Home Improvement

In the late 19th century, settlers in northwestern Nebraska found themselves in a predicament. The Sandhills region they inhabited had no lumber for building, and there were no nearby railroad depots to bring in supplies. With little good sod present, which was better used for livestock crops, they had to find an alternative. This led them to build houses, schools, and churches out of straw bales by piling them on top of each other and covering them with a simple, sloped roof.

Initially, these temporary buildings were not meant to last long. However, once settlers started applying plaster to the walls, they discovered that these houses could keep them cool during summer and warm during winter. The homes could withstand the high winds of the prairie, and they were quiet as well.

Straw bale building declined in Nebraska after World War II once cement became popular. However, it is gaining attention as a natural building method and an estimated 1,000 new straw bale structures are built each year around the world.

So, why are people interested in straw bale homes? What advantages do they offer? We’ll explore these benefits in the following pages.

Advantages of Building a Straw Bale House

As the cost and availability of lumber continue to decrease, straw has emerged as a renewable resource that is easily accessible as a byproduct of grain production. In the United States alone, approximately 200 million tons of straw go unused every year, making it an abundant and cost-effective building material [source: U.S. Department of Energy]. Since straw is often available locally, transportation costs for construction are also reduced, which can significantly lower the greenhouse gas emissions associated with the construction industry [source: Amazon Nails].

Although straw is cheaper than traditional building materials, such as brick or lumber, building a straw bale house typically costs the same as a conventional home. The wall budget usually accounts for only 10 to 15 percent of the total building budget, with other expenses like the foundation, roof, doors, and windows adding to the overall cost [source: Magwood, Mack, Therrien]. However, building a straw bale house with a group of people can save on labor costs and make the process go faster. Many resources are available online and on DVDs to help people learn how to build their own straw bale homes, but it’s important to know when to seek professional help.

The real cost savings of building with straw bales come from the energy efficiency of the finished product. The bales, covered in plaster, have a high R-value, which measures the insulation resistance of the wall. Straw bale walls provide excellent insulation, keeping heat in or out depending on the climate. This can result in up to 75% savings on annual heating and cooling costs [source: Morrison, Amazon Nails]. Straw bale walls are also great for soundproofing and have been used in recording studios and homes near highways.

Despite concerns about fire hazards, straw bale houses are actually three times more fire-resistant than conventional homes. The tightly packed bales limit oxygen and reduce the risk of combustion. Plaster coatings on the walls also add an extra layer of fire resistance. The National Research Council of Canada conducted tests where straw bale walls withstood temperatures up to 1,850 degrees Fahrenheit (1,010 degrees Celsius) for two hours [source: Magwood, Mack, Therrien].

Photo courtesy StrawBale.com
The thick walls of a straw bale home provide good insulation.

Straw, not hay, is the preferred material for building a straw bale home as hay contains leafy material that attracts animals and rodents. Straw, on the other hand, is not a food source and when tightly packed and combined with plaster, makes it difficult for critters to enter the walls. Those with hay fever and allergies will also benefit from using straw as it does not contain pollens. It is a natural, breathable material that is often compared to modern building materials that may contain harmful chemicals. Additionally, hay decomposes naturally, while straw requires additional nitrates to decompose. Moisture is the main threat to straw bale homes, but this issue will be addressed in later sections.

Designing a straw bale house involves more than just stacking straw. The home should be designed to maximize energy efficiency by considering factors such as the sun’s position, wind direction, and nearby sources of water. Trees and shrubs can be used to block wind and sun. Post-and-beam infill and load-bearing are the two main methods of constructing a straw bale home. Post-and-beam infill involves filling the space between the house’s frame with straw bales while load-bearing uses the bales to support the roof. Load-bearing has some design limitations, including a height restriction of one story and limitations on wall length and window and door placement.

