Materials research Report:
Straw Bale Construction
Visal Patel, Jeison Nieves and Matthew Iacono
Mr. Jeffrey Johnston
Building Envelope
221-430-VA
Table of Contents
What is a straw bale? Pg.3
Aesthetics Pg.4
Structural requirements __________________________________________Pg.5
Durability Pg.6
Compatibility with other building materials Pg.7
Fire safety Pg.7
Construction Types Pg.8
Installation Pg.9
Costs Using Straw Bale Pg.12
History of Straw Bale Pg.13
Environmental impact Pg.15
Code Requirements Pg.15
Conditions Pg.16
What is a straw bale?
A straw bale ultimately is a bundle of straw, most commonly wheat, rice, rye and oats that are tightly compacted and help together with cords or hoops. It comes from matured plants that have been harvested and are no longer alive. This makes it a waste product since farmers have no real use for them other than landscaping or animal bedding. Farmers also burn the remains and this can cause air quality problems as well as greenhouse gas emissions. Bales can also be made from some other fibrous materials such as bean, corn stalks or pine needles. Straw should not be confused with hay. Hay is grass which has been cut and dried and is used for feeding animals, it is also more expensive compared to straw. Lately, straw bale has become popular in construction due to the fact that it is not expensive, it is ecological and its conventional style of construction. Straw is a large waste product from the agricultural industry, and it should definitely be used as a sustainable building material.Nowadays, straw bale construction is used more and more and not only in Nebraska but also Canada, the United States as well as Australia between others. Certainly, it has become more popular due to its sustainability performance, its durability, the cost as well as it is environmental friendly.
Aesthetics
Aesthetically, these straw bales are surfaced with a stucco, mortar/ concrete, gypsum plaster, earthen plaster or lime plaster. The finishing can be any color you wish. Not only does this provide stability to the wall, it allows the wall to achieve a fire rating of two hours. These materials also make living in a straw bale constructed home more appealing. This type of construction is adapted to suit traditional designs as well as new and creative designs. Curves, rounded edges, deep sills, and built-in appliances such as window benches or book cases are some of the things you can find in a straw bale house. Since the walls are so thick, they help reflect sunlight making room brighter. Aesthetically talking, it makes a house unique and different.
Structural requirements
As for the structural requirements, there are two different ways straw bale homes can be constructed, the first is post and beam construction, which is normal construction using wood, however the walls are filled with straw. This type of construction uses the wood as its structure. The other type of construction is structural straw bale construction or "Nebraska" style. The bales are stacked and are typically anchored together using wooden stakes for structural stability. The plaster applied at the end will give it the final stability needed for the walls to stay up. By that time it is too late to remove the wooden stakes from the straw bales and these are left inside providing reinforcement to the walls. This type of construction relies on the strength of the straw bales to hold up the roof.
Durability
Durability comes into question when taking moisture into account. The straw balesshould be kept away from moisture as it would diminish durability. Ultimately the bales should have moisture content lower than 14% and should be kept dry after construction.If construction is well done and straw bales are properly sealed from moisture, then buildings could last up to a hundred years such as the 1928 Pilgrim Holiness Church.
