Straw Bale Homes: A Natural Building Method

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Home Improvement

In the late 1800s, settlers in the Sandhills area of northwestern Nebraska faced a dilemma. The region’s vast grass-covered sand dunes provided no lumber for construction, and there were no nearby railroad depots to import building supplies. The little good sod available was better used for crops that fed livestock. To address this challenge, the settlers began constructing houses, schools, and churches out of straw bales in the late 1890s. Using stacked hay bales for insulation and the recently invented mechanical baler for producing big bundles of straw, the settlers built one-story dwellings, piling one bale on top of the other and covering them with a simple, sloped roof.

Initially, the buildings were not intended to be permanent. Many were not, with one recorded straw bale building being a one-room schoolhouse built in 1896 or 1897, which cows ate in 1902 because the walls were not plastered. However, once the settlers began plastering the walls, they discovered that these temporary homes could keep them cool in the summer and warm in the winter, withstand the high winds of the Nebraska prairie, and provide quiet spaces. Straw bale building in Nebraska faded out around World War II as cement became more popular. Nonetheless, in recent years, straw bale construction has re-emerged as a natural building technique.

A straw bale house utilizes straw bales as insulation or as the structural building block of the home. The walls are then finished with plaster. This type of construction is gaining attention as a natural building method, with an estimated 1,000 new straw bale structures being built worldwide each year [source: Amazon Nails].

So why are straw bale homes gaining popularity? What benefits do they offer, and is it safe to live in a house built with blocks of straw? We’ll explore the advantages of straw bale building on the following pages.

What are the Benefits of Building a Straw Bale House?

Straw has become a popular renewable resource for construction due to the high cost and low availability of lumber. Each year, the United States wastes 200 million tons of straw, which could be used for construction instead [source: U.S. Department of Energy]. Using straw for building is cost-effective since it reduces transportation costs, and it’s available in most parts of the country. The construction industry and transportation are responsible for more than 50 percent of greenhouse gas emissions. By using straw, we can significantly reduce these emissions [source: Amazon Nails].

Although building a straw bale home may seem cheaper than using conventional materials, the wall budget is only about 10 to 15 percent of the total building budget. Other expenses such as foundation, roof, doors, and windows can make the cost of a straw bale home similar to that of a traditional home [source: Magwood, Mack, Therrien]. However, you can still save money by participating in straw bale raising parties, where a group of people can stack bales together like building blocks. Straw bale homes offer excellent insulation, and the finished walls have a high R-value. These walls can save up to 75 percent on heating and cooling costs annually [source: Morrison, Amazon Nails]. The thick walls also provide excellent soundproofing, making them ideal for recording studios or homes near busy highways. Straw bale houses have a fire resistance of up to three times that of conventional homes due to the tightly packed bales and plaster coating [source: Morrison, Magwood, Mack, Therrien].

There are many resources available online and on DVD to teach you how to build your own straw bale home. While little experience is needed to participate in building a straw bale home, it’s important to know what you can do on your own and where you may need to hire a contractor.


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

Straw, not hay, is an essential material for building straw bale homes. Hay contains leafy materials that attract animals, while straw is not a food source. Straw bale walls, tightly packed and combined with plaster, make it difficult for critters to enter. Using straw instead of hay should also ease the concerns of hay fever and allergy sufferers since straw does not contain pollens. Unlike modern building materials, which may contain harmful chemicals, straw is a natural, breathable material. However, moisture is a significant threat to straw bale homes, so proper measures need to be taken to address this issue.

Designing a straw bale house involves more than just stacking straw. The home’s orientation should take into account factors such as the sun’s position, wind patterns, and nearby water sources. Natural barriers such as trees and shrubs can also help block heavy sun or wind. Two main construction methods are used for straw bale homes: post-and-beam infill and load-bearing. The former is closer to standard construction and is usually more acceptable to building officials, lenders, and insurers. The latter is the original method used by the first straw bale builders and uses fewer resources, but comes with some design limitations. Local building codes should be consulted to determine which construction method is required in the area.

The current trend of building homes using straw bales is mostly concentrated in the desert regions of Southwest United States and Southern California. This technique is most effective in places that experience extreme temperatures as the insulated walls help in blocking excess heat or cold. Although moisture poses a significant threat to straw bale homes, people have successfully built these houses in rainy Pacific Northwest and snowy New England. However, humid areas are not suitable for this type of construction. The Straw Bale Registry maintains a database containing registered structures from all over the world, with most of them situated in the United States and China.

