How to Check Concrete Thickness and PSI Before Installing a Car Lift

You've found the car lift you want, measured your ceiling, and figured out where it's going in the garage.

Then you get to the installation manual:

Minimum concrete thickness: 4 inches. Minimum concrete strength: 3,000 PSI.

There's just one problem.

How do you know how thick your existing garage floor is—or what PSI the concrete is?

This is a question we hear regularly from customers shopping for a 2-post car lift, especially when the garage floor was poured years ago and they weren't the original owner.

The good news is that checking concrete thickness is usually fairly straightforward. Determining the actual compressive strength, or PSI, of existing concrete can take a little more work.

HeavyLift Direct is a family-owned and operated automotive equipment dealer, and we've sold thousands of vehicle lifts to homeowners, repair shops, dealerships, and commercial facilities across the country. Here's how we recommend approaching both questions before installing your lift.

Why Does Concrete Matter for a Car Lift?

A vehicle lift doesn't just need a flat floor. For many lifts, the concrete underneath it is an important part of the installation.

This is particularly important with a 2-post lift and concrete thickness because the columns are anchored directly to the concrete. The lift manufacturer's installation requirements specify the slab and anchoring conditions needed for that particular model.

Concrete requirements can include:

• Minimum slab thickness
• Minimum concrete compressive strength (PSI)
• Minimum distance from cracks, joints, or slab edges
• Anchor type, size, and embedment
• Concrete condition
• Minimum concrete age
• Reinforcement or footing requirements in certain applications

There is no single concrete requirement that applies to every car lift.

A 7,000 lb 2-post lift may have different requirements than a 10,000 lb, 12,000 lb, or 15,000 lb lift. Requirements can also vary between manufacturers.

Always use the installation manual for the exact lift you're purchasing as the final authority.

If you're still deciding which type of lift is right for your garage, browse our complete selection of car lifts for garages.

How Do I Check the Thickness of My Garage Concrete?

If you don't have the original building plans or information from whoever poured the floor, the most direct way to verify slab thickness is to physically measure it.

Option 1: Check an Exposed Edge

Start with the easiest option.

Look around the perimeter of the slab, at garage door openings, floor drains, utility penetrations, or other areas where the edge of the concrete may be visible.

You may be able to measure the slab without drilling anything.

However, don't automatically assume that one exposed edge represents the thickness of the entire garage floor. Slabs can vary in thickness, particularly around edges, footings, drains, or areas that were poured separately.

For a lift installation, you want to know the thickness where the lift will actually be anchored.

Option 2: Drill a Small Test Hole

One practical way to check slab thickness is to drill a small test hole in the area where the lift will be installed.

Using an appropriate masonry bit, drill vertically through the slab until you reach the material underneath it. You can then use a thin rod, wire, depth gauge, or similar method to estimate the depth of the concrete.

For example, if you measure approximately 4.5 inches from the top of the slab to the bottom of the concrete, you have approximately a 4.5-inch slab at that location.

Don't Check Just One Spot

This is important: concrete floors aren't necessarily perfectly uniform.

If you're verifying the floor for a 2-post lift, consider checking the slab in more than one location in the general areas where the two columns will be installed.

You're trying to answer:

"Do I have the required concrete thickness underneath both lift columns?"

Not simply:

"Is there 4 inches of concrete somewhere in my garage?"

Important: Before drilling, make sure you aren't drilling into a post-tensioned slab, radiant floor heating, plumbing, electrical conduit, or other embedded components. If you're unsure what's underneath or inside the slab, have a qualified contractor evaluate it instead.

Can I Tell Concrete PSI by Drilling Into It?

Not reliably.

This is where concrete thickness and concrete strength are very different.

Drilling through the floor can help determine how thick the slab is. It does not tell you whether the concrete is 2,500 PSI, 3,000 PSI, 4,000 PSI, or something else.

PSI refers to the concrete's compressive strength.

Concrete that feels extremely hard while you're drilling isn't automatically a certain PSI, and concrete that drills relatively easily isn't automatically too weak for a lift.

How Do I Find Out the PSI of My Existing Concrete?

Before paying to have your concrete tested, start by looking for documentation from when the slab was poured.

Possible sources include:

• Original building plans
• Construction records
• Concrete supplier records
• Contractor invoices
• Building specifications
• The previous property owner
• The builder or general contractor
• Local building department records

If the garage or shop is relatively new, you may be able to determine what concrete mix or compressive strength was specified when the slab was poured.

For many homeowners, this is the easiest way to establish the specified concrete strength without physically testing the slab.

What If I Can't Find Any Concrete Records?

This is extremely common, especially with older garages.

Maybe you bought the house five years ago. The garage was built 20 years ago. You don't know who poured the concrete, and nobody has a receipt or building record showing the concrete mix.

If verifying the actual concrete strength is necessary, the next step is usually to contact a concrete testing company, structural engineer, or qualified concrete professional.

The Most Definitive Method: Concrete Core Testing

One recognized method for evaluating the compressive strength of existing concrete is to remove a cylindrical core from the slab and have it professionally tested.

