Build Naturally

Cob Oven Video - Parts One & Two

2012-01-02T10:07:00.001-05:00

Here are our first two videos explaining how to build a cob oven.
For more information on cob ovens, I recommend Kiko Denzer's book "Build Your Own Earth Oven"...it's a complete "how to" including how-to sketches, list of tools, inspiring photos, and much more.

Part One shows how to prepare the base and dome mold for building a cob oven. This oven is 36" interior diameter, so the height of the interior is 75% of that, or 27" tall. The thermal mass layer is 4" thick, plus a 6" thick insulating layer over that, so the whole oven is 10" bigger than the fire cavity all the way around. The base is made with stones gathered from the site and held together with a clay + sand (cob) mortar. Also note, the primary reason to use firebrick is that they do not crack under the heat of a fire.

Part Two shows how to mix & install the cob thermal mass layer (no straw) and the insulating layer (lots of straw). Note that our soil was about 50% clay and 50% sand content. We want about 25% total clay, so we added an additional 2 parts sand for each 2 parts soil. Since the soil is already 50-50 sand-to-clay, the total is 1 part clay to 3 parts sand, or 25%. The thermal mass layer has no straw. This is the layer that gets hot and holds the heat from your fire. The second layer has tons of straw...basically as much as you can mix in. Straw is a good insulator, so the second layer helps hold in your heat.

Low-Cost, High Performing Living Roofs

2011-09-14T17:18:00.002-04:00

A living roof, or green roof, describes a system that allows plants to thrive on the surface of rooftop without access to groundwater. The idea is to create a self-sufficient ecosystem that doesn't need you to water once the plants are fully established. This type of roof does provide energy-efficiency benefits in the summer, because the plants provide a net cooling effect. Even one inch of planted soil lowers overall average roof temperatures and reduces day-to-night temperature swings on roof surface. A green roof does NOT provide insulation to speak of, so you still need to insulate your roof, just like you normally would. Additionally, plants absorb and filter rainwater, reducing the negative impacts of excess storm runoff in watersheds, which is especially beneficial in areas with high percentage of impervious surfaces, such as cities and suburbs. (Yes, I did write suburbs! A mowed lawn only allows an average of 40% of the rain that falls on it to absorb into the groundwater table!)

The most important detail with a living roof is to select plants that will thrive in your climate and with the amount of sunlight striking your roof. (See below for a living roof plant resource.) First and foremost, your plants need to be able to survive without access to groundwater and rely just on your local rainfall. If you get tons of annual rainfall, you will want to be sure you select plants that can handle "wet feet", and be sure your roof drains well. If your roof is in full sun, you will need to select plants that will not wither under the heat of relentless summer sunshine. Etc.

full shade allows greater variety of plants

Most planted roofs are installed on reasonably flat surfaces. But this is by no means a requirements. Steeper roofs (above about a 30-degree slope) do require additional erosion control, especially while the plants establish their root systems. Most commonly, I use a wooden trellis type grid that rests directly on the drainage layer (not fastened to the roof). Then plant in between the grid of the trellis. As the plants establish their root system, the wood biodegrades, providing additional nutrients for the plants. By the time the wood has composted, your plant roots become your erosion control.

plants thrive on shallow or steep slopes, even curves!

Here are the layers I have used with great success on numerous small scale roofs:

sheathing (such as plywood) - typical roof sheathing is 1/2", but my engineer likes to bump it up to 5/8" to prevent any sagging from the weight of the soil. The sheathing is part of your structure, so I make sure an engineer approves the roof framing as well as the sheathing.
waterproofing membrane - the lowest cost option I've found for this that has high effectiveness is 60 mil EPDM (rubber pond liner). I also recommend reading "Stoneview: How to Build an Eco-Friendly Little Guesthouse" (New Society Publishers) by Rob Roy for additional suggestions for waterproofing membranes.
drainage/filter layer - I don't skimp on this because it keeps your soil medium up on your roof, even with heavy rainfall. My favorite drainage layer with integral filter fabric is: Enkadrain 3615 (by www.colbond-usa.com) because it is easy to cut & easy to install, especially on curvaceous roofs.
growing medium (soil) - I have used everything from compost to an engineer mix of expanded shale & organic soil; they all seem to work well. The only advice here is to be sure if you are using compost, that it is sterile, ie, that there are no active seeds (or you will be up there weeding like crazy) and if you use a mix with high inorganic content (like expanded shale) be sure it's mixed with at least also 60% organic soil (like sterile compost)
plants - I use ONLY sedums and other rock garden plants. These are plants that don't rely on ground water, but instead have ways of storing rainwater (their leaves act like a cistern) or can pull humidity from the air for moisture. Be sure to select plants that will thrive on your roof and in your climate, ie, whether your roof is in full sun or full shade and how much rainfall you get in a year. For recommendations on plants, see www.greenroofplants.com

typical living roof detail

For additional information, including books and other resources, see my full article on Living Roofs at www.buildnaturally.com/EDucate/Articles/LivingRoof.htm

Clay Plastering Strawbales - SECOND COAT

2011-08-01T15:12:00.000-04:00

I would like to address issues & tips for the 2nd coat of clay plaster on strawbale walls today. Note, I am assuming you are using clay plaster for all 3 layers of a 3-coat application. For tips on applying the 1st coat of clay plaster, see my previous post "Clay Plastering Strawbales - FIRST COAT". I will address finish plaster in a separate post.

GOAL for 2nd coat of plaster
The goal for the 2nd coat of plaster is to sculpt the walls into the desired shape. The first coat created your amazing bond to the strawbales. And your finish coat will create the texture you desire. This second coat is where you create the shape you want your walls to have. Your shaping/sculpting plaster is bonding directly to the first coat of clay plaster you applied, so the bond of that first coat is essential. Since your first coat usually is lumpy & bumpy, you have excellent surface area to physically key your second coat of plaster to the first coat.

transformation from 1st coat (left) to 2nd coat (right)

In this coat of plaster, I care very much what it looks like...not how it feels, but how the shape looks. I try to minimize or avoid cracks, I work sculpted areas a lot so they look exactly how I want them to, and I spend as much time as needed to shape the wall into something that is beautiful to me. Then I'm well-prepared for a nice, even coat of finish plaster, where I can work on texture.

WALL PREPARATION for 2nd coat of plaster
1. Work any loose spots - I go around the dry first coat of plaster and make sure there are no loose spots. There will usually be a wide, tell-tale crack if you have a loose spot at a strawbale seam, where the first plaster was not worked in well. I also check corners, around windows, and the tops of walls, to be sure all the walls feel nice and dense and tight.

