How to Build a Cinder Block Wall

Long-Lasting, Durable Privacy for Your Outdoor Space

By
Lee Wallender
Lee Wallender
Lee Wallender

Lee has over two decades of hands-on experience remodeling, fixing, and improving homes, and has been providing home improvement advice for over 13 years.

Learn more about The Spruce's Editorial Process
Updated on 11/20/23
Reviewed by
Kelly Bacon
Kelly Bacon
Reviewed by Kelly Bacon
Kelly Bacon is a licensed general contractor with over 40 years of experience in construction, home building and remodeling, and commercial building. He is a member of The Spruce Home Improvement Review Board.
Learn more about The Spruce's Review Board
Fact checked by
Jillian Dara
Jillian Dara
Fact checked by Jillian Dara
Jillian is a freelance journalist with 10 years of editorial experience in the lifestyle genre. She is a writer and fact checker for TripSavvy, as well as a fact-checker for The Spruce.
Learn more about The Spruce's Editorial Process
Cinder Block Wall

Andrey Atanov / Getty Images

In This Article
Project Overview
  • Working Time: 4 - 5 days
  • Total Time: 5 days - 1 wk
  • Yield: 10-foot by 6-foot wall
  • Skill Level: Advanced
  • Estimated Cost: $200 to $400

Building a cinder block wall gives your yard or garden a special touch, and the final product offers low-maintenance durability that can last for decades. Wood fences are popular for their economy and easy buildability, but concrete or cement walls can provide more privacy and an even greater degree of soundproofing. Also, cinder block wall construction doesn't require professional concrete forms, like a poured concrete wall, allowing you to tackle this project as a DIY. However, cinder block walls can cost more than poured concrete, but the cost is worth it, as a well-built wall is a long-term investment in your home. Read on to learn the steps to build a cinder block wall.

Tip

A concrete or cinder block wall is sometimes called a cement wall. But this is only informal—the true term is concrete or cinder block wall. Cement is a fine binding ingredient that, along with other materials such as sand and gravel, forms concrete. Cement is never used on its own to make a wall. So, while you can have a concrete wall or a cinder block wall, you cannot have a cement wall in the literal sense.

Cinder Block Wall Basics

You can build an entire concrete wall with just concrete masonry units (CMUs), often called concrete blocks or cinder blocks. Mortar is the glue that holds them together below and to the sides.

Dimensions

Cinder block dimensions are typically 16 inches long, 8 inches high, and 8 inches wide. The blocks are hollow in the center. A concrete web separates this area into two, smaller hollow sections. These blocks are available in nominal thicknesses of 4, 6, 8, 10, 12, 14, and 16 inches.

Stability

All concrete walls need to rest on concrete footings for stability. Some concrete walls need a 1/2-inch metal reinforcing bar (or, rebar) to be run vertically and horizontally through them.

Strength

The strength of cinder block walls is a minimum of 1,900 pounds per square inch. This cinder block wall is non-load bearing, so it is used for privacy or as a decorative element and not as walls of a structure, such as a garage.

Lifespan

Cinder block walls are more durable than fences made of wood. When properly maintained, cinder block walls can last up to 80 years and provide a nice sound barrier, to boot.

Number of Blocks

Calculate the necessary cinder blocks by square feet. The typical cinder block is 8 by 16 inches, meaning that a cinder block covers an area of 1.125 square feet. The total cinder blocks needed will be the area of the wall divided by 1.125, but be sure to subtract the openings such as windows, doors, or any other architectural features. The wall area is calculated by height times its length. Add 5 percent more to the number of blocks needed to account for waste, damaged material, or necessary fillers.

When to Build a Cinder Block or Concrete Block Wall

Concrete block walls differ from cinder block walls, as concrete blocks are solid and cinder blocks are hollow. Cinder blocks are often used for non-loadbearing walls, to create outdoor fireplaces, and for garden privacy. Concrete blocks, on the other hand, are more durable and often used in load-bearing walls, like the foundations of houses and retaining walls.

