MaxJax's Concrete Information 101
You’ve already decided on a MaxJax portable auto lift and look forward to all of its advantages. Although there are a few important install steps to follow, once underway the process is fairly straightforward and your new MaxJax lift will not only provide years of rugged service, but it will also provide more working access under your vehicle. All of this begins with a properly installed MaxJax lift, mounted on a strong concrete footing.
What You’ll Need to Check to Install Your MaxJax:
- Concrete Slab Thickness (4.25” or more)
- Concrete-MaxJax Indoor Installation Only
- Concrete-No More Than 3-degree Slope
- Concrete-Comprehensive Strength 3,000 psi or Greater
- MaxJax Lift Location
- Overhead Clearance, Approach Clearance, and Obstructions
- Concrete Condition (no significant cracks or defects, especially under lift pillars)
- Traditional Slab or Post-Tension Cable Slab type verified
- Note-MaxJax hold-down bolts/anchors require 90 ft-lb tightening torque
Start at the Bottom
For a proper lift installation, begin by evaluating your concrete area and its existing specifications. This begins by inspecting your concrete slab to make sure it’s an adequate 4.25” thickness or more, has cured at least 28 days, and the surface has no more than a 3-degree slope. For a MaxJax installation, the slab should at least have at least a 3,000 psi Comprehensive Strength.
Working Under Pressure
The surface condition of the concrete is also important. You do not want to install a lift on cracked or defective concrete. The anchor bolts (torqued to 90 lb.-ft.) used to secure the MaxJax in place on the concrete must be at least 6 to 12 inches from significant floor cracks, and/or away from a wall. Note too that a MaxJax lift can only be installed on suitable concrete, not asphalt. Although many general construction slabs are at least 3,000 psi, your local concrete company should be able to assist you in determining your concrete’s psi strength if you’re skeptical. PSI (Pounds per square inch) such as 3,000 psi is a measure of compressive strength, or the ability of the material to carry loads and handle compression. A higher psi number means a given concrete mixture is stronger, so it is usually more expensive. But these stronger concretes are also more durable, meaning they last longer. If needed, compressive strength ratings can be tested by breaking cylindrical concrete specimens in a special machine designed to measure psi. For more info, check with your local concrete company.
Two Types of Concrete Slabs
You’ll also want to determine if your slab is a “traditional concrete” slab or a “post-tension cable” concrete slab. Either type will work well, but different concrete drilling procedures are applicable. This is significant because if anchors are not installed in proper locations, drilling into a post-tensioned cable slab can be severely hazardous to property and the installer if a hidden cable is cut and releases. If it is determined that you have a traditional concrete slab, you can continue on with the regular install and drilling as noted. If it is determined that you have a post-tensioned cable slab, you have good company as these are used in many areas. You simply need to gain some particular information about your slab first before learning where to specifically drill.
What is a Post-Tension Concrete Slab?
Yes, post-tension cable slabs are often used in residential construction. Since post-tension cable slabs have been in use since the early 1950’s, there is the possibility that many residential homes could have this system in place. Post-tension cable slabs are sometimes used in areas where the climate is especially dry, causing the soil to contract and form crevices, thus leaving voids under the foundation. To counter this, a post-tension system works to provide rigidity to the concrete so that it can maintain its structural integrity through many weather changes and permanently stay in place above sometimes changing soil voids. A post-tension concrete slab is engineered with a steel cable network that runs below the concrete’s surface to add strength. During original construction and before the concrete is poured, a tension cable system is laced into a grid across the sub-surface and the ends mechanically tightened at a specific time while new concrete is setting up. With the concrete in place over the cables, the post-tension system teamed with the cured concrete slab is much stronger than concrete without reinforcement. This also helps reduce or minimize future cracking.
How to Determine if Your Slab is a Post-Tension Cable
Most homes that have been constructed with post-tension slab systems have an identification that is stamped into the concrete garage floor. These identifications are typically near the edge of the garage door in plain view. To determine if you have a post-tension cable system, there may be easy-to-find visual clues. Older homes that have post-tension slabs may have a plastic or paper sign fastened to the wall. These are often placed next to a door that goes from the garage into the house. Evidence of a post-tension slab may be found by inspecting the perimeter of the home, looking for small circle type areas about 1 1/2″ to 3″ wide that have been patched outside of the slab area. These circles are usually about 2 to 4 feet apart. They indicate the end of the post-tension cables and may not be easily visible because landscaping or the patching and painting of the cone shaped voids covers them. There may also be slabs where there are no visible signs on the wall or stamped into the concrete floor. So another source of information may be the builder or local building department. They may review the building plans and advise if the structure has a post-tension cable slab, its thickness and location of the cables. If you’re still not sure if the slab has a post-tensioned cable system, most cities have Post-Tension Cable locator services that can inspect existing concrete, often with ground penetrating radar. But again, if there is a post-tension cable slab, a MaxJax can still be installed. Just make sure that the underground cables are mapped out by a professional or with original building plans to determine location and avoided while drilling down in the concrete. If colored sheath comes up during drilling, stop drilling immediately as you’re possibly accidently drilling into cable.
Ready for Lift Off
Once you have determined what type of slab is present, a test hole (if needed) can be drilled in an inconspicuous and safe area to determine the depth of the concrete. To keep the test hole as inconspicuous as possible, consider drilling just a ¼” hole and then using a stiff wire to measure the depth. Before proceeding with the MaxJax install, double check location and measurements, make certain that the base plates of each column are aligned with the chalk/crayon lines. FOLLOW PROCEEDURE EXACTLY FOR PROPER FITTING AND ALIGNMENT OF ANCHORS. MaxJax Lifts are supplied with installation instructions and concrete anchors that meet the criteria set by the American National Standard “Automotive Lifts. Using the Base Plates as guides, drill each hole 5” deep using a “rotary hammer drill” with a 7/8" concrete bit. Avoid drilling all the way through the concrete. Remember to remove as much concrete dust as possible from the hole and the area after drilling. This can be accomplished with either compressed air or a shop vacuum. This is so the concrete anchors are able to grip the concrete hole as they are being torqued to 90 lb.-ft. Continue following the remaining MaxJax lift install instructions and you’ll be ready for a steady lift off.