where is straw bale construction used

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What are the benefits of straw bale building?

What are the benefits of Straw Bale building?

• Annually Renewable Resource Like wood, straw is produced by photosynthesis, a natural process, fuelled by solar energy. ...
• Reduced Environmental Impact: Straw is essentially a waste product. ...
• Energy Efficiency Plastered straw bale construction creates long lasting, super-insulated buildings offering superb thermal comfort. ...

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What are the advantages and disadvantages of straw bale?

Straw-bale constructions are environmentally sustainable: the raw material is fully natural and is locally available. Moreover, once you have your straw bales, the construction is really fast, and the material can completely be recycled when no longer in use. These are few of the environmental advantages. Straw bales are a perfect thermal insulation.

How much does it cost to build straw bale house?

You might be surprised to see how much a project cost varies based on its location. For example, a straw bale home built in Southern Oregon may cost about $180/SF while that same house in the California Bay Area might cost $350/SF and the same house, yet again, in rural Iowa could be no more than $100/SF.

Why build with straw bales?

The Pros and Cons of Straw Bale Wall Construction In Green Building

1. Straw bales are made from a waste product. Once the edible part of the grain has been harvested (such as wheat or rice), the stalks often become a disposal ...
2. Homes insulated with straw bale can have insulation values of R-30 to R-35 or more. The thicker the bale, the better the R-value.
3. Straw bale walls are at least eighteen inches thick. ...

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What are straw bales used for in construction?

Straw bale is used in two basic styles of construction: “Nebraska”-style structures, which resemble Southwestern adobe-style architecture and use the straw for structural support; and post-and-beam construction, with straw-bale infill for insulation. Some structures incorporate both of these styles.

What is straw mainly used for?

While some are quite traditional like the bedding for animals and mulch in the garden, it can also be used as a quality cattle forage, heating fuel, ethanol production, or even as a building material. Far from waste, straw has so many better uses than being burned in the field.

Is straw bale construction cheaper?

Although straw is cheaper than building materials, such as brick or lumber, constructing a straw bale home will usually cost the same as a conventional home because the wall budget is only about 10 percent to 15 percent of the total building budget [source: Magwood, Mack, Therrien].

How is straw bale construction made?

A straw bale house is made using straw as either a main structural element, insulation, or both. The buildings are constructed by stacking rows of compact straw bales on a strong foundation before sealing with a moisture barrier and outer plaster layer.

What is straw used for commercially?

Cereal straw accounts for a significant proportion of this and is attracting increasing attention as an animal feedingstuff and chemical feedstock. Its fibre also has many uses-in construction, insulation, packaging, and papermaking; its potential extends even to textile manufacture.

What products are made from straw?

Straw is a bi-product of the food growing industry. For thousands of years it has been used in house construction, as stuffing for mattresses and upholstery, for basketry, as a fuel and as bedding and feed for horses, cows and pigs. There are many sustainability benefits to using straw as a material resource.

How long will a straw bale house last?

100 yearsIf built correctly a straw bale home can last 100 years at least. When it's life cycle is complete, a structure stripped of all but the walls can be tilled back into the earth.

What is the cheapest house construction method?

The cheapest way to build a home is to design a simple box. Sticking to a square or rectangular floor plan makes the building and design simple. Generally speaking, building up is cheaper than building a sprawling one-story home, so you may want to consider planning for a multiple-story home if you need more space.

What are the disadvantages of straw bale construction?

Since straw bale homes are built using a stacking technique, they can be susceptible to structural movement. This can lead to cracks in the plaster and even the collapse of a load-bearing wall, especially if the house wasn't built well in the first place.

Is straw a good building material?

Straw is a renewable material offering good thermal insulation properties and a much lower environmental impact than many current mainstream construction materials. Straw bale is very suitable as infill insulation for timber- frame buildings with either an external render or timber rainscreen finish.

Can you build a house from straw bales?

Another advantage of straw bale buildings is their longevity. If they are designed and built well with appropriate materials, and maintained throughout their lifetime, they should last more than 200 years. It is also usually a joyful and collaborative experience to build your own house from straw.

Why is straw bale construction sustainable?

The crops that leave the husks that are turned to straw trapped carbon during its growth cycle, and because straw bale can often be sourced locally, its use in buildings is often carbon-neutral and can even be carbon-negative.

What are the recycle of straw?

Plastic drinking straws cannot be recycled and belong in the garbage. Metal straws should last forever but if they somehow become damaged, they can be recycled with scrap metal. Straws made from paper or startch can be composted and belong in the organics.

Is straw used for food?

Uses. Straw may be fed as part of the roughage component of the diet to cattle or horses that are on a near maintenance level of energy requirement. It has a low digestible energy and nutrient content (as opposed to hay, which is much more nutritious).

