Cement blocks laid wall for foundation of house on construction site.

What is a block foundation? (2024 guide)

Rochel Maday Contributing Writer

Rochel Maday is a contributing writer for USA TODAY Homefront. She specializes in home improvement topics and is dedicated to providing valuable information that empowers homeowners to tackle their projects with confidence.
Her work has been published in Angi, Bob Vila, Forbes and elsewhere. When not writing, Rochel enjoys digging into gardening projects and watching documentaries with her husband and their four kids.

Updated Aug. 9, 2024

Key points

A block foundation is a durable and cost-effective type of residential foundation.
Block foundations should be waterproofed and maintained regularly.
You can install a block foundation yourself, but we recommend working with a professional.

The block foundation is made from concrete cinder blocks. These blocks are a mix of cement, sand and water, and are reinforced with steel. This makes them strong, while the two holes in the blocks make them easier to handle and better for insulation. Cinder blocks are a cost-effective option.

Choosing the proper foundation is paramount, whether for a cute cape cod or an oversize office building. Block foundations offer a unique balance of strength and ease of construction, making them popular for many builders and homeowners. However, like any building material, they have their own challenges worth considering.

What are the types of foundations?

Choosing the right foundation for a home starts with knowing your options. Here are the most common types of foundations used in construction:

Block foundation: This type is made from stacked cinder blocks reinforced with rebar and filled with concrete. It’s robust and allows for easier handling during construction.
Concrete slab: This simple, cost-effective foundation consists of a thick slab of concrete poured directly on the ground. It’s best for warmer climates without freeze-thaw cycles.
Crawl space foundation: This raised foundation creates a small space under a house, providing easy access to plumbing and electrical systems. It’s good for areas with high moisture levels or flood risks.
Poured concrete foundation: This type uses wooden forms and poured concrete to create solid, continuous walls. It’s strong and resists water damage.

How are concrete block foundations built?

Building a concrete block foundation is a step-by-step process that requires careful planning and execution. Here is a basic summary of how a new home foundation is built using blocks:

Step 1

Step 2

Step 3

Step 4

Masons begin by mixing mortar to act as the adhesive. They measure and mark the foundation layout on the prepared footers.

Next, they start laying the blocks at the corners, which are critical reference points for proper alignment. A string guide is stretched between the corners to ensure the rows are straight.

Then, masons lay the first course of blocks on a bed of mortar, checking each block for level and alignment. As they continue laying blocks, they reinforce the walls with ties and add extra mortar at the corners for added strength. Occasionally, blocks may need to be cut to fit properly, and the joints between blocks are staggered for stability.

Once the walls are built, the top courses are filled with mortar, and J-bolts are inserted to anchor the sill plate. Finally, masons smooth the joints for a clean finish, inspect the foundation and backfill around it to complete the process.

What are the benefits of block foundations?

Block foundations are a popular foundation choice that offers numerous benefits, including the following:

Cost-effectiveness: Block foundations require less specialized equipment and materials, making them more affordable than other foundation types.
Durability and compression strength: Block foundations are known for their durability and ability to bear heavy loads, making them a reliable option for supporting large structures.
Flexibility in design and construction: Block foundations provide flexibility in design. You can easily adjust the layout of a structure and add reinforcements where needed.

Are there any potential drawbacks to block foundations?

Block foundations do, however, come with a few potential drawbacks that need consideration, including the following:

Cracks and voids: Block foundations may develop cracks and voids due to settling, shifting soil or water damage. “You should worry about foundation cracks if they are wider than a quarter inch, appear in concrete block walls or are visible on the exterior of your home,” said Tim Tracy with Groundworks, headquartered in Virginia Beach, Virginia. Cracks or voids can weaken the foundation and lead to further structural problems if not addressed.
Susceptibility to water infiltration: Hydrostatic pressure from saturated soil can exert significant force on block foundations, leading to bowing or buckling walls and forcing water into the foundation.

What are some methods for waterproofing?

As discussed, properly waterproofing your block foundation walls is crucial for maintaining a dry, healthy home environment. Otherwise, you may encounter issues such as mold, mildew and structural damage.

Since a proactive approach can save you time and money in the long run by avoiding costly repairs, here are a couple of options to consider:

Exterior waterproofing membranes: These membranes create a barrier between the foundation wall and the soil, preventing water from seeping into the foundation.
Interior drainage systems: Installing interior drainage systems such as sump pumps and French drains can effectively manage any water that does find its way in.