Cinder blocks are less strong than concrete blocks, but are also more affordable and work great for non-loadbearing yard projects. Still, you'll need to dig a trench and lay the foundation by pouring concrete footers for your wall, making this a weather-dependent project. If the ground is frozen, you will not be able to dig by hand, and extreme cold can affect the curing process of the mortar.

Once your wall is erect, you can fill the blocks with sand to stabilize the structure. Filling cinder blocks with poured concrete is not recommended, as this will create moisture pockets within the wall, leading to wet concrete.

Permits and Codes

Free-standing concrete block walls may require permitting. Check with your local building department to determine if a permit is required. Even if the wall is exempt from permitting in your area, it may still require zoning approval. Check with your local planning department for zoning requirements.

Rebar Requirements

If the wall were built to load-bearing specifications or even as a free-standing wall, alternating centers of the cinder blocks may need vertical rebar or a ladder mesh reinforcement running from the top of the wall to the bottom of the concrete footing.

Some of the cavities may need to be filled with either mortar or concrete. You may also need to run horizontal rebar the length of the wall, between every third course of blocks.

Discuss your intended concrete block wall with your local permitting department for information about rebar or reinforcement requirements.

Safety Considerations

Working with masonry materials is labor-intensive, so take frequent breaks and stay hydrated. Keep your back straight and use your legs when lifting. Wear heavy-duty gloves when handling the concrete blocks. When pouring mortar or concrete or for any other activity that creates dust, wear breathing protection.

Consult a structural engineer to design the footing including where to install the vertical reinforcement, which usually is placed every 24 inches. Normally a foundation wall with seven rows of blocks will be 24 inches wide and 12 inches deep and should have a footing 30 inches below grade. Remember to build a leveled footing where the cinder block will be placed.

What You'll Need

Equipment / Tools

  • Trenching shovel or trenching machine
  • Trowel
  • Mixing tub or mixer
  • Chalk snap line
  • Garden hose and sprayer
  • Bubble level
  • Clean bucket
  • Mason's string line
  • Rubber mallet (optional)
  • Chisel or mortar rake (optional)
  • Concave jointer

Materials

  • 75 cinder blocks, 16 inches x 8 inches x 8 inches
  • 3 bags of mortar
  • 3/8 inch scrap plywood
  • 8 concrete cap blocks, 8 inches x 16 inches
  • Rebar (optional)
  • Concrete for footing

Instructions

How to Build a Cinder Block Wall

  1. Plan Footing

    • Make sure the poured concrete footing is twice the width of the intended concrete wall. So, for an 8-inch-wide cinder block, the footing should be at least 16 inches wide.
    • Use only high-strength concrete for building the concrete wall footing.

  2. Create Trench

    Use a trenching machine or a trenching shovel to dig down below the frost level for your area. If your area experiences freezing temperatures, building above the frost line will result in frost heave, a condition where expanding soil causes structures built on top to move and sometimes fail.

  3. Pour Concrete

    • Fill the trench with concrete until it is just below the frost level. The thickness of the footing will vary based on where the frost level is and how deep you dug your trench, but it should be a minimum of 8 inches thick.
    • Note that if rebar is required, prior to pouring the concrete, you will need to set up the rebar so that the concrete can be poured around it.
    • Wait two or three days for the concrete to cure.

  4. Snap Chalk Line

    • Snap a chalk line down the center of the intended placement of the bottom row of concrete blocks. Have an assistant help you with the chalk line.
    • Snap two more lines: one on each side of the intended bottom row of blocks.

  5. Establish Two Leads

    • Dry-fit one full-size block between the lines.
    • Add a 3/8-inch spacer of plywood at the end to represent the mortar that will eventually be filled in there.
    • Continue dry-fitting the course until you reach the end.
    • Mark the locations of the two end blocks, or leads, then remove them.

  6. Mix Mortar

    Use high-strength mason's mortar mix for setting the blocks.

    • Mix up the mortar in a motorized mixer or in a masonry tub using the amount of water specified on the package.
    • Test the mortar with the trowel by picking up some mortar, and then holding the trowel to the side. If most of the mortar remains on the trowel, the ideal consistency has been achieved.