What plant is used for straw?

straw, the stalks of grasses, particularly of such cereal grasses as wheat, oats, rye, barley, and buckwheat. When used collectively, the term straw denotes such stalks in the aggregate after the drying and threshing of grain.

Why do farmers grow straw?

Wheat straw is used as animal bedding for a variety of domesticated animals and is a valuable commodity in the horse industry. Straw is also used as mulch by homeowners, landscapers, and small fruit growers.

What is straw bale building?

Straw bale building typically consists of stacking rows of bales (often in running-bond) on a raised footing or foundation, with a moisture barrier or capillary break between the bales and their supporting platform. There are two types of straw-bales commonly used, those bound together with two strings and those with three. The three string bale is the larger in all three dimensions. Bale walls can be tied together with pins of bamboo or wood (internal to the bales or on their faces), or with surface wire meshes, and then stuccoed or plastered, either with a lime-based formulation or earth/clay render. The bales may actually provide the structural support for the building (" load-bearing " or "Nebraska-style" technique), as was the case in the original examples from the late 19th century. The plastered bale assembly also can be designed to provide lateral and shear support for wind and seismic loads.

What is straw bale?

Straw-bale construction is a building method that uses bales of straw (commonly wheat, rice, rye and oats straw) as structural elements, building insulation, or both . This construction method is commonly used in natural building or "brown" construction projects. Research has shown that straw-bale construction is a sustainable method for building, from the standpoint of both materials and energy needed for heating and cooling.

Where were straw houses built?

Straw houses have been built on the African plains since the Paleolithic Era. Straw bales were used in construction 400 years ago in Germany; and straw-thatched roofs have long been used in northern Europe and Asia. When European Settlers came to North America, teepees were insulated in winter with loose straw between the inner lining and outer cover.

What is a field bale?

Typically "field bales" (bales created on farms with baling machines) have been used, but recently higher-density "precompressed" bales (or "straw-blocks") are increasing the loads that may be supported. Field bales might support around 900 kg per linear meter of wall (600 lb./ lin. ft.), but the high density bales bear up to 6000 kg per linear meter of wall (4,000 lb./lin.ft.), and more. The basic bale-building method is now increasingly being extended to bound modules of other oft-recycled materials, including tire-bales, cardboard, paper, plastic, and used carpeting. The technique has also been extended to bags containing "bales" of wood chips or rice hulls.

Why is straw bale wall important?

However, proper construction of the straw-bale wall is important in keeping moisture levels down, just as in the construction of any type of building.

What are the disadvantages of straw?

Disadvantages include susceptibility to rot, difficulty of obtaining insurance coverage, and high space requirements for the straw itself. Research has been done using moisture probes placed within the straw wall in which 7 of 8 locations had moisture contents of less than 20%.

What are the advantages of straw bales?

Advantages of straw-bale construction over conventional building systems include the renewable nature of straw, cost, easy availability, naturally fire-retardant and high insulation value. Disadvantages include susceptibility to rot, difficulty of obtaining insurance coverage, and high space requirements for the straw itself. Research has been done using moisture probes placed within the straw wall in which 7 of 8 locations had moisture contents of less than 20%. This is a moisture level that does not aid in the breakdown of the straw. However, proper construction of the straw-bale wall is important in keeping moisture levels down, just as in the construction of any type of building.

Why are straw bales used in buildings?

Straw bales provide cost-effective sound insulation, which contributes to the liveability of this kind of construction. Walking into the space created by a straw bale structure, you can appreciate the quietness and hear the difference from conventional buildings.

How many storeys are straw bales?

The structural capability of straw bales is surprisingly good. In the loadbearing (‘Nebraska’ style) straw bale method, walls of up to 3 storeys have been constructed. Most straw bale construction uses a frame of timber or steel for the building structure to comply with the National Construction Code. There are many examples of multistorey buildings in framed straw bale construction.

How much does a straw bale weigh?

The Australian straw bales suitable for domestic construction have 2 strings (American how-to books often show 3-string bales) and are typically 900mm long × 450mm wide × 350 to 400mm high, and weigh 16 to 20kg. Agribusiness produces large round straw bales that cannot be used for building purposes but rectangular ‘jumbo bales’ are available (2400mm × 1200mm × 1200mm) which can be used for large structures and require mechanical lifting.

Why are straw bales compressed?

With straw bale construction, bales are usually attached to a frame and laid like giant bricks. Bales are compressed to minimise settlement and movement.

What is a true window?

A ‘truth window’ is a common feature in straw bale homes, providing a glimpse of the material that is otherwise rendered over and hidden in the finished building

Why is it important to insulate roofs and windows?

Thus, it is essential to insulate roofs and windows to maintain the overall performance of a straw bale building.