The selection of straw is an essential factor when designing a straw bale home. Straw bales are available in various shapes and sizes, but the most common ones are two-string bales and three-string bales, named so because they are tied together using two or three lengths of wire or twine. According to the U.S. Department of Energy, the measurements for these bales are as follows:

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

An online bale calculator can help you determine the number of bales required for building, and you can purchase bales from feed stores or farmers. It is crucial to choose dry bales and look for those with a golden color, indicating less moisture. Hand-held moisture meters can be used to check the moisture content of the bales, and a moisture content of up to 20% is considered safe. Tight and well-strung bales retain their shape when lifted or dropped.

Constructing a Straw Bale House

Once you have decided on the type of structure, whether load-bearing or post-and-beam, the design options for straw bale homes are similar to those for conventional homes. Any type of foundation or roof can be used, and features such as solar-paneled roofs can enhance the home’s environmental friendliness and energy efficiency. For a load-bearing home, the foundation is laid, and the straw is stacked, followed by placing the roof frame and assembling the roof. For post-and-beam straw bale homes, all the structural elements, including the foundation, frame, and roof, are put in place, and straw bale is filled between the posts.


Photo courtesy StrawBale.com
A toe-up

When building a straw bale house, it’s important to raise the bales off the ground to prevent moisture from seeping in. This can be done using toe-ups, which are platforms made of lumber and gravel attached to the concrete foundation. Nails or pins are hammered into the toe-up, and the bales are placed onto them. Once the first round of bales is situated, the rest can be stacked like blocks. To insert windows and doors, wooden frames are used, and baling needles can be used to cut and retie bales. Chain saws can be used to create architectural features. Plastering is done using materials such as stucco cement, gypsum plasters, and lime. Moisture is a major concern, and precautions must be taken to prevent mold and rot. Straw should not be waterproofed, and breathable paints should be used. Proper plastering and painting techniques will help prevent moisture from affecting the straw.

Building a Straw Bale Home: Challenges and Solutions

When designing and constructing a straw bale home, it is essential to keep water out of the house. Overhangs in the roof design and carefully sealed windowsills and joints can help prevent liquid dangers from rain and snow. The use of natural, breathable plasters can also keep moisture from accumulating in the walls. However, cracks in these plasters are the primary maintenance issue for straw bale homes.

Building a straw bale home can pose challenges since it is still a relatively new construction method. Building codes may not account for straw bale methods, and conservative banks, lenders, and insurance agents may not finance such an experimental method. To gain financing and insurance, one needs to be well-versed in straw bale building and may have to hire consultants to vouch for them with institutions.

Finding a contractor knowledgeable in straw bale construction can also be difficult. The Last Straw, a quarterly journal about straw bale building, maintains a list of resources. Alternatively, one can look for contractors to provide individual services such as plastering or roofing. However, one needs to know how to work effectively with the contractor.

There is little data on the resale value of straw bale homes, but some evidence suggests that they might receive a lower resale value than conventionally built homes. An educated owner/builder can explain the value of a well-insulated home to potential buyers and convince them to pay more than the appraised value.

Straw Bale Additions and Retrofits

One can still use straw bales for additions and retrofits even if they are settled in a conventional home.

Adding straw bale extensions to an existing structure involves connecting the addition to the current house. For each row of straw bales, a sheet of metal mesh called a lath is placed on top and secured with dowels or landscape pins. The lath is then folded at a 90-degree angle and stapled to the existing house’s frame. If wooden frames are used, they can be directly attached to the house’s frame. The process of plastering the addition is the same as building a straw bale house.

A contractor can help match the exteriors of the house and addition. When laying the foundation for the extension, the thickness of the bales and plaster must be considered to ensure the finished product aligns with the existing house.

Improving energy efficiency can be achieved by wrapping an existing home in straw. Moisture prevention is crucial, and the design must include large roof overhangs to protect the walls from rain. Changing the slope of the roof and extending it may be required for a retrofit.

The foundation must be larger to support the additional width of the bales, and epoxy bolts can be used to attach the new foundation to the existing one. Toe-ups are necessary to keep the bales off the ground. Instead of stacking and plastering, the bales should be dipped in earthen-based plaster before stacking. A wire netting must be used between the house and bales to provide ventilation.

