Straw Bale Homes Hit Mainstream

Green Means

Straw Bale Homes Hit Mainstream

By Shannon Scott

            Early Nebraska settlers were the first straw bale builders in the U.S.  The early sod huts didn’t insulate or protect prairie homes too well, but when mixed with large amounts of straw – voila! 

            In grain growing areas where straw was a common leftover from harvests, straw became a popular building material especially after steam powered bailers came on the scene.  Baled homes were relatively common up until the 1950s when assembly line construction materials became more broadly available.    

            In the early 1970s, as fuel prices escalated, developed societies began demanding more energy efficient, less toxic homes.  Cheap and readily available with high r-value insular qualities, straw bale building saw resurgence.

            Universities and construction professionals conducted r-value, shear strength and other structural integrity tests on individual straw bales and completed baled structures.  Well conducted, valid studies provided proof that bale homes were in fact structurally sound and more energy efficient than the common framed homes of modern decades.

Load Bearing and Non-load Bearing

            Structurally speaking there are two types of straw bale homes, load bearing and non-load bearing.  Load bearing refers to how the roof weight is supported and transferred down to the foundation.  Load bearing straw bale homes bear the roof load on the bales themselves.  Non-load bearing homes use modified post and beam or more traditional post and beam construction to support roof weight.

            Modified post and beam style utilizes two-by dimensional lumber nailed to plywood sheaths cut the width of the bales.  The “posts” run from the upper portion of the foundation to a top plate, “beam” spanning across the top of baled walls.  All-threads, anchored in the foundation, impaled through bales, and cinched down on the top plates, compact bales and distribute the roof load resting upon the top plates down to the foundation.

Moisture

            Moisture is a straw bale’s enemy.  With what we now know about harmful molds to human health, excessive moisture buildup has become a concern to all.  Two key considerations when designing and building a straw bale home are to keep the bales up and covered.  Design so that lower portions of bale walls are up from the grade of the surrounding land, so snow packs or rain cannot accumulate against them.  Bales must be kept covered with adequate porch or roof overhangs so that water cannot rest atop walls.

            During construction, bales must be kept dry, protected from the elements with tarps.  Once walls are built, make sure they stay covered until exterior finish is applied. 

            Below left: A modified post and beam garage with bales well protected until plastered or finished.  Notice that straw bales rest 2 feet above grade on well tarred and sealed concrete blocks, so that snow loads will never accumulate against bales and so that condensation will not permeate from cold concrete up into the bottom of bales. 

              Below right:  A post and beam exoskeleton design.  The wrap-around porch 2 feet above grade ensures driving rains and snow loads don’t get near walls.  Like with the garage photo, bales are covered with heavy gauge tarps before exterior finish.

Noise

Straw bale homes provide superior noise reduction from the outside world.  Of course window placement and other factors affect interior sound, but generally the thick walls not only insulate from heat and cold, but noise as well.

More Fire Proof

Contrary to what many believe, straw bale homes are more fire resistant than conventional homes.  Studies show that straw bale homes typically have three times the fire resistance of a standard framed home.  A conventional framed wall has plenty of air space between framing studs.  Once a fire breaks through paper sheathed sheetrock, houses go up in flames quickly. Since straw bales are dense, compressed tightly, and sealed with multiple layers of lime plaster, stucco, or other interior and exterior wall finishes it’s darn tough to get them to burn. 

Aesthetics

            Straw bale structures lend themselves to artful design.  Straw can be rounded, finished with undulations in the exterior and interior spaces, and lends easily to window seats.  Thick walls make inhabitants feel more protected from the outside world.  They look solid, feel solid, and are much stouter than typical framed buildings.

Healthier

            Finishing interior walls with natural clay plaster allows any moisture in the home to move in and out of the wall’s porous surface.  This infuses interior environments with negative ions.  Negative ions are odorless, tasteless, and invisible molecules that we ingest in heavy quantities in particular environments: beaches, near waterfalls, and during thunder storms. Negative ions are thought to elevate serotonin levels that fight off the blues, making us feel good. 

            “Negative ions increase flow of oxygen to the brain.  This results in less sleepiness and greater mental energy”, according to Pierce Howard, PhD and author of The Owners Manual for the Brain: Everyday Applications from Mind Brain Research.  Negative ions may also protect against particulates that irritate mucous membranes making us sneeze and cough.  Of course, clay can be applied to sheet rock surfaces as well, but feels and looks richer on thick straw walls.

Green Choices

            Green living means sustainable lifestyle choices.  Plan well to reduce waste, maximize energy efficiency, and be conscience of your home’s environmental impact.  There are many green and sustainable options available now, but straw bale still leads as one of the more interesting, user-friendly, and aesthetically pleasing options.

