Published on September 2nd, 2013 | by Kata Polano0
A Journey Through the Natural Building Techniques: Straw Bales
When it comes to insulating your home you may feel as though your choices are quite limited. You are likely to be standing in the aisle of your local hardware store, gazing up at various fiberglass insulation, rigid insulation, cellulose, or even spun rock insulation called Roxul, and wondering which is the healthiest for you and your family. If you’re lucky, you might even see some sheep’s wool available to stuff into the cavities of your walls back home. Here is an interesting independent article comparing most of these. Of all these choices, the wool, cellulose, and Roxul are the top picks for conscientious builders needing an off-the-shelf insulation. However, if you’re still unsatisfied with these “better options” you might be a perfect candidate for Straw Bale building. You’ll just end up with thicker walls than usual, which lend themselves wonderfully as cozy corners to curl up in with a book. You can also feel reassured that no wolf, or gale force wind, will blow your house down!
The wolf may not be able to blow down your straw bale home, but if you build with hay instead, you run the risk of other little critters eating your house down to the ground. So as not to confuse the two; hay is food for animals, it has seeds and is cut green, straw is a waste product left after harvesting the wheat, rice, flax, and other such grains and seeds. Farmers used to burn the straw stalks left after harvest; but natural building not only offers them a better alternative, it also provides a second stream of income. Who doesn’t want to help support their local farmer while building better homes?
Building better and healthier homes doesn’t have to be a thing of the past, or far away future for that matter. In the early 20th century, settlers were forced to build with what they had, and they had straw. Nebraska was the birthplace of Straw Bale building, and some of these original structures still stand in good condition today. Check out this article if you want to read about them.
In the 1980’s, Straw Bale building started seeing a comeback. Today there is an ever-growing populous standing behind the viability of building with straw bales. You are more likely to find a Straw Bale building in your neighbourhood, or district, than you may think. If you’re curious about whether you have a neighbour living in a Straw Bale home, you can check out this interactive map, which is a living document of natural buildings worldwide.
The map, and any diligent digging, will show you that Straw Bale building has seen a large increase in popularity as it becomes more widely accepted by both homeowners and building officials. Studies have been ongoing for years that look into the various properties of straw bales as a safe and acceptable building medium. One of the most dedicated groups conducting such research is DCAT, the Development Centre for Appropriate Technology. They have a video on fire testing of Straw Bale walls available on the Ecological Building Network, which itself offers a plethora of natural building articles and publications. Here, in Canada, we are lucky to have a relatively new group working hard for the acceptance of Straw Bale building into our building codes. The Alternative Solutions Resource Initiative, ASRi, has recently published their work, which can be purchased and used by anyone needing accurate information and best practices guides to move their Straw Bale project forward. This publication is focused on permits within B.C., yet is an incredible resource for anyone looking into this building method.
When it comes to staying warm, keeping that howling wind out, saving on heating bills, and building sustainably, there really is no better option than Straw Bale building. With an R-value spanning 26-30, and no thermal bridging from a stud framed wall, straw bales will not only help avoid highly processed materials, they will also help you save money. Depending on where you live, bales can be extremely affordable. The closer you live to the source, the cheaper they are. There are a few things one should know about building with straw bales before they go ahead and order a truckload of bales.
Bales come in different shapes and sizes; from 2-string bales, all the way to giant bales, or even round bales. Choosing what bales to buy can be pretty simple. I would first recommend seeing which are available close to home. If you have a choice, here are some points to think about.
The 2 and 3-string bales are the most popular and readily available. The smaller the bale, the easier it is to handle. However, this same bale will give you a little less insulation, and perhaps thinner walls. Don’t worry though, you’ll be sweating enough when it comes time to stack your bales, you don’t have to sweat over this small difference.
The giant bales or round bales are more of a novelty for adventurous builders who want to do something different. Round bales can be fun to make pillars, yet the size of these is most fitting to a large castle or fortress. So, if you’re getting ready for a werewolf invasion, then these massive bales might be your top choice, as no wolf, were or otherwise, will be able to budge these monsters.
Once you decide what size of bales from which to build your home or fortress, you will want to know a few things about quality control. Tight bales are the best. There are a number of ways to check if your bales are tight, some people grab them by the strings and twirl them around, but I just give some good tugs on the strings to see how loose they are. You want good compression, bales that don’t fall out of shape easily, and strings that are fairly evenly spaced and away from the edges. If your bales have been baled a little less than ideally, you can always retie your bales, though this can be quite the task, and hard on the hands.
You also want dry bales! It is worth investing in a moisture meter if your builder doesn’t have one. This is a simple probe that will read the moisture level of the inside of your bales. Don’t forget to keep these nice dry bales dry! Invest in a good tarp and protect your bales during the building process. If they get wet, the only good place left for them is the garden.
As for what type of straw to use, this is usually what is locally available. If I had the choice though, I would use wheat straw for Straw Bale building, rice straw for Light Clay Infill (future article), and would only recommend flax bales if you don’t need diagonally cut bales for your design.
Now that you have some good bales chosen, you will need a good design to place them into. Here is where I highly recommend engaging with a knowledgeable and reputable Straw Bale builder. When going over the plans with your contractor or builders, you will want to make sure you see foundations that take into account the thickness of your bales, a toe-up (see section titled Other Moisture Considerations near bottom) with mechanical key atop your foundation, and proper spacing of any timber members. You can choose to have your bales bear the load (weight) of your roof, therefore eliminating wooden framing, use bales along with a timber frame, or even stud frame your structure and place the bales between the studs. Whether you decide to place your bales on end, on side, or laying flat is really up to you. On side gives you great insulation with thinner walls, leaving you more living space for your overall footprint. It’s also believed by some to give better insulation, as the straws run vertically, reducing the chance of airflow even more.
Beyond the walls you will also want to ensure that you have a good overhang to protect your bales from the elements, as is smart for any natural building. Personally, I prefer, and recommend, that the roof be installed before you start stacking bales. You never know when it is going to rain, and the last thing you want to be doing is taking wet bales off the wall because your tarps didn’t quite keep them dry.
Stacking your bales can be a lot of fun, and a very dirty job! There are a few neat tricks to make stacking easier, and plastering faster. You can build steps up with other bales not in use yet, leaving the last wall to stack the only tricky one best done by acrobats on ladder, or some good scaffolding. You also have the option of stacking dry bales, or french-dipping your bales first. No, you aren’t dipping them in coffee, you’d be dipping them in a clay slip, then wrestling them up to the top of the wall, yet saving on having to get slip on them later. This is the messy part of the job, and if you have a nice timber frame in place, you will want to be sure to cover it, as you will quickly find out that everything, not just the bales, gets covered in clay.
Once your roof is on and your bales stacked you will want to stuff and cover your naked bales as soon as possible, even if you have dipped them. No, they wont get cold, nor embarrassed, but they could become the warm, cozy home to more than just your family members. Little critters love to curl up in giant straw bale nests, so getting your bales plastered a.s.a.p. is crucial. Determining what to plaster with is the topic of a whole other article however, so be sure to come back and follow the journey.