Jim Reiland

Hi there Andrea!

You could certainly try working with aluminum rod.  It's probably easier to drill into (for the needle's eye) and cut push/pull notches, but I'll note that all the bale needles I have used or seen have been fashioned from either steel welding rod or stainless steel, which--if you have the right tools--isn't that difficult to work with either.  In theory, the stress on a bale needle is primarily from pushing and pulling the needle through a dense straw bale; it seems that aluminum should be able to tolerate that.  Over time though, bale needles get a fair amount of bending stresses; I think aluminum is less tolerant of that.

Try it--let me know what you learn!

Jim

Hi Jack,

Sounds like you’ll have your hands full not just for the year or two you’re building but for at least the next fifteen!  

I have seen couples with small children play a very active role in building their own homes, whether straw bale or not.  I have also seen it not work, but if you go into this knowing how much you can take on and where you need help, you’ll be fine.  

Taking a straw bale building workshop is excellent preparation, at least for the straw bale stacking and plastering parts of the project (unless the workshop also covered foundations, framing, roofing, windows, doors, electrical, plumbing, VAC, etc.).  Probably less than 20% of a straw bale building, in terms of materials, time, and cost, has anything to do with the plastered straw bale wall assembly, even though that’s the defining part of the building.  The rest of it is a lot like any other construction project.

Twelve years years ago my wife and I worked evenings and weekends on our own straw bale house while we held down full-time jobs.  We supplied about 50% of the labor, and with the help of family, friends, and a handful of contractors to do those things we didn’t have much experience with we finished in eighteen months.  Although I’m still working on it (a contractor’s house is never really finished?) it was a deeply gratifying experience.  Like you, we had taken a few workshops and remodeled a previous home so had a pretty good idea of what we were in for.

Unless you have plenty of time, money, or skill, I recommend keeping the design simple, e.g. a rectangle with a gable roof, or something similar.  As we say in Chapter 2 of the book, the longer it takes to draw your house on paper, the more complicated and costly it will be to build, and the longer it will take.  

Montana Resources.  You might check with the folks at the Natural Building Alliance, until very recently known as the Colorado Straw Bale Building Association—they have members throughout the Rocky Mountain states.   I’d also contact two very talented folks from Idaho and Montana who attended recent CASBA conferences.  Lindsey Love is an architect with Love-Schack Architecture out of Driggs, Idaho, and has worked on straw bale building projects.  Also, Mark Jensen out of Bozeman, Montana has a lot of experience building with bales.

Good Luck!  

Hi Mark,

That's a good question, and the book doesn't get into alternative foundation systems.  Although I would really like to see an alternative to concrete and or some combination of concrete and rubble emerge that has wide spread acceptance and is code compliant, there aren’t many options at this time.  

As the book project evolved, we considered including what might be called "guerrilla" building practices--there are many places in a construction where someone could substitute materials or methods that may have some foundation in local tradition, or are locally established and effective, but otherwise haven't been tested, and aren't in the building code.  Bob even coined a term for structures carefully assembled from simple, local, common materials (e.g. pallets)--he calls them "feral" straw bale buildings.  But we decided against.  

Straw bale construction already enjoys widespread support in the natural building world, and where/when builders aren't required to follow codes, they might make those substitutions. We hope those builders find the book useful, if only to let them know what the building code requires as it pertains to the straw bale wall assembly, and more importantly, why.  

We also want to promote the use of straw in the more mainstream building world, because of the approximately one-million new houses built in North America last year, probably less than 5% were "green" (energy efficient but not necessarily made with natural building materials), and a very tiny fraction of those used straw or any other "natural" material in them apart from wood.  

If we want to make a bigger difference for both healthier housing and a healthier planet, we need more than a few thousand new straw bale houses each year; we need tens and hundreds of thousands more!
So the book's focus is on the straw bale wall assembly, not on challenging other building norms, much as they need to be challenged.  Using straw as insulation and plaster as thermal mass is already a lot for most mainstream builders and would-be straw bale building homeowners to embrace. but we need them to embrace it because that's where 99.99% of construction is today!