2. Make test plaster mixes - I make several test plasters and apply them directly onto the first layer of clay plaster. What I'm experimenting with in my tests are the proportions of ingredients. Since I use almost exclusively clay soils to make plasters, it means I'm using different clay each time, and each clay has different properties. So I make test areas at least 24" x 24" in area with varying proportions of clay and sand, and I write my proportions directly into the plaster surface. When the test areas dry, I look for the one that cracks the least, but that I can press into firmly with my thumb and it is not crumbly or dust, but nice and firm.

3. Wet the walls down - I can't stress this one enough, and as I mentioned in the post on 1st coats of plaster, this is the most common error I see...applying plasters over dry substrates! I hose down the 1st coat of clay plaster the evening before I plan to plaster, again in the morning, again about 30 minutes before plastering, and then continually as the wall dries out over the course of working. If the 1st coat of plaster is dry, the clay sucks moisture out of the 2nd coat of plaster, and causes the bond between new clay to old clay to pop apart. When deconstructing plaster coats that have been applied to each other without dampening the substrate first, the two coats of plaster are quite distinct, and you can easily pry them apart in separate layers, like sheets of slate. Similarly to 1st coats of plaster, I allow time for water to saturate the clay substrate, because a water slick on the surface will cause new plaster to slide right off the wall.

In order to maximize control over the shape of the walls as well as the quality of the plaster, I do the following:

SIFTING. I use mostly clay soils to make plasters and there are often stones and large clumps in the mix. So I sift clayey-soils through a 1/2" or 1/4" screen to break up the soil into smaller pieces. Basically you want a screen that is slightly smaller than the thickness of plaster you intend to apply (otherwise stones will drag with your trowel against the hard 1st coat of clay).

PROPORTIONS. I use sand & straw, and sometimes manure, to control cracking in this second coat of plaster. The reason is because clay expands in volume when wet, which means it shrinks when it dries. Shrinking clay can translate to cracks in your plaster. Sand, on the other hand, does not absorb water and so does not increase in volume when wet nor decrease volume when it dries. So having a high percentage of sand in your mixture helps to control shrinkage of the plaster, and thus cracks. However, the clay is your binder, it holds everything together and onto the wall, so you need to be sure that your plaster has enough clay to stay sticky, otherwise your will end up with a dusty mess. The exact proportions of sand-to-clay depend on the properties of your clay, but roughly speaking, I usually end up with between 15% and 30% total clay content, the remainder being sand. (Note that this includes any sand in your soil, if you are using clayey soil for your plaster.) The straw component helps to bridge gaps where cracks are likely to occur. I add a fair bit of chopped straw (3" or less in length) to my second coat of plaster to provide ample structural integrity and I add additional straw when sculpting the clay or where I'm trying to fill in deep holes. Finally, I use manure whenever it is available, and it is probably my favorite additive for plasters and cob. The manure is both sticky (like the clay) and fibrous (like the straw), so you augment two properties of the plaster mixture with a single ingredient.

applying the 2nd coat of clay plaste

APPLICATION. In order to control shaping the walls I use a fairly long (16" to 18") rigid trowel to apply this layer of plaster. Because the trowel is rigid, I can push the plaster around easily and because the trowel is long, I can create a gently undulating, reasonably flat wall surface. I find a short trowel does not let me see low spots in my wall surface as well, and I find a flexible trowel just follow the shape of that lumpy, bumpy first coat, so I save shorter, flexible trowels for finish plastering. If you have a lot of dips in your wall that you want to fill, you will want to add lots of straw to your plaster so it has more structural integrity. I also limit the thickness that I apply on any one day, and instead, fill deep spots in multiple passes. Even waiting one day before adding more plaster will allow the first batch of fill to dry enough, and bond to the first coat below, to support more weight of a second layer. Again, remember that clay is a liquid until it dries, and can only support a limited weight of additional plaster before it tries to flow off the wall. If your plaster is slumping or falling off the wall, it is probably too thick (or your clay surface below is not adequately damp).

walls become sensuously shaped with sculpted elements

SCULPTING. This 2nd coat of clay is also the layer that I sculpt into...including niches, wall reliefs, and any clay frames around truth windows. For thick reliefs, I add a lot of chopped straw, making almost a cob-like mixture, I make sure my surface is saturated with water, and I build up slowly...perhaps 1" in thickness at a time. If I'm feeling impatient, I use burlap embedded into the surface of the sculpting clay, and I use the burlap to bridge the thick new clay onto the existing wall surface. (more on burlap below)

using burlap at window sills to prevent cracking

BURLAP. I use burlap mostly as a preventative measure in places where cracks are most likely to develop, or where the additional strength of surface fiber will be a benefit. I also use burlap to apply clay plaster to surfaces that otherwise are too slick for plaster to adhere to, such as wood. So at windows, I use burlap embedded into the surface of the 2nd coat of plaster to prevent horizontal cracking along the bottom edge of the window sill, as well as at the joints between the jambs and the sill (and the jambs and the window head). The burlap provides exceptional surface tension, and holds the clay together as it dries, so that it cannot crack in those vulnerable locations. The important trick is that the burlap MUST be fully embedded into the surface of the clay, otherwise it is not bonded and you actually create a loose spot instead of a strong surface.

burlap must embed completely into the clay

I also use burlap where plaster meets wood, and I don't want the plaster to shrink away from the wood, wherever I worry about wide cracks translating into my finish coat, and wherever I want to plaster over a slick surface, like a wood post, any rigid foam, or any roofing felt. I had one workshop participant declare "burlap is like magic!" And I pretty much agree!!

leave 1/4" reveal at electrical boxes for finish plaster

ELECTRICAL. Finally a quick note about electrical boxes...I work the placement of all electrical boxes while installing this 2nd sculpting layer of plaster. I straighten boxes. I pull them out if they are recessed too far. I push them in if they are bulging way past the plane of my wall. My goal is a level box that sticks out with an even 1/8" to 1/4" reveal from the plane of my 2nd coat of plaster. Then I can run my finish coat of plaster right up flush with the electrical box, and the cover plates will fit on squarely and tight to the wall surface. It's also not a bad idea to put a bit of tape over the screw holes to keep mud out.

I'd love to hear other people's experiences and tips! So please feel free to add comments below.

