Straw Bale Construction
Maybe you’ve read about the secret of straw bale construction. Or you’ve found a newspaper article about this way of building that is efficient and sustainable, beautiful and strong. Possibly you’ve gone by one of my houses as it’s being constructed.
And if you’re thinking “Isn’t this too good to be true?”, or “Prove to me this is true!”, I think you’ll enjoy the article ahead.
Because after 23 years of building with this material, I have a lot to say about the sober truth of this material.
In 1991 I founded a straw bale construction company in Albuquerque New Mexico. Building with straw was a very unknown building method at the time, so I had to invent a lot of the techniques as I went.
Straw Bale As A Science
Along the way, I realized I had to stop idealizing straw bale as a building material and start looking at it critically, analytically—like a scientist, if you will.
The purpose of this post is to give a brief overview of the advantages and challenges of building with straw. Some of this you may already know, some of this may be new. So whether you’re thinking about starting a project, or whether you’re in the midst of your own, I hope you find something you enjoy.
If you have any questions, please feel free to contact me. I offer a free initial consultation, and would enjoy hearing about your project in the comments below.
Eight Advantages of Straw Bale Construction
1. Straw bale construction is affordable
Straw bale homes cost almost exactly the same amount of money to build as traditional stick-frame homes. If you’re interested in calculating and comparing the specific costs of building a straw bale home vs a stick frame home, feel free to contact me.
2. Straw bale walls are very well insulated, when built correctly can have an R-value between 40 and 60, depending on the thickness of the wall
There are many great resources out there that discuss the insulation characteristics of straw bale. The quality of insulation that a straw bale wall provides depends on a number of factors including the way the bales are stacked, the way the bales mesh with the roof’s insulation, the type of post-and-beam structure or if loadbearing the type of top plate, the type of plaster used, the quality of the plaster work, and the design of the house itself, among many others.
3 .Straw bale homes are more fire retardant than traditional stick-framed homes. *
This can be a topic of much debate. There are a numerous studies testing the flammability of straw bale, and even more articles talking about their results, including this Mother Earth News Article. The idea behind the material’s resistance to fire comes from the concept that the bales are so tightly packed that oxygen cannot enter in between the straws and fuel a fire. It is true there are tests that prove their inherent resistance to fire. However, there are still numerous factors that will allow a straw bale house to burn, especially during construction. This is not to discount the material’s flame retardant nature, but to remark that they are not impossible to burn, especially in certain circumstances.
4. Straw bales are an agricultural by-product (wheat, oats, rye, barley, and rice),
If you’re looking to build with a small carbon-footprint, this is a note to consider in your green conscience. Straw is an annually-renewable resource, not at all like lumber which can take decades to produce trees capable of yielding 2×4’s. It takes almost no extra energy to harvest bales, as opposed to the transportation-and-milling costs of lumber prior to producing the 2×4’s. The straw harvests are in flat and previously-cultivated fields, not wrestled from forests, and therefore no environmental harm is done during the harvesting process. Compared with other building products like wood, concrete or steel, bales are extremely light and easy to transport from the field to the construction site. And unlike lumber, concrete and steel, straw is produced in almost every state of the union, thus saving fuel costs and less travel time to a work site.
5. Within the lower 48 states of the US, straw bales are almost always locally available.
If you’re looking for bales in the southwest, and are having trouble finding any suppliers, feel free to send me an email and I’ll do what I can to help you find some good quality bales to build a house.
6. Stacking bales can be incredibly fast and easy.
You will be amazed how fast an entire room can come to life when you’ve got several people working together stacking bales. Over the years, I’ve developed a couple trade-secrets that can improve the process dramatically. Contact me for some exclusive tips. Or attend one of my workshops.
7. Straw bale walls are gorgeous.
Most people love the look of the deep windows, niches, and bookcases that are made possible by straw bale construction. One caveat, though: if you’re very concerned with perfectly straight lines, bales might be rather frustrating for you.
