What Are The Types Of Foundations Used For Steel Buildings?

Posted by CDMG Team on Jun 12, 2019 2:44:18 PM
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We've all heard the saying, "you can't build a great building without a solid foundation."

In some instances, the saying is a metaphor for life.

In other instances, like when you're constructing a metal building, the saying is very literal.

A well-designed foundation is essential for any building, especially a metal building.

A strong foundation ensures durability, and it will help prevent most forms of building deterioration in the future.

Leaking, flooding, shifting or tilting walls, and some structural damage can all be prevented if you have your building put on a solid foundation.

For steel buildings, the design of the foundation will determine the rest of the planning and construction process, making it one of the first things put into motion when you start planning your metal building.

In the article below, we will discuss step by step the things you must consider when planning your foundation, and we'll discuss some of the foundation options available for your metal building.

Lets dig in!

Table Of Contents

 

The land you build on plays a significant role in choosing your foundation

The Land

Before anything else can happen, the land you plan to put your metal building on has to be professionally surveyed and marked for leveling.

The builders will need to know the boundaries of the plot, so they know how much space they have to work with.

The measurements of your land, as well as the quality of the soil, will have a significant impact on how the foundation should be designed.

Grading the land will shape the soil to the height and conformation of the land as marked by the surveyor's stakes.

If the soil on your land is low quality, it can lead to the sinking and shifting of steel buildings, no matter how the foundation is designed.

Foundations can be designed around poor soil, but it is much less expensive and risky to excavate the existing dirt and replace it with high-quality soil.

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The Load

Most steel buildings have a higher horizontal load, which means that they are impacted more by lateral forces like high winds and earthquakes.

Forces like these can cause buildings to overturn or slide off of their foundations.

A proper foundation can help distribute or resist the high horizontal column reaction of steel buildings with the use of steel tie bars that are connected to anchor bolts.

A foundation with an increased footing size can also help resist the high horizontal column reaction, but an increased footing size often results in higher costs.

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The Wind

Speaking of the wind, high winds can create s suctioning effect that can lift a building from its foundation. This is known as columnar uplift.

Steel buildings are at increased risk for columnar uplift, and prevention starts with the foundation.

Heavy foundations, foundations with topsoil on it or deeper footings in the foundation are all options for reducing uplift in a steel building.

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Other Considerations

Other things to consider when choosing your foundation are:

  • The local frost lines
  • The weight of the equipment or vehicles to transport and install the building
  • The locations of the anchor bolts to attach steel framing columns
  • The dimensions and weight of the building

The type of foundation you should choose is mostly dependant on the land, the load, and the wind uplift estimated for the building.

Ultimately, the goal of the foundation is to act as an anchor for the columns of the building, giving it stability and strength.

You need to choose your foundation accordingly, keeping these factors in mind.

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A concrete engineer will help design your foundation

Who Designs The Foundation For My Metal Building?

In most instances, you will hire a concrete engineer to design the foundation for your metal building.

A local engineer will be most familiar with the types of soil in the area and how the local environment is going to interact with the concrete and steel.

Your concrete engineer will need a copy of the building plans, including the anchor bolt plans.

The manufacturer of your metal building can supply these plans and any more technical information that's needed.

Anchor bolt specifications are given but are locally sourced instead of arriving with the building kit.

The foundation will then be completed and cured before the building kit arrives on site so construction can begin immediately when it does.

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The Types Of Foundations

Floating Foundation

A floating foundation, which is also known as a floating slab, or just slab, is a popular option for most commercial and industrial buildings.

It's a simple concrete slab with a continuous grade beam.

It's poured and spread under a column or reinforces along the bottom and carries the vertical weight of the columns.

Once the structure is completed, the slab will be your floor.

Floating structures are easier, quicker, and more affordable to build than the other options, and it doesn't require much digging, and they don't require piers or footings.

Floating foundations are also better in wet and coastal areas with softer soils because they prevent sinking and unevenness over time.

Keep in mind that with a floating foundation, the sewer pipes and much of the electrical conduit has to be embedded in the slab ahead of time.

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Pier, Footing, And Grade Beam

This type of foundation is ideal for agricultural metal buildings, riding areas, and open pavilions.

The foundation sits on piers which rest on square or rectangular footings with a grade beam wall.

In some cases, drilled piers can be used instead of the footing.

Each pier carries the weight of a column, and the floor can be left as dirt or gravel.

The piers and footing will carry most of the vertical load of the steel building.

The deep drilled piers will work better with dry soil, and the depth will also prevent wind uplift to the building.

The grade beam works against passive pressures to the soil and therefore resists horizontal column reactions.

The piers can be tied together underground to eliminate shifting.

This type of foundation is more expensive, but it's more reliable and gives you more versatility.

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Perimeter Wall

Perimeter walls, or perimeter footings, is a foundation that is poured around the exterior of the structure, supporting the exterior steel framing walls.

Perimeter walls are often used in conjunction with piers or concrete slabs.

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Portable Foundation

You guessed it; portable foundations are portable.

They are useful for buildings that need to be transported periodically for many reasons.

Portable foundations typically consist of an industrial plate that is connected to a concrete perimeter with anchor bolts.

While portable foundations are less robust, they are more flexible to varying landscapes.

A portable foundation will also eliminate the risk of losing building height.

Overall, this option is the easiest, speediest, and cheapest construction process, while serving its function of allowing a steel building to be movable from location to location.

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Can My Metal Building Have A Basement?

Just like conventional buildings, steel buildings can also have basements under them.

Either type of building will have similar construction concepts in regards to the basement, footers, and foundation.

The load from the metal building will be sent to the exterior walls and corners, and the basement will need to be strong enough to support that load.

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Be sure to choose the best type of foundation for your project

Choose The Best Foundation For Your Metal Building

Soil, prevailing winds, and the building load all play an essential role in deciding what type of foundation you should use for your metal building.

The most popular option is a floating foundation because it is less expensive and installs much faster than the other options.

Agricultural buildings are best suited for pier, footing, and grade beam foundations.

If your building needs to be moved on occasion, you are better off using a portable foundation.

And, if you so choose, you can even have a basement under your metal building.

There are few, if any, specifications for metal building foundations to be found in local or national building codes.

The help of an excellent concrete engineer is critical when it comes to building an appropriate foundation for your metal building.

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Topics: steel building, Prefabricated Metal Building, pre-engineered metal building, foundation