Straw Bale Construction

Building with bales of straw has become almost mainstream in some parts of the country, especially in the Southwestern United States. Some says this technique we have been following since Palaeolithic period. Records shows this was pioneered in Nebraska. While reading the Nebraska settlers story – I thought as we know the Pauranic history of India, we know the Rishis and even our gods Rama and Krishna has also stayed in the huts made of grass and as they were staying in the jungle, keeping the Gaushala and horses, definitely this grass was not the food for the animals. Then it must be the straws which doesn’t have the delicious leafy parts for the animals.
Lets talk about the straw bale construction advantages and disadvantages, short comings and techniques.

Straw is a renewable resource that acts as excellent insulation, super energy efficient, environmentally friendly, attractive, and can be designed to match the builder's personal space needs, aesthetics and budget. It is a cheap and easy-to build option for self-builders, and even large-scale structures can be erected using timber framework filled with straw. The thick walls provide excellent insulation and are about 75 percent more energy efficient than conventional homes [source: Morrison]

There are two major categories of building with strawbales: load-bearing and non-load bearing. A post and beam framework that supports the basic structure of the building, with the bales of straw used as infill, is the most common non-load bearing approach. This is also the only way that many building authorities will allow. While there are many load-bearing strawbale buildings that are standing just fine, care must be taken to consider the possible settling of the strawbales as the weight of the roof, etc. compresses them.
Erecting bale walls can go amazingly quickly, and does not take a lot of skill, but then the rest of the creation of the building is similar to any other wood framed house. In fact strawbale houses typically only save about 15% of the wood used in a conventionally framed house. The cost of finishing a strawbale house can often exceed that of standard construction, because of the specialized work that goes into plastering both sides of the walls. The result is often worth it though, because of the superior insulation and wall depth that is achieved.

This kind of construction is gaining attention as a natural building method. In 2001, a British firm estimated that about 1,000 new straw bale structures were being built each year around the world

With the rising price and decreasing availability of lumber, straw has gained attention as a renewable resource that is regularly available as the byproduct of growing grains. Farmers use a little straw to fertilize the ground, but most straw otherwise goes to waste. Each year, 200 million tons of straw go unused in the United States [source: U.S. Department of Energy]. Straw is available in most parts of the country, which reduces transportation costs of construction. With more than 50 percent of all greenhouse gases produced by the construction industry and the transportation associated with it, these savings can be significant [source: Amazon Nails].

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]. When you factor in other expenses, such as the foundation, the roof, and the doors and windows, the price of straw bale houses rises in line with more traditional houses.

However, you can squeeze out some cost savings depending on who builds the house. Straw bale raising parties, similar to barn raising parties, are a chance for a bunch of people to stack bales like building blocks. Little experience is needed to participate in building a straw bale home, and it can go fast. Many Web sites and DVDs are available to teach you how to build your own straw bale house, but it's important to realize what you can do on your own and where you might need a contractor's help.

The real cost savings of straw bale building relate to energy efficiency. The straw bales, finished by plaster, have a high R-value. The R-value measures the insulation resistance of the wall; straw bale walls provide an incredible insulation that can easily keep heat in or out, depending on your needs. A straw bale home can save up to 75 percent on heating and cooling costs annually [source: Morrison, Amazon Nails]. This represents a huge savings over the life of the house. These thick walls also provide excellent soundproofing. Straw bale building has been used for recording studios and for homes near busy highways.

It might seem like straw bale houses pose a tremendous fire hazard, but they provide roughly three times the fire resistance of conventional homes [source: Morrison]. Loose straw is indeed flammable, but the bales are so tightly packed that they actually increase fire resistance. In a tightly packed bale, there's no oxygen, which reduces the chance for combustion. The plaster coating of the walls adds an additional fire-resistant seal. The National Research Council of Canada conducted testing where straw bale walls withstood temperatures up to 1,850 degrees Fahrenheit (1,010 degrees Celsius) for two hours [source: Magwood, Mack, Therrien].
¬The main threat to straw bale homes is moisture, as it is for many homes. Moisture in the bales causes mold, which causes the straw to rot. You have to take precautions from the moment you buy the bales. A rainy day of construction could ruin exposed bales, so it has to be stored off the ground and under tarps.

During design and construction, special care has to be taken to keep water out of the home. Just as the toe-ups on the foundation provide protection from moisture below, roof designs that incorporate overhangs will provide protection from above. Windowsills and joints must be carefully sealed. These methods will keep out the liquid dangers posed by rain or snow, while using the natural, breathable plasters. Cracks in these plasters are the primary maintenance issue for straw bale homes so that moisture doesn't accumulate in the walls.
Other possible concerns with straw-bale walls are infestation of rodents or insects, so the skin on the straw should resist these critters.

Many localities have specific codes for strawbale construction, In an area in which they're not common, one might have to work more closely with building officials to get plans that will meet codes and pass inspection. and though some banks now a days are willing to lend on this technique.

As for reselling a straw bale home, little data exist, maybe because straw bale owners don't leave them. Some evidence suggests that straw bale homes might receive a lower resale value estimate than conventionally built homes [source: Magwood, Mack, Therrien]. However explaining to a potential buyer the value of a well-insulated home may help someone decide to pay more than the appraised value.

Like in the story of the little pig who threw some straw together and called it a house, only to have the big, bad wolf huff and puff and blow the structure down. But applying the plaster techniques makes this house sturdy to even be unaware of tornado raging outside.[source: Hammett].