Photo courtesy StrawBale.com
A post-and-beam house

The current trend of building straw bale homes is mainly popular in the desert climates of Southwest United States and Southern California. The method is most suitable for locations with extreme temperatures as the insulated walls block excess heat or cold. Although moisture is a major threat to straw bale homes, people have successfully built them in rainy Pacific Northwest and snowy New England. However, humid climates are not ideal for straw bale construction. A database maintained by the Straw Bale Registry shows structures all over the world, with the majority being in the United States and China.

Choosing the right type of straw is a crucial factor in designing. Although straw bales come in various shapes and sizes, the most common ones used for building are two-string bales and three-string bales. The U.S. Department of Energy has specified the measurements and weight of these bales:

Type	Dimensions	Weight
Two-string bale	18 inches by 14 inches by 36 inches	50 pounds to 60 pounds
Three-string bale	23 inches by 16 inches by 42 inches	75 pounds to 80 pounds

You can use an online bale calculator to determine the number of bales required for construction. Harvest Homes provides an example of such a calculator.

You can purchase dry bales from feed stores or farmers. It is important to choose bales with a moisture content of up to 20 percent, which can be checked using hand-held moisture meters. Golden-colored bales are preferred over lighter ones as they indicate less moisture. Tightly strung bales should be selected to maintain their shape when lifted or dropped.

Construction of Straw Bale House

Once the decision on using a load-bearing or a post-and-beam structure is made, the design choices are similar to those of conventional home building. A straw bale home can have any type of foundation or roof, but solar-paneled roofs are preferred to enhance the environmental friendliness and energy efficiency of the house.

Photo courtesy StrawBale.com
A toe-up

For a load-bearing home, the straw is stacked on the foundation and a roof frame is placed on top of the straw followed by the roof assembly. In the case of a post-and-beam straw bale home, all the structural elements, including the foundation, frame, and roof, are installed first and then straw bales are filled in between the posts.

When building a straw bale house, it is important to raise the bales off the ground to prevent moisture from seeping in. Builders often use toe-ups, which are platforms made of lumber and gravel that attach to the concrete foundation. Nails or pins are hammered into the toe-up and the bales are placed onto the nails to anchor them. After the first round of bales is situated on the toe-ups, the rest of the straw can be stacked like blocks. Builders use baling needles to cut and retie the bales to the desired size and shape, while chain saws are used to make notches for wooden posts. Electrical cables can be installed directly into the walls, but plumbing should be kept out of straw bale walls whenever possible by using internal walls. After the bales are stacked, some builders use poles or pins and wire mesh to keep everything in place before applying plaster. It is important to use breathable plaster and paint to prevent moisture from affecting the straw. Moisture is the biggest challenge when building with straw bales because it causes mold and rot, so precautions must be taken to store bales off the ground and under tarps.

Building a Straw Bale Home

It is important to keep water out of the home during the design and construction process. Incorporating overhangs into roof designs and carefully sealing windowsills and joints will provide protection from rain and snow. Using natural, breathable plasters will keep moisture from the air moving through the home. Cracks in these plasters are the primary maintenance issue for straw bale homes to prevent moisture from accumulating in the walls.

Photo courtesy StrawBale.com
Straw bale home before plaster

Photo courtesy StrawBale.com
The final product

Building a straw bale home has its challenges, as this construction method is still fairly new. It might be difficult to find a contractor knowledgeable about it, and building codes may not account for straw bale methods. Conservative banks, lenders, and insurance agents may not want to finance such an experimental method. To gain financing and insurance, be ready with data to help explain straw bale building to someone who may not have heard of the method before. You may also have to hire consultants to look over your plans and methodology and to vouch for you with the institutions.

Little data exist about reselling straw bale homes, but an educated owner/builder can explain the value of a well-insulated home to potential buyers. Straw bale homes may receive a lower resale value estimate than conventionally built homes.

Straw Bale Additions and Retrofits

If you are already settled in your house but interested in straw bale building, you can still use straw bales for additions and retrofits.

Photo courtesy StrawBale.com
Straw bale construction

When looking for a straw bale contractor, it might be easier to find contractors to provide individual services, such as plastering or roofing. The quarterly journal “The Last Straw” maintains a list of resources for straw bale building, and you can also check out a database of green builders. To work effectively with the contractor, you will need to be well-versed in straw bale building.

