Different Types of Anchors for Metal Buildings: A 2026 Complete Guide

By Bulldog Steel Structures • Updated May 2026

There are many different types of anchors for metal buildings, and choosing the right one is one of the most important decisions you’ll make when installing a carport, garage, or prefabricated steel building. After all, the anchors are what keep your structure firmly secured to the ground. If the anchors fail, the building can shift, lift in high winds, or even collapse.

Whether you’re building a carport from the ground up or having a prefabricated steel building installed, choosing your anchors wisely is of the utmost importance. Remember: your structure is only as sturdy as the connections it has to the foundation it’s built on. The wrong anchor for your surface type is one of the most common — and most dangerous — installation mistakes.

In this guide, we’ll cover the four primary types of metal building anchors, how to choose the right one for your foundation, where to place them, anchor bolt specifications, and answers to the most common questions about anchoring metal buildings.

Metal Building Anchor Types at a Glance

Before we dive into the details, here’s a quick-reference comparison of all four anchor types and when to use each:

The 4 Primary Types of Anchors for Metal Buildings

There are four primary types of anchor bolts for metal structures, each engineered for a specific foundation surface. Using the correct anchor for your surface is essential for both safety and longevity.

1. Mobile Home Anchors (Augers)

Commonly referred to as augers, these anchors are designed to keep a structure securely fastened to dirt or soil. Augers are driven into the ground and twist in like a giant screw, gripping the soil tightly as they go deeper. The wide helix at the bottom resists pull-out forces, which is exactly what you want when high winds try to lift your building.

• Best for: Dirt and soil installations. To meet certified ground installation requirements, mobile home anchors are typically the only type that will suffice.
• Keep in mind: On very loose or sandy soil, augers may need to be longer or paired with additional reinforcement to hold properly.

2. Concrete Anchors

If you’re pouring a concrete base for your metal building, concrete anchors are the right choice. These anchors expand once installed, wedging tightly against the concrete to create an extremely strong hold. Concrete is the most secure foundation you can anchor to, which is why most professional installers recommend it for permanent buildings.

• Best for: Concrete slabs and footings.
• Important warning: Concrete anchors should only be used in concrete. If installed in asphalt, the expansion force can fracture the surface and compromise the foundation.

3. Rebar Anchors

Commonly used for the installation of metal buildings, rebar anchors secure structures to gravel or soil. They consist of long steel rebar rods driven deep into the ground at an angle, anchoring the base rail firmly in place. Rebar anchors are economical and effective for many ground installations.

• Best for: Gravel and soil foundations.
• Important note: Rebar anchors are not recommended for sandy areas. If you’re installing onto loose or sandy soil, an auger (mobile home) anchor will hold far better.

4. Asphalt Anchors

Designed exclusively for securing a building to asphalt, asphalt anchors do a great job because they’re engineered not to compromise the integrity of the asphalt surface. They grip the asphalt firmly without the cracking or fracturing that would occur if you tried to use a concrete anchor on the same surface.

• Best for: Asphalt driveways and pads.
• Keep in mind: Asphalt anchors are surface-specific — don’t use them on concrete, gravel, or soil.

Have questions about the best ways to anchor your metal building? Or ready to own your own high quality metal carport, garage, barn or other metal building? Contact us at 888-551-2156 or request a free quote!

How Do You Know Where to Place the Anchors?

Regardless of which anchors you use, they must be placed appropriately or they’ll be of no use. A certified carport or prefabricated steel building comes with detailed instructions specifying exactly where each anchor should be installed.

It’s crucial that installers follow these instructions as closely as possible. Proper placement does more than satisfy the warranty — it directly increases the durability, longevity, and overall safety of your structure. Anchors that are misplaced, too few, or installed at the wrong angle create weak points where the building can fail under stress.

Generally, anchors are spaced evenly along the base rails of the building, with additional anchors at corners and load-bearing points where wind uplift and lateral forces are strongest. The larger and taller your building, the more anchors it will require.

What Type of Foundation Should the Anchors Be Secured To?

Most professional prefabricated steel building installers recommend pouring a concrete foundation. Concrete provides the strongest, most permanent anchoring surface and is often required for permitted residential and commercial buildings.

An experienced concrete engineer can help determine how deep the concrete should be poured and assess how long the steel anchor bolts need to be. You’ll want to know the suggested concrete depth and recommended anchor bolt length ahead of time, because both directly impact site excavation and preparation.

That said, concrete isn’t the only option. Gravel pads work well with rebar anchors for storage buildings and agricultural use, and compacted soil can be anchored with augers. The key is matching your anchor type to your chosen foundation — and making sure whatever surface you choose is properly leveled and prepared before installation day.

