leangreen.org recycled renovation on a low-budget ration

To mine the backyard dirt for its valuable clay, we first sifted out the earthworms, rotting leaves, tiny rocks and other non-clay chunks.  We built three sifting frames with different metal mesh sizes:  1/2-inch, 1/4-inch and 1/8-inch grids.  We dug a pit in a spot where we'll need to remove soil for leveling the patio, and sifted the soil through the three different meshes (big to small) and deposited the sifted clay in a big plastic tub.  Once we had the tub half full, we added water and mixed with our drill-powered paddles.  It made a sloppy mess and our backs hurt a bit, but it was also sorta fun.  We reminisced about childhood mud pies and dirt bombs.  We have yet to immerse ourselves into the tub, but we imagine that a mud bath will be rejuvenating once we finish plastering all the walls and ceilings.

We could pay someone a few thousand dollars to mud the walls. But why start subcontracting out jobs now? Being broke helps motivate us to find alternative solutions that are leaner and greener. Our latest adventure: mud, real mud, free from the backyard mud. And it's going on our walls.

A gypsum wall finish is a standby for many reasons: it's white, smooth, easy to paint and a cheap, abundant natural resource. It dries quickly and therefore requires some skill to apply. The endless sanding creates dust. Silica is not something you want to breathe day after day (because it would take us weeks or months to do ourselves). Joint compound additives (i.e. vinyl, formaldehyde) are not as benign as gypsum's main ingredient, calcium sulfate. While it's not tremendously expensive to do it yourself, getting a quality job in a short time frame would take funds away from other projects. And then we'd have to paint, another expense and more time and more gallons of goo to manufacture and trash. As we learned from deconstructing the old house, anything painted gets sent to the landfill.

In the meantime, we know that the backyard needs to be re-leveled so that we can seamlessly walk out of those big barn doors onto a patio, an outdoor extension of our kitchen. We've seen the American Clay plasters in "green home" tours. The way the walls absorb and reflect light makes you want to avoid shiny plastic paint forever. But it's expensive, which seems odd if it's just clay. Isn't our own soil full of clay?

To see if it was even feasible, I visited Sasha at Villa Sobrante, a home retrofitted with strawbale and clay. Sasha teaches classes on clay plaster and shared on-the-wall evidence that clay plaster is doable and durable. She recommended an informative book full of recipes and inspiration: Using Natural Finishes by Weismann and Bryce. According to the book, the clay content of soils used for plaster should be at least 15 percent. Our soil showed promise. It formed easily into a ball or log and retained its shape when dropped from head height. We dug up several samples, added water, shook them up in glass jars and waited for the soil layers to settle. We waited days for the water to clear (a sure sign we had lots of clay). Here's how it finally shook out.

Time to process the clay for our walls.