8. Straw houses will save you money, year after year.
The walls are thick and will give you a cool house in the summer, a warm house in the winter. It has a natural “trombe” effect, in other words it soaks up the coolness or the heat of the inside and stores it/releases it like a giant heater or an efficient refrigerator. Places that confound stick-frame construction’s ability to properly insulate, like around windows and doors, behind electrical fixtures, or near the ceilings, they cease being places where heat can escape out of the house and are part of a seamless high-quality insulation that will astonish you with low monthly utility bills. And because the inside of the walls are almost always stuccoed rather than having thin sheetrock nailed to 2×4’s every couple of feet, those interior walls are much stronger and will need much less repair during normal household activities, especially when children or teenagers are around!
eight Challenges of Straw Bale Construction
1. Building with straw is not fully-accepted as method of construction in many parts of the country. **
Plenty of building officials, inspectors, structural engineers and local authorities have been known to laugh in your face if you bring up the idea of building (or retrofitting) your home with straw. The nursery rhyme of the three little piggies will invariably come up, along with some understandable concerns regarding insects, mold, and longevity.
2. Talking of insects and mold…
Straw bales will harbor both of those things if they are consistently wet or relentlessly exposed to high-humidity areas such a showers and sinks without adequate protection. Of course, a conventional house will also easily host insects and is susceptible to mold, too, if not built right. But straw is more sensitive to such things than wood-constructed and fiberglass-insulated structures.
3. It may take more time to acquire a building permit for a straw bale structure than it would a conventional one.
This is more to do with the social conception of the material, rather than the material itself. In some areas of the country, especially the Southwest, straw bale building is a well-accepted method; in other areas where there is more moisture, cities and counties may look askance at the use of bales and might require additional assurances—such as paying a local structural engineer or requiring unnecessary moisture testing—before releasing the building permit.
4. Because of the thickness of the bales, you will lose square-footage inside a home.
- A stick frame wall is around 6 inches thick
- A straw bale wall is around 18 inches thick.
So that extra-thick wall will indeed eat up some of your interior space. Most people simply make the exterior footprint of the house a bit bigger to make up for that lost space, or they live with a little less space inside. But designing the house a bit bigger will add some costs to the construction of the house: you’ll need some extra concrete in your foundations, for example, and you’ll need to make your roof trusses a bit longer.
5. If the bales aren’t stacked properly, there can be small gaps in the walls that create thermal break-points in the otherwise well insulated walls.
Unless you’ve done a lot of work with straw, as you put up the bales you’ll tend to ignore those little spaces between the bales, or places where the bales abut the post-and-beam, or the areas next to the ceiling where the bales don’t quite fit, etc. Those places in the wall where solid straw bales stack firmly on top of one another are going to provide the greatest insulation. But the areas around the doors and windows are can be hard places to do the firm stacking, and sometimes loose straw gets stuffed into a corner without being securely packed – and then settles over time. This becomes a spot for thermal leakage. So when you’re stacking your bales, pay attention to the ‘hard-to-reach’ places. It really does make a difference, and really is easy to overlook.
6. Plaster is the crucial point of the construction process, and is often done poorly.
I have experienced so many different problems with plaster throughout my 23 years of straw bale construction. Both stucco and adobe have their pros and cons. Either way, the plaster job needs to be done right, and a poor plaster job is going to prevent the material from performing like it should. Check out my Adobe vs. Stucco article for more information on this one. And if you are going to do the plastering yourself, get ready for a lot of fun –and even more hard hard work.
7. There are no studs at regular intervals
Alternate ‘hanging’ methods must be utilized to hang heavier pictures, mirrors, and cabinets on, and putting up shelves in closets where one of the walls is next to the bales needs to be done differently. This may be a bit frustrating at first, but there are some cool alternative ways I’ve developed over the years.
8. Working with Straw is fun, but often becomes a skin irritant.
This can mean nothing much more than itchy skin, but working with bales for days on end will make you want to have an air compressor or a hose nearby at all times. Breathing straw dust, especially as you cut the bales with a chain saw, will set you coughing. Or straw flakes will get in your eyes as you put up the top row of bales. Just a thought.
What’s Your Project?
I’m eager to know your thoughts and opinions on the advantages and challenges of straw bale construction, and if you’re starting a project please let me know what you’re up to in the comments, or send me an email if you have any questions.
**Recently, an article titled, “Straw Stuck” was posted on The Tyee stating, “The myth of straw bale as an inferior building material is gradually changing as an increasing number of people in B.C. start to use natural, renewable materials to build their homes.” which is great to hear.
Here is a list of similar articles and blog posts with good information:
- http://www.buildingwithawareness.com/blog/2009/04/the- pros-and-cons-of-straw-bale-wall-construction-in-green-building/
- http://liberstilo.com/welcome-home/diy/building-with- straw-bales/