Concrete block construction can be an excellent option for building sturdy and long-lasting structures. However, like any construction method, it can be prone to mistakes that compromise the quality of the final product.

Whether you’re building a house, a garden wall, or any other structure, it’s essential to be aware of the common mistakes that can occur and how to avoid them. In this blog post, we’ll be exploring the top five mistakes to avoid when building with concrete blocks.

By planning and paying attention to essential details, you can ensure that your construction project will succeed and stand the test of time.

Inadequate Planning

Planning is essential in any construction project, and building with concrete blocks is no exception. Inadequate planning can lead to many problems affecting the structure’s stability, durability, and safety.

  • First, it is crucial to consider and comply with the local building codes and regulations. Construction codes vary based on location, and not adhering to them can lead to problems during or after construction.
  • Secondly, it is essential to consider the structure’s intended use and load-bearing capacity. Failing to do so can overload the structure, causing it to collapse or not provide a stable foundation.

Both of these factors can affect the strength and stability of the structure, leading to potential safety concerns. Taking the time to plan accordingly and consult with experts can ensure the success of your construction project.

Improper Block Orientation and Spacing

How you lay the concrete blocks is another critical factor that directly affects the strength and stability of the structure.

Before applying blocks, ensure you have a level and solid foundation. One common mistake is not checking the alignment of the blocks. If blocks are not level or square, they can cause structural issues and create uneven surfaces for further construction.

Ensure that every block in each course is level and aligned correctly with the previous one. Proper spacing between blocks is also essential for the structural stability of the block wall. Keeping short gaps or maintaining consistent spacing can result in structural strength and strong points in the structure.

To avoid these mistakes, consult a specialist or use an online calculator to determine proper spacing and orientation. Always consider alignment, level, and consistency throughout the installation process.

Poor Foundation Preparation

Concrete block structures rely heavily on their foundations’ strength to support the building’s weight. Poor foundation preparation can lead to uneven settling, cracking, and instability.

Before you build, prepare the foundation by digging a trench deep enough to accommodate it and compacting the soil to ensure it is level. Next, install reinforcement materials like rebar to increase stability and strengthen the foundation.

Additionally, if the foundation is below the water table, you need to install proper drainage systems to prevent water accumulation that can lead to structural decay or create an unstable base.

Completing the proper steps to prepare your foundation is crucial to a successful construction project. If you lack experience, it’s highly recommended that you consult with an expert to avoid endangering the lives of others and safeguarding your property.

Incorrect Mortar and Mixing

Proper mortar mix and mixing are vital components of building with concrete blocks. Using a low-quality mortar or mixing it incorrectly can lead to strong and stable walls installed with irregular spacing, causing issues with bonding between blocks.

Mortars and mixes come in various types designed for specific applications, and selecting the appropriate one for your project is essential. Before mixing, ensure the mortar components have been adequately measured and mixed according to the instructions.

Also, an appropriate water-to-cement ratio is necessary to ensure the structural integrity of the blocks. Mixing with incorrect water or cement quantities will weaken the bond strength between the blocks, causing the structural joint to fail and potentially leading to structural issues.

To avoid this mistake, consider employing a professional contractor skilled in mixing mortar and using appropriate mixes to create a sound and stable structure capable of withstanding environmental damage and the elements.

Lack of Waterproofing

Water damage is one of the most significant causes of deterioration in concrete block structures. Installing proper waterproofing membranes and drainage systems can help protect the structure from environmental elements such as snow or rainfall.

Failing to use waterproofing material or divert water away from the structure can lead to moisture accumulation, resulting in mould, mildew, and, ultimately, structural decay. Proper installation of waterproofing membranes and drainage systems ensures the structure is adequately protected from water damage.

Additionally, appropriate drainage systems ensure water flows away from the building and does not accumulate around the foundation or walls. Flooding or leakage from a water source can cause damage to the structure, so you should consider installing a drainage system such as a sump pump to remove the water from your property.

To ensure the longevity and maintenance of your structure, always consider implementing proper waterproofing solutions to protect against water damage.


In conclusion, building with concrete blocks can be a cost-effective and efficient way to construct walls, foundations, and other structures.

However, to ensure the project’s success, avoiding common mistakes such as inadequate planning, improper block orientation and spacing, poor foundation preparation, incorrect mortar and mixing, and a lack of waterproofing is crucial. These mistakes can lead to unstable and unsafe structures, resulting in costly repairs or even complete reconstruction.

Therefore, it is essential to take the time to properly plan and execute the project, including ensuring the foundation is solid, the blocks are correctly spaced and oriented, and the mortar is mixed and applied correctly. Applying a waterproofing sealant will help protect the structure from water damage, ensuring it lasts for years.