Learn the simple steps of how to make adobe bricks with our comprehensive guide. Over the past two winters I researched, practiced, and tested adobe bricks and built a small adobe building. It was supposed to be a house but I lost many bricks during wet season when I was away during the summer. I recorded the information that I learned and I am sure it will help many.
Make adobe bricks by:
- testing soil using worm, hand, and jar tests
- choosing brick size
- building the form
- logistics
- adding straw or rice husk
- mixing the soil
- placing soil in the form
- drying the bricks
- Testing
Adobe Soil Tests Detailed Guide with Photos and Videos
If you have access to soil on your property you can take soil samples from various areas of your property for testing. Use a jar or a plastic bottle and fill the bottle to one-third full and top up with water. Make sure to label each jar or bottle to indicate the locations of the soil samples.
I used to work in a lab and had it drilled into my brain to keep track of everything. When I had many samples or even a few, I create a rule for myself. I work from the left to right.
Check out the FROG that made a home in the video below!
For soil requirements and brick quality building codes in New Mexico please check out their building codes here.
So the first sample collected is on the left and each sample thereafter is lined up to the right.
Learn through my articles how to make adobe bricks water proof here and advantages and disadvantages, and how many you need, and 10 best anchors for a strong house.
Scott Boyd

Adobe Soil Worm Clay Test
The adobe soil worm clay test is super simple and can be done in minutes with the following 8 steps:
- fill a bottle or bucket with water
- go to the location where you hope to dig your adobe soil
- grab a handful of soil
- add water if it is dry
- mix it together by smashing and kneading it together
- roll it in your hands to create a cylinder about 3/4” (2cm) thick
- attempt to bend the ends towards each other to create a horseshoe
- the soil has enough clay if you can make a horseshoe. If the soil cylinder breaks halfway or sooner then there may not be enough clay content and a jar test should be performed.
Adobe Soil Hand Clay Test
The adobe soil hand clay test is another very simple test requiring only soil and water. Mix together with hands and smush and crush it together until well mixed.
Clay content is guesstimated by opening your hand and noting how sticky the soil sample is and how quickly it falls out of hand when the hand is held palm down. Compare your sample to the results in the pictures below.
Adobe Soil Clay Jar Test
The adobe soil clay jar test is the best quick test to identify the gravel, sand, clay, silt, and organics on your soil sample. 10 steps to test clay in soil include:
- obtain enough pop bottles or jars for the number of soil tests you wish to perform.
- label each bottle or jar for each soil sample location.
- grab a handful of soil and mash it into the bottle or drop it into the jar until approximately one-third full.
- add water to about 90% and seal the bottle or jar.
- shake the sample vigorously for 60 seconds and let it on a stable surface.
- allow samples to settle for a few hours until the water is clear.
- measure the height of the various soil type levels. The materials settle in the following order:
- gravel
- sand
- silt
- clay
- organics
- gravel
Keep in mind that not all soils have all the soil contents on this list. For example, the soil is mostly sand and clay here in Isaan, Thailand near the Cambodian border. So you can see in the photos below what soil samples look like with 100% clay, sand, and clay, and sand, clay, and organics.
Use a measuring tape to measure the height of each layer of soil and divide the number by the overall height of the total soil (to the point the water turns clear).

Adobe Brick Size
Adobe brick size varies throughout the world and depends on several factors such as
The most common adobe brick size in the US is 4 x 10 x 14. Common sizes and weights in the world include:
Height x Width x Length in Inches | Approximate Weight in Pounds |
3 x 5 x 10 | 8 |
4 x 8 x 16 | 30 |
4 x 10 x 14 | 35 |
4 x 18 x 16 | 38 |
4 x 12 x 18 | 50 |
5 x 9 x 18 | 48 |
5 x 12 x 18 | 60 |
6 x 12 x 14 | 100 |
7 x 7 x 14 | 35 |

For more information about brick sizes please see:
Investigation of Mass Production of Adobe Bricks
Alyousif, Mostafa; Alfazza, Alfarooq; Alawatmah, Bashar
Civil Engineering Department
Eastern Mediterranean University
Gazimağusa, North Cyprus – 2012
Adobe Bricks Form DIY
Anyone can build an adobe brick form with the proper information and a few hand tools. Wet adobe mud sticks to the wood form, but it is the most readily available material and it is easy to work with.
Folks in construction may consider aluminum fascia metal covering the inside of the wood form as it is much more slippery. A metal bending “brake” makes this process easy, but anyone can bend the thin aluminum to shape over the wood forms and fasten with fascia or finish nails.

7 items needed to build adobe form include:
- locate or purchase 2 x 4, or 2 x 6, or 1 x 6 boards
- scrounge for a few nails or screws
- hammer or drill
- handsaw/circular saw
- square (or anything that is a right angle such as a factory cut board or a book as I used)
- a flat and hard surface makes life much easier
- pencil
6 steps for adobe bricks forms DIY include:
- Calculate the length of the boards. The measurements must include an extra 0.25 inches to allow for shrinkage. If you are building a long but narrow brick the width only needs an extra 0.125 inch. So if you are building 4 x 10 x 14-inch bricks the inside measurements of the form should be 10.25” x 14.25”.
- If you are using a 2 x 6 board the inside two boards are 10.25 inches long.
- Mark the length of the two 10.25-inch boards using a square or book to make the mark straight and at 90 degrees (square). Cut the two inside boards.
- Add two inches to the length of the other two boards to provide “handles” to grab when removing the form from the wet adobe brick, which is 16.25 inches. PLUS 1.5 inches for both width boards (3 inch total). Therefore the total length is 19.25 inches. Cut the two longer boards.
- Measure back 2.5 inches from each end of the length boards, make a mark, and use the square of the book to make a square mark across the entire width of the board. Mark an X on the outside of the line (nearest the end of the board) to indicate which side of the line to fasten the board.
- Drilling screws is much easier than hammer and nails as I can vouch for! Screw the boards together following the lines to keep the boards square.
Process Logistics Strategy
Planning prior to mixing the adobe mud can make the entire process easier and more efficient. Considerations include:
- Deliver soil as close to the building site as possible. Hopefully, the soil is close to the building site if you are digging soil onsite.
- Buckets are needed if there isn’t a water supply near the mixing area.
- Keep the mixing area, and brick storage locations as close to the building site as possible.
- Mixing in the building on the foundation is great if you are using a mechanical mixer and buckets. Obviously, this requires electricity also.

