How to Build a Cinder Block Wall

Building a cinder block wall gives your yard or garden a special touch, and the final product offers a 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.

Tip

A concrete or cement 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.

Basics of Building a Cinder Block or Concrete Wall

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.

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.

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

When to Build a Cinder Block or Concrete Block Wall

Concrete block walls differ from cinder block walls, as concrete blocks are made of solid cement 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 concert 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.

Estimating 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 1.125 times the area of the wall, but be sure to subtract the openings such as windows, doors or any other architectural feature. The wall area is calculated by height times its length.

Remember to add five percent to account for waste or any material that will be damaged. When completing the estimate, make sure you have also included some material that will be needed as fillers that might be required when the height or wall-to-wall dimensions are not according to plan.

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

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. 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.