CMU Walls And Types Of Cinder Blocks

Kevin Brown

CMU walls, commonly found in large buildings and skyscrapers, are strong, durable, and among the safest types of walls in modern architecture. Their popularity is well-deserved.

CMU Walls And Types Of Cinder Blocks

CMU walls are built with concrete blocks called cinder blocks that come in various shapes and sizes. They are more versatile and cheaper than bricks, which are a common type of industrial wall.

A CMU wall is made of CMUs, also known as concrete masonry units. These units, also called cinder blocks, are used to construct concrete walls and buildings. While not commonly used in residential homes, they can still be used for that purpose.

CMUs have many applications for homeowners, and there are numerous projects that can be done using them. For inspiration and ideas, check out these cinder block projects, which can be tailored to any budget.

There are different types of CMUs available.

CMU Walls And Types Of Cinder Blocks

There are different types of glazes, finishes, and colors of CMUs, but they can be sorted by type or shape. Take a look at the available types of CMUs.

Keep in mind that knowing what each type does isn’t important for most people. Masons already know each type and their uses, so you can ask the mason installing your CMU wall to teach you.

Stretcher blocks are the most common type of CMU. They are simple cinder blocks with four lips, two at each end. These lips provide space for mortar, resulting in a stronger hold.


The kerf block is a stretcher block with flat ends and a small slit in the center. It has six flat sides and retains the two large holes on the inside.

A double corner block resembles a kerf block but lacks the center slit. It is completely flat without any protrusions or holes, except for the two large holes in the center that provide lightweightness.

A single corner block is similar to a double corner block, with one side featuring a stretcher end. This creates protrusions on one side while the other side remains flat. The two large holes are still present.

Lastly, an open end block

An open-end CMU block opens one end to accommodate different reinforcements. It resembles an A shape from the top, with one end like a kerf block and the other end open.

See also  Faux Bois Candle Sticks

The double open-end block, shaped like an H from the top, has two open ends and allows for vertical reinforcing. However, it is not as structurally strong as closed-end blocks or a single open-end block.

A bond beam, with a dip on top resembling an ice cream scoop, enables horizontal reinforcing while leaving the sides intact. This design provides ample space for horizontal reinforcements.

A knockout bond beam features the same horizontal reinforcing capability, but with additional areas where material can be removed.

The knockout bond beam blocks are made to go along with bond beams. They have slits that allow masons to locate horizontal reinforcing by viewing them through the slits or knocking out the spaces easily.

The U lintel looks like a U from the end and allows for a lot of horizontal reinforcement. However, it isn’t as structurally strong as a bond beam, so it hasn’t completely replaced it, despite providing more room for reinforcements.

The sash block is popular because it allows joint control for doors and window frames. It has slits on each end in the center that can be placed next to a frame, securely holding it even without mortar.


Bullnose blocks have a rounded corner, which can be used on building corners for a smoother look or to prevent accidents. They are more aesthetically pleasing than square blocks.

Scored blocks have slits that improve mortar setting and allow for secure placement of rebar and other materials. The number of scores can vary based on the mason’s needs.

Ribbed blocks also have slits like scored blocks, but they always have multiple slits. This allows for a better grip of mortar.

Column blocks, as the name suggests, are designed for building columns.

Column blocks are C-shaped and used for making columns. They are typically placed with their open ends together, creating a square concrete block when mortar is applied.

Column blocks with pilasters have a square on the outside of each one on top, resembling Ps back to back. These unique CMUs have limited use but can create stunning architecture.

See also  Edison Bulb Vintage And Energy Efficient Light Source For Your Home

CMU walls are installed as follows.

CMU Walls And Types Of Cinder Blocks

CMU walls are installed by stacking the blocks like bricks and using mortar. Certain types of blocks can lock into each other and work without mortar. Galvanized steel is used to support them from the inside.

Professional mason installation is important to ensure safety, even for non-load-bearing walls.

Benefits of CMU Walls

CMU walls are incredibly strong, low-maintenance, and highly resistant to storms, including hurricanes. Additionally, they are much more affordable than bricks. Here are the key benefits of CMU walls:

– Price: Concrete blocks are significantly cheaper than other similar structures. On average, a cinder block costs less than $5.

– Strength: CMU walls are exceptionally durable and can withstand immense force. They are commonly used for storm shelters and other high-risk areas.

  • Lifespan – CMU walls can last centuries. They will likely last through multiple generations, especially if installed by a professional.
  • Fireproof – CMUs are fireproof and work as a great fire barrier to protect your family from expanding fires. They can stop fires short, unlike wood walls which struggle even with fire-resistant treatments.
  • Insulating – CMU walls insulate a room due to their thickness. If insulation is added during construction, you’ll have an energy-efficient room.
  • Environmentally Friendly – CMUs are made with natural, non-harmful materials, making them safe for humans and the environment.

    Simple Installation – Professional installation of CMU walls is recommended, as it is quicker compared to using stone due to the large and symmetrical blocks.

    Why Not To Use CMU Walls

    There aren’t many negatives to CMU walls. However, they tend to absorb moisture, which can be prevented with a moisture barrier and glaze applied to the blocks.

    CMU walls take up a lot of room and can be bulky. They have a modern or industrial look, so they may not be suitable for every design style. Additionally, making changes or installing windows in CMU walls can be challenging.

    Unlike wooden walls, which can be taken apart as needed, CMU walls must be demolished to make significant modifications that could impact the home’s structure. Therefore, the initial installation of CMU walls determines what will remain.

    See also  Exquisite Kitchens Designed by Italian Brands Reveal Their Recipes For success

    Now, let’s address some frequently asked questions about CMU walls:

    – How many types of cinder blocks are available for CMU walls?

    – There are two categories of CMUs: hollow and solid, with around sixteen main types. You can find more information in the “Types of CMUs” section.

    – How do you build a CMU retaining wall?

    We have guides on how to build a retaining wall with CMU blocks. Another unique option is a railroad tie retaining wall, which has a cute and rustic look.

    CMUs cost around $3 per block, with some being as low as $1 or as high as $5. The average cost is $3, so you can estimate the project cost if you choose CMUs as the material.

    Calculating the right amount of mortar can be tricky. On average, you will multiply the area of the wall by 0.02 to determine the cubic yards needed for a typical CMU wall.

    If you’re considering CMU walls, keep in mind the cost and calculating the necessary amount of mortar.

    It depends on your priorities. If you value storm safety and durability, CMU walls may be ideal. However, for aesthetic purposes, they may not be the best choice, especially for farmhouse or beachy designs.

    Feel free to experiment!

    Leave a comment