Why is rice straw better than wheat straw?

Rice straw can make more durable bales than wheat straw because its high silica content improves rot resistance. Rice straw bales are slightly denser, and therefore heavier, but can otherwise be treated the same as straw bales.

Straw is a traditional building material, but today's building methods are relatively new. Discover how modern straw bale construction has evolved

Straw is a traditional building material, but today's building methods are relatively new. Discover how modern straw bale construction has evolved.

Two Approaches to Straw Bale Construction

One version of a straw bale home is a “Nebraska-style” structure. Bales are piled on top of each other and support the roof, which can be made from any conventional roofing material. Another way: Build a structural frame to support the roof and use the bales to fill in the walls.

Pros of Straw Bale Construction

Each year, some 200 million tons of straw are burned in the U.S., adding to the already dangerously high concentration of carbon dioxide in the atmosphere. Straw bale construction sequesters some of the carbon released by burning, thus helping reduce global warming.

Cons of Straw Bale Construction

Straw bales shouldn’t get wet. They won’t be damaged by rain or inclement weather when properly coated with a protective material, but they can still be vulnerable to persistent high humidity.

Finding Contractors

Like any building project, a straw bale house needs to conform to building codes. Best to consult with a contractor, even when planning this as a DIY project. Straw bale contractors aren’t common, but their numbers are growing as this building method becomes more popular.

How does moisture get into a straw bale wall?

There are two main ways that moisture gets into walls: it infiltrates as a vapor or it flows in as a liquid. Liquid water can be prevented from entering a wall through careful detailing (at wall penetrations and horizontal surfaces). Bales should also be “dry” before applying finishes (moisture content should measure lower than 20%) to eliminate the potential of trapping large amounts of water inside the wall. Airborne vapor is a concern only if it becomes trapped. To prevent water vapor from getting trapped in walls, vapor barriers are eliminated, thus creating walls that “breathe”. Finishes are also selected for their ability to breathe.

What are the two types of straw bales?

There are 2 basic types of straw bale construction: loadbearing (or Nebraska style) and non-loadbearing (or infill). Loadbearing construction, as its name implies, utilizes straw bales as large bricks that support all of the building loads.

How thick is straw bale insulation?

One of the aesthetic benefits of straw bale construction is that it creates a thick-wall system. Typical bales are 16 to 18 inches wide, resulting in a finished wall assembly that is 18 to 20 inches wide. Since compacted straw has good insulating properties (R=2.7 per inch), these thick straw bale walls result in highly energy efficient buildings, with R-values of approximately 43 to 48. (Note that walls with R=19 are considered to be “super-insulated”.) Insulation acts to slow the transfer of energy through the exterior walls and roof, and a higher R-value signifies more insulation. The less energy is “lost” through the building envelope, the less heating and cooling equipment operates to provide comfort levels. Straw bale structures, therefore, require substantially less energy to heat and cool than conventionally framed structures. (It should be noted that since most energy loss is through the roof, care should be taken to insulate the roof to at least the same R-value as the walls. In addition, straw bale is most commonly finished with thick plasters on interior and exterior. The plaster acts as a thermal mass, effectively “storing” energy just inside and just outside the wall system. This helps to mediate temperature fluxuations inside, and modifies the temperature differential between interior and exterior, resulting in even greater energy efficiency

What are the resources that are grown from straw?

Straw, the stalks remaining after the harvest of grain, is a renewable resource, grown annually. Each year, two hundred million tons of straw are under utilized or just wasted in this country alone. Wheat, oats, barley, rice, rye, and flax are all desirable straws for bale walls. Even though the early bale homes used hay for the bales, hay is not recommended because it is leafy and easily eaten by creatures great and small. Straw, tough and fibrous, lasts far longer. The U.S. Department of Agriculture indicate that Americas farmers annually harvest enough straw to build about four million, two thousand square foot homes each year, nearly four times the houses currently constructed (D.O.E.)

What are straw bales used for?

Straw bales were used to construct many types of buildings, including schools, barns, houses, corner stores, etc. Some 75+ year-old buildings are still inhabited today, and historic straw bale structures can be found in a variety of climates. Straw is the stalk of any grain plant (oat, wheat, rice, barley, etc.).

How long does it take to build a straw bale?

This process could take from 2 weeks to 6 months, depending on the jurisdiction you are building in and the degree to which the permitting office is in inundated with other permits.

How to address concerns with straw bales?

Address each concern expressed by the building officials in a clear, concise, and informed manner, and submit your response to them in writing. Be aware that they may respond with additional concerns for you to address. Again, if you are not confident in your knowledge, hire a professional that is knowledgeable with straw bale construction.

Overview

History

Method

Thermal properties

Problems with straw-bale

See also

Further reading

External links