A Big Winter Hug

Lantern

In Missouri on February 5, 2014, we have a few inches of snow, and the afternoon temperature is 14 degrees with a -18 wind chill factor.  But, inside our straw bale house we have 72 degrees, a toasty fire and a piping hot cup of java heated from our wood stove.

Brrrr…This is the coldest winter we have had in Missouri in a good while!  We feel so thankful to have a cozy, warm home! Ari Warm and Cozy Our Casa’s highly insulated and thick r 30 straw bale walls make us feel like we live in a big hug. Of course, our Casa’s hat (attic) is insulated, and its boots (foundation) has some insulation in it and around it. Wood heat centrally located in the house keeps us very warm, and we use approximately 1 ½ to 2 cords of wood per winter to keep us warm.  This wood stove works double-duty heating our water for the hot water tank, which will be covered in an upcoming article.  

Weatherization is a *hot* topic close to everyone’s heart…well…pocketbook, anyway. If it isn’t, maybe it should be. One look at a Plant Hardiness Zone Map, and you will know exactly where you stand with cold temperatures.  So really, don’t underestimate the importance of insulation here in Missouri!  Concrete, cob, earth, rock, sand, and brick are not insulators, and cold finds its way through these very easily.  

We feel badly for people who are having trouble staying warm, especially if they are paying for the privilege. The quality of the available housing stock is questionable.  Some houses, especially older homes, have minimal insulation.  Leaky doors and windows, recessed ceiling lights, and other unsealed penetrations in the house exchange far too much warm, conditioned air for cold, dry, winter air. It seems that some of the poorest housing stock has been turned into rental property. Renters will move in, unaware of previous utility costs, and find themselves unable to pay the high heating bills, so there is a huge turnover in these rentals.  One great option is to take advantage of the low-income and other weatherization programs where available.

Folks who heat with propane must have been in for quite a shock when the price of propane doubled this last month!  For rentals or older home purchases, propane companies do not have to tell you how much propane that house was using, unlike with electric.  Also, it can be hard to tell exactly when propane was used and how much was left in the tank.  Be sure to check before you purchase!  Having a walk-through and a peek into the attic or crawlspace done by an energy auditor is also advisable before you purchase your new home. At least, you would have a much better idea about what you are getting into!

Many older homes and some newer homes have HVAC duct work with gaps and poor fitting connections in unconditioned spaces, which are areas of the house that are not insulated as part of the thermal envelope, such as crawlspaces under the floor, uninsulated basements or in the attic. This duct work needs to be sealed with mastic (recommended) and then insulated, because much of the heating capacity is being diminished by the unheated space, adding significantly to the cost of heating. Also, hot water pipes should be insulated at any place accessible, along with the first 5 feet of the cold water pipe above the water heater.

Passive Solar should not be overlooked or underestimated.  Passive solar uses sunlight without active mechanical systems, which would include technologies such as heat collection, thermal mass, thermal insulation, proper window glazing, proper window placement and shading.  These same design principles would also apply to reducing your summer cooling requirements.  Active solar includes mechanical systems such solar thermal heating systems. Employing passive solar techniques in your house design can save from 20% to 50% and even more in your day-to-day energy costs!  If you can save annually upwards of 50% using passive solar, then why not?

Building Green really is the smart, fiscally sound option. Let us know if you would like to talk energy conservation in your home!  If you want to build with straw bales, we can help you stay warm and dry.

cup o joe 2Cheers!

Straw Bale vs. Cob Building

What is the difference between cob and straw bale building?

Cob  Good question – we get it a lot!  Give a Lift web large

We assume you want a comparison of building method, insulation, and function/wear.  There are several aspects that need to be addressed to answer this question.  Basically, a home can be built with either cob or straw bales, or both. Their function is different, though.  Straw bales are insulators, holding in the temperature and keeping the interior of your home warm or cool, depending on time of year.  Cob functions differently, not as an insulator but as thermal mass, in that it absorbs any radiant heat or cooling and then slowly releases it as it cools off.   