Clay Plastering Strawbales - FIRST COAT

2011-07-26T22:14:00.002-04:00

I would like to share a few tips I have learned through trial & error over many years for plastering with clay on strawbale walls. In this post, I address issues and tips for the 1st coat of clay plaster applied directly to strawbale walls. I address 2nd coats of clay plaster in my post "Clay Plastering Strawbales - SECOND COAT"

I will address finish coats in a later post.

Goal for 1st coat of plaster
The primary goal for the 1st coat of plaster is to create your bond between clay and straw. The goal for the second coat is to shape & sculpt the wall the way you would like it to look. And the finish coat is where you achieve your textures and sometimes color. The strawbales provide ample surface area for the clay to bond to, so I do not use any lathing or metal mesh or anything else that may actually get in the way of working the clay directly into the straw. Instead, I work a sticky clay plaster directly into the straw surface.

1st coat of plaster is often lumpy & bumpy

Because the goal is coating the bales with a well-bonded layer of clay plaster, your first coat of plaster often follows the contours of the bales. This means the first coat is usually not that pretty...but rather comes out rather lumpy & bumpy. This is OK! You will shape the wall with the next coat of plaster. It is more important that you set up great contact with the strawbales so that the weight of all the plaster to come adheres well to the wall surface. You can shape the wall a little bit with this coat of plaster, especially in wedged areas, like the cracks between bales. But remember that the clay is a liquid until it dries...and its stickiness can only support a limited weight of plaster before is flows off the wall. If you find the plaster is slumping, this is usually a sign that your plaster is too liquid or that you have put on too thick a layer and the weight is pulling it off the wall. Once the plaster dries, it is bonded to whatever it is touching, so best to be patient, use a thinner layer, work it into the straw really well, and wait until it dries and is strong before adding more weight with subsequent plaster.

WALL PREPARATION for 1st coat of plaster
1. Shape the straw - this means trimming the walls as closely as you can to the shape you want. Spending more time shaping the straw pays back in magnitudes of time saved mixing and applying plaster. I also cut niches and identify any truth windows prior to plastering the first coat.

2. Install electrical - I find that it is much more challenging to install electrical boxes after you have plastered the strawbales, so I get this out of the way before plastering. This also makes an electrical inspection more straightforward, if you need one, since you have not covered up any of the wiring with plaster.

3. Make sure your walls are tight - this means achieving a pre-compression of the strawbales before plastering. If you plaster before the bale wall is compressed downward, then the weight of the plaster can cause the strawbale wall to sag, leaving an open gap at the top of the wall. A gap can be filled in with insulation, but it's usually easier, less stressful, and cheaper to compress the bales first. There are many ways to achieve a tight wall, starting with purchasing tight strawbales to construct with. (The looser your bales are to start with, the more they will compress in place.) I make sure the top bale in any wall is installed very tightly up against some kind of framing above (floor, trusses, etc.). You can also use temporary straps to compress your walls. I'm sure there are many other solutions, but the general goal here is that the more compressed your straw is, the less your wall can settle from the weight of the plaster.

4. Trim the straw - the trimmed side of a bale, with all of the straw sticking out perpendicular to your plane of plaster, is an easier surface to plaster than the folded "fuzzy" size of a strawbale. So trimming your bales with a weed whacker, chain saw, hand saw, or whatever works for you, saves you time applying the plaster. Trimming also gives you the opportunity to sculpt the straw surface to the desired shape of the completed wall, which saves you time mixing and applying plaster or cob-like plaster to fill in voids and shape your walls with clay later.

5. Fill in voids - this also saves you time later! Unless you want your wall to remain lumpy & bumpy, I find it is the least amount of work to make sure that voids between the strawbales (and at seams with other surfaces) are stuffed tightly with straw or light clay straw before I begin plastering. Otherwise you are making additional plaster or cob-plaster to fill those voids later. I use handfuls of long pieces of straw, align them all like a rope, twist the rope, and then fold it in half. This lets you make relatively compact bunches of straw that you can then push between strawbales.

6. Wet the walls down - I think the most common error I see is applying plasters over dry substrates. I hose down the surface of the straw until the water drips off, and then allow the water to absorb for 20 to 30 minutes. The straw should feel pliable (not prickly), but all the water you spray on should be absorbed (not creating a water slick). If you have a water slick, the clay plaster will slide right off the straw and drive you crazy. If the straw is dry, it has a tendency to quickly suck water out of your plaster, which can cause the bonded clay to dry too quickly, which can subsequently reduce the adherence of the clay to the straw.

TIPS for 1st coat of plaster
In order to ensure a fabulous bond of the first coat of clay to the strawbale wall surface, I do the following:

high clay content - I used to try to control cracking in the first coat of clay by adding sand & sometimes straw, but this mixture is so difficult to apply because it is not as sticky. So I have shifted gears toward a very high clay content, shooting for between 1/3 and up to 1/2 total clay content (the remainder is sand from the soil or added concrete sand). I do not add straw to this layer, instead working the clay into the surface of the strawbale walls. The high clay content means you will have shrinkage, and therefore probably lots of cracking, in that base coat of plaster. But I find I am able to get a much stronger bond with the base coat if the mixture is nice and sticky, and you can easily address the cracking in the next layer of plaster.
sift soils through 1/2" screening - if you are using site soils, I recommend to sift the clayey-soil through a 1/2" screen to break up the soil into granola-sized chunks. This makes the plaster easier to mix, and you don't end up with large chunks in your plaster that are difficult to impossible to work into the wall. You don't need finer screening unless you are troweling onto a hard substrate in thin layers.
apply 1st coat with your hands - when I teach plaster workshops, I used to invite everyone use their hands or a trowel to apply 1st coats of clay plaster on strawbale, depending on their own comfort level with tools. And invariably, someone with troweling expertise, would apply a vast amount of plaster on a wall, and it would look great, and then...it would fall off. What was happening is that by using the trowel instead of their hands, they couldn't feel whether the clay was worked into the straw. So now I always apply the 1st coat of clay plaster directly onto the strawbales exclusively by hand (or with gloves), and not at all with a trowel. This way you can feel...with your hands...the tactile bond between the clay and the straw. You can feel if the straw is loose, like at seams between bales, and you work additional clay into those spots. You can feel if the clay is tight on the straw or if it shimmies like jello and is not bonded.
really work the plaster into the straw - this is probably the toughest to explain in words, but basically, you want to work the sticky plaster onto the surface of all the strawbales, but also into all of the nooks & crannies between strawbales as well as the joints where straw meets other materials. I use the palm of my hand as a trowel to apply plaster to the surface of the strawbales, and I use my fingers to kindof massage the clay into any loose spots between bales. Once you have some sticky plaster bonded to the straw, you can add lots of straw to your mix, and use that heavy-fiber plaster to fill in any big voids. The straw-plaster will stick nicely to the clayey-plaster that you already worked onto the bales.
don't worry how it looks - the most important quality for the 1st coat of clay plaster is that the clay bonds well to the straw...it is not what the shape of the wall looks like. That is not to say you cannot shape the wall with this coat of plaster, but the primary goal is the bond to the straw, not the look of the wall.