How else do you care for a block foundation?

Waterproofing alone isn’t enough. You’ll also want to keep up on regular maintenance to make sure your waterproofing method of choice remains effective.

Check foundation regularly: “Every six to 12 months, a homeowner should take time to visually inspect around their home and document areas of concern, then compare the results each time,” said Josh Kemp, director of research and development at Olshan Foundation Solutions, a national company. Look for signs of water damage, such as dampness, mold or musty odors, and address issues promptly.
Consider a dehumidifier: Installing a dehumidifier can help reduce moisture levels, further protecting your foundation.
Manage gutters and downspouts: Keep gutters and downspouts clear to ensure proper drainage away from the foundation.

What are some common block foundation repair methods?

Block foundations can encounter issues over time, requiring different repair strategies to maintain their structural integrity. Prompt repairs are essential for preserving the integrity of block foundations.

Epoxy injections are used to fill voids and cracks in block foundations. This method is effective for repairing minor cracks and preventing water infiltration. “For small concrete cracks there are DIY repair kits available that would help fill and seal those cracks,” Kemp said.

Another option is adding reinforcement, such as rebar or steel rods. This method can strengthen block foundations and help resist the effects of hydrostatic pressure. It is often used alongside other repair techniques for added stability.

If there’s any uncertainty on how to repair a foundation crack or issue, it’s best to reach out to a professional. “It’s hard to tell if a crack will cause foundation damage just by looking at it, so it’s important to get a professional’s opinion,” Tracy said.

Is a block foundation right for you?

When determining whether a block foundation is the right choice for your home, take into account the following factors:

Budget and construction timeline: Evaluate a block foundation’s cost and construction timeline. Block foundations are generally more affordable than poured concrete walls but may take longer to construct.
Local climate and water table: Climate and water table levels in your area can influence the risk of water infiltration and foundation damage. Block foundations may be more susceptible to water-related issues in areas with high rainfall or a high water table.
Soil conditions: The stability and composition of the soil on your property can help you decide whether a block foundation is an option. Some soils may require additional reinforcement or drainage considerations, which could make other options more affordable and effective.

Other foundation types, such as stone or wood foundations, may be suitable depending on your specific needs and property characteristics. Each type has advantages and disadvantages, so weigh them carefully.

Before deciding, consult with foundation professionals who can provide a free inspection and expert advice. They can assess your property’s unique characteristics and recommend the most suitable foundation type based on your needs and budget.

What’s next?

A block foundation offers a sturdy and cost-effective option for many construction projects. However, they come with specific considerations, such as proper waterproofing and regular maintenance to prevent water infiltration and structural damage.

If you’ve decided that a block foundation is the right choice for your project, the next step is to consult with a professional. Hiring a qualified and experienced mason or foundation expert will ensure that your foundation is built to code and tailored to the specific conditions of your site.

Don’t hesitate to reach out to a local contractor or foundation specialist to discuss your project and get started on building a robust and reliable base for your home.

Editorial note: The name “Homefront” refers to the alliance between USA TODAY and Home Solutions that publishes review, comparison, and informational articles designed to help USA TODAY readers make smarter purchasing and investment decisions about their home. Under the alliance, Homefront provides and publishes research and articles about home service and home improvement topics.

Homefront has an affiliate disclosure policy. The opinions, analyses, reviews or recommendations expressed in this article are those of the Homefront editorial staff alone (see About Homefront). Homefront adheres to strict editorial integrity standards. The information is believed to be accurate as of the publish date, but always check the provider’s website for the most current information.

Go Back to Top

Rochel Maday, Contributing Writer Homefront

Learn more about Rochel Maday

Alyssa Trostle, Editor Homefront

Learn more about Alyssa Trostle

Alyssa Trostle is an editor at USA TODAY Homefront. Having read dozens of warranty booklets from every vehicle manufacturer and over 100 sample contracts from third-party providers, Alyssa is an expert in the auto categories of warranty and shipping categories. Alyssa earned an MFA in creative writing with a concentration in creative nonfiction from Chatham University, which honed her skills in writing and editing both creative and professional content. In her spare time she enjoys reading contemporary fiction and following Pittsburgh sports.

More on this topic...