When you are building with straw bales, you are essentially using the bales as your framework, especially when building a load-bearing, Nebraska-style structure.  Straw bale building is done with straw bales (not hay bales), which then need to be covered – usually with earth plaster, lime plaster or cement stucco**.  A covering is just that – a cover material (generally, layers totaling about 1″ or so thick) that protects the bales.

Cob is a lot like earth plaster, although it is much more specific. You want the right amount of clay-soil (binder), sand (aggregate), water, and straw or horse manure (tensile strength).  Cow manure also makes a nice additive binder to clay-soil, creating a nice texture that functions differently from horse manure, more as a binder but not a strengthener.  You want your mix to hold together, for the individual clay platelets to cover each of the tiny bits of sand. Clay binds it, sand (or other aggregate) keeps it from cracking, and water makes it all possible. Straw/manure/fiber makes it stronger.  You want to get your cob mix right so that it doesn’t crack too much when it dries out.  If you rely on water to bind your materials without getting the mix right, you might be disappointed with the results.  Also, clay and water is really pleasant to work with, but too much clay and not enough aggregate will definitely crack too much and fall apart.  You have to have a lot of aggregate – a lot more than clay, generally 2 or 3 parts aggregate to 1 part clay-soil.  All of this specificity is important when building a cob oven or something structural.

When building with cob (or cobb, as some refer to it), you are making the balls or loaves into the actual building material, essentially sculpting your house with no framework; the cob is the framework.  Cob can also be used within framework, such as within stud walls.  One application might be to use cob in a south-facing wall for heat absorption when the sun is lower in the autumn, winter and spring, allowing for slow release of heat on cool nights. Also, cob can capture the cool of a summer night and slowly release that cool into your home during the day.  With these bitter cold Missouri nights, a really good application is to use cob on the interior of your straw bale house – in the form of a bench or trombe wall – capturing and absorbing the sunlight pouring in through your south-facing windows.  An earthen floor will also capture solar gain.  Everything works best if your foundation is well insulated, as well as good ceiling insulation and weatherization techniques.

Straw bale building really performs optimally.  We personally love the marriage of straw bale and cob architecture. You can have the insulation you need for colder winters by building with straw bales, and cob can be used on your home’s interior for absorption/thermal mass, to round out straw bale walls and/or to add sculptures and depth.  How you use these materials just depends on the climate where you live and the dreams you want to manifest.  Missouri is the perfect place for a marriage made in heaven, a love between two “naturals” – clay and straw.  🙂  

 decorative_sun**About Cement Stucco:  We aren’t really recommending cement stucco for covering bales anymore, now that we have more experience and knowledge about the function of earth plaster vs. cement stucco.  Here in moisture-rich Missouri USA, large roof overhangs or a covered wrap-around porch adequately protect straw bale walls from water. Further, if earthen walls become moistened/wet, the hygroscopic properties of the clay/earth kicks in. Clay gets wet and tiny clay platelets expand; as clay dries out, platelets shrink. If your bale wall takes on some moisture (using precautions mentioned), the clay will literally suck/absorb any moisture back out of the bales. This is the “breathing” process often referred to – straw bale walls need to be able to “breathe”so that moisture doesn’t get trapped in the straw, causing rot. This is why you do not paint with synthetics on your interior walls (see Natural Paints and Finishes).This is also why we would not now recommend using cement stucco as a cover material for straw bales (or cob or anything natural, for that matter). Cement will absorb water, but it does not release water very quickly or in the same way that earth plaster does.  We have cement stucco covering our house – so far, so good, but we live in a protected woodland, and our house has large overhangs; due to Missouri’s moisture, we would recommend having an earthen exterior. Even though clay/earth (not topsoil) is well suited to absorbing and releasing water, you still need to have good roof overhangs (approximately 2 feet). As a final cover, lime plaster (with or without colorant) will give a lot of added protection to your walls.