I'd love to hear other people's experiences and tips! So please feel free to add comments below.

Shake Test

2011-06-15T22:24:00.001-04:00

Video blog today, showing how to test your soil for clay

content, including worm test & shake test

Finding Good Strawbales

2011-06-14T07:37:00.003-04:00

What is a "good" strawbale?
The most important characteristic of your strawbales is that they are dry! I do not use bales that are, or have been, wet for any construction project (including mixing in to cob or plasters). To check for moisture content, I start by visually inspecting the strawbales. First, I look at the conditions under which the bales are stored. I make sure they are not sitting directly on the ground (if they are, I let the farmer know that I do not want those bales). I make sure there is air-flow around the bales and that the roof isn't leaky. And I make sure the bales aren't leaning up against metal anywhere (metal will condense moisture and make the adjacent bales wet). Then I start inspecting the bales themselves. I look on the surface of the straw for any signs of mold. It usually is black in color. I smell the bale to make sure it smells like straw (not mold or any other contaminant). I pop open at least one bale to inspect the inside for mold too. I lift a few bales to check if they are unusually heavy. 2-string bales typically weigh about 45 to 55 pounds. If they are very heavy to pick up, it can mean they are super tight, but often means you are picking up lots of moisture absorbed by the straw. Finally I look to make sure the straw is not contaminated with unusual amounts of dirt or detritus. (This is usually not a deal-breaker, but clean bales are much more pleasant to use.)

Next step is to test the bales with a moisture meter. The farmer you are purchasing bales from may have a moisture meter (usually called a hay moisture meter, which is fine) that they can test your bales with. They are several hundred dollars to purchase, so I would try to borrow one unless you intend to use it for multiple projects. Insert the moisture meter probe into roughly the center of a bale and check the moisture content. I do this in several points of each bale and test at least 20 bales. They should read below 18% moisture content as an absolute maximum. Lower is better. (Note that the bales will continue to dry out unless moisture is introduced.)

In addition to being dry, the bales are much easier to work with at every stage of construction if they are nice & tight. To check for tightness, simply lift a few of the bales up by one string. It should be difficult to get your hand underneath the string, and the deflection of the string should be small enough that you don't feel like the bale could fall apart when lifted by the single string. (If the bale is loose, it feels like the string is just going to slip off the side.) The only other visual inspection is to check that the bales are reasonably rectangular. Sometime one string is tight and the other is loose, and you have bales that all curve to one side, which is kind of a pain in the butt when building.

How can you locate strawbales near you?
To find bales I recommend a two-prong approach:

First, check www.hayexchange.com. Click on your state and also check any neighboring states. (You can even expand to further states if you are coming up short.) For each of the states you will see a list of suppliers and what they sell. Many of them may list hay, alfalfa, etc., as the website name implies. But there are also straw listings. You just need to make sure they are not listed as round bales or as mega bales (unless that's what you are looking for). Any grain variety is fine. I think barley is the nicest to work with, as it is bright & pliable (doesn't seem to break as much), but it really doesn't matter.

Second, I recommend looking for a very local farmer, which can mean lower priced bales and often free delivery if they are very close. You can first see if there is a farmer's newsletter for your region. These might be found at an agricultural supply store or someplace similar. Here on the East Coast, lots of farmers simply put up a sign on the road that offers "straw for sale". If you are building somewhere similar, I recommend driving around and looking for those signs.

How many bales do you need?

2011-04-05T14:19:00.000-04:00

How many bales will you need?
To calculate the number of bales, I assume that we are building something without doors or windows. That gives you enough extra bales for ample waste during installation, stuffing gaps, and straw for plastering as well. You will want to know roughly the size of your bales. Where I work on the East Coast, bales are usually 2-strings, usually about 14" high, 18" deep, and an average of 32" long (though length varies with any given stock of bales). Once I have this information, I calculate the quantity of bales as follows:

Determine how many rows of bales high you will need for each wall height (not including any triangular gables). For example, if your bales are 14" high, and your walls are 8-feet tall, then you will need 7 rows of bales for each wall. (The number of rows will change if your walls are a different height, if your bales are a different dimension, or if you are laying the bales on edge.)
Calculate the total wall length for strawbale walls of that height.
Take your wall length in inches and divide by the average length of the bale. For example, if I have a 10-foot long wall, that's 120-inches. Assuming my bales are 32" long on average, that's 120 divided by 32, which equals 3.75 bales. I round this up to the nearest 1/2-bale, in this case up to 4 bales. This is the number of bales you need in each row.
Now multiply the number of bales in each row by the number of rows you need for your wall height. In our example, this is 7 rows of bales with 4 bales in each row, or a total or 28 bales.
For gables, the calculation is number of rows needed at the peak of the gable, times number of bales needed along the first long row, divided by 2.

I use a little spreadsheet and calculate each wall separately. Below is an example for a building with 8-foot tall walls, 2 peaked gable ends, and with exterior dimensions of 10-feet by 20-feet.

Location	Bales per row	# of rows high	Total Bales
Level One South Wall	7.5	7	52.5
Level One North Wall	7.5	7	52.5
Level One West Wall (subtract width of South & North walls)	3	7	21
Level One East Wall (subtract width of South & North walls)	3	7	21
Level Two Gable Ends (2 gables so rows x bales only)	4	6	24
Total Bale Count			171

For a 10-foot x 20-foot building, the long walls are 240" and the short walls are 120". The long walls will be 240" divided by 32" (average bale length), or 7.5 bales per row. The short walls will be 120" minus the width of the long walls (since the corners overlap) so 120" - 2(18" bale width) = 120" - 36" = 84". Dividing by 32" (average bale length) is 2.6, so I round up to 3 bales per row. The height will be 8-feet tall, or 96". Each bale is 14" tall, so 96" divided by 14" equals 6.8 bales tall, which we round up to 7 bales tall. The gable dimensions vary depending on your roof slope and design, but notice my example shows 2 gable ends, so I do not need to divide each by 2 as you would if it were a single gable

Cool Strawbale Tool!