  7. Lay Mortar Base

    • Lightly moisten the footing with the garden hose and sprayer.
    • Lay two rows of mortar, each row about 1 inch high by 1/2 inch wide, using the two outer chalk lines as reference marks.
    • Use one 80-pound bag of mortar mix to lay a course of about 12 to 14 standard-size concrete blocks.

  8. Lay Cinder Block Leads

    • Press the cinder block for the first lead down onto the lines of mortar. The holes should be facing vertically.
    • Continue to do the same for the other lead at the far end of the wall.
    • Press firmly, but not so hard as to extrude the mortar from the sides.
    • Check on all sides with the bubble level.
    • Adjust the block by tapping on it with the handle of the trowel.
    • Tap the block for more force with a rubber mallet or place a piece of scrap two-by-four against the block and tap with a hammer.

  9. Fill Bottom Course

    • Continue the entire bottom course, often checking for level and plumb by laying the bubble level along the top and sides of the blocks.
    • Maintain the 3/8-inch distance between each block.
    • Butter the side of a block with the trowel before laying it so that it will stick against the adjacent block.

    Tip

    Always keep a bucket of clean water nearby. If you need to take a break, you can drop any tools that have been used for concrete or mortar in the bucket. This keeps them clean until you use them next.

  10. Set Closure Block

    • Use a closure block to fill in the last open space in a course.
    • Butter each side of the closure block and set it straight down.
    • Fill in any extra space between joints with mortar.

  11. Start Second Course

    • Start the second course, beginning with two half-sized 8-inch blocks, one at each end of the wall.
    • Lay mortar on top of the bottom row of blocks, similar to the lines of mortar that were laid on the footing.
    • Lay the mortar only along the two outer ridges of the blocks but not on the center web.
    • Press the two end 8-inch blocks into place, checking for level and plumb with the bubble level.

    Tip

    Frequently trim or remove any excess mortar that squeezes out from the sides or below the blocks as you are building the wall. It is far easier to clean off the mortar earlier when it is wet than after it has dried. A mortar rake or light taps with a chisel can be helpful for this task.

  12. Continue Second Course

    • Run a mason's string line along the tops of the 8-inch blocks on the second course. This will help each row maintain uniform height and straightness.
    • Use full-size blocks on the second course. Lay them in a brickwork pattern so that joints fall in the center of lower blocks. This running bond helps the wall gain strength and greater lateral stability.
    • Continue building the remaining courses.

  13. Remove Excess Mortar in Joints

    Run a trowel between blocks to smooth out the mortar every so often when it becomes putty-like or stiff between the joints. You'll know when to do this if the mortar is stiff enough to imprint your finger.

  14. Add Cap Blocks

    • Add mortar to the top of the blocks when the wall has reached its full height.
    • Install the cap blocks, alternating across joints.

  15. Strike the Joints

    • Use a concave jointer to compress and smooth (strike) the horizontal joints first, then the vertical joints, to allow water to run freely down the wall.
    • Scrape off excess mortar and run the jointer along the joints again.

When to Call a Professional

If you are building a load-bearing cinder block wall, it's best to call in a professional to do this. Due to the large quantity of concrete required for the footing, you may want to have a concrete professional pour the footing and set the rebar properly so it can pass building inspections.

FAQ
  • Which is cheaper, a cinder block wall or a concrete wall?

    The price to lay a cinder block wall varies with region, however, in general, laying a cinder block wall costs about 20 percent more than poured concrete but it is less prone to cracking.

  • Does a cinder block wall need a foundation?

    Yes, you will need to pour concrete footers.

  • What are the issues with cinder block walls?

    Cinder block walls are prone to water damage, especially in areas with a high water table. They are also expensive to fix. Additionally, cinder block walls cost more to construct when compared to wood or poured concrete.

The Spruce uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.

  1. Typical Sizes and Shapes of Concrete Masonry Units. National Concrete Masonry Association.

  2. Density-Related Properties of Concrete Masonry. Building Construction & Design Viewpoint, Masonry Advisory Council.