STRAWBALE
CONSTRUCTION – THE SMART ALTERNATIVE
Many of us have noticed that local, state and the federal governments
are urging us to save our air and our natural resources. Some people say that the great American dream
is one of owning your own home. So how
do we put the two together? We can build
new homes and save resources, such as lumber and energy, by building an
alternative construction home! A home
that is made with used tires, aluminum cans, steel beams or straw bales are
examples of this type of home. These
items are either recycled or are easily renewable resources. In general, these homes are made with
renewable resources, are extremely energy efficient and can cost the same or a
little more per square foot to build than a conventional home. Though there are
records dating back to the 1800s, strawbale is only recently gaining popularity
as a preferred type of construction used for homebuilding.
All through history, people have built homes using straw and
grass. These resources were used because
they were easily obtained and readily available. Historians have said that there are European
houses built of straw that are over two hundred years old and still in use.
When straw/hay baler usage became common place in the 1890s, homesteaders in the
northwestern Nebraska Sandhills area began using strawbales in construction
because of a shortage of trees for lumber. Settlers used strawbales to build
their homes and farm buildings. They
also built other structures such as churches, schools and grocery stores.
Today, many people have found that this type of home is easy to build, will,
last a long time and they save both natural resources and energy.
Early settlers had a need for cheap and readily available building
material and saw the big, solid, hay blocks as a possibility. Baled hay became
a significant construction material. Back then, the bales were approximately
three feet to four feet long and about one and one-half to two feet
square. They were stacked like bricks,
one bale deep, with the joints staggered. Some people used mortar between the
bales while others simply rested one bale directly on the other. Wooden rods
(in some cases, metal rods) were driven down through the bales to hold them
together. The roof plate and roof were also fastened to the top bales of the
wall with rods or stakes. Though the straw bale wall can support most any type
of roof, the most common type of roof was some sort of hipped roof. The window and door frames were set in place
as the walls were erected. The walls
were left to settle for a few months before they were plastered. Then the windows would be installed in the
frames.
The U.S. Department of Energy researched the history of straw bale
construction to help support and reinforce the use of it today. They found that there are many structures
still standing that were built between 1900 and 1940. Built in 1903, the oldest known structure is
the Burke homestead near Alliance, Nebraska. Though
it was abandoned in 1956, it continues to survive the temperature extremes and
strong Nebraska winter winds.
One long time Nebraskan recalls that because her childhood straw bale
home was so soundproof and quiet that her family was not aware of a tornado
passing outside. They continued to play
cards inside right through the storm.
The D.O.E. gives the following account as to the durability of straw
bale construction:
In Wyoming, straw-bale
structures have consistently withstood severe weather and earthquakes.
"The earthquake was in the 1970s and it was either 5.3 or 5.8," Chuck
Bruner, a resident of one of the houses told The Mother Earth News. "There
wasn't a single crack in the house. You can live in this house comfortably
during the summer. It stays nice and cool. We have never needed any air
conditioning, and in summer we get days up in the 90s. Also, last winter, I
only turned our small bedroom heater on twice. If I had to guess how our
utility bills compare to those of our neighbors, I'd have to say our bill is
about half.”
History has shown that homes made of straw will last. As of 1994, three states (South Dakota, Nebraska and Alabama) were known to have strawbales homes still
standing that were built before 1940.
Since then they have also been found in Kansas.
According to the D.O.E., there are more modern strawbale homes in at
least 35 U.S. states.
How have these homes survived the over the years with changing weather
and climate extremes? It is believed
that they survive because they are more resilient and flexible than
conventional construction. In the case
of earthquakes, if the internal frame structure gives way, the bale wall will
continue to hold the structure together by absorbing the shock created by
seismic activity. And, because they are
flexible and breathable, they can withstand high winds. Old and new finishing treatments for the
exterior walls have added to the resiliency of the overall structure.
Straw bale structures can and do last.