2011-03-28T16:29:00.001-04:00

During construction of one of my projects in Maryland, the builder came up with an ingenious method for installing nailers into the strawbales. These arrows were used for trim nailers, to attach electrical boxes, and anywhere we would need to nail something to the strawbale walls. The credit for this ingenuity goes to Jeff Geddes of Paragon Custom Homes in MD. You can see progress photos of this project at Adrienne's Blog (she's one of the homeowners-to-be). Below are step-by-step photos of how to make the arrows. To use them once you made them, simply hold the arrow facing toward the strawbale wall at the location where you need a nailer. Then push and then hammer the arrow into the straw. One warning...they are difficult to get back out, so check your location carefully!

start with a 12"-long 1x4

cut an arrow head on one end

kerf angled cuts into the sides as shown

whack along the grain to remove excess between kerfs

You may need something more substantial in locations where you are going to hang something heavy on the strawbale walls (like kitchen cabinets or a heavy bookcase). In this case, I would sew a longer ledger (made from a 2x4 or 2x6) that is almost as long as whatever you are hanging. Drill an even number of holes in the ledger every 8 to 12 inches. The holes need to be big enough to get your strawbale needles through. Sew a long piece of baling twine through the first hole and all the way through the strawbale wall. Send the twine back through the strawbale wall approximately 8 to 12 inches away along your board (whatever your hole spacing is). Feed the baling twine back through the strawbales and through the next hole in your ledger board. Push tightly on the ledger board, pull the twine very very tight, and tie off the two ends of twine together. (You can use the same knot you use to resize bales.) Repeat this for each pair of holes in your ledger board. This nailer will be very strong!

You can also sew small items to the strawbale walls by using a wood or plywood washer (as shown below). Make sure your twine wraps into the kerf cuts, and tie everything very tightly, so that the washer pulls into the face of the straw.

wood or plywood "washer" for strawbale walls

Why Infill Stawbale?

2011-03-28T14:43:00.003-04:00

Strawbale walls can be constructed in two basic ways: loadbearing or infill. Loadbearing strawbale, as its name implies, involves constructing strawbale walls in such way that they support all roof and any second floor structural loads directly on the bales themselves. The first strawbale structures in 19th Century Nebraska were built this way because wood was a scarce commodity. Infill strawbale involves building some independent structural system - stud walls, post-and-beam, etc. - to support all structural loads, and then strawbales are infilled between or around that structural system.

So the question is: if you can use the strawbales as your structure, why would you build any other way? It turns out there are two main benefits to building infill strawbale structures instead of loadbearing structures.

EASE OF PERMIT APPROVAL
Infill strawbale meets the current building codes throughout the U.S. That's right, infill strawbale meets the current codes! See my blog post on this topic. Loadbearing strawbale walls, on the other hand, are taken on a case-by-case basis by your permit officials (unless you live in a region that has passed a separate loadbearing strawbale code). Because strawbale as a loadbearing material is not in current U.S. building codes, you need to demonstrate precisely how the structural capacity of the strawbales will support the building. This usually means you will need the assistance of a structural engineer to demonstrate to the permit office that the strawbales will indeed support the structural loads of your building. This may mean you incur an additional cost (for the engineer) and your permit may require additional time for review.

THE WEATHER!
If you live in a climate where it rains during the construction season, then infill strawbale may make your life less stressful when you build. When using infill strawbale construction, the roof is completely on and leak proof before you begin installing your strawbales. This means that all strawbale installation is protected from rain during construction. The concern with water infiltration is only on the top of the bales, not the sides. So as long as you install entire sections of wall from floor to ceiling, your bales should stay dry during construction until you are ready to plaster. (NOTE: the side of the wall that faces out is not a concern unless you lay your bales on edge; if you lay your bales flat, with the straw ends poking inside-to-outside, then any rain will only penetrate and inch or two into the bales and then come right back out, leaving your bales nice and dry inside where it matters.)

I am not advocating one or the other technique for building with strawbales. Both methods work nicely and both result in beautiful, well-insulating walls. However, I find it helpful to take all variables into consideration when deciding which construction technique is right for you.

What is a Rubble Trench Foundation?

2011-01-26T13:32:00.004-05:00

The function of a foundation for any structure is to take all of the weight from the building above, and distribute that load evenly to the ground below. The type of foundation that makes sense for a particular structure depends on the size and shape of the building, the type of structural system for the building, the slope of the land, the capacity of the soil to support weight, and how deeply the ground freezes in your area in winter. A rubble trench describes one low-impact option for the footer, which is typically the part of a foundation that is below ground.

WHAT IS A RUBBLE TRENCH FOUNDATION?
A rubble trench is simply a continuous trench footer around the structural perimeter, dug as deeply as the ground freezing point in winter, and filled with stone. A structural (usually concrete) grade beam (a beam that rests on the ground) is poured on top of the stone-filled trench, and distributes the structural loads of the building across the surface area of the trench below. This type of foundation uniquely provides both structural bearing as well as water drainage in a single foundation system. The width of the trench determines the bearing capacity for loads above (as with a standard concrete footer). A filter fabric liner between the soil and the stone provides insurance against silt filling-in the cavities between the stones, which would impede the flow of water over time. Drainage is important with most foundation systems, since water is the single largest culprit for foundation failure. Liquid water can erode the ground bearing around a foundation footer. Frozen water expands when it freezes, which causes the ground around your foundation to also expand, which subsequently causes the foundation to heave upward in Winter and drop it back down when the ground thaws in Spring. That heaving movement can crack the structure or cause uneven settling of the building. When installed correctly, a rubble trench results in a resource-efficient, high-performing, eco-friendly, and low-cost foundation footer.

All sizing & structural details must be provided by a structural engineer

Various forms of the rubble trench foundation have been used for thousands of years in construction. Earthen walls in the Middle East and Africa, for example, are built on top of shallow ditches filled with loose rock. The ditches are shallow because the ground does not freeze. Frank Lloyd Wright came across the rubble trench foundation system around the turn of the 20th Century. He observed the structures to be "perfectly static", meaning they showed no signs of heaving, because of the complete elimination of water around the foundation. From then forward, he built consistently with what he termed the "dry wall footing". Many time-tested structures stand as testimony to the durability of the rubble trench.

STEP-BY-STEP PROCESS

1. Dig a trench to frost depth plus 4 inches and slope to daylight or dry well. (Slope should be 1/8" per linear foot, minimum.) I usually do a minimum of 16" wide trench, but the width required for structural support depends on the specific soil bearing capacity and building loads.

