Most people spend plenty of time thinking about what a building looks like above the ground.
Floor plans get discussed. Countertops get debated. Paint colors somehow turn into a three-day family negotiation. In commercial construction, attention goes toward square footage, parking, equipment placement, entrances, and how the finished space will function.
Meanwhile, some of the most important parts of the building may eventually be completely invisible.
I’m Elwin Ordoyne, Vice President of E.C.O. Builders Inc. in Slidell, Louisiana, and pilings are a good example of construction components that rarely receive much attention after a project is finished. They are underground doing exactly what they were designed to do: helping support the structure.
In South Louisiana, that can be particularly important.
Why Are Pilings Necessary?
A building needs a foundation capable of supporting its weight and transferring those loads into the ground.
Sometimes the soil close to the surface can provide adequate support. Sometimes it cannot.
Louisiana has plenty of soft soils, clay, moisture, and other subsurface conditions that can make foundation design interesting. And by “interesting,” I mean something engineers spend considerably more time thinking about than the average person probably wants to.
Pilings allow structural loads to be transferred deeper into the ground.
Instead of relying entirely on the soil immediately beneath a building, pilings can extend downward until reaching soil conditions capable of providing the support required by the design.
The type of piling depends on several factors, including soil conditions, building loads, access to the construction site, engineering specifications, and the type of structure being built.
There isn’t one piling that works for everything.
Timber Pilings
Timber pilings are probably among the most recognizable types in Louisiana.
They are essentially long, treated wooden poles driven into the ground. Treatment helps protect the wood from decay, insects, and environmental conditions.
Timber piles have historically been used for houses, camps, docks, elevated structures, and other construction throughout coastal areas.
The piles are driven into the ground using specialized equipment until the required depth or resistance is achieved according to the project design.
Timber pilings can work well in certain applications, but their use depends on the loads involved and the conditions beneath the property.
A piling isn’t selected because somebody likes wood.
There is considerably more math involved than that.
Precast Concrete Pilings
Concrete pilings are another common option.
Precast concrete piles are manufactured before arriving at the construction site. They are typically reinforced internally and transported to the property, where equipment drives them into the ground.
Concrete can handle significant compressive loads, which makes these piles useful for various residential and commercial applications.
Because these pilings arrive at the site already manufactured, logistics become part of the process.
The piles have to reach the site.
Equipment has to maneuver around the property.
There needs to be enough room to position everything.
This can become considerably more complicated on a tight construction site than on a large open piece of property.
Steel Pilings
Steel piles enter the conversation when project requirements call for the characteristics steel provides.
Common examples include steel pipe piles and H-piles.
These systems can support substantial loads and reach significant depths, depending on the design. Steel piles are frequently associated with larger commercial, industrial, and infrastructure projects, although their use is not limited exclusively to those applications.
One useful characteristic of certain steel systems is the ability to splice sections together when additional depth is required.
That can matter when suitable bearing conditions are deeper underground than originally anticipated.
And yes, sometimes construction involves discovering that Mother Nature did not read the plans.
Drilled Shafts
Not every piling system gets hammered into the ground.
Drilled shafts are created by drilling into the soil and placing reinforced concrete into the resulting excavation.
Depending on the project, these may also be called drilled piers or caissons.
Drilled shafts can have substantial diameters and depths and can support significant structural loads.
Engineers determine the required dimensions, reinforcement, concrete specifications, and depth based on the structure and subsurface conditions.
One advantage of this approach is that it avoids some of the vibration associated with driving piles, which can become a consideration on certain properties or around existing structures.
Helical Piles
Helical piles look a little different.
Picture a large steel screw being turned into the ground.
That is basically the concept.
Helical plates are attached to a steel shaft, and specialized equipment rotates the pile into the soil. Resistance during installation can help provide information about the conditions encountered underground.
Helical piles can be used for new construction, additions, foundation stabilization, and certain repair projects.
They can also be useful when working in areas where getting large pile-driving equipment onto the property would be difficult.
The Soil Makes a Big Difference
One of the most important things to understand about foundations is that two properties that look nearly identical above ground can be very different below ground.
Soil isn’t uniform.
Different layers can contain clay, sand, organic material, loose soils, dense soils, and varying moisture conditions.
That is why geotechnical information can become important on projects requiring deep foundations.
Engineers need to understand both sides of the equation.
How much load is the building creating?
And what is underneath it capable of supporting?
Those answers help determine the type, size, number, spacing, and depth of the pilings.
Residential and Commercial Projects Have Different Demands
A single-family house and a multistory commercial building obviously don’t weigh the same amount.
Commercial construction can introduce concentrated structural loads, large spans, mechanical equipment, elevators, storage loads, and numerous other considerations.
Residential projects can also create unique foundation requirements.
Elevated homes, additions, waterfront properties, flood-zone construction, and homes built over challenging soils may require different foundation approaches.
At E.C.O. Builders Inc. in Slidell, foundation considerations are part of understanding how an entire project comes together. What happens underground affects everything constructed above it.
And that’s really the important thing about pilings.
Nobody finishes a building, walks outside, and says, “Those underground pilings really tie the whole place together.”
Nobody sees them.
Nobody thinks much about them.
But kitchens, offices, bedrooms, warehouses, bathrooms, conference rooms, roofs, walls, and everything else inside a building ultimately depend on what is supporting them.
Sometimes the most important part of construction is the part nobody ever sees.
