Metal Building Anchoring Options: Concrete, Asphalt, Dirt & Gravel Anchors
Anchors are one of the most important parts of a metal building installation. They help secure the structure to the installation surface and play a major role in how the building performs after it is installed.
The right anchor system depends on the type of building, the surface it is being installed on, local requirements, and whether the structure is tubular steel or red iron. A building installed on concrete will not use the same anchoring method as a building installed on dirt, gravel, or asphalt.
At Legacy Carports, we help customers understand anchor options before installation so the building, foundation, and site preparation all work together.
Quick Answer: What Anchor Options Are Available?
For many tubular steel buildings, the main anchor types are earth auger anchors, rebar anchors, concrete anchors, and asphalt anchors.
Earth auger anchors are commonly used for dirt or gravel bases. These are also sometimes called mobile home anchors. Rebar anchors may be used as supporting anchors on dirt, gravel, or asphalt bases. Concrete anchors are used when the building is installed on a concrete pad. Asphalt anchors are used when the structure is installed on asphalt.
Red iron buildings are different. Instead of using the same style of post-install anchors found on many tubular steel buildings, red iron structures often use anchor bolts that are placed into the concrete while it is still wet at each column base.
The correct anchor type depends on the foundation, building design, surface condition, certification requirements, and local code expectations.
On This Page
-
Tubular Steel Anchors
-
Earth Auger Anchors
-
Rebar Anchors
-
Concrete Anchors
-
Asphalt Anchors
-
Red Iron Anchor Bolts
-
Concrete Pad Sizing
-
Flush Mount Kits
-
Certified Building Anchors
-
FAQs
Why Anchoring Options Matter
Anchors help connect the building frame to the installation surface. Without the right anchor system, even a well-designed metal building may not perform the way it should.
Anchoring can affect stability, certification, permitting, wind resistance, site preparation, and installation requirements. It can also affect how the building sits on the surface and how the siding lines up with the pad.
The anchor system should match the surface. Concrete, asphalt, gravel, and dirt each require different installation methods and different anchor types.
What Legacy Carports Looks at Before Recommending Anchors
Before recommending anchors, Legacy Carports looks at the building type, surface type, foundation, local requirements, certification needs, and how the structure will be used.
We also consider whether the building is being installed on dirt, gravel, asphalt, or concrete. For concrete installations, we look at whether the customer wants the siding to sit flush with the pad or whether the pad will be sized slightly larger than the building.
For red iron buildings, anchor planning is more closely connected to the engineered foundation because anchor bolts are often placed into the concrete before the building is installed.
Anchors for Tubular Steel Buildings
Tubular steel buildings commonly use anchors that are installed during the building installation process. The exact anchor type depends on the surface.
For dirt and gravel, earth auger anchors are commonly used. Rebar anchors may also be used as supporting anchors depending on the surface and requirements. For concrete pads, expansion-style concrete anchors are commonly installed after the pad is poured and ready. For asphalt, asphalt anchors are used, and rebar anchors may also be used as supporting anchors in some cases.
Because anchor requirements can vary by manufacturer, location, certification, and site conditions, customers should confirm anchor needs before installation.
Earth Auger Anchors for Dirt and Gravel
Earth auger anchors are commonly used when a tubular steel building is installed on dirt or gravel.
These anchors are designed to secure the structure into the ground. They are often used for carports, garages, RV covers, storage buildings, and other tubular steel structures that are not installed on a concrete pad.
Ground conditions can affect how well anchors work. Very loose soil, rocky soil, soft ground, or poorly compacted gravel may require additional site preparation or review before installation.
Rebar Anchors
Rebar anchors are commonly used as supporting anchors on dirt, gravel, and asphalt bases.
They may be used to help secure the base rail to the installation surface, depending on the structure, manufacturer, and installation requirements. Rebar anchors are often used in combination with other anchoring methods rather than being the only anchor type on every project.
Because they are surface-dependent, rebar anchors should be reviewed based on the site conditions and building requirements.
Concrete Anchors
Concrete anchors are used when a tubular steel building is installed on a concrete pad. These are commonly expansion-style bolts that are installed after the concrete pad has already been poured and is ready for installation.
This is different from many red iron buildings, where anchor bolts are often placed into the concrete while it is still wet at each column base.
