So, you’re looking for the highest quality of foundation for your project and are confused between a concrete poured foundation wall and concrete block wall. Well, the truth of the matter is that both foundation systems yield superior footing walls and are used widely.

Both of the systems have their pros and cons and the decision is purely yours. But to make a well-informed decision; you should know the positives and negatives of both foundation systems.

Both materials are readily available in any urban areas. In comparison between both it is difficult to beat the versatility and durability of the concrete wall foundation but surprisingly when built to code a block wall foundation offers the same stability. Anyhow, the foundation is the most important aspect of a building and one must be very careful before jumping to a conclusion.

Feeling mixed-up? Don’t’ worry; let’s discuss each one by one so you can choose the best for your project.

Block Foundation Walls

The concrete block foundation is built up by using a concrete block of typical size 16 x 10 inches and is secured together with a Type S mortar mix. It is quite easy to install blocks once qualified trades are on site. The blocks are placed like bricks in a stretcher pattern at half bond to interlock them and give the wall stability along with strength. Reinforced block masonry includes installation of steel bars, also called re-bar, block-lock and fill which all connects the blocks with the concrete footing.

The Block foundation wall is quite easy to construct as you don’t need to install formwork. If properly installed and reinforced with steel rebar (typically 15mm), the block foundations are long-lasting and durable.

Anyhow, due to shoddy workmanship and improper reinforcement, some consider block foundations can be considered vulnerable.

Poured Concrete Foundation

With increased load comes the need for increased strength. If your project needs a foundation with increased strength, density than poured concrete foundation is your pick. The concrete foundation is built by pouring ready-mix concrete into formwork that has been secured on-site for the new wall construction. Reinforcement bars designed as per imposed load are already installed in the footing before pouring concrete.

This type of foundation takes a similar amount of time to build as block foundation walls and offers exceptional strength.

Building specifications

The Ontario Building code has stipulated building specifications for the foundation wall thickness and lateral support for concrete foundation wall and block foundation wall. The specifications are summarized below for your ready reference:

  • For Solid Concrete block having 15 to 20 Mpa strength, the minimum wall thickness shall be between 200 to 300 mm. (8-12 inches)
  • In the case of the concrete foundation wall, the wall thickness shall be greater of
    • 200 mm (8 inches) or
    • The thickness of concrete in the wall above.
  • For walls made with insulating concrete formwork shall be supported laterally from the top and the bottom.
  • A concrete block wall that is to be reinforced must have a continuous horizontal bond beam along the top of the wall, at a connection with the floor, and sill of openings. The vertical reinforcement for such walls must be along the centerline of the wall.
  • For reinforcement of concrete blocks walls block-lock will add lateral reinforcement and be installed at every bed joint of every second masonry course.

Load bearing capacity

The width of the concrete or block masonry footing wall depends on the load-bearing capacity of the soil measured in PSF (pounds per square foot). All sizes of walls like 8-inch, 10-inch, and 12-inch width walls have different load carrying capacity but the size must be selected keeping in view the load-carrying capacity of the soil. It follows the simple rule that more the lower the soil bearing capacity, the wider the footing needs to be.

Cost difference

The concrete foundation walls have a hefty price tag in comparison to block wall construction. The cost for the concrete foundation walls comprises of cost for concrete, formwork, finishing, and reinforcement. Whereas for block foundation walls, the labor cost is reduced, and you also don’t require any heavy machinery for form placement.

The Bottom Line

Both concrete foundation walls and block foundation walls are popular foundation choices. The materials in both cases are readily available and both are durable and long-lasting. However, despite all the similarities, both foundation types have their pros and cons. One must prioritize the needs of their project requirements and analyze site situations before selecting the type of foundation system. Remember not to cut cost at your foundation or rising walls, this is the most important part of your project.