Mountain View Cottage 16’10″x12’3″

Is a straw bale house more energy efficient?

Yes. A typical straw bale wall is roughly three times as efficient as conventional framing. Over the life of a typical thirty year mortgage, this superior insulation can reduce energy costs by up to 75%, saving money and vital natural resources.

Isn’t a straw bale home at greater risk for fire?

No. Canadian and U.S. materials laboratories have found that: “The straw bale/mortar structure wall has proven to be exceptionally resistant to fire.” In these tests, the flames took more than two hours to penetrate the plastered bale walls. Conventional framing built to commercial standards took only 30 minutes to one hour to burn. Due to their tight compaction, bales contain very little oxygen and thus resist combustion. It’s like trying to burn a phone book. Loose straw; however, is at risk for fire and should be cleaned from the job site daily. Walls should be plastered as early as possible to increase their fire resistance.

Fire and Straw Bale Video

What about pests?

Pests are more of an imagined concern than a real threat. Once the walls are properly plastered or sided, there is no way for bugs or rodents to get into the bales. If pests were to get inside, they would find it almost impossible to move in the densely packed bales. Termites and other pests pose more of a problem to conventional construction than they do to straw bale structures.

Do the thick walls provide good sound insulation?

Straw bale homes provide superior sound absorption compared with conventional houses. This will be especially important in the town homes. The sound absorption between units will help create separation between common wall homes.

How do I find good straw bale to build with?

There are a number of things to keep in mind when shopping for bales. Know the size you are designing to (two string, three string, etc…). The straw should be golden in color. Darker straw is often an indication of water damage. Check the density of the bales. The bale should not deform dramatically when lifted by one string. Use a hand held moisture meter to check moisture content. Bales have to be below 20% MC for construction. Finally, check for uniform shape. If the bales are all shaped properly, the baling machine was most likely set well, producing consistent bales.

Finding Good Straw Bales

How can I learn the ins and outs?

The best way to learn the art of straw bale construction is by taking a workshop. We offer 7 day comprehensive hands-on workshops in several locations each year.  These events are not only highly instructional, but also a ton of fun and often a life changing experience for those in attendance.  You can find the list of current workshops here.  If you are unable to take time off work and attend, consider purchasing one of our instructional Straw Bale DVDs. We cover all aspects of Straw Bale construction from foundation tips to finish plaster and everything in between.

Learn the Post and Beam Method

Learn the Load Bearing Method

How do I teach subcontractors what to do?

This takes experience. You might want to build a small structure yourself, start to finish, like the one shown in our straw bale DVDs and instant download videos. The techniques described in the videos will help you fully understand the needs of the subcontractor. Scheduling is a little different that conventional homes because the inclusion of bales affects the installation of rough wiring and plumbing.

Should I be concerned about the straw getting wet?

Moisture concerns can be handled easily with proper design and construction methods. So long as the bales are installed when dry (moisture content of 14% or less) and are properly sealed within the plaster and protected from water infiltration, they will perform well. The 2015 and 2018 International Residential Code, Appendix S (“Straw Bale Structures”) has standards in place to accommodate this design and construction. Even if a building is heavily rained on, it will be fine as long as it is allowed to dry out. Problems arise when high moisture levels above 20%) are sustained for long periods of time.

Won’t the straw decompose?

Organic material requires both oxygen and water in order to decompose. With proper construction techniques, water will not enter the building thus making decomposition impossible. Rice straw, in particular, has a high silica content which increases its resistance to decay. Straw has been used as an insulating material for many centuries, and has even been found in excellent condition in Egyptian tombs thousands of years old. Straw will not decompose as long as its moisture content is kept low.

What does it mean that straw bale walls “breathe”?

Bale walls do not breathe in the sense of allowing air to move through the walls. In fact, it is a good idea to limit air infiltration into the walls as air carries moisture. When we say they breathe, we are referring to the movement of moisture through, and out of, the walls. It is critical that moisture moves out of the walls. Permeable plasters such as Lime or Earth should be used in wet or humid climates and Cement based plasters should only be used in dry climate climates, if at all. This transfer of moisture improves indoor air quality without sacrificing energy efficiency and keeps the bales dry. Straw is a natural material, and as such it does not off gas the way conventional insulations do, adding to the health of the home and its occupants.