ASTM C42/C42M – Standard Test Method for Obtaining and Testing Drilled Cores and Sawed Beams of Concrete provides standardized procedures for obtaining, preparing, and testing concrete cores.

This is much different from simply drilling a small hole to check the thickness of your garage floor.

A concrete core is removed using specialized equipment and then properly prepared and tested. If you have an older garage with no records showing the original concrete PSI and need to verify whether the slab meets your car lift manufacturer's requirements, professional core testing can provide much more meaningful information than trying to estimate concrete strength yourself.

If testing is necessary, we recommend contacting a qualified concrete testing company, structural engineer, or concrete professional familiar with ASTM C42/C42M rather than attempting to determine PSI based on appearance, age, or how difficult the concrete is to drill.

What About a Concrete Test Hammer?

You may also hear about a rebound hammer, sometimes called a Schmidt hammer.

These tools measure the rebound of a spring-loaded mass against the concrete surface and can be useful when evaluating concrete uniformity or estimating strength when properly correlated and interpreted.

However, a rebound hammer should not automatically be treated as proof that your floor has a specific compressive strength.

Surface condition, moisture, aggregate, age, finishing methods, and other factors can influence readings.

If a particular PSI is critical to determining whether your slab meets the lift manufacturer's requirements, we recommend consulting a qualified concrete testing professional rather than relying on a DIY surface test.

What If My Concrete Isn't Thick Enough for a Car Lift?

Finding out that your existing slab doesn't meet the requirements doesn't necessarily mean you can't install the lift.

It may mean the concrete needs to be modified.

Depending on the lift manufacturer's requirements and your particular building, a contractor or engineer may recommend cutting out portions of the existing floor and installing appropriately sized reinforced concrete footings or pads underneath the lift columns.

The size, depth, reinforcement, concrete strength, and construction of those footings should be determined according to the lift manufacturer's requirements and, where appropriate, a qualified professional.

Don't simply pour a few extra inches of concrete over an inadequate slab and assume you've solved the problem.

What If My Garage Concrete Is Cracked?

A crack doesn't automatically tell you whether a slab can or cannot support a lift, but it shouldn't be ignored.

Before anchoring a lift near a crack, control joint, expansion joint, slab edge, or damaged section of concrete, check the manufacturer's installation requirements.

The location and condition of the concrete around the anchors matters—not just its thickness.

If you're unsure about significant cracking, deterioration, or the structural condition of the floor, have the slab evaluated before installing the lift.

Do 4-Post Lifts Have the Same Concrete Requirements?

Not necessarily.

A 4-post car lift distributes its load differently than a 2-post lift, and some 4-post storage lifts are designed to be freestanding rather than relying on floor anchors in the same way as a 2-post lift.

That does not mean the condition of the floor can be ignored.

You still need a suitable, level supporting surface and must follow the requirements specified by the manufacturer for your particular lift.

This is one reason customers with questionable existing concrete sometimes ask us whether a 4-post lift may be a better fit for their garage.

How Much Concrete Do I Need for a 2-Post Lift?

There isn't one correct answer for every 2-post lift.

You'll commonly see minimum concrete specifications expressed as something like:

X inches of concrete at X PSI.

But those numbers must come from the manufacturer of the exact lift you're installing.

Don't assume that because one 10,000 lb lift requires a particular slab specification, every 10,000 lb lift has the same requirement.

When comparing 2-post car lifts, check the installation manual before purchasing if you're working with an existing slab.

Concrete Checklist Before Buying a Car Lift

Before ordering your lift, try to answer these questions:

1. What concrete thickness does this specific lift require?
2. What minimum concrete PSI does the manufacturer specify?
3. How thick is my slab where the columns will actually be installed?
4. Do I have records showing the specified concrete strength?
5. Are there cracks, joints, damaged areas, or slab edges near the proposed anchors?
6. Is there anything embedded in the slab that could make drilling unsafe?
7. If the slab is questionable, do I need a concrete contractor, testing company, or engineer to evaluate it?

If you can confidently answer those questions, you're in a much better position to choose and install the right lift.

Don't Guess About Your Concrete

Concrete is one of those things that's easy to overlook when shopping for a lift.

Customers naturally spend more time thinking about lifting capacity, ceiling height, vehicle size, arm reach, and price. But for lifts that depend on anchors, the floor underneath the lift is just as important.

Thickness can usually be physically measured. PSI generally cannot be determined accurately just by looking at or drilling into the concrete.

When documentation isn't available and concrete strength needs to be verified, professional testing may be the right answer.

Most importantly, check the installation manual for the exact lift you're considering before making assumptions about your floor.

Need Help Choosing the Right Car Lift?

HeavyLift Direct is a family-owned and operated automotive equipment dealer, and we've helped customers across the country select and install thousands of vehicle lifts.

If you're unsure whether your garage, concrete, ceiling height, or vehicle will work with a particular lift, contact us before ordering. We'd rather help you verify the details ahead of time than discover a problem on installation day.