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.
Project SafeCom 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.
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 how 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.
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.
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.
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.
In the second photo, 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(at)ironstraw.org
For more information click on the IronStraw logo or e-mail
The Ironstraw Group at: info(at)ironstraw.org
P.O. Box 715
Cashmere, WA 98815