The 10 Best Anchors for Adobe Walls for a Strong House

I built a small adobe building and incorporated many of the below strategies for anchoring my adobe walls to make sure it doesn’t land on my head while I am sleeping! I also added four bamboo hooks in the walls to hold two hammocks so the walls had to be strong or my fat butt would put them in on top of me.

The best anchors for adobe walls include:

  1. Foundation keyway
  2. Brick keyway
  3. Anchor bolts
  4. Lacing corner bricks
  5. Metal reinforcement
  6. Bond beam
  7. Tie Beams
  8. Buttress walls
  9. Built-in benches and planters
  10. Rafters (notched around the walls)

For more details on the building codes for adobe house construction you can check out the resources below:

How to anchor in adobe walls?

Foundation Keyway

A free and simple method to help prevent the bottom of the wall from shifting is to etch the concrete about six inches in from the edges when you pour the footing, curb, or slab.

You can simply use a piece of lumber on its edge and notch a trench around the footing, curb, or slab. When you lay your first course of mortar it will fill this trench, which will lock it into place so that it cannot more in or out from the foundation.

Brick Keyway

This works exactly the same as the foundation keyway, but you need to do this when you are pouring your adobe mud while it is wet. Once the brick is dry it is too late.

I did about half of my bricks with keyways as I was experimenting with various ideas. So this is another free and fast method to make your adobe walls stronger.

First row of adobe bricks and Septic tank cover (I dug and installed that by hand).

Learn through my articles how to make adobe bricks water proof here and advantages and disadvantages, and how many you need, and can you paint them.

Scott Boyd

Anchor Bolts

There are two types of anchor bolts that I usually use when framing a wood house. These both work the same by fastening the first row of adobe bricks to the foundation. However, one method is much easier to use IF you have access to electricity and a good hammer drill and bit. The two types are:

  1. Concrete embedded: The base, or bolt, of these anchors, are embedded in the wet concrete while pouring the foundation. This system works better for wood framing because the wood is easily drilled wherever there is an anchor bolt.

    Not so easy with bricks. You can try measuring and accounting for the thickness of the mortar and good luck to you haha.
  2. Compression anchors: These require a good concrete hammer drill and drill bit. As you lay your first couple of brick you can easily drill a hole in the concrete exactly at mortar joint. Drill hole, pound in the anchor with a hammer.

    And make sure the anchor bolt is higher than the brick. After the next brick is laid install the large washer and nut and use a wrench or socket to tighten the bricks to the foundation. Repeat every six feet.
adobe brick with keyway
I used my finger to add a keyway to increase adhesion and reduce movement
Adobe Walls
Wall under construction at the farm. This became a toilet and shed after I lost many bricks due to the wet season while they were in storage.

I found this to be the best resource to make my experience much easier and even more enjoyable!

Lacing Corners

The corners of the walls should alternate. It is difficult to describe, but if you are using bricks that are 16” long and the wall is 12” then the corner would look like:

For example, the first brick laid on the first row on the north wall will have a full 16” brick from the corner. The next brick laid on the west wall is also 16”. Now the second row will reverse this order.

The west wall will lay the full 16” brick in the corner. The first north wall brick will now start in 12” from the corner. This makes for a very strong wall.

Anchors for Adobe Walls
My bricks were the same length and width so lacing was more difficult. I used a cheap handsaw to cut bricks in half to offset each row and have some interlacing in the corners. I had Portland cement left over so I made the mortar with cement and sand.

Metal Reinforcement

According to Pima County Building Codes Approved Standard for Earthen IBC Structures Section 2114.14 Metal reinforcement:

“All walls shall be anchored at their intersections, at vertical intervals of not more than 16 inches with joint reinforcement of at least 9 gauge when using earthen units (e.g. adobe block).

Horizontal reinforcement shall be used throughout the wall system and be continuous at the intersections. Reinforcement used throughout the wall system shall be not more than 4 inches narrower than the wall thickness.”

door opening in adobe wall
When possible the openings should not be close to the corner as it makes the corner weak. This is a small building and I used cement mortar and a concrete (gravel) bond beam to beef it up. I could not make a functional design with the door in the middle of the wall.

Bond Beam

If you are building in a municipality or county with building codes you should consult with the building inspectors to review any building codes for adobe brick construction before building.

The best way to anchor in adobe walls at the top of the house is with a bond beam. A bond beam is a continuous sold beam that ties all the walls together at the top of the walls.

This beam prevents the roof from pushing the top of the walls out or in depending on the design. Some of the forces on the top of the wall include:

concrete bond beam
Concrete bond beam hand-packed rather than building forms. There is very little wood in Thailand and lumber is crazy expensive. The rebar is two rows of bamboo tied with rebar tie wire.