I recently shared with colleagues at the California Straw Building Association my list of top "unknowns" where I'd like to see more research funding, and one of them is an alternative foundation system, or at least less concrete intensive foundations.  Since most thick wall construction (straw bale, light-straw-clay, cob, et. al., are quite heavy compared to more conventional wall systems using far less natural materials (SIPS, fiberglass, foams of any kind), the code level foundations for these natural buildings tend to be somewhat larger—and require more concrete, which reduces the net positive impact of using as much locally grown (straw, wood, hemp) or gathered (stone, clay) materials as possible in the building.  As I mentioned in other posts, the book was an entirely volunteer effort by all the contributors—book royalties are earmarked for research and development to further the use of straw as a building material.

So, back to your question.  We don’t get into rubble trench, grade beam, charred timber, or sand bag foundations.   My understanding is that where building permits and codes apply, when an alternative foundation system is used a structural engineer who is familiar with the alternative system is involved with the design.  The building code officials evaluating the permit want to know that someone has “done the math” to make sure the foundation can handle whatever loads are imposed on it (gravity, soil movement, frost heave, seismic, etc.)

Hi Dillon,

The book has lots of window flashing  detail descriptions and illustrations.  We also address what to do on top of the bale wall--yes, it's best that it's closed off from above. A box beam or layer of plaster over the bales is an effective way to do this in an insulated building like a house.  The book doesn't cover straw bale wraps of existing structures whether barns, mobile homes, or existing permanent dwellings, although many of the details in the book would be applicable, because the walls would still need to be supported by a foundation, protected from weather, infestation, and moisture from inside and above.  Finally, the book is a guide for site-built straw bale construction.  We're very much looking forward to when prefabricated straw bale panels are available throughout the United States and Canada, because there's a high likelihood that it will lower building costs while improving consistency in the wall's thermal performance.  Quite a few other benefits.  A few straw bale panel manufacturers have been operating in Europe for several years now, and there's also an Austrian company that has developed "blown in" straw insulation similar to the blown in cellulose (recycled newspaper) we're all familiar with.  Since we're replacing housing stock at the glacially slow pace of 1% or 2% per year, it'll be a very long time before we have replaced or current energy in-efficient housing stock with super energy efficient (and carbon storing) structures.  If the climate change reports are accurate, we have a few decades before we pass the point of no return, and if we believe that better buildings can be part of the effort to dial back our climate changing impacts we also need to upgrade existing housing with air sealing, insulation upgrades, more efficient HVAC systems, etc.  Blown-in straw insulation holds promise there, as do straw or wood fiber insulation panels, because they have a much lower embodied energy and store carbon, unlike most other conventional insulations.

Any time we build something we create habitat.  The longer any building is left unsheathed there are entry points for critters.  To them its a vacuum, and nature abhors a vacuum.  We usually install the windows and doors and soffits within a week of stacking the bales, prep for plaster (screed, bead, paper, lath, mesh) and get a scratch coat on the exterior soon afterwards.  Not only does that afford some protection from fire, it keeps things from entering the building.

Hi Thekla,

If the steel sided barn is already up, the questions I have are what kind of foundation will the bales be sitting on? and if lateral wall bracing is already in place, will it be enough to restrain the bales as well?  Even an an 8' tall wall is quite heavy--a typical foundation is usually reinforced concrete as wide as the bales, and at least 18" deep.  In many parts of the country tension only metal cross bracing can work on straw bale walls, although that system is generally thought to be inadequate in high seismic areas.  

It may also be that you're not so concerned about this as it's a barn?

At any rate, assuming the bales are elevated off the ground/barn slab on  2x or 4x sills that ire anchored to the slab or foundation, I'd set the sills in from the existing steel siding by an inch, and run 1 x furring strip up the inside of the steel siding to help the bales "stand off" the siding and maintain that air gap.  The gap allows moisture moving through the bales to be released at the gap instead of condensing against the metal siding and dripping back onto the bale.  I'd definatley "butter" the bales with clay slip as a fire retardent.  I don't know if it's possible to plaster them with a thick scratch coat before setting them in place.  I wouldn't leave exposed bales with a 1" gap--the fire department calls that situation a "chimney."  Sparks or flame entering near the bottom of the wall would rapidly climb the looses straw into the rafters and roof.  Be sure to install some kind of insect and rodent screen at the top and bottom of the wall, and as the exterior of the bales can't be plastered to provide an effective air barrier, do a good job on the inside plaster.  

