How to Make an Unbaked Brick

Mud brick structures can last for hundreds of years.

People in many parts of the world have created homes and other structures out of unbaked bricks since antiquity and continuing at the present time. The United States has unbaked brick structures made by certain Native American tribes and historic buildings erected by settlers. Also called mud brick or adobe, unbaked bricks are a free and plentiful source of building material. It provides good insulation year-round, helping to keep out the heat even in desert environments. For an educational activity, learn how to make an unbaked brick.

Things You'll Need

• Dirt
• Bucket
• Stir stick, such as a paint stick
• Straw or grass (optional)
• Loaf pan

Instructions

1. Add water to dirt in a bucket. The amount of water needed varies according to the soil's moisture and composition. Aim for a workable mud consistency. Add water until you have thick mud, similar to cookie dough.

2. Add more dirt if the mud becomes runny. Drier mud works best; you want to be able to work it with your hands. Stir in a handful of straw or grass to bind the mud if desired.

3. Press the mud into a loaf pan or other brick form, such as a wooden box the desired size for the brick. Tamp the mud into the form with your hands.

4. Spread straw or leaves, or turn the brick mold over on grass. This will keep the brick from sticking to the surface so it will be easy to remove when it's dry. Turn the form upside down and bang it on the ground to release the brick.

5. Leave the brick in the sun for at least one month. This cures the brick, making it dry and strong for building.

Tips & Warnings

• Dirt that contains clay and sand works best for unbaked bricks, also called sun-dried bricks. Potting soil or dirt that contains a lot of mulch or loam, such as soil from under a tree, doesn't hold together well enough to make strong unbaked bricks. Rake away any loose debris and dig to find heavier soil. You can sometimes see tan, red or gray areas of clay in areas that have heavy water run-off.

• Adding straw or grass helps keep unbaked bricks from cracking. Not all makers of unbaked brick use these additions.

• Mixing dirt and water creates mortar to hold unbaked bricks together.

• Watch your footing on clay-rich soil or spilled mud to avoid the risk of falling. Clay is slippery when it's damp or wet.

References

• National Park Service: Preservation of Historic Adobe Buildings
• Scholastic: The Anasazi and Pueblo Indians

Resources

• PBS: Sand and Soil