NO! Our listed concrete requirements are sufficient. But, if it makes you feel better, you may pour the concrete as thick as your pocketbook will allow.
You may install (anchor) your lift (four days) after the concrete has been poured. You must wait a total of seven days before using the lift to its rated capacity.
Drill a test hole and measure the thickness. Most garages will have at least four (4) inches. If you mount the lift and the "anchors" begin to lift out of the concrete over a period of time, you will need to relocate your lift or pour "new concrete pads" under the columns. There is also many types of epoxy concrete adhesives that help anchor your lift in marginal concrete.
The new pad should be at least 4' by 4' and 10" thick. These new concrete pads should have "rebar" installed into the new pour and into the sides of the existing concrete slab.
Concrete slab should be at least two feet longer and wider than the four columns to offer maximum stability. The lift may or may not be anchored to the slab...depending on the lift's weight capacity. Optimally, the concrete slab should be the same size as the floor of a normal garage for either a two-post or four post lift.
To allow for water drainage, many garages have a 1" to 2" slope from the back of the garage to the front. This minimal slope will not affect the safety or lift capacity of your lift. Four post lifts (with lock ladder columns) can be easily leveled. The lock ladders' locking positions may be adjusted so that the runways will be level when raised and/or in their locked positions. Columns can be "shimmed" with plastic or metal shims. If the column is to be "mounted with anchors"...make sure you use extra length anchors to compensate for the "shimmed" area above the concrete.
Yes, but you need to determine the "hot water pipe configuration" in your floor. If you are pouring a new concrete floor with hot water heat, then allow plenty of room for the columns to be installed. If you have in-floor heating already installed and do not have an accurate installation diagram; spray a small amount of water on your floor and turn the heating system to the highest setting. You may be able to see the outline of the heat pipes as the floor water begins to evaporate. Drill where it is wet. Dry areas indicate a heat pipe underneath.