What Is CMU Wall – Construction, Size & Price

What Is A CMU Wall?

A Concrete Masonry Unit (CMU) wall is a type of building construction made from precast concrete blocks.

These blocks are available in a variety of shapes, sizes, and finishes and are used to construct walls for buildings, retaining structures, and foundations.

CMU walls offer several benefits such as strength, fire resistance, durability, and versatility. They are also cost-effective and easy to construct, making them a popular choice in construction projects.

Read More: Cavity Wall – Construction, Advantages & Disadvantages

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CMU Wall Details (CMU Block)

CMU blocks are made from Portland cement, aggregates, and water. As a building material, CMU blocks offer several attractive characteristics to designers and builders, including the following:

• Durable
• Easy to install
• Fireproof
• Low maintenance
• Decorative finishes available
• Ornamented after installation

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CMU Block Dimensions

CMU blocks are manufactured in a variety of sizes. They are distinguished by their depth – i.e. the thickness of the wall they create. For Example, a 6″ CMU is nominally 6″ deep while a 10″ CMU is nominally 10″ deep.

These blocks also come in half-sizes, which are helpful in reducing the need to cut blocks in the field at corners or the end of walls.

The architect always tries to design buildings using the nominal dimensions to the nearest half-block size to reduce waste and labor due to cut blocks.

The nominal and actual sizes of CMU blocks are given in the below table. In which CMU blocks having sizes 4″, 6″, 8″, 10″, and 12″ are the standard sizes, some manufacturers offer other sizes not listed below

CMU CCMU Blocks Size	NOMINAL DIMENSION D x H x L
4” Full Blocks	4″ x 8″ x 16″
4” Half Blocks	4″ x 8″ x 8″
6” Full Blocks	6″ x 8″ x 16″
6” Half Blocks	6″ x 8″ x 8″
8” Full Blocks	8″ x 8″ x 16″
8” Half Blocks	8″ x 8″ x 8″
10” Full Blocks	10″ x 8″ x 16″
10” Half Blocks	10″ x 8″ x 8″
12” Full Blocks	12″ x 8″ x 16″
12” Half Blocks	12″ x 8″ x 8″

Read More: 10 Types Of Retaining Wall With Full Details

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Standard CMU Block Wall Detail

CMU manufacturers must conform to ASTM standards when fabricating concrete blocks. The standards identify appropriate materials, compressive strength, dimensional tolerance, moisture absorption, and other performance characteristics.

Concrete brick is made from concrete similar to concrete block, but concrete bricks are fabricated in sizes that match traditional clay bricks (i.e. 2 2/3″ tall).

The following table provides the ASTM standards that apply to concrete masonry units. ASTM C90 covers most conventional CMU construction and is the standard referenced by the ICC codes.

ASTM DESIGNATION	TYPE OF CMU
ATSM C55	Concrete Brick
ASTM C73	Calcium Silicate Face Brick
ASTM C90	Load Bearing Concrete Masonry Units
ASTM C139	CMUs for the construction of Catch Basins and Manholes
ASTM C744	Calcium Silicate Masonry Units and Prefaced Concrete
ASTM C936	Solid Interlocking Concrete Paving Units
ASTM C1372	Segmental Retaining Wall Units

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CMU Block Shapes

CMU blocks are available in an infinite variety of shapes in the market. The following image shows the popular types of CMU block shapes.

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CMU Block Weight

The weight of CMU blocks varies depending on the density of the concrete mix used.

 There are three classifications of CMU:

1) Lightweight CMU Blocks = Weight less than 105 lb/ft³,

2) Medium weight CMU Blocks = Weight between 105 lb/ft³ and 125 lb/ft, and

3) Normal weight CMU Blocks = Weight more than 125 lb/ft³.

Lighter CMUs are less expensive, require less labor to install, and tend to have better fire resistance properties.

Heavier units tend to reduce sound transmission, have much higher compressive strengths, and have greater thermal storage capacity; however, they are more expensive and cost more to install.

Architects must specify the CMU weight if a particular weight is required.

CMU Blocks Compressive Strength

The CMU blocks and masonry walls Compressive strength varies from approximately 1,000 psi (7 MPa) to 5,000 psi (34 MPa) based on the type of concrete used to manufacture the unit, and the quality of mortar used.

CMU Wall Construction

Generally, all walls constructed with CMUs follow the same elements, although the application of those elements can vary considerably depending on the size, shape, and use of the wall.

Foundation. All CMU walls must rest on a firm and hard foundation of poured concrete. The foundation depth and size will vary depending on the size of the concrete block wall and the weight it must support.

But, generally, the depth of the foundation must be at least twice as wide as the wall itself and extends about 1 foot down below the frost line.

CMU block. The selection of shape and size of blocks is generally taken to match the function of the wall and the configuration of the wall.

Most CMU walls will use several different types of blocks, especially stretchers and corner units. Mortar joints.

Each layer of the joint is connected to adjoining blocks with either type N (above grade) or type S (below grade) mortar.

For higher-strength of walls, they are constructed such that the vertical joints are offset (staggered) from one course to the next.

Reinforcement freestanding wall is not strong enough to resist the stresses that can crack joints and destroy walls, so both vertical and horizontal reinforcement is common.

Vertical reinforcement in the form of a straight-length steel bar is embedded in wet concrete that is poured into block cavities at prescribed intervals.

Horizontal reinforcement is provided with strips of metal laid into the wet mortar after every third or fourth course of the block.

Most CMU house construction is single–wythe walls, which means they are constructed from single-wide rows of blocks stacked one over the other.

In case, there is a need for higher structural strength you can construct double-wythe walls, in which two courses of blocks are laid together.

CMU Block Cost

CMU block cost is $3 per square foot for split-face concrete or cinder units and adds $9 to $12 per square foot for installation labor, supplies, and equipment.

A completed, 100-square-foot project will cost between $1,200 and $1,500, depending on the difficulty of the installation. An average 100-square-foot wall will run about $1,350.

Conclusion

In conclusion, Concrete Masonry Unit (CMU) walls are a popular and versatile building solution for construction projects due to their many benefits. They offer strength, fire resistance, durability, versatility, cost-effectiveness, and ease of construction.

Additionally, with the availability of various shapes, sizes, and finishes, CMU walls can be tailored to meet the specific requirements of a construction project.

With proper maintenance, CMU walls can last for many decades, making them a sustainable choice for building construction. Overall, CMU walls are a reliable, cost-effective, and sustainable option for any construction project.

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