Types of foundation: how the base of your house is chosen

Updated on 07/06/2026 by EZA Engenharia

The most common types of foundation in houses are the spread footing, the raft slab and the piles, and the choice between them is not a matter of preference: it is the result of the soil survey and the structural design calculation. Every plot tells a different story beneath the grass, and it is that story which defines where the house will rest. In more than 35 years building in Criciúma and the region, we have learned that a smooth project starts with this step well resolved. In this text we explain what each type does, when it comes into play and why the decision is technical, not aesthetic.

The foundation comes from the terrain, not from taste

The foundation has just one job: to transfer the weight of the house to the soil safely. And soil is never the same in any two places. On one lot, the firm layer appears just below the surface. On the neighboring one, it may be several meters deeper. That is why there is no such thing as a better foundation, only the right foundation for that soil and that house.

It is common for the client to arrive with a fixed idea, because their brother-in-law used a raft foundation or because they heard that piles are only for buildings. In practice, the answer to that question comes from the soil investigation combined with the structural calculation. The rest is guesswork, and guesswork in foundations is expensive.

If you are just starting to plan now, it is worth understanding where the foundation fits into the whole path in stages of building a high-end house.

Soil survey: the test that comes before everything

The most common soil survey in residential projects is the SPT, the standard penetration test. The equipment drills the ground at defined points and measures, meter by meter, the soil's resistance, as well as the type of material and the presence of water. The result is a report that shows where the layer capable of supporting the house lies.

Without that report, the structural engineer calculates in the dark. With it, the right foundation can be sized: neither undersized, which causes cracking and settlement, nor oversized, which wastes concrete and money. Compared to the total cost of a high-end house, the soil survey is one of the cheapest stages of the project and one of those that most avoids losses.

In Criciúma and the region there's everything: firm soil right at the surface, soft clay, old landfill. Each situation calls for a different response, and only a soil survey shows which is the case for your lot.

Types of shallow foundation: footing and raft

When the soil survey shows firm ground near the surface, the foundation can be shallow, also called a direct foundation. The spread footing is the best known: reinforced concrete blocks beneath the columns, which spread the structure's load into the soil. It works very well in single-story houses and two-story houses when the ground cooperates.

The mat foundation is a single reinforced-concrete slab that covers the entire footprint of the house and distributes the weight evenly. It usually appears in lighter constructions and on ground with good bearing capacity. It demands strict control during execution, especially of the piping embedded in the slab, because once it is cast there is no way to change it without breaking it.

Deep foundations: when the pile comes into play

If the resistant layer is far from the surface, the solution is to seek support down below. That is the role of piles: elements that pass through the weak soil and discharge the weight of the house at depth, through the tip, through friction with the soil, or through both.

There are several types, and the choice depends on the soil, access to the site, the neighborhood and the size of the project. The most common in homes are these:

A pile in a house isn't a sign of a problem. It's a sign that the design respected the terrain. What you can't do is discover the need for one with the project already underway, after budgeting everything on the basis of a different foundation.

• Bored pile: the soil is drilled and the pile is cast in place
• Continuous flight auger pile: drilling and concreting in a single operation, with speed and good control
• Precast pile: arrives ready and is driven into the ground, which requires equipment and generates vibration

The structural design is what decides

With the soil survey in hand, the structural engineer calculates the loads of the house, column by column, and defines the type, depth and size of each foundation element. It is calculation work, following technical standards, with registered accountability. It is not a catalog choice.

At EZA, this care is part of the way we work. We coordinate the designs before executing, precisely so that structure, plumbing and electrical talk to each other and the foundation doesn't become a surprise halfway through. And concrete pouring here is overseen by an engineer, because a well-executed foundation doesn't accept a middle ground.

A mistake in the foundation is among the most expensive to fix, because everything sits on top of it. A crack that keeps growing, a door that goes out of alignment, a floor that sinks on one side: many problems in a finished house began down there. It's the kind of thing that shows up on our list of common mistakes when building a house.

Going to buy a site? Think about the foundation first

Two plots side by side can require very different foundations, and that affects the cost of the project. A cheaper lot that demands a deep foundation may, in the end, turn out more expensive than the neighboring one with firm soil.

If you are still choosing where to build, take this into the negotiation. If the lot is already yours, the path lies in building a house on your own lot in Criciúma, and the first technical investment is the soil survey.

A foundation is no place for opinion. It is a place for soil testing, calculation, and closely supervised execution. Footing, raft slab, or pile, the right answer lies in your plot and in the structural design, and that is how a house is born without headaches. If you are planning to build in Criciúma or the surrounding region, EZA Engenharia has been building for over 35 years with in-house engineering, from design to execution. Reach out to us on WhatsApp (48) 99191-2018, write to [email protected], or see the projects at eza.com.br. We talk about your plot before making any promises.