How to Build Earth Covered Homes

Earth homes have been around since the beginning of agricultural settlements.

The garden-roofed monolithic adobe is the most effective way to build a home surrounded by earth. These homes are energy efficient, very low cost to build and can bring a family together because it's fun and relatively simple to build.

Things You'll Need

• Rocks or recycled cement blocks
• Sliding double-pane glass door
• Window for upper loft
• Plywood roofing sheets
• Roof support beams
• Rubber pond liner to fit over entire roof
• Used carpet
• Old cardboard box sheets
• Downspout
• Gravel
• French drain pipe
• Guide book: "The Hand-Sculpted House"
• Shovel
• Lumber
• Garden soil
• Mixing tarp
• Sand, clay or supply of any soil amendment needed
• 5-gallon buckets
• Bales of straw

Instructions

1. Dig a trench to go under your planned walls. Dig the trench two feet wide by 18 inches deeper than your frost line by the diameter of your planned cabin. Dig a french drain field two feet out from your cabin walls, all the way around your house. Place the french drain pipe at the bottom of this trench. Make sure it will siphon off any water that might try to gather under your walls. Place the end of the drain pipe emerging, pointing down-slope. Fill both trenches with gravel.

2. 

   This rock and earthen mortar foundation wall is much higher than a foot.

   Lay the foundation stones or blocks on top of the wall trench gravel. Mortar is not necessary if your blocks are flat, like recycled cement, and you also do not live in an earthquake zone. Place the blocks tightly together like a jigsaw-puzzle stem wall. Make the wall about 1-1/2 feet high (or up to your knees). Remember to measure and leave an opening where the sliding-glass entry door will be installed.

3. Place your mixing tarp on the ground, and load two or three buckets of earth into the middle. Add them slowly while stomping, twisting and mixing with your feet while adding water and straw. Pull your tarp at the corners, toward the middle and continue to mix and pull until your earth mix looks and feels like a folded burrito. Mixing earth, sand and clay with water makes a bond between the clay and the sand. This creates a dough that dries like a rock in the sun. Load this mix onto your stem wall. Shape this mass so the earth hangs slightly over the rocks so no water will slip under your earth wall.

4. Continue loading the earth mix until your walls rise three or four feet above the hole for your sliding door. Place the upper-level loft window by setting the window onto the wall (depending on the weather) near the out or inside of the wall. Shape the earth up the sides of the window. Work the earth with your hands and fingers, and use a stick or tool to push the layers of earth together when you add new loads.

5. When nearing the top of your cabin walls, embed the beams you will use to anchor your roofing plywood to hour house. Now is time to frame your sliding door for hanging, as well. Nail your roofing plywood directly to the top of the embedded roof beams. Nail a lip or frame around the edges of the plywood sheeting for a 6-inch-deep bowl that holds garden soil. Make sure your plywood extends a full 2 feet out over all of your walls. Shape the edges to please the eye.

6. Lay the rubber liner into the roof-boat frame. Fix your downspout to a corner or edge so it will handle any water runoff. Fill the liner with old carpet, then cardboard, then at least 6 inches of soil to form an earth roof that can last up to 100 years if properly fitted. Seed this roof with red clover or another useful garden cover crop.

Tips & Warnings

• Anything you build small with earth, you can build big. Make a scale model, 1 inch representing 1 foot. If the window is large, place a beam horizontally above the window, embedded into the earth mix to spread the weight above the glass. Trim and smooth your earth walls as you go.

• Use caution and your legs---not your back---when lifting heavy rocks. Add any soil amendments learned from reading your book, and test your soil before starting.

References

• House Alive: Cob Workshops
• Cob Cottage Company: Latest News
• Living Earth Structures

Resources

• The Hand-Sculpted House; Ianto Evans, Michael G. Smith and Linda Smiley; 2002
• Natural Villages: Legalizing Earth Homes