But why are people beginning to take a second look at it now? Today, conventional home building in the
world uses from one sixth to one half of the world’s lumber supply. Lumber comes from trees and trees are
important natural resource that needs to be preserved for the future of the
earth and the air we breathe. In the
February 1993 edition of The Permaculture Activist, Peter Bane states
that “Preserving forests has enormous importance for soil and water
conservation, wildlife habitat, genetic diversity, and absorption of
atmospheric carbon.” He goes on to
explain “Trees covering an area twice the size of Connecticut are cut every year to supply the U.S. need for paper and wood products.” Depending on the type of wood used, it can
take twenty years or more for a tree to mature enough to be used as building
lumber. Straw, on the other hand, can be
renewed within 1 year. Straw is
primarily a waste product of cereal grains.
Farmers and growers burn off tons of straw each year because it doesn’t
break down quickly enough if it is turned under in the fields. Using it for construction not only reduces
the amount of lumber used but also reduces the greenhouse gases produced by
burning. All of this provides advantages
to our environment, cereal growers, builders and home owners.
What are some additional environmental advantages of strawbale
construction? Besides cutting down on
the use of lumber, a strawbale home is more energy efficient. The mass of the bales and the plastered
finish increases the thermal efficiency of the wall system. The increased insulation allows for the use
of smaller indoor heating and cooling systems.
Also, the overall look and feel of a strawbale home is appealing and
comforting.
The environmental effect of using strawbales in construction can reduce
the effects of global warming. Removing
it from the fields can substantially reduce methane emission from
decomposition. The requirement for the
use of lumber would be reduced. And because there is less of a need for paints
and solvents, there is less of an effect on human health and the atmosphere (Gray,
Strawbale Homebuilding 4).
What are the cost advantages to strawbale construction? An article by Willow Louisa Whitton in The
Last Straw; The Comparative Cost Analysis Between Building Methods,
describes a comparative study of the costs of conventional and alternative
construction. The study compared “Twin
Homes”, identical size and designed homes.
She created detailed material lists, which included quantities and costs
of materials commonly used for building in Washington. She
found that because of the amount of involvement by the owner in the
construction, costs can be cut down.
Also, because the wall raising events involve volunteer labor, the cost
of the overall labor is reduced. She
also found that in many alternative construction projects, there is a wide use
of “deconsumer” materials. Deconsumer
materials are items that are not purchased retail. Strawbales can be purchased directly from a
farmer instead of a feed store. In the
study, Whitton states that the average cost per square foot on a conventional
home is $65-$75 where an alternative construction home can cost about $27.50
per square foot. This showed her that
alternative construction homes can be built at considerable cost savings. This is only an average based on this one
study. The cost can be more or less
depending upon owner involvement, additional features and the costs of hired
contractors and labor.
The U.S. Department of Energy conducted a study on strawbale homes.
They found much the same results on cost but also defined energy
efficiency. They found that the average
strawbale home has an R-value of 70.3 where the conventional wood frame home
has an R-value of 15.4. R-value is a
measurement of the ability of a material to resist heat flow. This means a lower energy cost to the owner
and a reduction in the energy needed which can lessen the effects of energy
production on the environment. These
statistics are for the most common type of construction. Though they also show the R-values of
different types of studs and different sizes of strawbales, strawbales still
rank higher in R-values.
Gene and Joyce Marshall of Realistic Living reside in north Texas in Fannin County. They built and currently live in a straw bale
home. They stated that “On the hottest Texas days, a mere two and half ton air conditioner
cools adequately this 2000 square foot house with 10 foot and 13 foot ceilings.
Our highest summer electrical bills have been $70. That is for an entire month
of three digit temperatures.” At another
North Texas straw bale home that has 3,200 square feet of
air conditioned space is cooled by a 4 ton central air conditioning
system. The contractors who installed
the ductwork for the system stated that they would typically install an 8-10
ton unit for a conventional home of the same size.
One of the unique elements in strawbale construction is that many of
the projects are built through a community effort. Friends, relatives and volunteer labor are
often involved in the wall raising. Once
the frame is in place, whoever is in charge of the project directs these
laborers where to start stacking bales in the walls. Depending on the type of design and the
number of people, the “wall raising” can take as little as four hours or as
much as two days. However, for those who
lack the time or talent to take advantage of this unique element, there are
many professional general contractors and architects who specialize in
strawbale construction.