To add a straw bale addition to an existing structure, first lay each row of straw and place a sheet of metal mesh called a lath over the bales. Attach the lath with dowels or landscape pins and then staple it to the frame of the existing house by folding it at a 90-degree angle. If the addition has wooden frames, attach them directly to the frames of the house. Plastering the addition is done in the same way as straw bale construction. To match the exteriors of the house and the addition, consider the thickness of both the bales and the plaster when laying the foundation. Wrapping an existing home in straw to increase energy efficiency is possible, but moisture prevention must be considered. The roof of the home may need to be changed to accommodate large roof overhangs for rain protection. A larger foundation may also need to be created to support the additional width of the bales. Bales should be dipped in an earthen-based plaster before stacking and wire netting should be used for ventilation between the house and the bales. If bales are on the outside of the house, windows and doors will need to be adjusted. Retrofitting with bales on the inside of the house can reduce space within the house. The costs of incorporating straw bale construction should be weighed against energy savings over the lifetime of the house. For more information, visit the related HowStuffWorks articles and links provided.

Below is a list of sources related to straw bale construction, including websites, articles, and guides. These sources provide information on everything from how to choose the right straw bales to retrofitting an existing home with straw bales. Some of the sources listed include StrawBale.com, Green Home Building, The California Straw Building Association, and The Last Straw. The U.S. Department of Energy also provides a guide titled “House of Straw: Straw Bale Construction Comes of Age.” These resources offer valuable information for anyone interested in exploring this eco-friendly and sustainable building option.

FAQ

1. What is a straw bale house?

A straw bale house is a type of building constructed using straw bales as the primary building material. The straw bales are stacked and compressed to form the walls, creating a highly insulating and energy-efficient structure.

2. How do straw bale houses compare to traditional homes?

Straw bale houses have several advantages over traditional homes. They are highly energy-efficient, with excellent insulation properties that can help reduce heating and cooling costs. They are also environmentally friendly, as straw is a renewable resource that is widely available. Additionally, straw bale houses are durable and can last for many years with proper maintenance.

3. Are straw bale houses safe?

Yes, straw bale houses are safe. They are constructed using a timber frame and the straw bales are treated with a fire retardant to meet building codes. Additionally, straw bale houses are designed to be structurally sound and meet the same building codes as traditional homes.

4. Are there any downsides to straw bale houses?

Straw bale houses can be more expensive to construct than traditional homes, as they require specialized building techniques and materials. Additionally, some people may find the appearance of straw bale houses to be unappealing, although this is largely a matter of personal preference.

5. Can straw bale houses be built in all climates?

Straw bale houses can be built in most climates, although they may require additional insulation or other modifications to meet the specific needs of the climate. In colder climates, for example, additional insulation may be needed to prevent heat loss through the walls.

6. How long does it take to build a straw bale house?

The time it takes to build a straw bale house can vary depending on the size and complexity of the project. However, in general, straw bale houses can be built relatively quickly, as the walls can be stacked and compressed in a short amount of time.

7. How much maintenance do straw bale houses require?

Straw bale houses require about the same amount of maintenance as traditional homes. Regular upkeep such as painting, roof maintenance, and pest control is necessary to ensure the longevity of the structure. In addition, it is important to monitor the straw bales for signs of decay or moisture damage, although this is rare when proper construction techniques are used.

8. Are there any special considerations for designing a straw bale house?

Yes, designing a straw bale house requires special considerations to ensure that the walls are structurally sound and provide adequate insulation. This may include using buttresses or other supports to reinforce the walls, as well as incorporating features such as overhangs to protect the walls from moisture damage.

9. Can straw bale houses be customized to fit individual preferences?

Yes, straw bale houses can be customized to fit individual preferences just like traditional homes. They can be designed in a variety of styles, including modern, rustic, and traditional, and can incorporate features such as solar panels, rainwater harvesting systems, and other sustainable technologies.