STRAWBALE CONSTRUCTION

StrawBale Construction

Table of Contents

INTRODUCTION3

COMPARING CONCRETE, CEMENT, MORTAR WITH STRAWBALE--SHOWING THAT USING STRAWBALE IS MORE ENVIRONMENTALLY FRIENDLY3

CLIMATE CHANGE11

CO2 EMISSIONS13

EMBODIED ENERGY (RELATE TO CO2)19

GREEN APPROACH27

REFERENCES37

StrawBale Construction

Introduction

A lot is heard lately about “green” home construction and houses that are “eco-friendly”. Most of the homes in question use conventional frame construction with more insulation, more efficient electrical appliances and low-flow water fixtures. Truly earth friendly house construction goes well beyond these measures. A popular “green” construction method in the western US is the straw bale house.

Comparing Concrete, cement, mortar with Strawbale--showing that using strawbale is more environmentally friendly

Despite the void of performance data on strawbale walls, tried and true construction methods exist due to the century-long use of strawbales as a building material. Currently, the AIHI utilizes a load-bearing strawbale wall system to construct its buildings, a system that combines techniques established by a multitude of experienced builders and developed through research and experience on seven AIHI demonstration projects. The load-bearing method has also proven to be volunteer-friendly due to the successful completion of AIHI projects by novice teams comprising students in the AIHI course series and Northern Cheyenne residents.

The common technique is to stack bales in a running bond on top of a base that provides a moisture break between the foundation and the bales. Various methods of reinforcement stabilize the walls, including pins, staples, and strapping. A box beam or wood frame provides a bearing surface for wood trusses or roof panels (shown) on top of the walls and distributes compressive loads over the entire wall system. Moisture protection is added around window penetrations and in some cases the lower courses of bales. Stucco lath is attached to the wood frame and pinned or sewn to the bales. A three-coat plaster veneer is applied, typically consisting of cement stucco with various types of finish coats. Based on experience with prototype projects, collaborators have developed several systematic methods to build stable load-bearing walls. These methods include the use of double-wide walls and buttresses to increase bearing capacity and stabilize walls, and the use of vertical and horizontal polypropylene strapping to reinforce the walls.

According to a 2003 report issued by the US Commission on Civil Rights, 40 percent of American Indians live in substandard housing, making them the most poorly housed sector of the US population. Many factors contribute to the third-world housing conditions on reservations including geographic isolation, severe weather conditions, overcrowding, insufficient infrastructure, low-income levels, inadequate workforce skills, and depressed local economies (NAIHC, 1999). With 26 percent of reservation populations living in poverty and only 56.5 percent in the workforce, most tribal residents remain dependent on government-funded Tribal Housing Authorities to address their housing needs (NAIHC, 2005). However, the funds that Housing Authorities receive from federal and state agencies are not sufficient “to adequately maintain and repair existing buildings, finance and oversee the construction of all the housing that is critically needed, and hire fully trained and competent staff to provide services”, leaving Indian country with an immediate need for 200,000 ...