2. Line trench with filter fabric to prevent silting-in of the footer over time.

3. Add 4 inches of stone and tamp it once around, by hand is fine. Ensure that surface of the gravel fill maintains the drainage slope and is at or below the frost line.

4. Lay 4-inch diameter perforated pipe continuous on top of the sloped stone. Slope the pipe to daylight, as for a standard foundation footer.

Note: technically the drain pipe is optional, since the entire rubble trench footer provides drainage. In some jurisdictions, I have found that including the drain pipe, even though it is redundant in function, facilitates getting a building permit.

5. Fill the remainder of the trench flush to grade, or just below, using 1-1/2 inch gravel, tamping after every vertical foot of fill. (See note below on stone size.) Hand tampers work just fine for this application...no need to use a pneumatic tamper. Just walk along the entire trench and drop the tamper over all areas. Tamping locks the stones together to provide strong bearing that won't shift over time.

Note that the rubble fill may be stone or crushed concrete, but in either case, it must be washed free of fines and should provide a variety of sizes with an average of 1 to 1-1/2 inches and a minimum of 1/4-inch. Fine dusty particles or sand-sized particles can clog you rubble trench and then it will not act properly as a drain. You can test the drainage in your trench with a hose before continuing.

6. Coat your formwork (for the grade beam) with biodegradable oil. This ensures easy release of your form for potential reuse. Any vegetable oil works well. I use 2x12's for the grade beam formwork and then reuse the same wood for structural framing once the grade beam has cured.

7. Set formwork for grade beam or slab-on-grade thickened perimeter beam. You will likely need steel reinforcing bar (rebar) inside your concrete. Have a structural engineer designate the structural requirements for your grade beam. If you are pouring a slab-on-grade with a thickened perimeter beam over the rubble trench and will install in a single concrete pour, the slab preparation is the same as what you would install with a conventional footer.

8. Pour concrete grade beam. The grade beam can be a discrete structural element around the entire perimeter of the structure, or can be integrated into the thickened perimeter of a slab-on-grade foundation (as this photo shows). Any structural elements above this point are completely standard, whether installing a stem wall and crawl space, a full basement, stud walls, a post-and-beam structure, or whatever. An engineer should size all structural elements.

Note the rebar still sticking out of the ground to support the wood form until the concrete has fully cured.

BENEFITS
Lower Cost. A rubble trench foundation requires less labor, uses less material, and reduces material cost compared to a standard concrete footing. There is no over-digging, no footer forming, and no backfill.
Minimal Site Impact. Digging is limited to only the outline of the building, so site disruption is minimized.
Lower Greenhouse Gas Emissions. Rubble trench footers reduce concrete use by an average of 80%, compared to a standard footer (depending on frost depth and the type of foundation installed). Production of concrete requires a great deal of energy and generates 1.25 pounds of greenhouse gas for every pound of cement in the mix. Reducing total concrete use translates to direct reductions in greenhouse gas emissions.
Can Contain Recycled Content. The rubble fill can use recycled crushed concrete instead of gravel, as long as fine particles are washed out.
Improved Drainage & Foundation Performance. A rubble trench provides full water drainage under every structural bearing element of the foundation, ensuring that the footer remains dry at all times. This type of static foundation system ensures that water cannot freeze under the foundation. When water freezes in the ground, the water expands, which can heave a building foundation.

CHALLENGES

Soils with low bearing capacity may require an extremely wide trench or some other footing alternative to achieve adequate bearing area.
Rubble trench foundations are not specifically identified in building codes, so may require additional dialog with permitting officials. It helps to provide drawings stamped by a licensed engineer.

BUILDING PERMITS
Rubble trench foundations meet the requirements and the intent of U.S. building codes, however, since this system is not specifically identified in current codes, acceptance is provided on a case-by-case basis. Since this puts permit approval at the discretion of individual building officials, it is recommended to initiate a dialog prior to submitting for a building permit. This provides an opportunity to inform and educate permitting staff and provide adequate information to satisfy everyone's mutual desire to ensure a safe structure. The article written by Elias Velonis for Fine Homebuilding magazine provides excellent technical information. Stamped structural drawings are also highly recommended.

For additional information on rubble trench foundations, see also my online article: Rubble Trench Foundations.

Yes you can! Build with Strawbale in Wet Climates

2011-01-14T12:43:00.002-05:00

I often hear people lament: "I would love to build with strawbale, but you can only do that in the Southwest." If that were true, I wouldn't have a job!! All new buildings I design here on the East Coast U.S. are strawbale, and usually have multiple natural building features...cob, living roofs, cordwood, natural plasters, etc. There are specific details that need a shift from the perceived norm of strawbale construction. But it is definitely possible to build durable strawbale structure in any U.S. climate.

The bottom line is that IF YOU CAN BUILD WITH WOOD, YOU CAN BUILD WITH STRAW!

This strawbale home is nestled in the snowy woods of New Hampshire.

Water is a problem when it accumulates to higher than 20%. At this moisture content, two things happen in organic materials. First, any dormant mold spores are activated to bloom. Second, the microbes that cause organic materials to biodegrade become active. This means any wood or straw will begin to rot. The particular issue with strawbale walls is that the rotting generally begins deep inside the wall, so by the time you know there is a problem (by observation at the surface of the wall), your wall is well on its way to compost. The key is differentiating between liquid water (rain, water in pipes, etc.) and air-borne vapor (humidity). You want to keep liquid water completely out of the wall. However, air-borne vapor is only a problem if it is allowed to condense, and thus become liquid, inside the wall.

I have taken clues from how we build durably with wood to inform how to build with straw in a wet and humid climate. We learn from long-lasting wood construction that there are a few basic rules to follow...protect the base, provide a good roof, keep liquid water out, but let walls breathe. The question then is how do we translate that to strawbale construction? Simply follow these four easy rules to durable strawbale in any climate.