10 Steps to Make Adobe Brick Mud
To make adobe brick mud manually use the following steps:
- Remove the top layer of dirt until you reach the soil you will use for adobe mud.
- Loosen the soil and pour in some water.
- Add approximately three percent chopped straw (3”) or rice husk to reduce brick shrinkage during drying. This step is not required, but if you have it toss it in.

- Beg your friends, children, children’s friends, family, neighbors, strangers, and anyone else you can think of for stomping mud to make adobe mud.
- Try to mix until there are no little dry clay balls hiding in the mud.
- Use your hands like shovels, or shovels, to fill 5-gallon buckets and carry them to the adobe pouring area.
- Ideally, the mud pouring area is flat and is sand or hard earth. If you pour the bricks on grass or straw they will stick to the bottom side of the brick.
Not critical, but less than ideal. Don’t pour the bricks on plastic, tarps, or poly feed bags as these hold the moisture on the underside of the brick and can create mold after a couple of days.

- Wet the form using a large bucket, scoop mud out of the bucket, and fill the form. Start filling in the corners and squish in well for solid strong corners without holes.
- Overfill the form with mud and pack it into the form and smack and jiggle the mud to remove air bubbles and fill voids similar to pouring concrete.
- Scrape the excess mud off the top and put it back in the bucket for the next brick.
- Use your finger to etch a keyway (1/4 inch mark) for better adhesion between the mortar and brick.
- Slowly lift the form straight up, wet the form, and repeat.
How to Dry Adobe Bricks
- Lift the bricks onto their side as soon as possible (typically 2 or 3 days).
- Stack them on end when dry enough for transport and can support the weight of several rows of bricks.
- Locate a dry storage area while the bricks dry for a couple of weeks. The bricks will wick moisture from the ground if there is moisture or water in the soil. Use a tarp under the bricks if required.
- Stack the bricks in a shady area. Stack them on end and alternate, for example, stack two or three parallel about 2” (5cm) to 3” (7.5cm) apart to allow airflow. The next row will sit perpendicular to the previous one and alternate the following rows.
- Cover the bricks with a tarp to protect against rain. Ideally, the tarp will not rest on the bricks, which can trap moisture.
- Adobe bricks can have up to 3” (7cm) cracks due to drying to meet the 2015 New Mexico Earthen Building Materials Code.



How to Test Adobe Bricks
Adobe brick strength testing is simple and can be done in minutes without tools. Sure you can build fancy devices, but why? I researched tests and created a few that are adequate for my adobe bricks and I hope they meet your needs.
The adobe brick strength testing guide is easy to follow and requires zero tools. Testing for compressive and tensile strength only takes minutes following the steps below in this guide.
Adobe Brick Compressive Strength Test
Anyone can perform a quick test for adobe brick compressive strength by dropping on edge from waist high, or about 3′ (1m). Drop the brick onto a hard surface such as concrete or asphalt. If it survives unscathed try it a few more times and then move on to the tensile strength test.
Adobe Brick Tensile Strength Test
There are fancy ways to perform this test, but if you don’t want to waste time building a test facility then this test is for you. This is a simple DIY test that does require one “tool” such as a shovel handle, broom handle, length of PVC pipe, or anything similar. Follow these steps:
- Place one brick on a flat and hard surface on the ground.
- Place another brick about the length of the brick less 1.5” (4.5cm).
- Place a third brick on top of the first two to build a mini pyramid. The gap under the top brick should be 8” (20cm). So this will work with any length brick and the gap can be increased for testing larger gaps, proving a stronger brick. For more information check out Physical-Mechanical Experimental Tests on Adobe Bricks.
- Place the round shovel handle (or similar) across the center of the top brick so it is perpendicular to the three bricks.
- Use another pole, building, or similar to assist your balance for the next step.
- Very carefully start adding your body weight on one foot to the shovel handle in the center of the brick.
- Gradually add more weight until you can stand on the brick and it holds your weight without failing. Obviously, there is a wide range of what people weigh, but we are not building pianos so if it holds your weight the brick should be good to go.
If you wish to increase the weight you can hold a bucket of water or bounce your weight on the handle.

Super Un-scientific Hammer Test
Simply smash bricks with hammers and if they crumble with a single swing or two the bricks may not have adequate compressive strength for your house project.
I fired about 100 bricks in a kiln that I built with adobe bricks and when I tested them with this method I learned that they were weak! I expected the compressive strength to increase, but I think there were three reasons the bricks failed:
- The clay content was too low resulting in a brick of mostly sand.
- The kiln did not get hot enough throughout.
- Not enough time in the kiln.
I dissembled the kiln the following winter since it was built at the location where I built an earthbag house.
If you have several adobe bricks made with different recipes such as varying straw, rice husk, clay, and size you can get an idea of what recipes require more effort to break with the hammer. This can help you choose a recipe for building your bricks for your house, shed, or garage project.