Simple Guideline for Anchor Bolts

The following is a basic overview of anchor bolt requirements for prefabricated steel buildings. Always defer to your building’s specific certified installation instructions, but these general rules apply to most structures:

• All steel buildings need at least four anchor bolts — and preferably more, especially for larger buildings.
• A concrete anchor or rebar anchor must be installed according to exact installation directions for your specific building.
• Foundation anchor bolts should be installed perpendicular to the foundation surface (at a 90-degree angle).
• If anchor placement is more than 1/16 inch off from the installation directions, it will need to be reinstalled.
• To decrease shifting and improve grip, anchor bolts are often shaped like a ‘J’ or an ‘L’ — these shapes resist pull-out far better than a straight bolt.

Why Proper Anchoring Is So Important

It can be tempting to view anchors as a minor detail, but they’re one of the most safety-critical parts of your entire building. Here’s what proper anchoring protects against:

• Wind uplift: Strong winds create lift under and around a building, much like an airplane wing. Adequate anchoring keeps the structure grounded during storms.
• Lateral shifting: Wind and ground movement can push a poorly anchored building sideways over time, racking the frame and damaging panels.
• Code compliance: Many areas require buildings to meet specific wind-load ratings, which depend on correct anchoring to certified specifications.
• Warranty protection: Improper anchoring often voids manufacturer warranties. Following the certified instructions keeps your coverage intact.

In storm-prone and high-wind regions, the difference between a building that survives a severe weather event and one that doesn’t often comes down to whether it was anchored correctly to the right foundation.

Frequently Asked Questions

What are the different types of anchors for metal buildings?

There are four primary types of anchors for metal buildings: mobile home anchors (augers) for dirt and soil, concrete anchors for concrete slabs, rebar anchors for gravel or soil, and asphalt anchors for asphalt surfaces. Each is engineered for a specific foundation type, and using the correct anchor for your surface is essential for both safety and the longevity of your structure.

How many anchors does a metal building need?

Every steel building needs a minimum of four anchor bolts, but most buildings require more. The exact number depends on the size, height, and wind-load rating of your building. Larger and taller structures need more anchors, with additional anchors placed at corners and load-bearing points. Always follow the certified installation instructions that come with your specific building.

What is the best anchor for a metal building on concrete?

Concrete anchors are the best choice for a metal building installed on a concrete slab. They expand once installed, wedging tightly against the concrete to create an extremely strong hold. Concrete is also the most secure foundation overall, which is why most professional installers recommend it for permanent buildings. Hooked J-bolt or L-bolt anchors are commonly used because their shape resists pull-out forces.

Can you anchor a metal building to asphalt?

Yes, you can anchor a metal building to asphalt, but you must use asphalt-specific anchors. These are engineered to grip the asphalt firmly without cracking or fracturing the surface. Never use concrete anchors on asphalt — the expansion force will damage the surface and compromise the foundation.

What anchors should I use for a metal building on dirt or soil?

For a metal building on dirt or soil, mobile home anchors (augers) are the best choice. They twist into the ground like a giant screw and grip the soil tightly, resisting the uplift forces caused by high winds. For certified ground installations, augers are typically the only anchor type that meets requirements. On gravel, rebar anchors are also an option, but augers hold best in loose or sandy soil.

Why are anchor bolts shaped like a J or an L?

Anchor bolts are often shaped like a ‘J’ or an ‘L’ because the hooked end embeds into the concrete and physically resists being pulled straight out. A straight bolt relies only on friction and adhesion, which can fail under strong wind uplift. The hooked shape provides a mechanical lock that dramatically improves the bolt’s holding power, making J-bolts and L-bolts the standard for anchoring metal buildings.

How deep should anchor bolts be set?

Anchor bolt depth depends on your foundation type, building size, and local wind and soil conditions. For concrete foundations, an experienced concrete engineer should determine both the concrete depth and the required anchor bolt length, since these affect site excavation. Your building’s certified installation instructions will specify the exact requirements. As a general rule, deeper anchoring provides greater holding strength.

Does improper anchoring void a metal building warranty?

Yes, in most cases improper anchoring voids a metal building’s manufacturer warranty. Anchors that are the wrong type for the surface, too few in number, misplaced, or installed at the wrong angle can all compromise the warranty and, more importantly, the safety of the structure. Following the certified installation instructions exactly protects both your coverage and your building.

The Bottom Line

Choosing the right anchors for your metal building is not a detail to overlook — it’s one of the most important factors in how safely and how long your structure will stand. Match your anchor type to your foundation: augers for soil, concrete anchors for concrete, rebar for gravel, and asphalt anchors for asphalt. Use at least four anchors (more for larger buildings), install them perpendicular to the surface, and always follow your building’s certified instructions. And if you’re still planning your purchase, remember that professional installation with the correct anchors is included with every Bulldog building — whether you buy outright or through our rent-to-own program, with no credit check required.

Have questions about the best way to anchor your metal building? Or are you ready to own a high-quality metal carport, garage, barn, or other steel building? Our team handles professional installation with the correct anchors for your specific site as part of every order.