How to build a rammed earth house
Preparing the right kind of soil, a proper foundation, good walls and the best finishing is the way to build a rammed earth house.
September/October 1973
By John O. McMeekin
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Back in the 40's I was considered an oddball. I wore a beard—revolutionary then—and I started, by myself, to build a house out of (of all things) rammed earth. People wondered about me.
Today—as a V.P. and corporation director—I appear Establishment, and my home doesn't look unusual either. It hugs a hilltop landscape, it's surrounded by spacious lawns and sheltered by big oaks ... and in the garage are two (count them, two) Mercedes. But my house is still made of rammed earth.
It's a good building: snug in winter, cool in summer, fireproof and termiteproof. Houses like it have stood for hundreds of years. When the windows are closed it's airtight, like a Volkswagen. In fact, a visitor wouldn't notice anything unusual except the thick walls. So what's different? Nothing, except that Those walls are free. Free, that is, if you don't charge for your own work.
PREPARING THE EARTH
You want to build a rammed earth dwelling? First of all find the right kind of soil ... sandy, but not all sand (between 50 and 75% is OK). You mustn't have too much clay, either or the finished wall will shrink and crack.
Once you've found the proper blend of earth, you're going to—in effect—turn it into sandstone the way nature does (with pressure) and the final result will be strongest and most pleasing if you keep your raw material as homogenous as possible. Your first construction step, then, should be the sieving of the soil through a slanted screen of 1" mesh hardware cloth to separate out any big stones, roots, etc. Spread a tarpaulin over the screened dirt to protect it from precipitation (if the soil contains more than 10% moisture it will puddle, not compress). When you make a ball of earth in your hand it should hold its shape but break and scatter when dropped.
FOUNDATION
My own home's foundation is of reinforced concrete that extends from 12 inches above ground to 24 inches below ... our local splash and frost lines. If you live in a climate with warmer winters than Pennsylvania's, you may not need to set your home's base so deep.
I laid our foundation in 8-foot sections, each dovetailed into the next and connected to it with reinforcing rods. The forms were 12 inches wide at the top tapering to 8 inches in the middle, then out again to 12 inches at the bottom (see Fig. 1). They were made of 2 X 6 planks, lined with building paper and strengthened on the outside by 2 X 4 uprights.
Before I filled the forms, I looped a chunk of baling wire around the uprights and snugged the supports tight by twisting the doubled strand in its middle. Make sure you do the same and don't skimp on this because otherwise your wet concrete will bulge where you don't want it to.
Though a concrete mixer would have been handy, I prepared my foundation mix by hand from 1 part of cement, 2 of sand and 3 of gravel.
After your first section of concrete is dry, move the plank forms forward so they overlap the previous pour only a foot or so. A chalk line and level will help you keep the segments straight. Frame in your door and window openings with 2 X 12's as you go along, and be sure to brace them thoroughly. Both concrete and the action of your rammer generate considerable pressure and may force the framing out of line. It s a drag to work with openings that aren't plumb and level.
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