Bale Walls Don’t Breathe

How are the walls finished?

Bale walls can be finished in many ways. The typical options include lime plaster, stucco, and earth plaster. Each of these materials has its pro and cons although some have more cons than pros. When choosing a finish material, consideration must be given to durability, maintenance requirements, permeability, flexibility, strength, ease of application, cost, embodied energy, and aesthetics. The most important factors are the finish’s breathability, embodied energy, and durability.

How durable is a straw bale house?

Bale homes built in the 1800’s till exist in Nebraska and Europe. Straw bale homes have consistently withstood severe weather and wind in Wyoming as well as major earthquakes in California.I will reply to your e-mail about Insider’s Guide #3 so we can get cranking on that material. Many architects and engineers consider straw bales to be the ideal “seismic-resistant” building material. In wind tests, bale structures see no movement in a sustained 75 mph gale and only 1/16 inch movement with 100 mph gusts.

How does building with straw bales help our environment?

The use of straw bales can have a huge impact on our natural resources and air pollution. Each year, the U.S. alone burns or disposes of 200 million tons of ‘waste straw,’ producing massive amounts of carbon dioxide. The use of straw as insulation reduces the need for initial energy outputs in regards to manufacturing. There is less embodied energy in straw as it is available in almost every local market, thereby reducing transportation costs and efforts. Straw is a renewable resource that has a one year growth/harvest cycle. By using this local, agricultural by-product as a building material, we reduce energy expenditures, the amount of straw burned, and the use of fossil fuels needed for material transportation.

How do I hang things on the wall?

When a quality plaster is used, most items can be hung directly on the plaster with conventional plaster screws and plugs. This is true for pictures, coat hangers, and other small items. In order to hang larger items such as kitchen cabinets, wooden drive stakes must be used to anchor the hangers into the bales before the plaster is applied. By driving a wooden stake into the tough interior of the bales, a solid base is laid onto which just about any load can be applied. In the case of extremely heavy loads, a bolt can be threaded through the bales and fastened to an over sized washer on the opposite side of the wall.

Straw Bale and Hanging Cabinets

What about plumbing?

In a perfect world, plumbing would be kept out of the bales entirely. Whenever possible, design a structure so that the plumbing can be run through the floor and interior stick frame walls. Check with your plumber about “wet venting” plumbing fixtures so the vents can also be run through the floor to interior walls. When it is not possible to keep plumbing out of the bales, you can either build a faux wall in front of the bales in which to run the plumbing or you can place the plumbing in a continuous sleeve which will contain any leaks or sweaty pipes.

How do I run my electrical lines?

Although Romex is allowed by many codes for straw bale construction, most building inspectors want to see direct burial cable (UF-B) in the walls when a sheathed wiring is employed. If wire upgrades are possible in the future, or if additional circuits may someday be added, it is a good idea to use flexible chases with single wires pulled through. If, at a later date, you decide to upgrade the system, you can simply pull new wires through the conduit to the desired location. To reduce the effects of electrical magnetic fields (EMFs) use metal cased, twisted wire. The twist in the wire along with the metal conduit reduces the emission of EMFs. Electrical boxes are typically screwed to tapered stakes driven flush with back of recesses cut into the straw. The wires are then let into the boxes. It is important to hold the wires back from the face of the bales so they are not damaged during the construction or post construction process.

How does the Mountain View Cottage do in truly cold climates?

Straw bale construction is famous for its high energy efficiency. You can expect to have walls with R-40 ratings, far exceeding code requirements. These cottages are perfect for cold climates, hot climates, and just about anything in between. The one climate they don’t do well in is areas with high humidity for long periods of time.

Included in the Mountain View Cottage Tiny House Architectural Plans

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