As added proof of the importance of continuing to build with straw
bales, many people are looking at ways they can be modified to withstand the
climate conditions in many different areas and countries. In an on-line posting
in 1996 titled Plastered strawbale construction, a student at the University of Minnesota at the time, Patrick Pierquet, discussed his
hopes of obtaining a research grant for his PhD work. Mr. Pierquet saw that most strawbale homes
had been built in the semi-arid areas of the U.S. He
wanted to be able to test them in colder and more humid climates. He believed that he could create construction
plans that would allow for their construction in underdeveloped countries with
limited natural resources. Since then,
there have been numerous studies on strawbale construction and the practice is
used more frequently world wide.
Now that we know many of the advantages of strawbale homebuilding,
let’s take a look at what at it is.
Essentially, it is a house that has walls constructed using straw
bales. Here, I must make a distinction
between hay and straw. I think the book,
StrawBale Building, by Chris Magwood and Peter Mack explains the
difference quite well:
It is
common for people to confuse straw with hay.
While bales of the two are the same size and shape, they are quite
different substances. Hay refers to any
combination of field grasses that are grown to maturity, cut while still
relatively green, and bales to use as livestock feed when fresh grasses are not
available. High in moisture content,
food energy – a full-course meal for critter big and small! – and having the
potential to sustain microbial activity that can cause rotting and mold, hay is
not what you want in your walls. Build
your house with straw. Feed the hay to your livestock. (13)
As stated earlier, straw is primarily a waste product of cereal
grains. Once it is dried and baled,
farmers use it for livestock bedding and gardeners use it as mulch. The need for it far outweighs the
availability so it is therefore, wasted.
A strawbale home is much the same as a conventional home. You have a floor, exterior and interior
walls, doors, windows and a roof. The
type and amount of materials used is different.
Two of the most common types of wall construction systems for strawbales
are modified post and beam and Nebraska-style or load bearing. Conventional homes are built with wall studs
that are either 2”x4” or 2”x6” boards spaced 12”-18” apart in the exterior
walls. Modified post and beam uses some
type of vertical support, usually wood, steel or masonry, to carry a top plate. These vertical supports are usually 12 feet
apart. It uses columns made with four
2”x4”s to create the corners of the building.
The window and door frames provide additional support. The top plate carries the weight of the roof. Nebraska-style structure gets its name from
the straw homes of old. There is very little
lumber used because it has no vertical supports or top plate. The bales themselves carry the load of the
roof. Because they use fewer or no
vertical supports, both of these systems use less lumber than conventional
construction.
For the floor, most people choose a concrete
slab though a conventional pier and beam foundation can be used also. The window bucks “float” within the strawbale
walls (Gray, Strawbale Homebuilding 84) or, in the case of post and beam
construction, they can be attached to one of the vertical supports. Window bucks are the framed structure around
a window. They are designed to withstand
the weight of the walls and roofs without distorting the window itself. Any conventional roof tops off the structure.
Straw bales today are much the same size as they were 100 years
ago. When stacking the walls, builders
usually start at the corners of the structure and work toward the middle to
prevent buckling. The bales are stacked
much like a mason stacks bricks. They
are stacked in alternating rows so that the bale joints do not line up (Magwood
and Mack 148). Partial bales are made to fit where a full bale doesn’t. Typically, partial bales are made by cutting
the bale wires, removing the amount of straw you do not need, compressing what
is left and retying it. As the walls are
erected, steel or wood pins are used to join the bales and reinforce the wall
system. This also aids in compressing
the walls to prevent settling which provides a more uniform finish when the
plaster or stucco is added. It also
reduces the amount of time the settlers of the 1900s used to wait for the walls
to settle.
Once the walls are erected, they are covered with a wire mesh – chicken
wire. Any stray stalks are removed by
hand or with a weed-eater. Upon completion
of the exterior components of the walls, they are typically covered with
stucco, sometimes referred to as “rendering”.
Stucco is a generic term for any type of finish that is hand applied
with the use of a trowel. However, it
can be applied mechanically with what is known as a stucco gun. It can be a cement based product that
contains Portland cement, some type of lime product and sand mixed with
water. It can also synthetic based
product that is similar to a heavy latex paint.