Windows and doors may require modification when bales are added to the outside of the house. Retrofitting with bales on the inside of the house is a viable option but reduces the interior space by the width of the bales.

Although the incorporation of straw bale construction may seem expensive, the energy savings achieved over the lifetime of the house should be considered. For more information on straw bale construction, visit the links provided.

The following websites provide information on straw bale building: StrawBale.com, Green Home Building: Strawbale, The California Straw Building Association, and The Last Straw. In addition, there are several sources of information on straw bale building including books, articles, and podcasts. These sources include: “Information Guide to Straw Bale Building for Self-Builders and the Construction Industry” by Amazon Nails, “Strawbale Questions and Answers” by Owen Geiger, “The Strawbale Search” by Jerilou and Kingsley Hammett, “Straw Bale Design and Site Evaluation” by Chris Keefe, “Straw-bale Construction” by Bruce King, “Expert Advice on Straw Bale Building” by Chris Magwood, Peter Mack and Tina Therrien, and “7 Essential Steps to Straw Bale Success” and “Adding Bales or a Bale Addition to an Existing Home” by Andrew Morrison. Additionally, Morrison provides information on how to choose the right straw bales, retrofitting a house with straw bales, and recent radio show podcasts. Finally, Kenton Shepard’s “Straw Bale Home Basics” and the U.S. Department of Energy’s “House of Straw: Straw Bale Construction Comes of Age” also provide valuable information on straw bale building.

FAQ

1. What is a straw bale house?

A straw bale house is a type of home construction that uses bales of straw as the primary building material. The straw bales are stacked and secured together to form the walls of the house. The bales can be covered with plaster or other materials to provide protection from the elements.

2. Are straw bale houses safe?

Yes, straw bale houses are safe. They are designed and constructed to meet all necessary safety requirements and building codes. In fact, straw bale construction is often considered to be more fire-resistant than traditional wood frame construction.

3. What are the benefits of building a straw bale house?

There are several benefits to building a straw bale house. They are energy-efficient, environmentally friendly, and can be built at a lower cost than traditional construction methods. Additionally, straw bale houses provide excellent insulation and have a unique aesthetic appeal.

4. What are the disadvantages of building a straw bale house?

One potential disadvantage of building a straw bale house is that it can take longer to construct than traditional construction methods. Additionally, straw bale houses require specific knowledge and skills to build, which may limit the availability of builders in some areas. Finally, straw bale houses may be less resistant to pests than other types of construction.

5. How long do straw bale houses last?

When properly constructed and maintained, straw bale houses can last for decades. In fact, there are examples of straw bale houses that have been standing for over 100 years.

6. How do you maintain a straw bale house?

Maintaining a straw bale house is similar to maintaining any other type of home. It is important to keep the house dry and well-ventilated to prevent moisture damage. Additionally, the exterior of the house should be regularly inspected for any signs of damage or wear.

7. Can you use straw bales for other types of construction?

Yes, straw bales can be used for a variety of construction projects beyond just houses. They can be used for outbuildings, fences, and even as insulation for existing homes.

8. How do you protect straw bale houses from moisture damage?

To protect straw bale houses from moisture damage, it is important to use appropriate construction techniques and materials. This can include installing a moisture barrier, using breathable plaster, and incorporating overhangs and gutters to direct water away from the walls.

9. Are straw bale houses more energy-efficient than traditional homes?

Yes, straw bale houses are generally more energy-efficient than traditional homes. The thick walls of the house provide excellent insulation, which can help reduce heating and cooling costs.

10. Can straw bale houses be built in areas with extreme weather conditions?

Yes, straw bale houses can be built in areas with extreme weather conditions. However, it is important to use appropriate construction techniques and materials to ensure the house is properly insulated and protected from the elements.

11. How do you ensure the structural stability of a straw bale house?

Ensuring the structural stability of a straw bale house requires careful planning and construction. The foundation must be strong enough to support the weight of the bales, and the bales must be stacked and secured properly to prevent shifting or collapse. Additionally, it is important to use appropriate reinforcement materials to ensure the walls remain stable over time.

12. Can straw bale houses be customized to fit specific design preferences?

Yes, straw bale houses can be customized to fit specific design preferences. They can be built in a variety of styles and can incorporate a range of materials, including wood, stone, and metal. Additionally, the plaster used to cover the bales can be tinted or textured to create unique visual effects.

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