Straw bale construction

Straw, grasses, and reeds have been used along with wood and earth to build structures for thousands of years. With the development of the modern baling machine in the early 1800’s, many structures, made of bales stacked like bricks, began to pop up throughout the mid west. Straw bales, made from the leftover stems of harvested grain, are considered a waste product by American farmers. Enough straw is burned or buried yearly by American farmers, nearly two million tons, to build 5 million 2, 000 s. f. homes. Straw bale construction can be of either load-bearing or non load-bearing construction. In a load-bearing home, straw bales are stacked and tied together with threaded rods from bottom plate to top plate, compressing the bales.

Non load-bearing walls are also considered infill, where straw bales are filled in between a load bearing heavy timber structure. Straw bale homes are finished with a plaster or stucco coat. Straw bale construction appeals to many new home builders due to its ease of construction, flexibility of design, affordability, high insulation value, and low environmental impact.

Industial Construction Materials

Innovative building materials fall into two general categories: new and improved materials (such as high performance concrete composites), and prefabricated assemblies of materials (such as insulation and exterior cladding).

Precast concrete is one prefabrication system benefitting immensely from developments in materials science. Polypropylene, steel, or glass fibres can now be added to concrete to make a less brittle composite material. Because it is less prone to cracking, this concrete is easier to use in precast applications where the component must be moved to the site. Research is being done to improve other material properties such as early strength, which will reduce the time between precasting and transport to the building site. One concern about high performance concretes is that they are more sensitive to mixing errors than regular concrete. Precasting in a quality controlled industrial environment makes these errors less likely, and allows for easier testing of the finished product. Testing of construction materials will be a major part of future quality assurance programs as building owners demand higher quality construction.

The development of other new composite materials is allowing designers to replace heavier conventional structures with lighter, more durable structures that can be more easily prefabricated and transported to the site.composite materials, such as fibre reinforced gypsum, can also offer improved fire resistance, sound absorption, and corrosion resistance. They will be used more widely in all construction fields, including prefabrication, as more research is done on joining methods and long term mechanical behaviour.

New plastic applications are surfacing every year. The use of polyvinyl chloride (PVC) as a structural material is the latest trend. As research continues to improve the viability of PVC as a replacement for timber and steel, prefabricated PVC wall panels, interior partitions, and modular housing will be developed.

The joining of two (or more) materials such as exterior cladding and insulation to form a multi purpose assembly is a common innovation. These prefabricated assemblies reduce on site labour and perform better than equivalent site built assemblies. Other combinations include plastic coatings for cladding, concrete and steel girders, and glass block and translucent insulation for glass walls. Building product and material manufacturers have been the only sector of the construction industry to actively develop or look for new technology to improve their products, and there are no indications they will stop doing so in the future. Accordingly, more and more of these industrially manufactured materials will appear and their use should continue to grow.

Computers

Once fabrication of building components has started, it is difficult to make changes to the design. This means that the design must be at an advanced stage before construction starts.computers have helped speed up design considerably in recent years, and can allow designers to thoroughly analyze the building for different purposes before construction starts. When they were first adopted, Computer Aided Design (CAD) packages were simply used to replace tasks normally done by hand, such as drawing, and were not a cost effective investment. Now, CAD packages can be used for many tasks, ranging from analyzing buildings for heat loss to generating 3 D interior mock ups. As computer technology and software improve, building designers will be able to do more advanced design work before construction starts.

Prefabricated building components must fit together properly at the site. Some building systems require precise positioning of structural components (e. g., for piping connections). When prefabricated materials and components are manufactured with varying degrees of dimensional accuracy, it can cause problems. For example, a window opening in a prefabricated panel that is too large can create an even larger headache for the window installers. The adoption of Computer Aided Design and Computer Aided Manufacture (CAD/CAM) techniques has helped overcome these shortcomings.computer controlled cutting and joining tools ensure good dimensional control, and are widely used in the Japanese and Scandanavian prefabrication industries. In Japan, most prefabricated houses begin with 3 D steel structures, although timber use is growing.

Completely finished prefabricated kitchen and bathroom modules (often from different companies than the main house builder) are added at a later stage.computers play a large part in providing the dimensional accuracy needed in these "pop in" modules.

Robots

The Japanese and Europeans are also pursuing the development of robots for construction applications. Robots are faster and more precise than humans, ideal for dangerous jobs, and they don't get sick or go on strike. Robots are most suited for an industrialized construction setting, where prefabrication can be broken down into standard repetitive tasks that can be controlled by computer. Robots can cut and shape, position and connect members to form structural frames with amazing dimensional consistency. There are robots that will paint, trowel concrete, shotcrete, handle materials, and inspect finished prefabricated components for flaws.

Robots are also being developed for site assembly of prefabricated components. Research is being done in England to reduce the complexity and variations of construction joints, so that robots can be used to join panels. The Japanese are developing robotized tools for the building site, and installing rails on prefabricated panels to serve as guides for robots.