Synthetics are not recommended because they can reduce the breathability
of the walls. With lime being one of the
components of stucco, careful handling and protection are required. Plastering
seems to be the most difficult part of the entire wall process because it requires
a specialized skill.
To finish the interior of the home, you have most of the same options
as traditional construction. Because of
the width of strawbales, they are not normally used for interior walls. Studs
and drywall are the most popular option and can be finished by painting,
paneling or wall papering. Special
consideration needs to be taken when attaching cabinetry to bale walls. The most common way to attach cabinets to
bale walls is with the use of “gringo blocks”.
A gringo block is a nailing surface of a length specific to the cabinet
that is permanently attached with bolts or wire to the bale wall at a height
appropriate for the cabinet.
When moving outside the conventional realm, many questions are
inevitably raised. Skillful Means, an
architecture and construction firm in California, provides detailed answers to most of the
common question asked regarding strawbale construction. Let’s take a look at a summary of their
answers.
Strawbales are unprocessed and unpreserved products. What keeps them from rotting? Straw can take about a year to decompose when
plowed into a field. If it is kept dry,
straw can last a lifetime. Dry rot can
occur if exposed to moderate levels of humidity for extended periods of
time. Because of the “meshed” nature of
a straw bale, humidity is dispersed through the bale and doesn’t settle in to
one place. The interior and exterior
finish of strawbale walls helps to prevent moisture from entering but because
the base of a strawbale structure can be exposed to standing water, it is
typically covered with a moisture barrier such as builders plastic before it is
finished. The top row of bales is also
susceptible to water seepage so they are typically covered with a builders
paper.
Doesn’t straw burn easily? Yes,
loose straw does but because bales are densely packed, oxygen is inhibited and
they tend to smolder rather than burn.
They will not burn easily but they can smolder for a long time. During construction, there is typically loose
straw around the job site. Precautions
need to be taken while building the home.
Because of the exterior rendering added to the walls, fire and flames
are prohibited from actually reaching the straw. The walls of a conventional home can actually
provide “chimneys” for fire to flow up between the framing studs. This allows fire to spread quickly. Because bales will smolder more than burn,
human life can be protected. The
Skillful Means FAQs page provides an excellent testimonial to this effect:
“Generally,
straw building can be considerably safer than conventional stud construction
and examples of the resilience and fire resistance of bale buildings are
impressive: In New Mexico, and unattended candle burned the ceiling of a wall
niche, which burned the wall above it before the owner returned and called the
fire department. The firemen told the
owner that if the same fire had begun in a conventional building, the entire
building would have been seriously involved by the time the owner returned
home. Instead, the only repairs
necessary were minor plaster patching.”
Straw is a natural product, what about
pests? Unlike hay, straw provides very
little nutritional value and will not support pests. Termites may be able to reach the window and door
frames but the straw bales will remain intact.
It is recommended that the straw bale walls be finished soon after they
are raised to help prevent intrusion by rodents and bugs. After completion, the finish and the density
of the bales makes it difficult for pests to travel through them. If there is a crack or break in the finish,
rodents may crawl in and take up residence.
In areas where there are significant rodent problems, it is suggested
that a smaller mesh than regular chicken wire be used on the walls before rendering. Andrew Skinner of Big Heart Builders in north
Texas suggests that for added protection, builders
should apply a mixture of boric acid and DE (diatomaceous earth) under the
first layer of bales and to dust each row of bales with DE during the wall
raising. DE is a non-toxic insecticide
in powder form that consists of the skeletal remains of fresh or salt water
diatoms consisting of mostly silica, a little aluminum, sodium and iron and
lots of trace minerals, including some that are rare. Care needs to be taken during application
because it can be an inhalation irritant.
Will a house made of straw bales aggravate
hay fever and allergies? Unlike hay,
which can have seed heads, straw will have very little pollen. With the bales encased in wall finishes, the
transfer of irritants is difficult.
Clean, dry bales contain few molds or pests. The breathability of the bales also allows
for a degree of air filtration through the walls, keeping the air in the
interior fresh.