1. PROTECT THE WALL BASE

Strawbale walls should always be lifted up off the ground. Water generally can enter the base of the wall in two ways: rising moisture from the ground and splashing rain off the roof. If your climate gets a lot of rain, you want to lift your bales 18" to 24" above the final ground height to prevent splashing rainwater from consistently wetting the same spot on your strawbale wall. You also want to create a deep roof overhang that extends away from the house, so that any rainwater falls well away from the house. I typically use a 2-foot eave. The exception is sometimes on the South side of a building, when a roof eave needs to be smaller to allow for winter solar gain. Then I adjust the South overhang only to the sun angle.

lift straw off the ground & provide a deep overhangs

2. PROVIDE REDUNDANT MOISTURE PROTECT AT ANY HORIZONTAL STRAWBALE SURFACE

If there is an unfortunate leak at a window or your roof, you want to know you have a problem right away so you can fix it before any damage is done. This is true for any type of construction! The difference between straw and wood construction is that strawbales can absorb an enormous amount of water and never give you any sign that there is any problem. So I recommend installing a waterproofing diversion at the top of any horizontal strawbale surface. This allows any leak to be diverted to the side of the wall, where it will stain the plaster and indicate to you that there is an issue that needs to be addressed. I use two layer of roofing felt on top of all window sills and at the tops of all strawbale walls, as shown below.

waterproofing at sills and tops of walls

3. AVOID CONDENSATION POINTS INSIDE THE WALL

Straw is warm to the touch at ambient temperatures. Air-borne vapor does not condense on a strawbale. However, a material that is cold to the touch at ambient temperatures, such as metal, can cause humidity to condense on its surface. Similar to water condensing on the outside of a glass of iced water when the air around is warm and humid. This same phenomenon will occur inside your wall if you use an ambiently cold material to pin your bales together. Air-borne vapor will condense on the cold surface, turn to liquid, and collect over time to create a wet spot inside your wall. So, instead of using metal rebar to pin bales, I recommend bamboo or wood. Bamboo has the added benefit in our region of being invasive, so people are generally more than happy to have you remove it for free. Similarly, I avoid the common detail of using pea gravel in the base of a strawbale wall. The stone is cold, so condensation can occur on their surface, creating a wet spot at the bottom of the bales. (Plus now you have a spot in your wall with no insulation!)

use bamboo or wood pinning (avoid rebar in the walls)

4. USE BREATHABLE FINISHES

In addition to avoiding condensation points, as described above, you want to create surface finishes that allow any vapor to travel freely through the wall. If they travel most of the way and then cannot escape through your finish, you could end up with moisture build-up inside your strawbale wall. This means plasters and paints should have excellent breathability if you are building in a humid climate. I use wood siding or lime plasters on the outside since they both shed rain water so well. And I use natural clay plasters, usually dug right from the site, to finish the straw on the inside. I also avoid cement-based plasters, since they are brittle and not very breathable, so liquid water penetrates any inevitable cracks, but cannot readily get back out (ie, moisture build-up). Paints and sealers should also be breathable, so I avoid acrylics, in favor of clay, lime, or casein based paints, or simply a burnished or clear linseed oil finish to prevent dusting.

use natural, breathable plasters & finishes

For more information on this topic, see also my online article: Five Tips for Keeping Strawbale Walls Dry in a Wet Climate.

Newsflash: Strawbale MEETS Current Building Codes

2011-01-07T23:33:00.003-05:00

This post is based on an article first published in the June 2006 issue of The Last Straw Journal and is also posted at www.buildnaturally.com

There seems to be a broad misconception that strawbale construction requires a fight with the local building permit office. This is simply not true, and a fighting attitude will probably end up being counterproductive. Instead, I advocate 3 simple steps to building permit success for your strawbale structure: 1) be informed, 2) get support, and then 3) collaborate with permit officials. The bottom line is that non-structural applications of natural building materials, including strawbales, are in compliance with current building codes. Structural applications generally require some additional support from a structural engineer.

Strawbale infill walls MEET codes

Rubble trench footers MEET most codes

THE FACTS:

The intent of ALL U.S. building codes is to ensure health, safety, and, to some degree, durability. Likely you have the same goal for your natural building project, so you are in alignment with the goals of the building codes.
The role of permit officials is supporting you to ensure #1 above. If you are open & collaborative, permit officials will generally collaborate with you to help you achieve your building goals.
U.S. building codes do NOT exclude alternative materials or techniques. Rather, each code begins with a caveat that allows for anything not specifically listed in the code to be approved as long as you show that it meets the INTENT of the code for durability, effectiveness, and safety (including fire resistance).
Demonstrating compliance with the building codes is possible thanks to many pioneers that have dedicated time & money to sponsor third-party ASTM (American Society for Testing and Materials) tests. The results of these tests demonstrate that strawbale wall systems not only meet the building code, but in most cases surpass the intent of the code compared to standard stud-and-drywall construction.

How to use these facts to your advantage: 3 STEPS TO PERMIT SUCCESS!
I have used the following approach with a 100% success rate to obtain standard building permits for over 20 natural building projects, many of which were the first alternative structure in their jurisdiction.

STEP 1: BE INFORMED
...on what you are building
Be familiar with your drawings and fully understand your natural building material of choice, whether strawbale, cordwood, cob, or whatever. Understand how it is installed, what the physical properties are, and what the pros & cons are. You will likely have the pro list at the tip of your fingers, since this is the material you chose. However, I also recommend understanding the limitations of your material of choice so that you can address any questions that come up in a realistic and honest manner.

...on your building codes
Confirm if your code jurisdiction has any building codes for natural building materials or methods. If yes, then make sure your proposed plans are in compliance with that code. If there are no existing codes, then find out which code is used. Find a copy of that code (I recommend the library, since code books are expensive) and write down each section that is effected by your material choice. For example, with strawbale walls, you will look for any code language that defines the performance of exterior walls (insulation, fire rating, etc.) Then you simply need support information that describes how your material meets the INTENT of that code section. For some items this is common sense...the fire rating for cob is a non-issue, since cob is non-flammable. For some items, like demonstrating the insulating value of a strawbale wall, you will need that third-party data available from natural building pioneers. Many of these tests are available for free online. See www.dcat.net/resources and scroll all the way to the bottom of the page. And remember, the question is not whether you can get a building permit, but rather, how to best communicate with local building officials that your natural building material is a viable, durable choice that meets the existing building code.

STEP 2: GET SUPPORT

I find it is extremely helpful to have someone on your team that has experience with whatever natural building material you are using. This can be whoever designs or drafts your building, it can be a structural engineer, or it can simply be a natural builder in your area that you hire as a consultant. This gives you someone you can ask questions to, as well as a resource for the permit office with any of their questions. A building official will generally have more confidence in your project when they know someone on your team fully understands and has experience with your alternative building material.

STEP 3: COLLABORATE WITH PERMIT OFFICIALS
Here I recommend scheduling a pre-submittal meeting with the permitting official to communicate your intentions to build with an alternative material. This meeting gives you the opportunity to describe the merits of your material, and gives the permit officials the opportunity to pose any questions they might have. They can educate you on process and performance requirements. You can educate them on your natural building material of choice. I recommend bringing some printed information with you, perhaps a book with photos of similar buildings, any code research you've done, etc. But try to keep the information to a reasonable quantity so it's not overwhelming. You can always send along additional information if requested.

