How Thick Should Your Concrete Footer Be

How Thick Should Your Concrete Footer Be

Whenever you’re planning on constructing a new concrete slab, it is a great idea to have a solid plan at first, doing so will make the operation way smoother, avoiding miscommunications and finishing the project faster. You should consider all the necessary things before starting the operation, this includes the thickness of your concrete footer.  

Why is it important? It is because the footing of the concrete transmits the load into the soil. Additionally, the lower the bearing capacity of the soil, the wider the footing needs to be. If the soil is very strong, the footing isn’t even strictly necessary just the soil under the wall would be enough to hold the building up.

Although the standards for a house’s foundation with typical soils, is usually 16- or 20-inch-wide footing, that is, for a relatively light weight of an ordinary house. There could be some things to consider when considering the thickness of a concrete footer. Below is a guide so you can have a better idea regarding your construction plan.

How deep should a footer be for a concrete wall?

When it comes to the footer of a concrete wall, the recommended depth may depend on factors such as the dimensions of the concrete wall itself. Although it is best left in the precise estimation of a professional, you can also roughly make an estimate yourself so that you have a general idea.

In general, the concrete wall’s footings should extend to, at the bare minimum, a depth of 12 inches below the undisturbed soil. For those that are living in places where the ground freezes during winter, their footings also must extend at least 12 inches below the frost line, you can also have it frost-protected if you would prefer.

As it is said, the professionals should be able to determine how deep the concrete footer really should be after taking a look themselves. After all, things to consider including the type of soil and rough weight of your concrete wall can only be determined after taking a look.

If you had an engineering design the footing based on soil testing numbers and your prints, he’d add up the actual weights of the concrete you’d be using in your building, factor in the required live loads, and come up with an estimate of the weight your actual house puts on the footing. It might be a little less or a little more than the code assumes.

How deep should footings be for a 3-foot wall?

When it comes to small walls, it may be relatively difficult to identify the correct dimensions, after all, it is completely different from normal and bigger-sized walls. Therefore, some may recommend that the rough estimate should be to bury about one-eighth of the height of the wall. 

For example, if your wall will be three feet (36 inches) tall, the first course of blocks should start five inches below soil level. The gravel base should start three inches below this. In any case, have a professional take a look at it.

For most footings, the minimum is 150mm (6″) in-depth, with the bottom 350 – 400mm (14-16″) below ground level on most soils. For clay soil, however, thicker and deeper footings should be used.

How thick should a footer be for a retaining wall?

A poured concrete footing for concrete, block or brick walls should be at least twice as wide as the planned wall. The footing should be at least as thick vertically as the wall’s planned width. Also, do remember that a retaining wall must have a properly compacted backfill. 

This is done so that it is able to provide proper drainage, at least 12 inches of granular backfill, which could be either gravel or a similar aggregate, that should be installed directly behind the wall. Compacted native soil can be used to backfill the rest of the space behind the wall.

Whenever you’re planning to build your retaining wall, it should be built on a solid foundation made from a paver base in order to avoid soil erosion. Like gravel, a paver base is a form of construction aggregate containing crushed rocks such as limestone. Choose a paver base with landscape rocks between 1/2-inch and 3/4-inch in size.

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