For tubular steel buildings, concrete anchors attach the base rail to the finished concrete surface. This makes the concrete pad size, building size, and siding placement important to review before the pad is poured.
Asphalt Anchors
Asphalt anchors are used when a tubular steel building is installed on an asphalt surface.
Asphalt is different from concrete because it does not hold anchors the same way a concrete pad does. For that reason, asphalt anchors are designed specifically for asphalt installations. Rebar anchors may also be used as supporting anchors on asphalt bases in some cases.
Asphalt condition matters. If the asphalt is thin, cracked, soft, or poorly supported underneath, the installation may need to be reviewed before moving forward.
Red Iron Anchor Bolts
Red iron and structural steel buildings usually use a different anchoring approach than tubular steel buildings.
With many red iron structures, anchor bolts are placed into the concrete while the concrete is still wet at each column base. These anchor bolts are part of the engineered foundation and are used to secure the main steel columns to the concrete.
Because red iron buildings are engineered around the specific project, anchor bolt placement is extremely important. The foundation, column locations, anchor bolt layout, and building plans all need to match before installation.
This is one reason red iron foundation planning should happen early in the design process.
Concrete Pad Size and Anchor Planning
Concrete pad size matters for tubular steel buildings. If the building is installed on a concrete pad without a flush mount kit, the pad should generally be 2 to 3 inches larger than the building on each side.
This extra space helps allow room for the base rail, anchors, and siding. It can also help prevent the siding from hanging past the edge of the concrete.
If the customer wants the siding to sit flush with the edge of the pad, a flush mount kit may be needed. This should be planned before the concrete is poured and before the building is finalized.
Flush Mount Kits for Concrete Pads
A flush mount kit can allow the siding to sit more flush with the concrete pad on certain tubular steel buildings.
Without a flush mount kit, the concrete pad should usually extend slightly beyond the building footprint. With a flush mount kit, the building can be designed so the siding lines up more closely with the pad edge.
This is the main anchor-related choice customers should think about when installing a tubular steel building on concrete. The decision affects how the building sits on the pad, how the siding lines up, and how the concrete should be prepared.
Flush mount options should be discussed before installation because they can affect how the pad is sized and how the building is anchored.
Anchors and Certified Metal Buildings
Certified metal buildings may have specific anchoring requirements. If a structure needs to meet wind load, snow load, permitting, or engineering requirements, the anchor system may need to match the certified design.
The anchor type can depend on the building size, frame type, surface, location, and local code requirements. A certified building on concrete may have different anchor requirements than a certified building on dirt, gravel, or asphalt.
Customers who need permits or engineered drawings should confirm anchor requirements before preparing the site.
How Anchoring Options Affect Price
Anchoring can affect the final price of a metal building depending on the surface type, certification requirements, foundation details, and any special installation needs.
A standard anchor setup on dirt or gravel may be different from a concrete installation, asphalt installation, certified structure, red iron foundation, or flush mount concrete setup.
The goal is not to choose the cheapest anchor. The goal is to use the anchor system that matches the building, surface, and local requirements.
Why Planning Anchors Early Matters
Anchors should be planned before the building is installed because they connect directly to the foundation, site preparation, and building design.
This is especially important for concrete pads. Customers should know whether the pad needs to be larger than the building or whether a flush mount kit is needed before concrete is poured.
For red iron buildings, anchor planning is even more important because anchor bolts are often embedded into the concrete at each column base. If the anchor bolt layout does not match the engineered building plans, installation problems can occur.
Planning anchors early helps prevent site issues, installation delays, and avoidable changes.
Get Help Understanding Anchor Requirements
Choosing the right anchor system starts with understanding the surface, building type, and local requirements.
In most cases, the installation surface determines the anchor type. Dirt and gravel, asphalt, concrete, and red iron foundations each have different anchoring methods. For tubular steel buildings on concrete, customers should also decide whether a standard concrete anchor setup or flush mount kit makes the most sense for their pad.
Legacy Carports can help you review anchor options for dirt, gravel, concrete, asphalt, tubular steel buildings, and red iron structures before finalizing your design.
Ready to plan your structure? Use our 3D Builder or reach out to Legacy Carports for help understanding the right anchoring setup for your metal building.