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

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

For concrete foundation walls, you require a massive amount of concrete for which you should have a nearby ready mix plant. If you can’t find one, better go with the block walls. But you will not get anything  with more versatility and durability than a concrete wall foundation. 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 by using a cmu’s (concrete masonry units) of typical size 16 x 10 inches and is secured together with Type S mixed mortar as it is load bearing. It is quite easy to install blocks as manual masonry skills are enough to cast a block foundation. The blocks are built in half bond pattern to interlock them and get stability along with strength. Reinforced block masonry includes installation of block-lock and re-bar which connects the blocks with the concrete footing along with fill.

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

Due to shoddy workmanship and improper reinforcement, block foundations may be considered vulnerable. This is not the case.

 

Poured Concrete Foundation

The concrete foundation is built by pouring ready-mix concrete into properly fixed formwork that is properly secured. Reinforcement bars designed as per imposed load are already installed in the footing before pouring concrete.

This type of foundation requires more set up time to cast than block foundation walls depending on access and availability of resources. However, it does offer more compressive and flexural 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 150 to 300 mm.
  • For the unreinforced concrete block, the minimum wall thickness shall be between 140 to 290 mm.
  • In the case of the concrete foundation wall, the wall thickness shall be greater of
    • 140 mm 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 reinforcement shall 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.

Cost difference

The concrete foundation walls have a hefty price tag. The cost for the concrete foundation walls comprises of cost for concrete, formwork, finishing, and reinforcement. Where as for block foundation walls, the labor cost is reduced, mobilization of forms is not needed and it can be built at a similar speed depending the contractor.

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 their project requirements and analyze site situations before selecting the type of foundation system needed for their structure.