You might want to build some kind of top plate above the walls, and perhaps run a few 2 x posts "paired" with the furring strips that are screwed to the metal siding.  Use baling twine to tie the bales tightly from furring strip to the 2 x 4, essentially "basketing" them togehter but maintaining that 1" air gap on the exterior.

You don't say if the barn ceiling will also be insulated? I hope so--most heat loss is through the ceiling.  Plastered R-20+ walls may not do much otherwise.  

Hope that helps!

I'm sorry I can't help you with that Chris, beyond to suggest you find out just what kinds of pesticides are being used, then do a search to learn if those same pesticides are subject to testing in another area.  For example, the recent legalization of marijuana for recreational use in parts of the U.S. has created an entire industry that produces test kits for all manner of contaminants people don't want in marijuana.  If the chemicals Thai farmers use are the same chemicals that might be found as residue in marijuana, you may be able to inexpensively acquire a test kit that analyzes for that pesticide.

Good Luck!

Timothy is absolutely correct! I'm lucky to be working in an area with will over sixty permitted straw bale residences--all built over the past thirty years, most of them in the last ten or fifteen years.  Since much of my work involves remodeling these older buildings I get to poke around inside the walls, see how the buildings have weathered, ask original and new owners about performance and energy costs, and have learned quite a lot.  

First, there are plenty of energy in-efficient straw bale buildings out there!  Just having plastered straw bale walls doesn't make the building efficient, even when the bales have been stacked tightly and the plaster applied well. What saves these structures from being uncomfortable is their incredible thermal mass--they may use more energy than necessary to heat and cool than if they had been built the way we know how to today, but the thermal mass delays abrupt temperature swings so they are, despite being full of holes, usually quite comfortable--just not energy efficient.  Conversely, there are also plenty of super air tight energy efficient buildings out there as well.

Second, there are things a homeowner can do to improve the efficiency of an inefficient straw bale building, mostly by filling these gaps and cracks.  Look at the joints between ceilings and straw bale walls, around windows and doors, and any plumbing or electrical outlets in the straw bale walls. If the gaps are large, you can use foam backer rod, followed by caulk (colored to match, more-or-less, the finish plaster or adjacent materials.  If the gaps and cracks are small a bead of caulk or other bits of insulation stuffed into the space can seal it. You can also use gap filling expanding foam in many places.  With clay plasters we can often wet and re-tool the area around the gap to close it off once the caulk or insulation has been installed. For electrical boxes, turn off power to the circuit, open the box covers, and if you can see straw through the little holes in the back of the box, air can come and go.  If the straw you see is discolored (grey or black), that might be the moisture from the escaping through the wall, deposited in the wall on its way through.  Openings like these account for five times more moisture in the wall than the highly vapor permeable plasters, and climates with very cold winters that water vapor can condense as it nears the exterior wall...so best to keep it out of the wall! caulk the holes and install outlet and switch plate cover gaskets.

Third, if building new, think about stopping air from passing through the wall as you build.  Straw Bale Building Details: An Illustrated Guide for Design and Construction is loaded with details showing easy things you can do that cost next-to-nothing.  One example: a single or double layer of building paper (I use 60 lb. Grade D because that's what I have around for separating wood from lime plaster) folded into the straw-bale wall's ceiling wall joint will be lapped by plaster on the wall, and lapped by sheetrock on the ceiling.  Should the plaster shrink a small gap might open there, but it's "backed" by the paper air barrier.  We do the same thing where partition walls about the straw bales.

I recommend getting a blower door test once the house is completed.  A competently applied interior and exterior plaster is an effective air barrier, as are well flashed and sealed doors and windows.  Anywhere plumbing enters or exists the building, or where wood stoves or range exhaust vents exit are potential leak areas.  Seal them up!

One way to learn how effectively you have sealed gaps and holes is to have a blower door test done on the house.  This test simulates the conditions of a windy day when air might be drawn (forced) out of your living envelop by the difference in air pressure between the inside and outside.   The test doesn’t tell you how much mechanical ventilation the house should have—only how much the building envelope leaks. The lower the score, the less leakage.
You may be wondering, but won't an air-tight house be dangerous.  Yes, if there isn’t some kind of ventilation system.  A lot of building scientists believe that all residences should have automated mechanical ventilation systems that exhaust stale, moist air and bring in fresh, filtered air all while exchanging heat so there’s no net energy loss in the building.  Some builders are aiming for a Passive House Air Change per Hour (ACH) of .6 or better, which absolutely requires a heat-recovery ventilation system.  But a lot of people just don’t like the idea of living in a nearly sealed envelope, and prefer to open and close windows to keep fresh air flowing in—knowing that some energy is lost out the window.  You can decide where on this scale you want to be, but know for certain that you don’t want a really leaky straw bale house!

