How to Build With Adobe

Adobe is an elegant building material.

Adobe is a natural, nontoxic building material. Adobe homes are solid, quiet and comfortable. They are warm in the winter and cool in summer. Building an adobe home is physically demanding but can be fun and rewarding. Adobe builder David Brackhahn once remarked that "good shoes and a good hat," or a solid foundation and roof, are essential to protect adobe walls from the elements. You will need to know how, or hire someone, to build a concrete foundation; frame a roof, door and windows; and build interior walls. You also can add built-in shelves, benches and other personalized features.

Things You'll Need

• Adobe bricks
• Masonry sand
• Clay
• Water
• Straw (optional)
• Lumber
• Nails
• Shovel
• Mortar mixer
• Wheelbarrow
• Trowels
• String line
• 4-foot level
• Plumb bob
• String level
• Hammer
• Circular saw

Instructions

Preparation

1. Draw plans for your adobe home. Check local building codes particular to adobe construction (or use New Mexico's state building code as a reference if your state doesn't have its own specifications). Have a structural engineer or architect review your plans.

2. Build a concrete foundation strong enough to support the weight of adobe walls. In most areas, a wall that is 14 inches wide requires a stem wall, which runs along the foundation, that is 20 inches wide. Frost line, the depth at which ground freezes, varies with climate; check your local building code.

3. Set up the work site. Bring adobe bricks as close to the wall location as possible. Build rough bucks, which are the wood framing to which you will attach doors and windows. Using two-by-four lumber, build boxes of the same size as an adobe brick; the rough bucks will be nailed to these. You will need enough boxes to place one every three rows, on both sides of every door and window opening.

Building the Walls

1. Mix the mortar. You can use native soil if it approximates the ideal mix of 25 percent clay and 75 percent sand. Use enough water so that the mortar barely holds its shape when squeezed into a ball. Remove stones larger than one-quarter of an inch in diameter.

2. Build the corners first. Lay a mortar base three-fourths of an inch thick, covering the entire adobe surface. Press and wiggle each brick slightly so that it adheres well with the mortar and does not slide. Leave a half-inch gap between bricks. Set five bricks in each direction. Lay three-fourths of an inch of mortar on top of the first row, then set the second row, filling the gap between bricks in the row below with mortar. Stagger bricks so the center of one is above a joint in the row below. Continue for five rows. Use a four-foot level and plumb bob to keep the walls level and straight, adding or removing mortar as needed.

3. Fill in the rows. After you have built all four corners, run a string line the length of one wall, from one corner to another. The string should be taut and just above, but not touching, the adobe bricks below. Use a string level to keep the rows level. Lay bricks to the string line, moving it up as you go. Use the four-foot level and plumb bob to keep the walls straight. Lay a maximum of seven rows in one day, so the weight of the bricks does not compress the mortar before it sets.

4. At every door and window opening, use one of the wood-frame boxes instead of an adobe brick every three rows, on both sides. Fill the boxes with mortar. When the row is at least half the height of the door or window, install the rough buck, nailing it to the wood boxes. Add temporary bracing so the bucks do not sag.

5. Leave space above every door and window for a timber or concrete lintel, which is a bridge that supports the weight of the wall above the opening. The lintel must be six to 12 inches wider on each side than the opening.

6. When the walls are eight feet high, add the bond beam. This joins all the walls together, spreading the weight of the roof over the entire structure. Use lumber to build forms for a 6-inch-thick concrete bond beam and any concrete lintels. Include steel reinforcing (rebar) to anchor the roof to the bond beam. Pour concrete and let it cure.

Roofing and Plaster

1. Build the roof on top of the bond beam. While a typical adobe home has a flat roof, pitched ones are common in areas with heavy snowfall. The roof must provide enough overhang to shed rain and snow away from the building walls.

2. Plaster the exterior walls. For the first coat, use the same mix as the mortar, adding chopped straw for texture. After the first coat dries, add a second coat, using the same mix or, for a smoother finish, finer clay and sand. You can also use concrete or synthetic stucco, or add pigment for color.

3. Install the windows and doors.

Tips & Warnings

• You can make your own adobe bricks, but it's easier to buy them. Most modern adobe builders use semi-stabilized bricks that contain additives to make them water-resistant.

• If you need a partial brick, score the adobe all around with a trowel, then rap the brick sharply against a hard surface to snap it in two.

• Don't worry about minor size variations from brick to brick, or evenness of an individual brick. Just keep the whole row level and straight.

• Don't let water pool against the adobe wall. Cover unfinished walls with tarps to protect from rain.

• Cement stucco may trap moisture, resulting in deterioration of the adobe wall. Natural adobe plasters might need to be patched periodically, but they allow moisture to evaporate.

References

• "Adobe Build It Yourself"; Paul Graham McHenry Jr.; 1985
• "Adobe and Rammed Earth Buildings: Design and Construction"; Paul Graham McHenry Jr.; 1984
• David Brackhahn; Adobe builder; Colorado and New Mexico
• "The Natural House"; Daniel D. Chiras; 2000

Resources

• Green Home Building
• "Adobe!"; Sandra Seth and Laurel Seth; 1988