            If you have always been curious about straw bale homes or are in designing/planning stages drop me an e-mail.  I’d be happy to answer questions or offer tips on what to do and avoid.  I’ll also be offering a green building course though Great Basin College’s Community Education program in late winter.   For anyone interested, registration is through the college.  The class should prove fun, informative and includes a tour of the straw bale home pictured in this article.

Minimizing Construction Waste

Green Means

Minimizing Construction Waste

By Shannon Scott

            Good green home designs maximize use of materials and minimize construction waste.  Honing down on scraps means planning well during the design process, not when cutting the first sustainably harvested two-by-four.  Design a home that maximizes every inch of lumber, pipe, concrete, and wiring.  You’ll build green and save money.

Build Up

            To minimize foundation and roofing materials build a multi-level home rather than one large single story.  Building up is simply less expensive than building broad – you get more square feet for your foundation and roofing investment.  You’ll not only save materials, but you’ll reduce the home’s footprint - the amount of land the building covers.  By creating a smaller footprint a home disrupts less land and reduces its overall environmental impact.  So you’re protecting resources on several fronts.

Minimize Angles and Curves

            Many artful and interesting homes are rid of curves and complex angles.  Every time a corner is added, estimate an additional 3% in cost.  Five extra corners means 15% greater bottom line in materials and labor.  More angles, means more cutting of materials.  More cuts, more waste. 

            Think: Frank Lloyd Wright the deity of clean lines and simple geometric shapes.  A more contemporary designer that follows Wright’s influence, and some hail as the leading residential home designer in the U.S. today, is Sarah Susanka, author of The Not-So-Big House and other books on home design. Wright and Susanka both created inviting, artful, functional spaces without multitudes of complex angles, steep slopes, or rounded anything.  While their homes may realize higher costs per square foot due to first-class finish materials, such as expensive hard woods, their designs don’t waste much of anything anywhere.  Green builders don’t either.

Think Even Numbers

            Generally, think in terms of even numbers when designing.  Odd numbered lengths lend themselves to a bit more waste.  Consider standard dimensional lumber.  Typically, lumber is cut in lengths from 8 feet to 20 feet in 2 feet increments.  So when planning ceiling heights, think 8 ft., 10 ft., 12 ft. etc. depending upon your style and budget.  Don’t decide upon a ceiling that is 9 ft., you’ll be cutting and wasting nearly an entire foot off every framing member that goes up. 

Reuse and Recycle

            Reuse and recycle lumber and other materials when possible.  When or if you build concrete forms out of two-by-sixes, two-by-fours, and plywood take special care of them.   After stripping the forms from the poured foundations and/or slabs scrape off any obvious concrete that may have stuck to the lumber and reuse clean boards elsewhere in framing.  This reduces the total amount of lumber you’ll ultimately need to purchase. 

Estimate Accurately, Order Conservatively

            Order slightly less materials than you need.  As you near completion of a stage and can determine more exactly how many more boards, pipes, or whatever then order the exact number. 

            The exception to this is tile.  When tiling there is a lot of cutting, and often pallets or boxes contain some broken tiles.  The general rule of thumb is to order 10% more.  So when tilingan area that’s 20 feet by 20 feet or 400 square feet, order enough tile to cover 440 square feet.  You likely will have some, but not much, left over and you can always find a decorative use somewhere for excess tile.

Lumber Yard Returns

Should you be long on excess materials make sure the local lumber yard will take back and credit you for what you didn’t use.  Most reputable places will be fine with this since they want repeat business.

Hired Help

            Granted this column is more geared to do-it-yourselfers, but for those hiring carpenters or other construction labor, make sure they have waste reduction in mind.  Often, hired laborers will not take care to plan well, cut precisely, or consider your bottom line philosophies or dime.  Insist that anyone working on your project understands green building methods and materials.  Explain that you are minimizing waste, using select premium sustainable materials, and that anyone working for you must adhere to seeing and following your vision.  They don’t have to share a green mindset, but hired help needs to do the job according to your specifications.  It’s still common to come across a number of building and construction supply professionals that pooh-pooh green building practices.  These too will go the way of the dinosaur as local codes insist more and more on sustainability.

Extra Material

            Recycling any leftover materials will save you money, and avoid adding to already over burdened landfills. 

            One use for plain lumber, not chemically treated, is fire wood.  You might not have a wood stove, but someone near you likely does and would be happy to have the ends and pieces. 

            What might you build down the road?  Are you going to need stakes for gardening?  I still use leftover two-by lumber pieces that are 4 - 8 inches long for placing in the bottom of large planters so not as much dirt is needed to fill them.  Water drains better from the pots and repotting is much easier as hardened potting soil comes out much more easily. 

            When mixing smaller batches of concrete for exterior steps and concrete counter tops, I used any leftover “mud” to make stepping stones for the garden.  Simply, form the concrete into 2” thick patties of the desired shape and size.  They work great for keeping out of the mud when weeding, planting, or watering.

            A little planning and thought goes a long way.  Think green, sustainable, and conservative when designing, you’ll be glad you did.