The sound absorbing qualities of plastered straw bale walls are largely unstudied and anecdotal.  That doesn't mean that they are not quite impressive!  And it makes sense.  Just looking at the materials you see a densely packed (but not solid) block of irregularly shaped stems and edges encased by plasters.  Sound waves strike one wall's surface, which itself may have a rough plaster coating that further absorbs and deflects sound energy.  The waves proceed through this tangle of irregular edges and air spaces until they strike the opposite wall and bounce back through the bale.  

I live in a straw bale house and work in a straw bale shop.  We never hear the UPS or FED EX trucks pull into our driveway, a mere twenty or so feet from either building, and only know someone is there when they knock on the door.

CASBA is making a list of much needed research that needs to be done so straw can be used more fully in construction.  One of the barriers to using strawbales in a shared wall in multi-family housing (among the lowest cost, energy efficient ways to build!) is that we don't have the test data to tell us what we already strongly suspect--that a plastered straw bale wall assembly is an outstanding sound barrier.

This is the kind of research that proceeds from sales of the book "Straw Bale Building Details: An Illustrated Guide for Design and Construction" will support.

Hi Bryan,

Nothing makes cellulose bad.  In fact, it has the second only to straw in having the lowest embodied energy of all building materials.  I should explain why that’s important.  Assuming you agree that humans have had something to do with the changing climate, and you agree that we don’t have generations upon generations to resolve the problem before we have passed some point of no return, which is not good for us or the many other species we share the earth with.  We have a decade.  Maybe two.

If you build a Net Zero (energy efficient) house with low embodied energy materials the house begins to make an immediate difference—it starts storing carbon while not using much off-site energy, if any, to heat or cool.  But if you build a Net Zero house with high embodied energy materials like foam, steel, concrete, etc., it might be years before that house begins to make a net contribution because the building materials have taken you into embodied energy debt.  Any house build is going to take some energy, but the fewer steps backwards that you take before moving forward, the better, because your Net Zero house will make a more immediate difference.  That’s why looking at the embodied energy of building materials is important.

I recommend using cellulose in ceilings and wall cavities where straw bale doesn’t make sense (e.g. upper portion of gable walls where bales just don’t easily fit into the triangular space).  I also use rock wool because it has a higher ignition temperature and most of my work is in areas prone to wild fires.

Cellulose doesn’t have the thermal mass of a straw bale, nor is it usually coated with up to 2” of plaster on the interior, so while it’s an incredible insulator, it doesn’t do both.

As for thermal mass, approximately 2” of plaster on the interior walls has about four times thermal mass of ½” of sheetrock.  This provides a broadly distributed heat exchange with the interior air, which moderates the interior temperature fluctuations.  The thicker the plaster (see my recent post about how thick the code allows—primarily an issue in seismic areas), the more mass.  

From an aesthetic perspective, cellulose walls look like most other conventional buildings—painted sheetrock on the interior, some form of siding on the exterior.  Nothing special.  Aesthetics is among the top reasons people are drawn to straw bale building.  They report experiencing a “sensory nourishment” we just don’t get with the industrially flat and angular surfaces and finishes more common in conventional construction.  It may be that the plastered straw bale walls resonate on some archetypal level; or that we appreciate the hand-crafted plastered surfaces, which are rarely sheetrock flat and smooth, so that the lighted wall surface has variety and movement throughout the day.

This is where straw bale and cob can be a good pairing.  Cob is excellent thermal mass, not so good as an insulator.  Having interior cob walls, cob benches, etc., inside the plastered straw bale thermal envelop boosts thermal mass.  Speaking of cob, insulated earth floors can play a role here as well.

For the best information on the extreme cold weather combo wall system pairing straw bale and cellulose, contact Chris Magwood at the Endeavor Center in Ontario, and Jacob Deva Racusin with New Frameworks Natural Building in New Hampshire (both contributed to this book!).  They have developed and refined this combo wall system and can explain much more about it.