One additional question regarding straw bale
homes is design. Most of us think of
straw bales as rectangular shaped blocks similar to bricks, only larger. Therefore, we cannot imagine that a strawbale
home could be anything else but square.
According to Robert Andrews of Balewatch in Pueblo, Colorado, you can use a wide array of interior and
exterior designs that are expandable and not always conventional. Andrews has design plans that include the
conventional square or rectangular homes.
He also has plans for round or diamond shaped structures as well as some
that combine different overall shapes.
Common concerns with any type of home
construction include building codes, financing or mortgages, and
insurance. Because it is different and
out of the norm, these questions can cause an even greater concern to the
strawbale homebuilder. Most straw bale
builders are independents and homes are built in rural areas. As they gain popularity, more local and state
governments are adopting building codes specifically for alternative type construction. The city of Austin, Texas, the states of California and New Mexico and some counties in Arizona currently have these codes. For this same reason, more insurance
companies are agreeing to insure these homes.
They can sometimes cost less to insure than traditional homes because
they are finished with masonry both inside and out. While not all mortgage companies are loaning
money on strawbale houses, it is gaining acceptance. Both residential and commercial strawbale
projects have been approved for 30 year financing.
The main disadvantage to straw bale construction is the inconsistency
of the strawbale itself. Strawbales are
made to an average dimension as opposed to an exact dimension. In traditional construction, most of the
materials are uniform in size. Because of the natural variations in the surface
of strawbales, the finish is not typically flat and smooth. Experience and careful planning are required
to connect the interior surfaces to the bale wall. Sheet rock walls that intersect bale walls
will need to be scribed to assure a tight fit because the bale wall will
probably not be perfectly flat. Scribing
is transferring the outline of the wall surface onto the sheet rock with a
pencil or a compass. Another
disadvantage to strawbale construction is that because of the size of the
bales, the walls take up a large amount of floor space. Additionally, the unique skills that
plastering requires might deter someone from building a strawbale on their own.
So why choose an alternative construction
home and why specifically a straw bale home?
According to the Smart Communities Network http://www.sustainable.doe.gov/welcome.shtml
, “sustainable development projects
●
Strengthen
your local economy;
●
Improve
and protect the quality of the environment; and
●
Enhance
the quality of life and the well-being of all of the people in your community”.
We are all concerned with our future and the futures of our
children. We need to conserve our
natural resources for the future.
Building a straw bale home offers the use of a highly renewable resource
– straw. The energy efficiency of a
straw bale structure lends itself to saving the resources needed to create
energy. This also means it will cost
less to heat and cool your home, which equates to cost and energy savings. Another reason for building a straw bale home
is that it has been shown that they are more resistant to natural disasters,
such as hurricanes and earthquakes, than conventionally built homes. Also, because of the thickness of the walls,
they are more sound proof and offer a greater sense of security. In the book, Strawbale Homebuilding,
John Glassford and Susan Wingate-Pearse describe the beauty of strawbale quite
well:
Strawbale
walls are a pleasure to look at and to touch, and give a soft, sound quality to
each room. Naturally plastered,
strawbale walls can breathe, resulting in indoor air that feels fresh, clean
and invigorating. Within these silent,
sculpted walls which impart a sense of timeless peace, a new and better vision
of shelter resides. (3)
Big Heart Builders specializes in straw bale construction. The owners, Andrew and Bob Skinner have been in business for 7 years but had
been researching and working in straw bale construction for 10 years. They have completed the building of a total
of twelve straw bale structures and one steel frame structure in North Texas. On five of these homes, the interior was
framed using light gauge metal studs.
These studs are 95% recycled steel.
When asked why they chose to specialize in strawbale construction, they
replied by stating that “they were intrigued by the energy savings and the
aesthetics of the final product. It made sense to be able to use a product that
was grown with fifteen miles {straw} as opposed to one that was trucked in from
over one thousand {Canadian lumber}.” (Andrew Skinner)
The need for shelter is basic to all of us and owning our own home is
the great American dream. Saving natural
resources, saving money in energy and construction costs and the ability to
take part in the construction process is appealing to many people. Strawbale homes offer this to those people
who are willing to accept the challenges and opportunities.