Gable Roofs
These pitched roofs are supported by two opposite walls where the wood framing rests. The weight of the roof framing and covering, snow and rain, and wind sits on top of the two adobe walls.

If standard trusses are used then the roof weight pushes straight down on the wall. But if the roof is a cathedral ceiling with rafters the roof framing pushes the top of the wall out.

Hip Roofs

Hip roofs are similar to gable roofs except that they distribute their weight on all four walls. This reduces the weight per linear foot on the walls and is, in my opinion, a nicer looking roof. But it does take more thinking and labor, but I think it is worth it.

Flat Roof

The framing for these roofs often sits only on two walls also as it is easier to build. If you have a live roof with soil and grass or just soil on top as I did, there is much weight on the rafters and they can sag after a few years.

If the rafters are attached to the top of the adobe wall the sagging rafters will pull the top of the walls in.

A bond beam is very important for the structural integrity of an adobe wall. It is a continuous solid beam around the entire wall to tie it all together. One of the two below types are most often utilized:

flat roof and bamboo table and chair set
Bamboo table and chair set only cost $50.24 with delivery. You can see the flat roof with the overhangs framed with eucalyptus trees tied together with the knots used for bamboo staging. Kinda cool eh?
  1. Wood bond beam: a minimum of two rows of 2” x 8” lumber fastened to the top of the adobe walls. The first 2” x 8 can be fastened using a minimum of 6” screws or lag bolts screwed into the top of the wall. Predrill the wood and brick to prevent cracks due to expansion.

    A minimum of four inches of penetration into the bricks is required and should have rows of two fasteners every 12”. Another option is to install leg bolts or carriage bolts with washers through the lumber and into the wet mortar at every joint.

  2. Concrete bond beam: before the roof is installed add two rows of rebar and tie them together at joints and at the corners. I used bamboo which grows on the farm and is comparable in strength to steel. Use rebar tie wire to secure and then pour concrete on top of the walls.

    Add forms if you can. I hand-mixed concrete 3/2/1 gravel, sand, and portland cement was very dry so I just packed it on the walls with my hands. It works and I am not building a piano in rural Thailand.

    If you want a pretty job you can use lumber to make forms and fasten them to the walls using 6” screws after predrilling the bricks.
  3. In Pima County the bond beam may not be 6 inches narrower than the wall width.

Tie Beams

“Tie beams shall be anchored to earthen walls at intervals of not over 48
inches by a connection with a shear strength of not less than the shear forces in both directions.

The shear between a cast-in-place concrete or masonry tie beam and the earthen wall shall not exceed 1/8 the dead load at the base of the bond beam unless an alternate attachment is provided compatible with the allowable stresses in Table 2114.6.A” or International Building Code Table 2109.3.3.1.

Buttress walls

If you have a long straight wall it should have some support and buttress walls add incredible strength. My 150 old home had massive buttresses installed due to the hydrostatic water press pushing up from under the concrete floor.

I lived on a hill, but you just never know where water is going to make problems. Buttress walls can include:

  • Interior walls for bedrooms, kitchens, living rooms, etc. The strongest buttress wall is one that continues across the entire building, such as an arch wall to allow access to other areas of the house.

    Another option is a straight adobe brick wall straight across to the other side with two or three-door openings for bathrooms, bedrooms, etc.

  • Exterior walls at the corners can extend for perhaps the same length as the height of the walls. These walls can taper down on a 45-degree angle to make them safe and not require reinforcing.

    A benefit of this method is that the wall extensions provide more shade, but they need roof covering too to protect against rain.

    A wall can also be installed in the middle of a long wall and also taper on a 45-degree angle, but this should be done at the same time as the exterior walls to lace the buttress wall to the main wall.

Built-in benches and planters

Build interior benches along long walls, especially in the middle. The higher the bench the stronger the wall. These should be built at the same time as the exterior walls so that you can lace these perpendicular bench walls for maximum strength.

If you plan to put a bed against a long wall in the house you may want to consider making a bed foundation with adobe bricks in the bedrooms. Just add a mattress to your super cheap and sold bed foundation.

Planters work the same except that they are on the exterior. This area is likely going to require plants and shrubs that love the shade. Another option is to build the planters or bench walls and add a wood top on hinges that can work as a seat and storage underneath.

Rafters (notched around the walls)

If you have a flat, or almost flat, roof you can lock the top of the adobe walls, or the wood bond beam, with notches in the rafters. This will provide much strength to inward forces on the top of the walls as the rafters will act as a horizontal jack post.

The rafters will also the walls in place from forces that push the top of the wall out from the house. This is an easy option and free option as long as your rafters don’t sag, which would pull the top of the walls together.

Those are the best anchors for adobe walls and most of them are free. And the others are cheap too. If you know of one that I missed please let me know via email and I will update the article.

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