homes. You should have no issues securing a loan through a bank (at least in central NY) as most banks are more concerned that you can afford your new home. Building code inspectors are generally familiar with SB design, but it might be a good idea to download and present some building code checklists available online. Overall, using straw to insulate will probably end up costing about 15%-20% of your entire home cost. But the greater benefit comes from living in an environment made up of completely organic materials–with no ill effects on your family–and the insulating features that will reduce your long-term costs substantially. You can also take pride in the fact that energy used to create the materials that go into your home was minimal. The great thing about straw is that the grass does all the work–and you can purchase it locally. Barely any fossil fuel waste goes into creating your home. In these modern times of building homes with materials that take a great amount of energy to produce, isn’t it comforting to know that you can buck the trend and use something that may be available in your own backyard? The actual building of your home can also bring communities together since anyone can assist easily in the creation and plastering of your new home. Have a straw-building party! It’s wise to obviously hire consultants for this type of work, but you can reduce cost by participating and engaging others in creating your dream home.

Below are some additional resources to help you get started on considering building with straw. Beware of old texts! They often have outdated building techniques–and straw design innovation moves very quickly in today’s focus on sustainability.

Development Center for Appropriate Technology
Works to enhance the health of the planet and our communities by promoting a shift to sustainable construction and development. Excellent source of nation-wide codes regarding straw bale building. Beware California–go for the Austin, TX codes–they have the most up to date techniques–no rebar!

The Last Straw Journal
The reader-written journal of straw-bale and natural building techniques. Excellent resource and community for discussing SB.

Serious Straw Bale: A Construction Guide For All Climates
Thorough explanations of how moisture and temperature affect buildings in seasonal climates, with descriptions of the unique capacities of straw and other natural materials to provide warmth, quiet, and comfort year-round.

More Straw Bale Building: A Complete Guide To Designing and Building With Straw
A completely rewritten edition of the 20,000-copy best–selling original, it leads the potential builder through the entire process of building a bale structure, tackling all the practical issues: finding and choosing bales; developing sound building plans; roofing; electrical, plumbing, and heating systems; building code compliance; and special concerns for builders in northern climates.

The Natural Plaster Book: Earth, Lime, and Gypsum Plasters for Natural Homes
For builders of natural homes (straw bale, cob, adobe, rammed earth, and other natural materials), this unique step-by-step guide takes the confusion out of choosing, mixing, and applying natural plasters.

Many thanks to the Ithaca Green Builders Association for the above information!