How to Build a Brick Wall on a Hill

Bricks are manufactured in a variety of sizes, colors and materials.

A brick wall can be an effective solution to retaining soil on a slope to prevent erosion. If the slope is steep, it is more effective to build several shorter walls in a terraced fashion than to build one tall wall at the base of the slope. Each wall should not exceed 4 feet in height and, ideally, not more than 3 feet. Installing proper drainage behind the wall is critical to keep the force of water from pushing outward on the wall. Brick may not be the optimal solution for a load-bearing retaining wall; larger wall stone, landscape timbers or natural stone will work better, but a brick wall can be built on a slope.

Things You'll Need

• Shovel or backhoe
• Course gravel for compacting
• Tamper
• Round gravel for drainage
• Perforated drain pipe
• Level
• Bricks
• Mortar (if not dry stacking)
• Container for mortar mix
• Trowel

Instructions

Preparing the Site

1. 

   Large walls may require heavy machinery to excavate for.

   Excavate a trench for the wall. The trench should be deep enough to accommodate a base of 4 to 6 inches of compacted gravel and to bury at least two full courses of block.

2. 

   Crushed limestone is a common material for wall bases.

   Add the course gravel to the trench. Add 1 to 2 inches, level and tamp. Do this in successive "lifts" until the desired depth has been attained.

3. 

   Overlapping the seams gives the wall additional stability.

   Lay the first course of wall to the desired length. If you're using mortar mix, this will need to be mixed prior and the first course will be set into a bed of mortar. Make certain to stay level with each brick. The smallest deviation in levelness on the bottom courses will be seen throughout the height of the wall.

4. 

   Make sure that there is no dried mortar on the trowel before using.

   Start laying the second course atop the first. Evenly spread a layer of the mortar on top of the first layer with a trowel (if dry stacking, set the second layer a fraction of an inch back toward the slope). Do this brick by brick as opposed to spreading a full layer of mortar as it will likely dry before you have set all of the bricks. Add mortar to fill the vertical seams as you go as well. Stagger the ends of the bricks so that they do not line up with the brick below it, as seen in the typical running bond pattern.

Constructing the Wall

1. 

   Make sure the weep holes of the drain pipe face upward.

   Lay the drain pipe directly behind the wall. Make sure that both ends extend beyond the length of the wall.

2. 

   Washed gravel such as pea stone is commonly used for drainage.

   Back-fill round gravel over top of the drain pipe. It can be as high as the top of the wall thus far.

3. 

   Test your level on a known level surface before relying on it.

   Continue adding courses to the wall as before. Make sure to trowel a thin layer of mortar on top of the block prior to setting the new one down and make sure to maintain your level throughout. If not using mortar, continue each successive layer with a slight setback toward the slope.

4. 

   Grass seed will germinate quickly and help to retain the soil behind the wall.

   Continue adding back-fill gravel as you continue up each course of wall. As you get toward the desired height, the excavated soil from the trench may be used instead so that you can plant or sow seed behind the wall.

5. 

   Terracing helps to prevent erosion on steep slopes.

   Follow the same steps for each successive wall if doing an array of smaller terraced walls.

Tips & Warnings

• Always check with municipal building codes to see if any permitting is required for wall construction. Often the finished height of the wall will dictate whether permitting is required or not.

References

• University of Minnesota: Installing Block Retaining Walls
• Oregon State University Extension: Building a Landscape Retaining Wall
• Structure Magazine: Structural Brick Masonry Walls