In Australia as well
as in many other countries in the world,
straw bale housing has been revitalised considerably since the rise
of the environmental movement from the 1970's onwards.
Straw Bale building has many advantages above
other building methods. Because of the thickness of the walls -
constructed from straw bales, as the name suggests - the obvious
high insulation factor is one the primary reasons for the popularity
of building with straw bales.
We also like the fact that that the building process is easy, understood by
many, and attractive for people to help. Straw bale building can be a
great community activity.
The IronStraw Group
Project SafeCom Inc. received permission from the USA based
IronStraw Group (Cashmere, Washington) to 'mirror' their pages of
technical information. We received that permission with great
appreciation. The IronStraw Group is a 501(c)(3) nonprofit
educational organization. The IronStraw Group is "....passionate
about its mission of Stronger Communities through Strawbale Building,
the Empowerment of At-Risk Youth to learn job skills and a healthy
work ethic...."
Further information from their Web Site explains: "IronStraw's
building projects are designed to provide youth as well
as disadvantaged and rural populations with skills needed to respond
to their needs for shelter. Developed to train youth to plan, design,
and carryout activities to create their basic shelter needs,
the building projects will remain to serve the community even after
the training goals are completed."
There are six sections of information from the Web Site of The Ironstraw Group;
they are reproduced on three pages. You can navigate through these
pages by clicking on the "Next" buttons, placed above and below the information.
The IronStraw Group pages (1)
The IronStraw Group
Building Technical Info
Section 1
On these pages we are going to provide you - "the builder" - with
helpful construction techniques, details, architectural drawings,
or anything that might help you with your construction.
We'll start off really slowly and see what happens in each
section as we expand on the technical portions. Our first building
suggestion is one you will hear over and over again by all strawbale
builders and advocates: Keep your straw dry! We know this sounds
basic and sometimes stupid but it is very
important and can not be overemphasized. Wet straw does not work
well and must be removed - a depressing job - so keep it dry to
begin with.
We'll spend more time in the next few sections describing how
to keep everything from getting wet in detail. Right now we want to
show you a drawing of a foundation so you can begin to plan on how
to build your home. This foundation is for a thickened concrete
slab foundation and has been approved by our [USA] county building
official.
![[Footing]](images/footing.gif)
This is one option for your footing (this drawing is for a 22"
bale and not intended to be submitted to a building official in
lieu of your own drawings.) It is easier to get this type of
foundation approved because it is very conventional in design and
uses concrete in the normal manner, the main difference is the footing
is the width of your bales (usually about 2' wide.) In the following
sections we'll show you a brick paver floor on sand with radiant heat
using the same footing and then a stem wall foundation.
The IronStraw Group
Building Technical Info
Section 2
In the previous section we showed a detail drawing for a concrete
foundation and monolithic slab as one method of building your
strawbale home.
Here is a photograph of the same concrete foundation during one
of our workshops.
If you look closely at the photograph you can see the rebar in the
footing that the first course of bales is placed on. The workers in
the foreground are sealing the area around the rebar and concrete
with liquid asphalt to prevent moisture from "wicking" up into the
straw. The workers in the background have then put down asphalt paper
that goes between the concrete and the first course of bales. Both of
these steps are necessary to insure your straw stays dry and does not
suck up moisture from your foundation.
Note also on the footing area to the left that the entire footing
is raised above the floor level. This is important: in the event that
a water leak or broken pipe floods the inside
of the house, the bales will still be protected since they are
elevated. This also makes building easier since you don't have to
be worried about water getting on the floor during construction.
In the photograph you can see some water from a previous days'
rain that does not affect the bale walls or the construction process.
This can be especially important if you are not going to get your
roof on your walls right away. Our trusses and roofing went on the
following weekend from our wall raising party so we covered the walls,
but did not have to worry about the floor.
Here's the next step:
Here the first row of bales has been placed on the rebar. Notice the
black asphalt paper under the bales in the foreground. You can also
see the corner guideposts. Nail two 2x6s together at right angles,
then place them at each corner and make sure they are vertical.
These are your guideposts, start each course of bales from these
corners and the door/window frames and build towards the middle of
each wall.
Note: If you want you can run a string guide line from each corner
post as you lay your bales. This may help your wall go up straighter,
but may get in the way a little bit.
The rest of the wall will go up quickly. Try not to force bales
into walls, this will cause your corner posts and window/door frames
to move around or your walls to bow. Snug, but not overly tight.
Bales vary in length, you can almost always find a bale the length
you need if it is a close fit. Check your corner posts to insure
they stay vertical. Next month we'll talk about window and door
frames, laying the rest of your bales and wall tie downs.
The IronStraw Group
Building Technical Info
Section 3
In the first two sections we showed a basic bale foundation and
how to start stacking the bale walls. This section will be short
on the descriptions and just show you some photographs that are very
self explanatory.
The first photo shows how hectic it can get around the frenzy of
bale stacking. It is an exciting time with people and bales all over
the place, but also one that you must keep control over. Each of your
four walls (assuming a rectangular home) should have a wall captain.
Someone who has been given instructions on how to do this prior to the
wall raising.
This person will keep the wall going up straight, that the bale
placement is correct and make sure all the window frames are
installed.
Here we see a door and window frame combination in the process of
being installed. Ideally, all your frames should be assembled and
ready before your wall raising starts. In this case the frames
are constructed of 2x4s and ½" plywood, stuffed with straw.
The last photo shows a corner completed up to the 4th
course, with the corner guide post still in place. With good bales
and careful placement the walls should be nice and level and straight.
You can also see in this photo the green poly strapping we used for
the wall tie downs. This is special 800 lb test strapping - specified
by our structural engineer (yes, we did have to do that - we were
the first fully permitted load
bearing strawbale residence in Jefferson County, Washington)
In the next section we'll give you more technical stuff again.
We just thought you would enjoy seeing what a wall raising weekend
looked like.
If you are interested in building, see
our consulting page to see how we can help
you. You can e-mail Michael Thomas, Co-Founder of
IronStraw Group in the USA at: thomas@ironstraw.org
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