What I bring to the pre-submittal meeting:

drawings of the proposed building
an brief overview of strawbale construction (I use “House of Straw – Strawbale Construction Comes of Age” by the US Dept. of Energy, available from www.grisb.org/publications/pub23.pdf), or cordwood, or whatever you are building with
some photos of similar buildings (from the internet or a book)
copies of related ASTM testing data (fire-related ASTM tests are at www.dcat.net/resources at the bottom of the page)

At a minimum, be prepared for the following common questions:

How does your wall system handle liquid water and vapor?
What is the fire rating & smoke development rating of the wall system?
Will the wall system attract pests, such as termites or rodents?
What is the insulating value of the wall system?
How is electrical and plumbing installed?

During the meeting, don't be afraid to admit you do not know something. I find it's more productive to say you will find the information and follow-up to get it to them, then it is to disseminate incorrect information. And don't be afraid to ask them to help you! Ask specifically what they would need to have...drawings, information, stamps from a professional, etc...in order to approve your project for permit. Remember that your building official is your ally not your adversary, and has the same goal as you: to ensure that what gets built is safe. Acknowledge your common interest for occupant wellbeing and safety. You will create connection instead of confrontation and open a dialog on how to achieve your common goal.

For the final permit submittal, my experience is that stamped structural drawings greatly facilitate the speed and ease of the permitting process, so I use a structural engineer on every project.

MY EXPERIENCE
I have to date not experienced any delays during the permitting process using this method of interaction with building officials. Increasingly, I find that building officials already possess some level of knowledge about natural building materials, especially strawbale construction. This was not the case on the East Coast of the U.S. even 5 years ago. In most cases, interacting with permit officials brought them fully on board and garnered curiosity in other natural building materials & methods.

FINAL NOTE
Finally, I would like to address the issue of adopting existing codes and details in different climates. I design structures in a wet, humid climate with hot summers and cold winters. However, many of the now-standard strawbale details have mostly developed in arid and temperate climates that are not necessarily durable in this mixed climate. For example, I do not recommend using rebar inside a strawbale wall in a humid climate, since the cold metal creates an artificial dew point inside the straw wall. The result is elevated moisture around the rebar, which can lead to rotting the straw over time. Instead, I recommend external pinning or using materials that are “warm”, such as bamboo. Similarly, pea gravel at the base creates an artificial dew point, as well as creating a thermal break along the entire base of the wall. My point is not that the originally developed details are inadequate, but rather that they are specific to an arid climate. So when adopting codes and details in different regions with different climatic concerns, ensure that what you propose will perform durably in your climate.

Strawbale vs. Cob

2010-12-29T02:07:00.004-05:00

Which material works best for which application...

strawbale detail around a beam


sculpted cob thermal mass wall

I often get asked this question: Which is better to use for my natural building, strawbale or cob?

The answer is simple: IT DEPENDS! (of course!)
To help sort out if strawbale or cob walls are better suited for your application, I'm going to describe the basic properties of each material, and then how to use those attributes to your greatest advantage.

STRAWBALES insulate. And they are thick, so they insulate really well. What this means is that a wall built of strawbales slows down heat energy traveling from one side of the wall to the other. A good insulator acts like a down jacket that keeps your body heat inside the jacket instead of getting disbursed to the cold winter air. A well-insulated house will use less energy to heat in winter than a poorly insulated house, because the insulation keeps the heat inside. If you use an air conditioner in summer, insulation will keep the heat outside, so again you need less energy to keep cool.

COB is a thermal mass because of its principal ingredients: clay & sand. Cob has limited insulating properties. Instead, a thermal mass is like a storage battery for heat (or cool) energy. This means cob is good at absorbing heat energy from the sun or a fire and storing that heat. When the air temperature around the cob is lower than the temperature of the cob itself, it releases its battery storage of heat into the air. In this way, cob can absorb a lot of heat energy and then release the heat over time, long after the heat source is gone. Conversely, a shaded thermal mass with no heat input will stay cool in the summer and absorb heat energy out of the warmer air around it (thus having a net cooling effect).

So how to best use these characteristics to your advantage?
The answer depends on your climate and what you are building. If you are using energy to change the inside temperature and keep it something different from the outside temperature, then you generally want a good insulator...ie, strawbales. If you live in a mild climate where the temperature swings are day-to-night instead of seasonal, then a thermal mass exterior wall generally will help to average out those temperature swings...ie, cob. Thermal mass can also provide a highly beneficial interior element in conjunction with passive solar design, to capture heat from the Southern sun in the winter (when the sun is low) but remain shaded when the summer sun is high in the sky.

STRAWBALES work best...

as exterior walls anywhere you are trying to keep the inside temperature different from the exterior temperature; the insulating strawbales will help keep the temperature exchange to a minimum, so the energy used to change the inside temperature will be minimized

COB works best...

as thermal mass built around a masonry heater or rocket stove (or near a wood burning stove), where the cob can absorb heat from the fire, and store the heat energy even after the fire is out
for trombe walls in passive solar design, with the cob thermal mass inside, where it is warmed by sun coming through South-facing glass
for any interior element when you are trying to keep the inside cool; this can be the same thermal mass used to keep warm in winter as long as there is no heat source warming it when you want to stay cool

I usually use a combination of strawbale and cob. Because I design for a climate that requires several months of heat in the winter, I use the insulating strawbales for exterior walls. This ensures that only a minimum amount of energy is needed to heat the spaces and the heat stays inside. I then position some cob element to the interior. Either it surrounds a wood-burning heat source or it is positioned so that low winter sun shines on the wall from the South. That same cob element is shaded and cool in summer. This way the cob helps to regulate the interior temperature in both winter & summer.

Welcome!

2010-12-28T23:17:00.003-05:00

Well, it's official...I've joined the 21st century! And it only took me 10 years...not bad! First facebook, and now a blog. I guess I'm not an early adopter, to say the least.

I'm going to use this blog to post natural building information, tips, workshops, things I've learned, and whatever else comes to mind that may be of interest to natural building enthusiasts.

If you have a particular question or topic you would like to see answered here, please feel free to comment or email me your suggestion. sigikoko@buildnaturally.com

If you are looking to participate in natural building workshops, I will be posting opportunities for hands-on natural building experience on this blog, on my facebook page www.facebook.com/buildnaturally as well as on my website www.buildnaturally.com.

Thanks, and here's hoping the reading inspires you to create something!