Cement Plaster Video

Here’s a brief summary of the cement plastering process we used on the exterior of our earthbag roundhouse:
Step 1: Put cement between the bags in the gaps.
Step 2: Add thin coat of cement over bags.
Step 3: Add more cement.
Step 4: Add more cement.
Step 5: Trowel the plaster smooth and use a sponge float to smooth out the finish.

As you can see, the process is quite simple, although labor intensive. It boils down to adding a little plaster at a time. Leave each coat rough so the next coat will better adhere. No plaster mesh is needed — the plaster sticks to the earthbags, no problem. Resist the temptation to overwork the plaster. The total process took about five days of work for two workers spread out over a little more than week (some days there was no work). A third worker helped the last day.

Caution: Research the techniques used by plaster professionals in your area and follow their lead. The techniques in this video show what works in a rainy/humid climate, but they can cause problems in dry climates.

More videos at my Earthbag Video Channel.

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Roundhouse Update: Light Fixtures

We just finished installing light fixtures in our earthbag roundhouse. This step has taken a lot longer than anticipated. The porch light by the front door was easy to find since it is conventional looking. But we wanted something special inside for our three wall sconces because they’re more prominent. Two sconces, one on each side of a fold-out bed, are located on curved earthen plaster walls. Another sconce is in the bathroom. We’ll add some table lamps after all the furniture is in.

One of the light fixtures in our earthbag roundhouse.

I spent hours scanning websites for something unique, beautiful, curved and inexpensive. My heart was set on rice paper lamp shades. (Do a Google Image search to see the amazing variety that’s available.) In the end though, we went with the dirt cheap option, since demonstrating how to build affordably is a major goal of the project. My girlfriend found some ridiculously inexpensive split bamboo lamp shades for $1.25 each. The light fixtures were $2.50 each, plus compact fluorescents. This keeps us on budget for $10/sq. ft.

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Straight Versus Zigzagging Barbed Wire

Do not zigzag barbed wire between courses of bags, because this will lessen its tensile strength. A load (stress) on the structure, such as a hurricane, earthquake or differential settling, would tend to pull the structure apart as the slack is taken out of the wire. Zigzagging the barbed wire would provide more attachment points, which at first glance seems like a stronger solution, however, you would lose some of the tensile strength that way. The recommended practice is to place barbed wire in concentric rings on domes and roundhouses and in straight, parallel lines on rectilinear designs, usually two strands of 4-point barbed wire per course.

Correct: Two parallel strands of barbed wire

Incorrect: Zigzagged barbed wire

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Other Uses for ¼” Steel Rod

An earlier post described how to use ¼” steel rod to install electrical boxes you may have forgotten. This steel is incredibly versatile and so it’s handy to have some around during construction.

¼” Steel Rod - Click to Enlarge

Here’s a list of things we’ve used it for: attaching bracket for wall mounted bath sink; attaching shelf brackets and nailers; reinforcing cast-in-place concrete countertop; reinforcing top of brick wall and arch; tying brick wall to earthbag wall; reinforcing brick wall footer.

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Freeform Earthbags Between Boulders

The folks at Phangan Earthworks in Thailand have created a marvelously meditative structure using earthbags placed between existing large boulders that was then capped by a wood-framed roof and eventually thatched.  The result is a symphony of forms that mirror nature and quiet the mind. The open, well-vented design remains pleasant at all times.

You can read about how they built this and see many more photos at earthbagbuilding.com

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Dispensers Versus Uncoiling Barbed Wire by Hand

I’ve seen various barbed wire dispensers being used and have wondered what design works best. I started making a dispenser for our roundhouse workshop, but gave up when things weren’t quite working out. It seems easier to move the roll of barbed wire by hand to where it’s needed instead of using a dispenser. Also, this makes it easy to remove the twist, straightening a little at a time as you go, so the wire stays in place against the earthbags.

Barbed Wire Dispenser

Uncoiling Barbed Wire by Hand

What do you think? I’d like to hear your thoughts on this subject.

Safety warning: Working with barbed wire can be dangerous. Use thick leather gloves and stay alert. Be aware that barbed wire can spring loose and cause injury.

Photo credit: Patti Stouter

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Earthbag Greenhouse at Sandhill Farm

The year-round greenhouse at Sandhill Farm is built with sustainable materials, including earthbags for lower walls and light straw/clay in upper walls. Greenhouse segment starts at 1:12.

Maybe someone from Sandhill Farm can chime in here and leave some comments.
More info:
Sandhill Farm
Dancing Rabbit TV

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Earthbag Building is Taking Off in Gaza!

I just discovered a new YouTube video from AlJazeera TV that describes how folks in the Gaza strip, who have been denied many building materials such as cement and steel, have taken to building with earthbags. This short video shows  how they are adapting some of CalEarth’s methods of using long tubes filled with adobe soil to build some marvelous forms.

One innovative adaptation is that they have connected many structures that have a square, vertical walled base, which then tapers upward to form a domed roof. This allows the maximum use of space in a series of connected domes.

They say that “necessity is the mother of invention,” and in Gaza they are being forced to find ways to build with very limited materials. This could provide the impetus for making earthbag building more known and accepted in that entire region…which is both good for them and for the world. Take a look: www.youtube.com

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Installing Additional Electrical Boxes

Let’s assume you want to add an extra box when you’re doing your electrical. The other boxes were installed in the right places during wall construction, but somehow you forgot one. (This would never happen to professionals, of course. [cough])

How to add additional electrical boxes to earthbag walls.

Don’t worry, there’s an easy fix. What I do… [cough] or would do if this ever happened to me, is use ¼” steel rod to pin the box to the earthbags. Cut two 7” long pieces of steel rod. Pound the rod in at opposing angles so the box won’t pull loose. (See drawing.) For example, angle one pin up and one pin down. Bend over the last 1-1/4” so it’s flat against the back of the box. This creates a very secure box. Just remember to have the front edge of the box protrude about 1-1/4” beyond the earthbags to allow for plaster thickness. Now you’re ready to run your electrical wire.

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Experienced Earthbag Builder Needed

There’s a job opening in Haiti for an experienced earthbag builder. An NGO there is planning to build an earthbag orphanage. All structures will be rectilinear. Send your resume to Matt Gunn: matt [at] haitianydc.org

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